Help me think about getting a printer. :)

[norbauer 1]

Hi all! I am very impressed by the UM community so far from what I've seen from of your active forum.

I have been considering getting a 3D printer for a while now, as I increasingly find myself working on industrial design projects, both for my hobbies (Star Trek prop replicas!) and for commercial projects as a designer, and I'm seeking some advice. I'm both looking for advice on what printer to get (understanding that there will be a strong UM leaning here) and also a bit of advice on what to expect.

These are the printers I'm considering:

 

• Ultimaker 2+
  
• Zortrax M200
  
• 
  
• Up Box
  

 

Here are the issues I'm considering.

On occasion, I want to be able to finish parts really well.

Sometimes I'll want to make prints that will be used for mold-making and casting of prop replica parts.

One of the things drawing me to the UM2+ right now is that I am especially interested in printing with the 0.25mm nozzle and at around 60 micron layer heights, on the assumption that it will make high-quality finishing easier. I need to see zero layer lines on finished parts that I use for casting, even if it takes some work to get there.

I have a blast cabinet with Polyplus media, which Stratasys recommends for finishing FDM parts. I have a lot of experience working with urethanes and milled plastics, so I have no problem wet sanding and polishing. (Not such a big fan of working with acetone.)

I'm thinking that perhaps ABS printing is going to work best for me, because I hear that PLA is a pain to wet sand and get a great surface finish, and I have some good results in initial tests in sanding ABS FDM prints.

ABS printing?

Therefore, ABS printing is important to me. Bed adhesion and also a warm build environment seem important for getting good results on larger ABS prints, and this seems to be an area where the UM doesn't hold up as well compared to something like the Up Box or Cubicon, with their closed heated build chambers.

Using ABS, I'm also somewhat concerned about fumes and will probably need to add an expensive after-market filtration enclosure if I get an UM2+ rather than a Cubicon or Up Box, both of which includes those features natively. Adding this cost makes the UM2+ significantly more expensive than any of the other printers I'm considering.

Or maybe I should just calm down and use PLA and plan to use something like XTC 3D to help in finishing? I know PLA is much easier to work with, and (unlike ABS) I'd probably be OK printing with it at home in terms of fumes.

Good support/community.

I know there is going to be a fair amount of tweaking and tinkering involved in any 3D printer. I'm fine with that, but I want to be able to know I can get help when I'm hitting snags. This is one of the main UM advantages as far as I can tell. The Cubicon is a new printer based out of Korea with seemingly minimal English-speaking community.

I don't like proprietary filaments or locked down slicing options (I want to be able to use Simplify 3D). These are major strikes against the Zortrax and Up Box.

Dimensional accuracy.

One of the main applications for me for a 3D printer is for prototyping. Mostly I'm designing parts that will ultimately be machined either in aluminum or ABS. My goal in prototyping will be to a) get a rough sense of sizing of parts by holding my 3D models in my hand in real life but also b) to be able to check things like fits of parts together. Are there software tools or other techniques that can be used to get decent dimensional accuracy on prototyped parts? Prototypes aren't worth much to me if none of the parts of an assembly fit together. To the the extent that this is a priority for me, perhaps with FDM I'm simply barking up the wrong tree?

Any insights and advice on any of the above would be most appreciated. Thanks in advance!

[IRobertI 520]

You can sand PLA just fine, you just need to keep it cool. I've used a power sander on PLA without any problem as long as I kept it wet. You can get it up to a "mirror" finish if you work on it hard enough.

As for dimensional accuracy, you'll need to be more specific. It's impossible to give a good answer there without knowing what you're expecting.

[norbauer 1]

You can sand PLA just fine, you just need to keep it cool. I've used a power sander on PLA without any problem as long as I kept it wet. You can get it up to a "mirror" finish if you work on it hard enough.

 

Interesting. I usually wet sand all plastics anyway. I have heard many people say PLA is relatively very difficult to sand and finish, but maybe they were using dry papers.

I need to experiment with ABS vs PLA in my blast cabinet and see how they both respond to it. Sanding with paper works nicely for flat surfaces, but it's tedious and sometimes impossible to get into deep grooves and recesses that way.

 

As for dimensional accuracy, you'll need to be more specific. It's impossible to give a good answer there without knowing what you're expecting.

 

I guess my question is whether the software (Cura or S3D) account for plastics shrinkage at all in order to try to make the parts more accurate to their designs. Or do most people who care about this simply apply a scaling factor?

I'm oftentimes prototyping assemblies of (usually 15mm+ in diam) holes and shafts where one needs to fit into the other. For machining, these are given the same nominal size in CAD and then tolerances are specified to the shop. However, in my limited experience getting FDM prints, oftentimes a hole and shaft given the same diameter won't fit into each other right out of the printer.

Edited April 10, 2016 by Guest

[jameshs 42]

I do wet sand PLA but of course you are altering the dimensional accuracy.

I do design for 'interference' fit - but it also depends on whether you are using a 'fixing' or a printed insert - as with a fixing you have a dimensional constraint of only the mating part, whereas when you print both the printer may act differently one the male and female part (if it shrinks both ways) - so you need to do your experiments and will get used to the printer.

0 layer visibility is difficult - I have seen some people achieve it, but it is a natural artefact of the process - like the mould line on injection moulding etc. Anything you do to the surface will then affect dimensional accuracy.

So most people would (I think) use the printer for prototyping - where the surface finish is not the critical factor, and then when everything fits, then a huge investment in 'finishing' would take place sanding, layers of sprayed primer, buffing etc, where you are then looking at a representational model.

It may be that the UM is mainly used for the first, and then a Form or other resin printer for the second.

There is no one miracle solution - but I use the UMs for prototyping all the time, and (in architecture) for representational models, as most viewers are able to overcome the 'lines' in their mind and see the intention.

As for which one - they can all do ABS and the enclosure is more about temp stability, none of then have a filtered air environment - so a well ventilated room is all that is required.

.25 nozzle will hugely increase print time - so use it carefully!

James

Edited April 11, 2016 by Guest

[avogra 68]

Grr, my post didn't make it into the thread :angry:In short: In general, im very satisfied with accuracy when printing pla. 2 problems stay to be accounted for: vertical holes being too small and first layer elephants foots. i usually compensate both in the model with +0.2mm diameter for the holes and a groove for the first layer. or i drill the holes afterwards / remove the elephants foot after the print. at the moment im trying other materials for mechanical parts like nylon and biofila platec. apart from more difficult bed adhesion, accuracy is fine too. im using an UM2, but i think you have the same results and problems with every quality fdm printer.

After you mentioned it i'm surprised, that slicers dont have options to add some options for this compensations. i will propose that to be included in cura