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RetinaCreate Optimal Rotation
I'm currently using FSL3d's RetinaCreate to prepare 3d-files for printing for research purposes. In this, I am relying on their Optimal Rotation feature which rotates the object by, as far as I can tell, judging models on their stability with regards to the printing direction. After rotating the model, supportstructures are generated to keep the model in place while printing without the bits and pieces floating about and to keep structural stability.
My question is, as I've neither found a manual nor any source-code (and admittedly I am terrrrrible at maths), how can I describe the kind of algorithm/logic used by the software here? This is essential for me, as I need to describe this in my research. Cheers, Jesse

Hard to say exactly what RetinaCreate is doing. You might try looking into other slicers and manipulation tools that might be documented better. Maybe MeshMixer has some info, for example.

It's closed source with no documentation available. This question is unanswerable bar by the makers of the software.

Optimal rotation can be considered from different perspectives. For example

as little support as possible. This way app tries to orient object so as much surface as possible doesn't overhang and doesn't need support
bed only support. App tries to orient object so all overhanging parts can be supported directly from the heatbed (not from the object itself)

But have a look on Meshmixer as Ryan Carlyle suggested. In this app you can see 3 kinds of auto orientation procedures. Additionally Meshmixer can create angle support and tree-like support.
In terms of mathematics.
I cannot suggest any sources but you can imagine the way it calculates such optimal rotation. Let's say it will be dead simple explanation of the second approach:
Let's get all faces (facets) and let's project their center points on the "floor" (heatbed) or "ceiling". If imagined projection line slices any other faces then rotation is not optimal. App can calculate "a weight" of such orientation and then try to find the smallest weight of all possible orientations.
Of course it's not that simple. App has to manage concavity, which face requires support at all, and many other aspects but in general you can imagine the algorithm.
edit

"as little support as possible" could be considered as easier to imagine "as little shaddow as possible" and the problem can be simplified to projection and ray tracing
similarly "bed only support" could be simplified to "cast shaddows but not on itself"

This fails to answer the question in two ways: (1) the question is about resin printers (for which orientation considerations are quite different), not FDM (2) this is just speculation, not what the software actually does.

I was almost sure you will argue this way ;) and you are right in some way but he asked "how to describe..." and my answer tries to describe the way the app is doing it. Is it FDM or not - the principles are more or less the same. Maybe "floor" should become "ceiling" but it's still the same. I mean he asked more how it's done than how it's done in this particular app.

The principles are completely different for a resin machine. You don't care as much about the amount of support needed, but for instance, if you have a model with a large flat surface, you do not want that surface parallel with the build plate because it will be difficult to peel (but instead at an angle so the surface in contact with the build plate isn't as large each time).

Reading question literally I don't really feel the issue is a printer type dependant. jesbengradev hasn't mention it. According to my understanding of the question - he needs help to explain/describe algoritm in his research work. So he would like to understand and get principles of optimal rotation rather than apply to his application (especially to his printer). But I might be wrong of course.

He asks about the optimal rotation feature of the FSL3d software, and this software is specifically for resin printers. As I've explained, the orientation considerations for resin printers are different than those for FDM, but without knowing how the FSL3d software works you can't answer this question. As I understand, they need to explain in their research paper how FSL3d works because that's what they used to orient their models, and the orientation of the models probably affects the results of their experiments.

Thank you for your discussion, this is already helpful. While I do solely use resin printers, I habe been using other software besides RetinaCreate, but with Formlab's Preform it seems pretty much the same deal. Could we assume that the "logic" used here is either something worth protecting or so banal in the developers eyes that it doesn't need documenting?

@jesbengradev definitely it's not such trivial task in terms of math. Does it need documenting? It depends on your research area :) I would say it's quite similar to projection in 3D or casting shadows by parallel rays (which is projection). And this is quite well documented. see here https://en.wikipedia.org/wiki/Projection_(mathematics) and here https://en.wikipedia.org/wiki/Ray_tracing_(graphics)

@darthpixel that's really good input, as I don't need to document an actual algorithm step by step but rather give a grounded idea of the general decision-making/logic that is at work here.


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Bridging islands in my stencil
I am using the MatterHackers MatterControl software. MatterControl has an option to convert an image into a 3d object. The image converter converts any image into an STL. I was wondering what program would work for bridging the islands? I tried SOLIDWORKS and I think the export messed up the file.

I am afraid that we (at least I) do not understand what you mean by an island. I can guess.. Are you saying you want to connect random peeks your software outputs? Which I still do not understand why you are trying to connect things. Or how that would look. Please provide images and or your files if you would like help. A stronger description of what you want to do would also help.

I've had good success editing STL files in Blender.  But typically Stack Exchange sites are not the right place to ask for software recommendations, as this attracts opinion-based answers.

You should know that there will be no such functionality anywhere because "make a bridge between islands" causes some questions:

what do you mean be bridge
where this bridge should be
how it should look like

Application cannot answer these questions automatically.
Conver image to 3D object is (almost) only to create logo-like-objects or text-like-objects.
If your image will consist more than one separate elements then MC will convert it into separate objects and these objects will be treated as separate islands. There will be no way to bridge them on certain level/layer. The only thing you can achieve is a solid "connection" between islands if they will be connected with line on the image. I'm sure it's not what you expect.
Almost all 3D apps have a functionality to create 3D obj out of image but it will always be a perimeter or surface which you can extrude.
You can create bridges in your app by creating additional 3D object according to your expectations or you can use sculpting app to extend a form. It means you won't add extra object but sculpt existing objects by  extruding/extending/pulling faces.
For such sculpting you can use Meshmixer for example.

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Heated bed - what are the benefits? Why use one?
When using a heated bed with your printer, I have seen claims of running temperatures of 90c throughout the print.
That seems like a fairly high power use to keep a large slab of, say, aluminium at 90c for long print times (ie multiple hours).
Is there a common 'sweet spot' for operating temperature?
Does it depend on material?
Is a heated bed required?

Did you read the reprap wiki's entry on heated beds? http://reprap.org/wiki/Heated_Bed

@kamuro - no I did not, thanks! Very new and jumping in at the deepend, looks a great resource.

Heatbeds have two purposes:

Increase surface energy of the print bed to improve bonding strength of the first layer (particularly important when using surfaces like PEI or Kapton)
Keep the bottom few millimeters of the print hot enough to provide a warp-free foundation for the rest of the print.

The bit about surface energy is straightforward. Most materials are stickier when hot than cold. In comparison, pure mechanical-bonding bed surfaces like fibrous painter's tape and perfboard don't particularly benefit from bed heat.
Warping is a bit more complicated. The basic cause of warping is when the previous layer is allowed to cool and thermally contract before the next layer is deposited. When you stick hot, expanded material on top of cold, contracted material, large shear stresses are generated when the fresh material cools and contracts. Those inter-layer shear stresses then accumulate over many layers into large-scale bending stresses that try to lift the edges of the print off the bed.
So, to prevent warping, we should minimize the amount that the previous layer is allowed to cool before the next layer goes down. But we DO need it to cool solid so the print doesn't sag in a mushy mess. This is a balancing act: cooling the plastic solid without over-cooling it. The optimal temperature for the print is right around the glass point of the plastic: this is the temperature at which the plastic becomes fully solid and thermal contraction stresses start to accumulate.
The extruder pumps more heat into the print as it deposits molten plastic and radiates a little bit of heat. So we want to set the heatbed temp a little bit below the glass point to ensure the print is able to cool solid. Now, this gets a bit difficult, because everyone's print bed temperature sensor is different. What matters is bed surface temp. Many people have to set their bed temp quite a bit higher than the actual surface temp. It's just something you have to calibrate via print results. The exact filament glass point (Tg) also depends on the blend.

ABS: Tg is around 105C, optimal bed temp 95C in a warm, low-airflow environment
PLA: Tg is around 55C, optimal bed temp is 55C in a cool, high-airflow environment because PLA holds heat and is slow to cool compared to other filaments
PETG: Tg is around 70C, optimal bed temp is 60-70C with mild airflow
Nylon doesn't really work with these rules because it's semi-crystalline, meaning it "freezes" far above its Tg and thus starts accumulating warping stress at fairly high temps... advice varies wildly, from printing cold to 120C bed
PC: Tg is around 150C, optimal bed temp is 130C

There are other schools of thought, for example printing the first layer onto a surface much hotter than Tg for good adhesion, and then dropping the bed temp to a value somewhat below Tg to allow the print to solidify. That works fine too.
But, with all that said, it's important to understand that the heatbed only keeps the bottom of the print warm. A centimeter up from the build plate, the print is typically much closer to ambient temp than it is to the bed temp. Heated build chambers are thus much more effective for large prints. But heatbeds are still quite effective, because they allow building a strong, warp-free foundation that resists warping stresses induced by the cooler zones higher up in the print.

Thank you, your answer has basically pointed out my fundamental question is 'why do you use a heatbed'. I think I should edit my question to suit.

@Beeblebrox Please do not edit your question to significantly change its meaning, as that means answers may become invalidated. Instead, you should ask a new question.

Well seeing how I changed it a few hours before your comment, hopefully it's still kosher ;)

Googling "what temperature for different filaments" gives a few good links, but the top link looks golden.
https://filaments.ca/pages/temperature-guide
They have temperature guides for both extrusion temperatures and heated bed, as well as suggestions for better adhesion. I'm not that experienced, but their information is similar to information I've seen elsewhere.
Their suggestion for PLA is 215-235 degrees Celsius and a bed temperature of 60 to 80 degrees. That sounds a bit hot to me but every brand (and type) of filament will perform best at different temperatures. I've had problem getting nice bridges at 210 degrees, but had excellent results at 190.
For ABS they say 230 to 240 degrees with the bed at 80 to 100.
Use these values as a starting point, when they fail you make an educated guess about what went wrong and adjust (one parameter at a time) til it works for you. Find a calibration object you like and trim the temperatures so it prints the best your printer can. At this point in the technology experimentation is a large part of making things work.
One thing that's important to remember is that the temperature that you set your bed to and the temperature that your bed gets to is not the same thing. Depending on the construction, assembly and quality of your heater the actual temperature can differ anything from almost nothing to twenty degrees or more.

Thank you, so am I right in understanding that heating is about adhesion and combating warp as the piece cools? And this only matters for the first layers?

It matters mostly about adhesion and warp. Mind you, when I'm using hairspray+pla, the print only sticks as long as the heat is on. When the build plate cools the print no longer sticks to the plate, so I can't turn the heat off after the first layer. When I find the time I'll experiment with higher temperature for first layer than the rest of the print. I.e. is there a benefit using a higher temperature on the first layer and/or a lower temperature for the following.

@TomvanderZanden That's a valid comment, I'm new here but I'm trying to learn. I've edited and hope that made it a better answer.

First you say 90c, which means you are talking about ABS likely. I state this as some PLA printers do not even use heated beds, and instead use elaborate rafts only. (Makerbot)
Now that I have gotten that out of the way I wanted to point out to you that it really isn't using that much power. 110 watts (based off this fellow)
http://reprage.com/post/39698552378/how-much-power-does-a-3d-printer-use
8 hours. 0.11 USD.
http://energy.gov/energysaver/estimating-appliance-and-home-electronic-energy-use
I am sure this number is not 100% spot on. That said having had used a power monitor when I first started out I can confirm getting very cheap results. Actually I calculated the costs of powering my 1 meter by 1 meter silicon heater. It was not that much.
This will not apply to every printer. Some are built better than others.
Last for Min Temp. You will pick the temp that works for the specific plastic. Every plastic is different. Materials with high pigments usually need higher temps for extrusions. That said, generally PLA is 60. ABS is 90-100. When it is wrong you will see more (almost always see some) heat warping.
I also want to mention that heat chambers give the best result and would not require you to use the bed as much. You don't see these on printers for two reasons. Heaters can catch fire, and because of patents blocking people from selling (nothing stopping you though. Look into just using a Box without an active heater if it is still a concern

Hi Tom. Hmm. I really hate to do this to you bud. Here is what you find if you google "patent stratasys heatchamber".. US 6722872 B1, US 7297304 B2, US 20040104515 A1,
http://forums.reprap.org/read.php?1,368470
Currently on the market in the sub pro is the z18 and a few other sub pro stratasys level companies.. That said there is always a way around it.. IE https://www.reddit.com/r/3Dprinting/comments/43zh0x/how_do_these_guys_avoid_the_heated_chamber_patent/ Bottom line there are patents, and most do not tangle with that evil company.

I am not going to comment about the difference in fire risk between a space heater that is enclosed verses a tiny resister.

Hi Tom, yes I covered both views in my reply for completion. Following bypassing is not the same as invalid. As anyone who works with patents know there is no perfect patent. That said, my stance is still these patents and the fear of the lawyers employed by Stratasys is exactly the reason you do not see these in the market. Frankly we are talking about posts titled "How do these guys avoid the heated chamber patent?" which infers that there is such an established and known patent issue. That said this might be a better discussion outside of comments as we are out of scope for this question.

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German RepRap NEO only heats to 130°C
I have a new German RepRap NEO 3D printer, and when I try heating the Extruder to 215°C with Repetier-Host Mac 1.0.1, it always stops at 130°C - does anybody have an idea what could be the reason?

A 24V heater on a 12V system might do this.

A few possiblitites.
You wire is too small. If your wire is HOT that is a fire hazard.
Your thermistor is bad. Check with a high temp heat probe or try replacing thermistor.
Your heating element is bad (rare).
Last it could be a limit in your firmware. But that would surprise me.
Any chance you have the bed and the hotend reversed? If you had the Bed as Hotend, then it would max out around 100. This last one I would say is most likely..

I think that there is a high chance that the problem lies somewhere connected to the temperature limit of the heated bed. Maybe the hotend is connected as bed. Here we'd need more information from the author.

The heated bed usually stops at 100ish. Hotend -- could be a bad heater core. There are a lot of cheapo crap ones on ebay.

The most likely problem is that your thermistor is either broken or not screwed in correctly. If this is not the case you should either check look through your firmware for issues, or buy a new heater cartridge and thermistor.


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First layer - not even infill
I'm using Repetier and Slic3r and it is printing a gap between the perimeter and infill on the first layer.
Also, the infill is lifting (as in photo).
Any advise?

I've never seen that kind of lifting, but are you sure that's perimeter on the outside and not a skirt? My best guess is that either the filament diameter or nozzle diameter is wrong in Slic3r.

The gap could be a wrong configuration in Slic3r for your printer. For the lifting try: thicker layers, higher bed temperature, bed leveling, different filament.

Are you trying to print directly on the PCB? Not a good idea.

Thanks for your help. I was printing on glass with hairspray as adhesive (can't see it in photo). My solution posted below as answer.

It looks like the right side is much smoother then the left side, so I'm going t guess your bed isn't leveled.

You're not sticking to your bed. Adjust your bed height. You are too far.
Otherwise you are going too fast and or too hot.
Calibrate the bed. Reduce speed. Then adjust temps.
Also could be material contamination
See this link for a visual troubleshooting.
http://reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide
http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide
In addition use some gluestick. That will often solve these issues. Last but not least add a raft if it continues. Or just ignore it. My bet is temp is too hot. I also like to smash my first layer, but not everyone likes that technique as it causes elephant footing.

I found a solution that works for me.
I have increased my first layer extrusion width to 250 %, reduced the print speed of perimeters to 30 mm/s, reduced the brim width to 1 and increased the infill/perimeter overlap to 30 %.
This was PLA with heat bed off (no heating), printing on glass and using hairspray as an adhesive.  Most of my settings were on default. (Repetier & Slic3r).

This is not a solution, this is a kludge. The real problem is probably that the nozzle is too far from the build plate (or grave underextrusion, but you'd notice that from the rest of the print).

So, it appears the "perimeter" is actually a brim. I've never needed a brim so far, and based on your image, I would say that you don't need one, either. I think Tom is right about the rest.

I was having these issues too on a CR-10S and I worked on it for months and the only thing that would fix it was the spread, overlap, and width of the extrusion, this may also be caused by the fact that I haven't really tried to use glue stick or anything to get my prints to stick better.

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How to 3D print an object with variable printing speed?
I have a object to print for which I want the base to be printed very rapidly because it's just a cube but as the print reached around 70 % a complex circular structure needs to be printed at a slower speed. Is there any way I could control the speed at the given percentage of job done?
I want the cube to be printed at 50 mm/s and the complex circular structure at 40 mm/s.
Printer Type - FDM

What printer? What slicer?

@TomvanderZanden I use Cura. I don't think this is a printer specific feature because the speed can be changed for RAFT and the object itself. The question could also lead to a suggestion of a software which could alter the printing as required by some parameters or a way to modify the gcode to alter the speed at a certain point.

It's printer specific in the sense that you hadn't even mentioned whether you have a FDM, SLS, DLP,... printer.

You know, 50 and 40 are nearly the same speed... even more so when you factor in firmware acceleration slowdowns around complex shapes. How much real print time are you saving by printing the cube part a little faster?

@RyanCarlyle Around 30-40 minutes. I would want to go even faster in some cases so I wanted a general solution.

Simplify3D has the ability to create more than one process, to be applied to the model at specific layers. It appears that feature fits perfectly with your requirements. As an example, you might create a process within S3D for layers 1 to 500 at the desired 50 mm / sec along with any other modifications you wish. The second process would specify layers 501 to 800 to be printed at 40 mm / sec.
The preview mode of S3D allows you to identify layer numbers in order to provide the necessary precision.

Can you also set, say, a 'pause' between layer groups? I'm thinking of a case where one might want to change filaments.

It would depend on the controller within the printer, but many devices support a pause g-code. This link is specific to reprap, but other printers as well as CNC devices have capability:  http://reprap.org/wiki/G-code#M226:_Gcode_Initiated_Pause

As @fred_dot_u mentions, Simplify3D has the capability to do this, but you can achieve the same effect by slicing the file twice, once at 40 mm/s and once at 50 mm/s, and then manually combining the generated G-code using a text editor. You should be able to find the point where it transitions from printing the cube to printing the circular structure by looking at the Z-height, and you can simply copy-paste the G-code from that point onward from the 40 mm/s file into the 50 mm/s file.
For instance, you might look for a point like this in the G-code (Cura):
G1 F3600 X113.543 Y94.098 E105.96969
;LAYER:25
G0 F7800 X113.743 Y91.369 Z2.700

or this (Simplify3D)
G1 X175.981 Y74.019 F2880
; layer 25, Z = 1.869
; inner perimeter
G1 X162.982 Y57.870 F7500
G1 Z2.069 F900

Note that the both include a comment line (a line that starts with ;) to indicate the layer. Everything before that you should copy from one file, everything afterwards from the other.

This is a neat tip. Could you show a quick example on what a person should be looking for?

Cura has a plugin called "Tweak at Z" that lets you change the speed at a specific layer/height, I used it when printing an object that's basically a curved box for 100 mm and then has tiny features in the last 10 mm and it worked very well.

Tweak At Z is no longer supported in the latest versions of Cura, 4.7

@AlvinStroyny There is now a plugin called ChangeAtZ that will do that.

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Belt driven axis question
I'm currently attempting to  make a repstrap using paper printed parts, like this guy : http://www.mariolukas.de/2012/05/repstrap-3d-drucker-aus-computerschrott-teil-1/
I replaced the DC motor in a paper printer carriage assembly
with a stepper motor (NEMA17). But there was not enough space to fit the axis of the nema 17 at the exact spot of the older DC motor axis, in short, the axis are not in the same place. The question is : if the axis is not in the exact same spot, will it affect the movement of the carriage or not at all ?
I supposed it would but i'm not sure since the carriage is limited in movement by the rails and that we still move the belt around.

Axis should definitely be at proper position. Otherwise you will get at least 2 issues.

Carriage will be pulled up which will cause stresses on rollers or slides and it will stress your belt
The way the carriage will go will change but because carriage itself is fixed then it will change the speed

3D printing is a precise process. Both issues will have impact on printouts and all your printouts will have broken dimension in the axis in which carriage moves.
Have a look on the picture (it is big to show details)

fig A shows a situation where carriage is far from the axis
In such situation the distance between vertical line of black cross and pink circle is almost unnoticable so both - the force and the distance (so speed) change are very small.
fig B shows a situation where carriage is relatively close to the axis
Then both - the force and the distance change is noticable

Thanks so much for that precise comment, but I gotta say I exaggerated a lot on the paint picture. The distance between the original shaft and the new stepper motor shaft is probably about 5mm or so. I suppose the print problems is of course dependent of the distance between the shafts so maybe if the distance is small, the problems are not noticeable (I hope so) ?

The higher difference in position the bigger effects. But the issue is that this "error" in not constant - it changes while carriage moves. It means your printouts will also be distorted non linear... But please remeber - 3D printing is preise process. Half milimeter is usually 2 times nozzle diam.

Damn, building a 3d printer from scratch is really hard... Thanks again for your answers.

A rotation of the stepper motor 90 degrees clockwise or counter-clockwise would move it more to the center.  You would only need lengthen or shorten the belt.

according to my experience the most of stepper motors (especially those used in cheap or home made) in 3D printers have rectangular shape and the shaft in in the center (precisely). As an exception I can pint geared stepper motors but I suppose it's not the issue here. So What do you mean by "rotation would move it to the center"?

As you state most are square with four point mounting shaft in center.  Not knowing how the offset shaft motor is mounted can only expect it is four point or two point or clamp.  But should be able to unbolt from the mounting plate and rotate the whole motor on the shaft axis.

He said - no room, which means for me - no room.

I understood no room was for changing stepper to a different one.  Not from rotation of existing.

5 min limit edits   What I was trying to say is the large circle the chassis or the stepper.  If it is the stepper then why no rotation, if it is the chassis then I understand the shaft is stuck to top of chassis and only option is a different smaller stepper.


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Print job stops when given serial command
I want to access the bed temperature of the 3D printer. I am able to get the temperatures using serial connection (Thanks to Demetris's help (Access Temperature sensor data of 3D printer via Serial connection)). The problem that I am facing now is that as soon as I give the command, I get the temperature values, however the print job stops. Is there a way around it? I want to get the temperature values as the print job goes on. TIA!

I think it would be best if you reverted your edit, since questions about programming are not on-topic on this site. "Why does my printer stop printing when I connect over serial" makes a reasonable question, but "Here's my code and please make it do what I want" is not (this would not even be accepted on the programming SEs).

Thanks Tom. I am not looking for a code solution from you, I just meant that this is what I am doing and just needed a point in the right direction from here since its a little difficult for beginners to interpret everything correctly right from the start. I was not asking you to make it do what I want to do, I can do that myself. I think you misunderstood. Anyhow, thanks for your help.

Opening a serial connection to your printer will usually reset the microcontroller, stopping the print.
The serial interface has a line known as request to send (RTS) that indicates to the microcontroller that the computer is ready to receive data. When the port is closed, this line is HIGH (indicating the computer is not ready), and when you open the serial connection the line goes LOW (indicating the computer is ready now) and the transition from HIGH to LOW triggers a reset.
There are a number of ways to prevent this:

In software: disable hang up on close (HUPCL). This prevents the RTS line from going HIGH after you close it, allowing it to be subsequently opened without causing a reset. However, this does not work for the first attempt (the first, initial connection still causes a reset). How this is configured depends on your software/driver set up, but it is widely supported.
In software: disable the RTS line from going LOW in the first place. I'm not sure if this is readily possible with common serial drivers.
In software: modify your workflow to always keep the connection open, preventing the associated reset from happening.
In hardware: your printer's board will have some circuitry on there that translates the RTS line transitioning from HIGH to LOW to trigger a reset, usually this is implemented in the form of a single capacitor between RTS and RST. RST is normally pulled high with a pull-up resistor (on the order of 10k or so), and when RTS transitions to low the capacitor briefly allows some current to flow, pulling RST low. One way to prevent this is to include a stronger pull-up resistor that overcomes the current drain associated with the RTS line going LOW. DisablingAutoResetOnSerialConnection suggests using a 330 Ohm resistor between VCC and GND.
In hardware: desolder the capacitor mentioned earlier.

Thank you Tom for your very detailed and informative reponse. I am very new to this field. I am trying to access the  bed temperature of 3D printer using a simple python code and sending M105 command. Could you please help me with this?

@TomvanderZanden I thought that serial communication was limited to a single connection between the bus and software. If you are using a serial connection to run the printer and attempt to push a command, you risk overriding the previous connection. So, potentially, your best bet would be to use slicing software with a wrapper API. Something like the Cura Engine might work like this.

I made the assumption that he was printing from SD, otherwise attempting to access the serial interface during a print would be insane as it is indeed limited to one concurrent connection in any reasonable implementation.

authors: لؤي بدر الدين


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What is the best 3D modeling software for a beginner on a 3D printed mini barrel project?
My goal is to 3D print a 5 liter miniature barrel with a side stand, similar to this wooden one on Amazon. I want it to have a removable top so that a boxed wine bladder may be put inside, and there should be a hole on the top as well so that the spigot may stick out and be used. I have no experience with 3D modeling or printing, but I have access to a public 3D printer at my local library. I know you can print parts individually (ex. curved wood-colored sides with staves and holes to interlock and make up the body of the barrel, the metal-colored hoops to go around the barrel). I don't know what software to use, though. I was thinking of starting to learn Blender? Would that be effective for this project?

Just to add on here since several answers mention Autodesk 123D.  Autodesk 123D has been discontinued and they are now pushing users towards Autodesk Fusion 360.

Your question begins in an inappropriate format for StackExchange, but you've ended it with one more appropriate by asking if Blender would work.
If you are willing to take the time to learn Blender, you are certain to discover that it will do as you require, and much much more. Your referenced model could be created using engineering-type design software such as Fusion 360 or SolidWorks or many of the free packages, but the free-form aspect is more suited to the flexibility of Blender.

2020 UPDATE: Fusion 360 now supports a sculpt feature, which combines organic modeling with the engineering-type for which it is previously known.

Even though Blender is not an engineering-type program, it has internal support for precise modeling. Should you learn to use those features, you get the best of both types of software.
If you construct your model in the software in segments/pieces as you suggest, your result will have greater flexibility at the printing stage, specifically with respect to color and filament choices. Instead of wood-colored sides, you can use wood-simulated PLA filament! Depending on the printer at the library, you could also use filamet, a filament containing 88 percent metal for the hoops.
I use Blender for some aspects of modeling, often importing the STL into Meshmixer to address things I've not yet learned in Blender.
I hope your reference to 5 liter is the original size and that your model will be a miniature of it. A 3d printer with 5 liter capacity would be a wonderful asset at the public library!

I've forgotten something you may find useful. Our local public library has an agreement with lynda.com, a substantial learning resource. I have only now examined the material available. There are many hours of tutorial information specific to Blender on the Lynda.com web site. If your library has this available, it will facilitate your objective and save money too!

I like the dual approach of generating the measured parts in Fusion and then working out more organic parts of the design in blender.

I recently purchased a 3d printer and have found that freecad suited me really well http://www.freecadweb.org/ and its open source.
I believe its very similar to onshape in its a parametric modeller but runs locally rather that online.
Using the Parts view i have made most of my models using basic shapes and  boolen subtractions.

If you have any programming background at all, consider OpenScad. It is a functional type of programming language that lets you do a lot of things quite easily without art skills.  OpenScad skills are useful for building customizable things on Thingiverse.
Here is a place to start

We get this question a lot in the facebook groups I manage.
The usual answers do not include blender as it has a stupid hard learning curve. That is overkill for what you are looking to do.
Look into 123d from autodesk. Free if you do not make money. I find this one to be the easiest.
http://www.123dapp.com/design
Also there is Google sketchup, with SLT out plugin. I find this one is pretty sub par due to the fact it does not create printable models well (ie missing triangles so it wont create solids, hard to fix)
http://www.sketchup.com/
I think this one pops up. I haven't used it and I think it costs, but worth a mention.
https://www.rhino3d.com/

I think Autodesk Meshmixer is the best, as you can easily make parts with boolean operations(if you're more of a cubic thinking guy) or drag-and-sculpt(if you're more of a freeform guy). (And thoses videos are old but still working).
If you want to get better reflexes in CAD engineering, I think Solidworks is the best (but really expensive if you aren't an enterprise), if you want to get better knowledge in 3D design and animations, maybe blender is good but surely not for CAD people neither for beginners in 3D (even if it's well-documented).

I'm no expert, but have done some research on this question and it seems to me that Fusion 360 is currently your best bet. It's designed to do exactly what you're planning, from start to finish. Design (Sculpting and precision modeling),
Test (fitting/animation analysis), and Fabricate (CAM and 3D printing) all wrapped into one program that has a logical workflow, and is WAY easier to learn than Blender. It's free for hobbyists and startups making less than $100K/yr. There are a bunch of free tutorials online, professionally produced by Autodesk. By the time you get through those, you should be able to complete your project.
(Edit): I don't know anything about onshape.com. Like I said, I'm no expert.

You can check out Tinkercad. It is an easy to use, online editor.
Even though it is not as powerful as Blender or Rhino3d, for easy 3d models it is more than sufficient.

I would highly recommend you checkout Onshape for your design.
https://www.onshape.com/
It is the easiest to use, full featured, free 3D CAD program. It is made (and in active development) by the creators of Solidworks, the most widely used CAD program out there for good reason! And it runs in the cloud, so you don't need a high powered PC with an amazing graphics card, just a decent internet connection.
Onshape looks like it's going to be the future of mechanical CAD whereas other programs like 123d and Sketchup are simply lightweight versions of "real" CAD.
Unless you want to get highly involved in organic, complex shapes, I would avoid Blender, you will spend so much time learning it you could have whittled your barrel from a log instead.

To the people saying 123design. I can only say I have been a blender user way before 3D printing was a thing and just cant get around learning 123design. It just feels so limited as it only have a few tools. Yes blender might have a hard learning curve but it does pay off in the future as you wont be limited to 3D printing models and its crucial to make more complex models

I'm not sure if this is really suited as an answer. The question is a bad fit for stack exchange to begin with, as it tries to solicit opinion-based answers. Answers and questions should generally be based on facts and not opinions, so perhaps you can rephrase this to be more factual. For instance, in what ways is 123design limited compared to blender?

authors: แม๊กเหนือเมฆ สิบเอกดนัยทองหนุน


text:
Why can't powder-based 3D printing techniques create enclosed or hollow structures?
Metal powders are the fastest-growing segment within the 3D printing materials market, and 3D printing with metal offers a range of highly-sought out characteristics, including immense strength, reduced weight, biocompatibility and corrosion or thermal resistance, making it ideal for high-demand industries such as aerospace, medical, etc.
Conventional methods require focusing a very intense energy source, such as a laser or electron beam, across a bed of metal powder, fusing the powder particles together in a pre-determined pattern to create the final 3D structure.
While this method does allow for incredibly strong metal 3D structures to be produced, it has its drawbacks, mainly:

it is prohibitively expensive and time consuming;
it does not allow for certain types of architectures, such as those that are hollow and enclosed, and;
it is limited by the types of compatible metals and alloys that can be used.

If we ignore the cost, why can't we do hollow or enclosed architectures to be printed with this technique?
Source: A closer look at the 12 biggest 3D printing tech innovations of the first half of 2016.

You should edit the question to include a reference to where you presumably read that this should be impossible.

Thanks for adding the reference but I don't really see where it says that metal printing can't do this. Generally, when you ask a question like "Why is it that X?" it is always a good idea to specify how you got the idea that "X" (which is usually due to reading the claim somewhere) to avoid confusion.

It's not hollow or enclosed structures that are a problem. It's structures that are hollow and enclosed. Think about it. The machine lays down a thin layer of powder, and then a laser fuses some of that powder together to make a shape. Then, it repeats the process for the next layer. If you try to build, for example, a hollow ball, the ball gets created in the middle of the powder, meaning that there will be powder around the outside of the ball and in the inside of the ball, and with the ball completely enclosed, there is no way for the powder that ends up inside the ball to get out. That's why hollow objects printed in this manner must have a hole somewhere to let out the powder contained in the object.
This is not only true of metal powder, but any 3D printing process that uses a bed of powder or a volume of resin and fuses some of it into a shape. Fused deposition modelling (FDM), the process used by most consumer-level 3D printers, build models in thin air, so only air is trapped inside the printed objects, making the printing of hollow, enclosed objects less of a problem. Of course, one has to deal with gravity. A hollow object might collapse before the filament hardens enough to support its weight.

This is true for all powder bed based printers, not just those using metal powder.

That is true. My answer comes from my experience modifying my FDM models to work with Shapeways, which uses laser sintering, as described in the question.

Hmmmm.. so how does one make a hollow ball with any other manufacturing method?  Glass-blowing, e.g. seals a viscous fluid just before cooling the object.  Can you produce a hollow steel ball w/o an exit hole that gets sealed post-production?

One could print two halves and fuse them together. The seam might be nearly invisible after polishing. With an FDM printer, a hollow ball is less of a problem because the arcs of the sides and closed circular layers would tend to hold things together. A hollow box, however, would be difficult. You'd have a large, flat area with nothing to support the middle. I'd probably print such a box at a 45° angle if I had to, so that nothing is horizontal.

This is exactly what I was going to say.


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What is stopping us from mixing 3D filament colors in an Extruder?
This came up in one of my groups today. That we could not color bend, or mix 3d printing filaments. I have researched but I am not finding anything talking about Plastic mixing in an extruder.
Why is it that we cannot take say a Diamond hotend, or a hotend with 5+ inputs, and mix any color we want? (assuming all the same type, ABSm, PLA). I think it would be interesting to at the least get a gradient effect on prints.
The best I have seen is natural plastic and a marker system. Or a powder / advanced / out of hobbyist price range process that sprays ink. The only Color Bending I know of is with Recycled plastic that uses multi color. Not quite what I am looking for.
Thanks!

Probably better (in theory) to build your own filament production tool, similar to those which 'recycle' plastic crud into new filament, and use that to generate each color you want.  Then for a multicolor object, swap filaments at appropriate levels.

Maybe I missed the point of the question, but you can totally do color mixing with a diamond hotend to produce a range of colors -- right now I think they make a 3 way one that allows Cyan, Magenta, and Yellow (like a traditional desktop printer). -- http://www.reprap.org/wiki/Repetier_Color_Mixing

Though, if you just want to do crazy gradients, you can just buy filament that gradually cycles colors every so often -- it produces neat  results: https://www.amazon.com/STAR-Alchement-Gradient-Filament-filament/dp/B01CNFUH6Q/

Any reason why you couldn't use individual heated reservoirs for filaments of varying primary colors and have the extruder use negative pressure to draw desired pre-melted filament using basically a micro valve system to control flow from each reservoir? Filament would back fill the reservoir only as the chamber empties and the slight pressure difference triggers a switch connected to the feeder.

@SteveW - Two problems. You would 'cook' the idle plastic, and there is no suitable vacuum source to generate your 'negative pressure'. Extruders work under high pressure to achieve good flow rates and print speeds.

On the 2018 Didacta in Germany I was able to see an almost marketed "full color" printer, that used ink cartridges and uncolored, natural PLA to directly embed color into the print: a XYZprinting DaVinci Color, that was called marketed as the first one to use this combination.

I just started with google and phrase "3d printing color mixing" and on the first place (in fact first two were valueless adverts) I got this Instructables - DIY Full Color Mixing 3D Printer.
How it works?
It uses magenta / cyan / yellow filaments and mixes it while printing with Diamond hotend.
It definitely does what you are asking for and it's exactly the same idea you come up with ;)
Overview

Getting the controller board ready for three extruders... I hacked
  a RAMBo board to drive three extruders, however, you can use any board
  you want... (most people use a RUMBA due to it having all the
  pins/components needed for 3 extruders native on the board)
Rewriting Repetier firmware to get color mixing working on your
  machine.
How to install, configure, and use the diamond hotend - tips /
  tricks / lessons learned / etc...
My original Bowden extruder design and various ways to mount the
  three extruders for your set-up
My universal magnetic effector plate and accompanying hotend mounts
  for quickly swapping various hotends. (delta specific)
How to design multi-color models and making STLs that can be
  exported and used as a individual STLs or combining them into an AMF
  file for slicing...
Configuring color mixing in Repetier and Slic3r to print above
  mentioned multi-color models.
Anything else I can think of later that I can't think of now.
Comprehensive overview of Quantum Mechanical Entanglement as it
  pertains to multi-color printing (just kidding, I don't understand
  that... But I will cover multi-color printing throughly)

Any other day this would get the selected answer, as it does what I wanted. Though with so many good answers, I will have to go with the direct question of what is stopping us. That said thanks for the link! I don't know why that did not appear in my googling.

Perhaps, the actual answer is "nothing is stopping you". -- This is exactly what the diamond hot end is for. -- Here's the reprap wiki guide for doing CMY color mixing with Repetier: http://www.reprap.org/wiki/Repetier_Color_Mixing

I would say this could be expanded on. That said this is the best solution at this point.

The three in one print head   is the closest to your concept of gradient printing and does some nice transitions.  But does not meet your color mixing.
Which I assume your looking for there is something like blue and yellow making green and by varying those percent getting shades of green.
The three in one head does get close to a dot by dot transition.
I have since I first seen the crowd funding request for the Palette been dwelling on this same concept true color printing in 3D like a laser printer prints paper.
The Palette Palette web site is moving closer to color mixing or fast transitions for multiple colors and again can make flowing color changes but still not a true mixer.  But is is still color striping.  I want one for simple sake of switching color spools with out pulling off and re-feeding filament.   And for my Rostock allowing two to four color switching with a single head.
For many months I have pondered taking their unit  for its software ability to pre-switch colors and feed it with a three color head.
My plan that I have been mulling for months now is cross mixing of their color switcher with five into one extruder with not a print nozzle but a 1.75 or 3mm filament production nozzle to produce a software timed output based on desired print color effect.  Then feeding that to your single nozzle printer would make a true multi-color mixer.
As I was thinking on assembling myself this and put it out there for use, but first I hate doing a lot of programing, second I have health issues slowing me down, third is way to many project.  So here is a concept.

Five extruders,  CYM-BW cyan, yellow, magenta, black, white
These feed a forming nozzle 1.75mm out into a pfte tube going to printer extruder
The forming nozzle is several centimeters long and has it own secondary heater.  The interior is milled with a 5 in to a swirl wall (like a mixing nozzle on epoxy).
Color filament feeding three of the nozzles are your primary colors set in the center of the color range.
PrintCOLOR(C, Y, M) command set basically like other color sets 0-255 range.  Difference being is 0 is white filament, 254 is black filament, 255 is no filament, 127 is pure color.  With 1-126 gradient mix of white and color, 128-253 gradient mix of black and color.
Feed by extruders into mixer must total extruder speed of printer, which is where need for PrintCOLOR(C, Y, M) programming is required.  For instance making green out of C and Y.  PrintCOLOR(127, 127, 0) would need half speed blue and half speed yellow.

So who knows maybe some one like the makers of Palette or some crowd funder can run with this.
I think it is fully do able.
Three color diamond head can not produce WHITE by mixing. To print white requires dropping one color to substituting in the white. And it requires major modification to many printers to add. The CYM filament picked for use on a diamond head alone sets the maximum darkness allowed. Having ability to mix white and black to CYM solves this issue. 5 color CYM-WB is minimum to get a true mix.

Add a 6th, natural, for "alpha channel" too. :-)

A Kickstarter campaign just finished for a full color 3D FDM printer, the RoVa4D Full Color Blender 3D Printer.  It used CYMK printing and includes black and white filament for 5 color filament feeds, plus additional feeds for flexible and support filaments.  They raised \$216k against a target of \$25k.
The company that is doing this has other printers in production, I believe.  This one adds the color capability.  It's planned for 12"x12"x18" print volume.
I am not associated with the project.

As darth_pixel points out, people have had limited success with feeding multiple colors into a diamond hotend and mixing them, but I would argue this is not truly what you're looking for.
The problem is that when feeding multiple filaments into a diamond-style hotend, the colors do not naturally mix completely: if you look at an object printed this way the color changes with the angle you view it from.
This would not be fundamentally impossible to overcome: you could make the melt zone longer, and possibly introduce something to promote mixing (like a spiral path for the molten plastic). However, this would greatly increase the force required to extrude and make retraction near impossible. Both of these issues would reduce print quality.
The results would also not be very good, as you'd need a long purge between colors, limiting the number of distinct colors you can use in a single model while keeping the print time acceptable. Moreover, given how limited the resolution of FDM is you could not make very detailed graphics either.
Over all, you're much better served with painting or assembling parts printed in different colors.
Given the limited potential for color printing in FDM and the mentioned obstacles to building a color mixing hotend, I think it is natural nobody has built one (*) but that doesn't mean it is fundamentally impossible.
(*) There have been some attempts, many on Kickstarter, but none have been truly successful.

Another problem is that it takes too long to switch from one color to another, since the old color has to be purged. A comment on the guy's YouTube video says it takes 100mm to fully switch colors. That would add up to quite a bit of waste.

So it comes out like toothpaste?

There's certainly a lag between color changes, but from what I've seen, the color mixing does happen correctly. -- As for the "purging" that seems like it can be accounted for / calibrated, to the point where the slicer can just use partially changed colors for the infill...

Branching off of TomvanderZanden's answer, this process cannot easily be done with an extruder alone. To properly color polymers, a pigment must be added during the initial treatment process (otherwise applied during any heat treatment). These pigments do not necessarily allow a simple red + blue = purple process to change the color for many reasons including:

Polymer Transparency
Polymer Refractive Index. Kinda goes with Transparency, but how light interacts with the surface of the material might set how people perceive the color.
Polymer Quality (how "virgin" it is). Non-virgin material may mean that impurities absorb the pigments easier or refract light differently, giving a different color.
Pigment Quality. If a cheaper pigment is used, it may not bind as well with the polymer.
etc

The above variables may hinder the desired color in even a single batch of plastic, let alone trying to mix two together. Also consider, that the pigments in each filament spool will be deluded as it has already bonded to the current filament. Review a phase diagram for an optimal temperature and time to introduce pigments.
The best case would be to create your own masterbatch and somehow re-color the filament as you would in a normal manufacturing process.

If you clearly observe the geometry of the print it has printed in different colours .the part is designed in such a way that it has the small height gap between the each colour but we cannot seen this gap in one projection plane..
We can print only in direct drive extrusion .by changing the filament of different colours without pausing the print by immediately changing the material . It is printed in single nozzle. The above image clears your doubt.it is designed with different heights.

Hey Ajay, the question is closely related to the mixing of colors, not the use of multiple colors.


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Can I repair my microwave with a PLA part?
The turntable support part in my microwave has broken. It is a three armed part, with small wheels at the end of each arm.

I'm confident I could print a replacement, and reuse the existing wheels (since they can be removed).
The heat of the food would be unlikely to conduct through to the PLA, but I'm concerned that it might get heated up by the microwave radiation. I can't find any clear information online about whether PLA absorbs microwaves, or if it is in any other way unsuitable for this.
Will this be a disaster, or should I give it a go?

This raises the question of what the original part was made of, and whether or not that material be used in a 3D printer.

I would AVOID plastics and anything involving heat, and foods. A lot of plastics are food safe, but their additives are not. Or they are cut with cheaper plastics that are not.

I would say PLA itself should not be heated up by microwave. It's because microwave oven creates oscilations which excites water particles (see microwave explanation here) so assuming PLA doesn't contain water, it won't heat up. (removed to not mislead as the water is not only material which heats up by microwaves. Thanx to Tom van der Zanden for being vigilant)
But as usual, it's more complicated.
First. PLA can contain water as while producing it can be cooled down in water bath. Of course well made PLA will have as less water as possible as water has an influence on printing process.
Second. PLA is absorbing humidity so in fact it gets water inside right from the air. This unfortunately causes problems in microwave oven.
Water can be overheated and oven can overheat water above 100C. But even at 100C, PLA will not be hard anymore so your 3 arm star would "collapse". Wheels could get oval or start sticking to their axis.
Eventually if high power is delivered to very "wet" PLA, I think it can... well maybe not explode but break.
Here goes a test which shows it can be used to defrost things on PLA plate in microwave
But here Daan Snijders claims PLA gets soft in microwave during the test
Will it be a disaster?
In my opinion it will work only for short uses of MW. Heating up a glass of milk or so. But for longer sessions when there will be much more heat (out of heating dish) it won't work.
SHORT TEST

20sec and 950W gives no effect on my sample (hotend cooling fan duct)
40sec and 950W caused the sample became a bit warm

Inspite that it's not a good idea to run MW without "proper-absorber" this little test confirmes my suspisious - short sessions are ok.

The idea that a microwave only heats up water is completely wrong. Many more materials can be heated by microwaves.

Of course you are right. But microwave is generally designed (oscilation selected) to excite water particles primarily. Many metals get heated up by MW (of more prcisely by eddy currents). But in terms of PLA and his 3 arm star it's not applicable :)

here is a part of the article you linked: "...and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy...". My understanding of microwave oven is precisely as this citation and my answer is based on this understanding. "Frequecy" means "oscillation" for me... and not only for me (wiki:frequency-This article is about the rates of waves, oscillations, and vibrations.) I have a feeling you are trying to over-generalize questions and then answers ;) no offence

Heat IS rotation/oscillation so obviously that will be involved at some point. However, you are making the claim that microwaves are designed to heat up water and only heat up water and therefore items not containing water do not heat up. This is not true. It could very well be (or not) that PLA has dipoles as well. The exact mechanic by which the heating happens is secondary to this (if you continue reading beyond the quoted portion you'll notice that they mention that heating through resonance is a common misconception which I thought your argument about oscillation was referring to).

:) I've read whole article in EN and in my native lang again to not argue without arguments. As I said - you are right but it's not really applicable to his question.

ABS filament tends to absorb water over time, so I would think and ABS part wouldn't hold up.

@JohnSensebe I'm not convinced that water is an issue. The water will only make up a tiny percentage of the total mass, so even if it heats up the plastic itself won't heat up much, and regular heating through the microwave may drive off the water.

You really shouldn't

PLA "glass point" (the temperature where it starts to get soft) is approximately 60C, even if it doesn't heat up from the microwaves it's way to likely the ambient temperature in the microwave will reach that level and cause the part to collapse (even if you "never" get it hot - it only have to get to 60C once during the lifetime of the part).
PLA is not safe for cooking (or even for food storage) and your typical PLA filament isn't even pure PLA, only god knows what chemicals there are in your specific brand of filament and what will be released into the air inside the microwave when it's heated.

In first glance ABS seem to be a better option because it has an higher glass point and food-safe ABS exists - but it's still bad because even food-safe-ABS is only safe for cold and room temperature food.
I don't know about other materials.

I doubt it gets that hot in a microwave. Do you have anything to back this up? The plastic part is sandwiched between the metal case and glass plate, both of which are heat sinks and stay quite cool to the touch - in my microwave anyways. 2. I'm pretty sure PLA is not inherently food-unsafe, but in any case, in his application this is not a problem because the plastic isn't anywhere near the food. There are lots of commercial uses of PLA in food applications.

@TomvanderZanden, I agree. Unless heating up PLA produces some off-gasses, I don't see any reason not to try it out. Worst case scenario the structure will bend and not function - which really isn't that big of a deal.

@TomvanderZanden - the way I see it, especially with cheap Asian filament that contains god knows what additives, unless the manufacturer specifically specified the filament does not produce poisonous gas when heated it should not be used in a Microwave (or anywhere else there's a combination of heat and food)

Yes.  You can.
I would think ABS would be a better idea, as it melts at a higher temp.
http://www.thingiverse.com/thing:385288

ABS does not cause any issues when heated?

You should elaborate a bit more on this. Why is it okay to use PLA, and why is using ABS presumably better?

Just because someone uploaded something to Thingiverse doesn't make it safe. If you were to attempt this, though, it'd probably be safest to use uncolored ABS because its glass point is higher than PLA and you never know what's in the colors.

There are Food Safe PLA filaments. These PLA filaments share similar qualities with ABS, in regards to temperature extremes et al. There are several on the market. (Eg. https://shop.germanreprap.com/en/pp-plastic-600g-3mm-black and http://www.formfutura.com/hdglass/ -- I've not used the HD glass personally but have been told it works well)
When shopping for food safe PLA filaments check for the Material Safety Data Sheet (MSDS) that comes with the filament. It will contain all the normal chemical warnings, some composition information, etc. but will also indicate if the material is Food and Drug Administration(FDA) approved.
PLA, food safe or not, can also have bacterialogical issues--the material is pourous enough to allow for bacterial growth. I would suggest using a polyurethane to seal the printed part to limit bacterial growth.
You will need to check what sort of extruder you have on your pinter. Many brass extruders also contain lead which can leach into the printed product. Switch to a stainless steel print head to avoid this issue.
General care--warm soapy water and handwashing.
I would not, as yet, recommend any printed product as a vessel for food--cup/bowl. This element is still somewhat new and I don't personally trust the materials for extended contact with food. (Knives/spoons et al. have much shorter contact with food vs. a plastic mug of hot coffee).
For your intended application, the piece in question would not come into direct contact with food to be consumed. As such, you should be fine with the correct filament.

This seems a very generic answer about food safety of plastics, while the question is about using the plastic in an application where it won't be in contact with food at all, and the main concern is how it would hold up to microwaves. You could have skipped the entire part about why PLA might not be food safe (which is irrelevant) completely and then the answer boils down to "Yes, you can do this" - completely ignoring whether microwaves might affect PLA.

As the application of the material is in an environment in which food is prepared, some of the context of why PLA, and even food grade(FDA approved) PLA, may not be food safe is completely relevant.

You are making an assumption that the piece won't be in contact with food at all. This is a microwave. Boil-overs et al. happen. Exposure to organic compounds/food etc. is almost inevietable. Therefore, some comments on prep(sealing the PLA piece) and clean-up(warm soapy water) also were justified.
I did not comment with specifics as to Food safe PLA reactions with microwaves as that would, depend on which product the user elected to go with. Such information would normally be contained in the MSDS sheets of said product(s) and would be available pre and post purchase.

You think people should look up the most essential piece of information asked for in this question in MSDS's (and you do not even mention that this could be an issue), even though you could very well make some general statement as to the microwave compatibility of PLA plastic in general? I find that very strange, since food safety is secondary to this question (and there are many good questions and answers about food safety already) and product specific as well (so for food safety your same line of reasoning says that it should be looked up in the product datasheets).

If something in your microwave boils over I don't think any reasonable person would try to eat the portion of the food that boiled over and came into contact with the plastic. In this application, it will never happen that something comes into contact with the plastic and subsequently goes into someone's mouth. I don't see how bacterial growth or trace amounts of lead could be a problem in that case.

Material traits:
I did reference reviewing the MSDS sheets in my original post. As each product will have varying physical and chemical characteristics, mentioning such, in detail, would also go well beyond the scope of the original query.
Food Safety:
So it is logical to have a component which is, if unprepared, prone to bacterialogical growth in a food preparation device? Such is not logical. Equally, there are more vehicles for cross contamination than simply oral.
However, the productivity of the exchange is clearly limited at this point. Best of luck in your endeavours.


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What should I think about if I want to design something modular?
For a while now, I have been thinking about designing things such as small bedside tables, game/dvd/bluray racks for 3d printing. I've always thought that making them modular would be a good way to go about doing this as well.
Modular design would help to create an end result that is vastly larger than the print volume of my 3d printer. I might even be able to recycle models for use in other projects. However, I'm not sure of what I need to think about if I decide to go ahead with these ideas I have floating around in my head.
I'm assuming that certain joints (dovetail, etc), tolerances for different types of plastic due to shrinkage, and print settings (% infill, in particular) would be important to have thought about and evaluated to some extent, but I'm not sure about what else I might be missing.
So my question is to anyone who has designed anything to be modularly printed. Have you really had to think carefully about the engineering side of the print? Or am I simply overthinking this? Should I just design what I want and give it reasonable infill, walls and whatnot, and just go for a trial and error approach? I'm sure there is a method to this madness, but is a concrete understanding of this type of engineering absolutely paramount when it comes to this sort of stuff?

EDIT: Although I've marked darth pixel's answer as accepted, I'm still going to follow JKEngineer's advise and check out that book as well since I feel as though proper engineering techniques alongside a good mentality towards how I would tackle the problem (as outlined in darth pixel's answer) would prove to yield better results in the long run.

I am not sure what you are asking? Are you asking about design of a 3d printed object? If so this is probably not the best area, and a mech engineering forum might be better.

There seem to be two questions going on here. One is "How to make a modular design?" and the other is "How do I make sure stuff fits together"? Your response to @darth_pixel's answer seems to suggest the second one was actually your question. Perhaps you can edit your question to make it a bit clearer what your question actually is.

I don't see how that is 2 separate questions, since if I'm designing something to be modular then I want the pieces to fit together.

I've edited the question. I'm not sure how I can make it more clear

All printers are designed with an idea of WYSIWYG for sure. Depending on:

printer - type/quality/settings/configuration/assembly precission
filament - type/quality/shrinkage
user skills - manual/using app proficiency
model complexity
environment conditions and so on

you can get different results.
I venture to say users know their printers (after some time and by trials and errors) so they know how to manage dimensions to compensate all above so you will get this knowledge too.
Mathematical formula can describe shrinkage of the material, all other elements are very hard to describe (mathematically) in a general way.
Of course someone can simplify it and say: more money you spend better effects you'll get. It's sometimes true ;)
So all your modular things will be better and better if you will increase (what is to be increased) in above points especially "user skills".
Is engineering paramount? It depends of whay you gonna create. If your modular things have to lock itself, have to have threads, screws and such stuff then this is engineering. Is it the most important part of the design? Not necessarily.
I would say 3D printing moved engineering to next level. I'm talking about this or this. Is it still art or engineering? :)
This is my receipt:
think > imagine > design > rethink > redesign > give it a try > get back to thinking
good luck

Great answer! Really reminded me of why I got into this in the first place. So, in essence, collectively, practice makes perfect and I should have a "measure twice, cut once" mentality?

Also, just curious, what about my question were you not sure about? I'd like to know so I can improve my future questions. Thanks :)

@JakeMillington if you think my answer is good then it means I did understand you correctly. And yes - practice makes masters.

A book you would benefit from reading is "Functional Design for 3D Printing...Designing 3D Printed things for everyday use - 2nd Edition"  by Clifford Smyth.
It deals with FDM printing only.  It deals with considerations of orientation of the parts being printed to address required strength in the 3 directions (x, y, z), tolerances, and designing parts in such a way that they can be assembled, have the strength needed, have flexibility, etc.  In some instances he shows how to split a single functional part into multiple parts so that, when assembled, it actually performs as required.
It's available from Amazon at Book on Amazon.  I received it as a present and have no commercial interest in it.
Here's a review: Book Review on 3D Printing for Beginners


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What are the long term material properties of VeroWhitePlus 3D printer material?
I have been 3D printing parts with an Objet 30 Polyjet 3D printer for about a year now, primarily using Stratasys VeroWhitePlus UV cured model material. In general, the parts seem to become more brittle over time, which I assume is due to the parts continuing to cure due to exposure to light. However, I have also noticed that when exposed to moisture for extended periods of time the parts are prone to warping even under little strain at room temperature.
I know that the material does display thermoplastic properties to some extent, but I was wondering if someone might be able to provide me with some additional information about the long-term material properties of either this particular material or similar UV cured 3D printed plastics.
The deformation of the parts in the presence of moisture, in particular, has me really confused, so any information about why this would occur would be greatly appreciated.

If the material isn't completely cured w/ UV during the production step, there's something wrong there.  Meanwhile, the MSDS, http://usglobalimages.stratasys.com/Main/Secure/MSDS/Rigid%20Opaque%20Materials/DOC-06124--Objet-VeroWhitePlus-RGD835-US.pdf?v=635508837056815513 ,  is only for the uncured state, suggesting (maybe) that the cured product is completely benign.  Beyond that, I recommend you contact the manufacturer directly.

Possibly more useful:  here's the cured-material data sheets:  http://usglobalimages.stratasys.com/Main/Files/Material_Spec_Sheets/MSS_PJ_PJMaterialsDataSheet.pdf?v=635785205440671440

As far as I know, the polymer is completely cured after printing. I was thinking more along the lines of some sort of post printing photodegradation or advanced curing may be causing the polymer to become more brittle over time.

The cured material data sheets do seem to indicate that the polymer will absorb water over time, but I'm still not sure why that would cause the advanced deformation that I have encountered.

In our experience, the parts will continue to cure. I don't have the chemical science background to provide proof or evidence, but I operate from an assumption that if the part requires UV rays to cure, it will continue to be reactive to UV rays after it is considered "cured".
I too have found the same brittleness over long periods of time. The only experience I have with the moisture issue would be a small component designed and built for a cable pulley in the tail section of an aircraft as a temporary solution (acting on a non-critical trim control surface). The aircraft is based down here in Houston, Texas where we get some pretty gnarly humidity. The part did begin warping after a few months but we don't have definitive information indicating it was a moisture problem, or something more structural.
I do know however, that if you aren't absolutely meticulous about cleaning ALL of that gelatin-like support material off of the part, it does wind up being more susceptible to slight deformities, and when you DO remove it all thoroughly,  it is then slightly more susceptible to the brittleness issue. Not sure if I'm the only one finding this, and apologies for not having the chemical background to provide more quantitative support.


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How do you heat a large glass print bed?
I have printed a MPCNC machine.  It has a print area of about 30" x 30" and up to 11" tall.  (yes, those numbers are correct).
I found a perfect piece of glass at a garage sale for $5.00 to use as my print bed.
My problem now is how to heat the glass?  I was wondering if there is some sort of tape that would perhaps mimic what is on the rear window of a car, but I couldn't find it anywhere.
Any ideas or links to something that can get me some progress on my search would be greatly appreciated.

Your best option may be to seek out a silicone rubber heating mat, using those terms for your web search. A quick search on my part shows many resources, some of which are known to the 3d printing manufacturing world, while others are equally suited for that purpose.
Don't bond the heater to the glass. You'll need to replace it when it breaks. Consider to use borosilicate glass for better heat tolerance and smaller chance of breakage. A quick search for such a large size pane comes up empty, invalidating that suggestion.
I've read of some people using water bed heaters for large area coverage, but they may heat the area unevenly.
It could be to your advantage to use multiple heater panels with temperature controls for each one. This would provide more uniform heating although more complex temperature management.
I would post links, but there are so many from which to choose.

Silicone heating pads such as those for reptile tanks (i.e. fishtank but no water, just a snake or lizard :-) ) might be a good choice, tho' they probably won't get as hot as you want.

It will be very difficult to heat such a large bed, simply because of the enormous power required. Thomas Sanladerer recommends at least 0.6 W/cm² but notes 0.4 W/cm² also works (but takes "forever" to reach the target temperature).
For a 30"x30" bed, 0.6 W/cm² would come out to 3.5 kW. At 110 V that would require 32 A and at 220 V, 16 A. These are extremely large currents, perhaps more than you can draw from a single circuit: both in the EU and US sockets tend to be fused at around 15-20 A (the standard EU Schuko plug itself is only rated for 16 A).
You will be forced to go with a lower amperage, for 0.5 W/cm² you "only" need 27 A@110 V or 14 A@220 V. 0.4 W/cm² is 21 A and 11 A respectively
As such, if you are in the US, then it will be impossible to heat such a bed from a standard wall outlet. In the EU it might just about be possible, but make sure that the wiring in your house is in good state and capable to carry the current required (and note that running electrical equipment at its maximum rating for an extended period of time is never a good idea).
If you are in the US, you should definitely look into getting 3-phase power installed. If you are in the EU, you might also consider this as an option. It is able to deliver more power, but you'd need a special type of heater.
There are some suppliers that make custom silicone heater mats. If you can get one in this size that would be a good option, though it would be considerably more expensive than your \$5 piece of glass.
In any case you should not attempt a DIY solution because this is extremely dangerous. The currents you are dealing with should not be underestimated. People have already set their printers on fire due to using high currents at 12/24 V; you do not want to make a similar mistake using even higher currents at 110 V.

There is an intermediate step of using a 240V outlet, such as a dryer outlet.  Often these are 30A or 50A, providing 7200W or 12000W respectively.

If using 240V, electrical safety precautions become more important, because (1) what would have been a 120V 'tingle' becomes 2X the current and cardiac arrest, (2) the increased power can make short circuits burn hotter and faster.  Probably want a GFCI outlet or breaker.

A water bed is a nice idea and, together with heavy insulation of the printing chamber, may work fine. Using the CNC he can mill a duct that ensures quite uniform heating, especially with a alu plate and a heat conductive rubber between water and glass.

I am heating my 1 meter by 1 meter plate (yes those numbers are correct) (in progress long term project) of tempered glass with a silicone heater bed I bought as overstock on ebay.
Silicone Heating Mat

From Reprap Wiki

Silicone Heater Pad in sizes
  silicone heater pad Pros: Fast heating Reliable Most use mains voltage
  - DOESN'T require any amps from the 12 volt supply Very low height Easy to install (adhesive backed) Can be relatively inexpensive 12 V
  types can be run directly from the controller MOSFET without a relay
  Integrated thermistor Long life span Cons: Can be expensive - silicon
  mat (50€) plus solid state relay (16€). Mains voltage, but can be
  purchased for 12 V. Need GROUND line to aluminum bed for safety.
  Relatively high temperatures possible (safety problem if thermistor
  dies/falls off).

I also talked to a few alibaba companies and they will happily make you a custom order. Just be wary working with them. You will also need to start another question about the particular parts you need. Actually I think I have a second one I bought from Aliexpress about that size. So no custom orders needed. Ran about 100 USD. I will note I used a MIC6 aluminum plate, custom cut at a local shop. That will have a more even heat profile than glass.
I will note that I have to run mine from 220 VAC not 110 VAC power lines.. But the actual electrical costs are pretty low!

As @Tom pointed out, heating that much area is a pretty big deal. I would just add:

You can't draw anywhere near that much power from the normal heatbed output on a PC board like RAMPs. You could, however, use the normal output to control a big relay (semiconductor or not); that also lets you keep the high-power wiring away from the rest.
You'll want multiple temperature sensors and heat zones, for at least 2 reasons: First, variation may be high over such an area; and second, you can save a lot of power by only powering up the portions you're going to use.

However, just like with home heating, having multiple zones makes things much more complicated. The software for managing heatbed temperature isn't likely to support multiple heaters (especially since most cards don't have enough outputs to make use of it).
I've done a bit with this since my printer is about 4x as long as normal (but not 4x as wide too, like yours). So far I just use one standard PC-board heatbed, and if I have to print something longer than that I do without the heatbed entirely (mine is easy to take in and out). Present plan is to get a few more of the same PC-board heaters, and have an entirely separate box with temperature dials to control each one.
But that still means the printer software won't be in control. So I couldn't (for example), have a different temp for the first few layers, or have the print stop if the heatbed gets out of range.
To put the printer back in charge, I'd have to do something like calculate the average (or maximum?) temperature of the zones, and create a signal that looks like what a thermistor or thermocouple would generate, to send to the printer software. The software would then turn the heat on or off as usual, but that output would go to the control box, which would decide what specifically to do about it. For example, even when the printer says to turn off, the heat control might keep the cooler zones on until they catch up.
In other words, it gets pretty messy... :(

Maybe you can stick a nichrome wire under the glass using a heat resistant tape. You'll have to make the appropriate calcs (or just trial/error) to achieve the desired temperature at a consistent timing.


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Filament is stuck in nozzle
I recently bought a Geeetech Prusa i3 x. After two full days assembling I can finaly try to print something. Having put in the filament into the extruder no filament actually came out of the nozzle. I opened up my extruder and the filament seems to be stuck in the nozzle.

Note that I have tried heating the nozzle up and both pushed and pulled but no movement.
Does anyone know what to do?
Thanks,
Merijn

If this is PLA, it is suggested to heat it to about 180 deg C to soften but not completely melt the filament. Do you know the temperature you've used during your attempt?

I used 210 since I figured this was PLA. It came with the printer and was only described as 'test filament'. Now that I have unscrewed the nozzle I notice the filament melts at way lower temperatures (as low as 140).. Any idea what this filament is?

Did you try pushing the filament from the extruder end using a very small sized allen key? It worked for me.

There are a number of options you could try. If heating up the hotend does not work, you'll have to disassemble it. Remove the nozzle and the heatbreak (the threaded part). To disassemble the nozzle, you will need to heat it up and use pliers or wrenches to unscrew the parts.

You can use a blowtorch to melt and burn out the plastic that is stuck. Make sure to do this outside.
You can use solvents to dissolve the plastic. This works especially well with ABS, which can be dissolved in acetone. You can also try dissolving different plastics with acetone, but for example PLA does not really dissolve in acetone (it does become somewhat soft, so this can still be helpful towards getting it out). You could also try using other solvents if acetone does not work for your particular plastic, but consider these tend to be quite toxic compared to acetone so be careful. Note that in any case, the plastic will need to soak in the solvent for at least a few hours or overnight.

Do not try to disassemble it while cold, the expansion and contraction of metal with heat makes this impossible. When reassembling, be sure to heat up the nozzle before giving it a final tightening (again, this is to make sure that when the nozzle expands as it is heated, it makes a tight seal).

If you use a blowtorch, make sure you have removed the heater cartridge and thermistor first! The thermistor will likely be permanently damaged if you exceed 300°C.

@BenoitMiller My answer said to disassemble the hotend first, then switch to the blowtorch. I think it should go without saying that either a blowtorch or acetone would permanently damage the thermistor, heater cartridge and wire insulation.

@TomvanderZanden at the risk of exposing my stupidity to everyone here, I didn't think of that the first time I did this, and burned a perfectly good thermistor. So it is not necessarily obvious, even though in hindsight I should have known better! :) These days I prefer simply heating the (unmounted) hotend to 280°C with its own heater and push the blockage with Nylon filament, avoiding the need to clean the nozzle of burned residue afterwards.

Thanks for the tips, I noticed it created a solid block in the threaded part above. I have removed it twice now, but it keeps blocking there. Any ideas why? The nozzle was totally clean.

@MerijnDenHouting Do you have cooling on the upper part. If the threaded part heats up, filament will become (slightly) molten and block. There needs to be a fan blowing on it.

@TomvanderZanden it's an geeetech prusa i3x, which has a cooling fan at the extruder motor level. So no, the threaded part doesn't get cooled directly but I wouldn't think it's a design flaw since so many of these printers get sold and work..

Yes, that cooling fan is what I was referring to. It doesn't need to be blowing directly at it.

Ok, great. Any other idea why this might happen? It is getting a bit frustrating since this is my first 3d printer and I haven't been able to print anything yet..

I will by the way mark your answer as 'the answer' since it did help clear out my nozzle.


text:
What is a good software for designing car parts
I am an absolute beginner when it comes to 3d printing. I want to get into the hobby by designing aero automotive parts such as fender flares, custom gauge and switch pods, lips etc. I've never taken a CAD course but I would say I'm proficient enough with computers as I work as a developer. My uncle is an architect and it seems like autocad might be something good to go with. What are some other good alternatives that allow accurate modeling down to millimeters and possibly breaking larger objects into smaller 3d printable pieces to mash together?

This question is a poor fit for this site. The range of possible answers is very large (as there are tens of suitable software packages) and you seem to be soliciting opinions (rather than facts) on which alternatives are "good". This question might be more suitable for Software Recommendations, if you edit it to fit their format.

Hi Adrian. I have put your question on hold, since I believe it is primarily opinion based. Improving the specificity of you question would certainly help (example  "What software gives me feature X,Y,Z?"), although the site Tom mentions might be a better fit for your question all together.

You've avoided a number of attributes of a poor question by specifying your objective in detail, while also providing some indication of your experience. AutoCAD is not well known as being 3d printer friendly, although a skilled AutoCAD design user may be able to create acceptable models.
One could consider more organic modeling software such as Blender, although it works in reverse of my comment above. It's great for free-form model building but not so much for engineering type construction. Again, a competent Blender user can avail himself of the parametric aspects of the software, but it's more work than one would necessarily desire to engage.
SolidWorks has a number of followers in the 3d modeling community. My experience with the software has shown me that it can be learned fairly quickly and is powerful enough to allow one to explode creatively over time.
The structure of Solidworks workflow fits in directly with your description, both to the reference to accurate modeling as well as the break-apart aspect. The construction of a model in SW is done via sketches and various actions performed on resultant objects created from those sketches. It's not free software, rather pricey, but it may also save you so much work as to pay for itself over time.
There are other options, of course, some of which are free to students and hobbyists. I did a quick Google search for "free parametric 3d modeling software" which resulted in this link:
https://www.matterhackers.com/articles/finding-the-right-3d-modeling-software-for-you
You will find many suitable programs in the list generated from that link, as well as many that are unsuitable for the reasons mentioned previously.
Consider also to view YouTube videos of your candidate selections. Most of the programs referenced will have tutorial videos which can give you a clearer idea of how well it fits your needs and perhaps how easily it can be understood.

Thank you for the detailed info! My main problem with my previous searches was due to the fact that I didn't know the correct terminology for what I was describing. "Parametric" is the exact keyword I needed.


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Chinese replicas of the E3D titan extruder
Has anyone used the Chinese replicas of the E3D titan extruders and multi-extrusion hotends? Are they reliable compared to the original ones?
Any other issues or advantages, please share.

I initially voted to close this as opinion based, but considering Good subjective, bad subjective this question could be answered in a reasonably objective way by somebody reporting their actual experiences with these hotends. One problem is that there isn't one "canonical" supplier of replica hotends, so what you get might vary what somebody else gets but I'm not sure how to avoid that issue.

Hi this is not a valid question for this group. It is vague and more suited for a forum. I would recommend http://forums.reprap.org/ or a facebook group. Cheers.

Hi, Francis. As pointed out by others, your question is too broad and opinion based in its current form, and can hardly be answered objectively. I therefore have to put it on hold for now. You can vote for your question to be opened after eventual edits.

I think you will find an answer here: Can cheap hotend parts sourced from China actually produce good prints?


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Kossel accumulates error along Z axis
I have a Mini Kossel and I am going through calibration.
I can home carriages and find the bed with paper-test getting some Z value with M114. Then I run the effector almost full height up and then down - and now Z value for the bed is greater!
If I repeat the process I get greater and greater values in paper-test. It seems that travel per step is different moving in different directions.
How can I fix that? I am using RAMPS 1.4 with Marlin firmware.
UPDATE:
Z values near bed after subsequent runs of five passes of G1 X100 G1 X10
100% speed: 0.1 0.3 0.5 0.7 1.0

 20% speed: 0.1 0.4 0.9 1.4 4.6 6.6

300% speed: 0.0 0.7 1.0 1.3

How can I check that? They seem to run smoothly. I also tried to increase motor current but the problem persisted at about the same level.

@NikolayZinov what current do you measure? Are your stepsticks hot? Are they cooled with fan? Try to do your tests (up/down) on min speed and max speed and share results.

@darthpixel I don't measure current directly; judging by VREF I have 0.5A current while my motors are rated at 0.9A. Spesticks are about 35C and do not have fan. I updated main post with my test results at different speeds

When I tested at 20% speed I noticed another sign of failure: after the test the hotend was not at the center of the bed but had shifted away from Z tower. So it seems to me that the problem is not with up-down movement but with motors synchronization.

IMO definitely the current is not enough and that's why you have such issues. Notice that both "failures" are caused by the same - not enough current. Have a look here: http://3dprinting.stackexchange.com/questions/1480/how-do-you-make-sure-you-have-the-right-voltage-on-the-timpots-on-a-a4988-steppe/1483#1483

@darthpixel Thanks for pointing at that link. Should I try to set stepstick current to my motors maximum rated?

Nope - do small steps and control position and temerature. Consider cooling stepsticks with fan. I highly recommend it.

After some more testing I checked that the problem shows up only on Z tower and is not related with current. Examining the tower I found very dumb mistake. Pulley on the motor didn't have a setscrew! Don't know how could I missed that. The fact that it could somehow run is even more amazing. Thanks @tom-van-der-zanden and @darthpixel for help. It is for sure that such synchronization failure could have been caused by current shortage as well.
UPDATE:
Oh! Y tower pulley doesn't have setscrew as well! But it was running smoothly and in sync with X (which has that screw). Amazing. - UPDATE2. Not really. After closer look only Z tower misses the screw, which explains all.
UPDATE3:
After setting a srew into pulley the problem is completely gone!)

ha ha ha! Funny issue. Now I know why all manual troubleshootings start with "insert the plug into the socket" ;) (just a joke). Nikolay - good to hear you've managed it.

According to discussions in comments, I'm pretty sure the problem lies in too low current.
Please review this answer to How do you make sure you have the right voltage on the trimpots on a A4988 stepper driver?.
Why it happens?
If there is not enough current then motors can omit some steps as the stress is not equal while going up and down. Sometimes inertia can have higher influence than friction.
Additionally because the resistance/stress/friction on towers is different for sure then there are some issues in centering hotend.
So friction/inertia/assembly inaccuracy and current settings inaccuracy can cause such effects. If you are "on the edge" your printer may work well one day but the other day it can fail positioning.
Please refer to post mentioned above. Perform calibration and temperature test (finger test could be ok). I hope you'll manage the issue.


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Materials testing of 3D printed parts
What parameters are needed when preparing to model a 3D printed part in (ANSYS or Abaqus)?
Are there specific tests?
Update
We have been using FDM printing, with PLA. Our parts are for a quadcopter arm.
I'm not worried immediately about having a strong part, I'm ultimately interested in modeling any 3D printed part. I think more important parameters are the printing parameters like bed temp, nozzle temp, layer height etc..

What kind of 3D printed part? What printing technique? What material?

We have been using FDM printing, with PLA. Our parts are for a quadcopter arm

Please use ABS first if you want a better strength!

I'm not worried immediately about having a strong part, I'm ultimately interested in modeling any 3D printed part. I think more important parameters are the printing parameters like bed temp, nozzle temp, layer height...

@user4038 For general comments or conversation, please utilize the comments section. Only post an answer if it, in some way, provides a solution for the question posted.

@user4038, I added your comments directly to your question (you can do this yourself with the "edit" button below the question text).

As with all AM related simulation existing FEM codes are not well suited to solving the material addition issue.
It is very hard for the codes you mentioned to simulate layer-by-layer and toolpath-by-toolpath material addition.
There has been significant research in AM simulation, most of it focuses on the metal additive manufacturing processes. The simulation of the entire build process with complex geometry and material addition almost never occurs due to computational cost. For example this work is one of the most sophiticated simulations developed and it is so computationally expensive that only a single laser scan was performed.
If what you actually want to achieve is stress/deformation of a FDM part then perform a structual analysis using anisotropic material properties that match that of your printed parts. I would assume that by now data for material properties of FDM parts with respect to machine parameters would be known at least for commonly implemented materials such as ABS and PC.


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What is needed to create dwg from drawing?
Does anyone know of an accurate method for building a dwg file from a scan of a scaled drawing or plan. The dwg files will also be referenced for or made into 3d models so pulling the information straight into a modelling software would work too if possible.

I’m voting to close this question because it doesn't show relevancy to 3D printing

It's not an easy task and according to my knowledge there is no way to do it fully automatically (I might be wrong of course).
You have options as follows:
Read scans and ...

recreate it manually in CAD application
recreate it using a digitizer (in the old days they had pucks - a kind of magnifier with crosslines to digitize from printouts/blueprints)
create 3D object omitting 2D drawings
convert bitmap to vectors in 2D app
use a scanning service like this (would be expensive)

Depending on complexity of your schemas, the easiest way, would be option 1 or 3. Option 4 is very doubtful (even if it's the most automatic way, it won't create useful data).
The most of CAD apps have an option to import bitmaps and then work on such a "background". For example, in AutoCAD use command Imageattach