ABS prints

Mostly Printed CNC - MPCNC Advice
1

I understand that ABS changes size when cooling… can it be somehow compensated?

Asking because I can print much faster on large ABS printers.

Are there certain parts that must be printed using PLA?

Thanks!

2

Shrinkage can be compensated for but warping can’t.

I have never seen a printer that can print ABS and not PLA, If you prefer using another material PET/PETG is a better choice.

That is not the only reason I suggest PLA though. PLA is more rigid, abs and PET are more flexible, that is why some say it is stronger, it doesn’t break as easily because it bends. PLA holds it form longer before it breaks, ideal for this use. The downside to PLA is its ability to withstand high heat, about 20 degrees C less than ABS/PET.

3

I had a conversation today with a person that looks after the 3D printers at one of the local colleges.
He said that there are ABS machines that can print quite a few parts of that size, at once.
And that he doesnt have a similar large machine that uses PLA…

4

Some of these parts take 12 hours each using the recommended settings. You can fit a ton of parts on a bed at once but generally you do not want to do that becuase your chance of failure goes way up. Putting more parts on the bed actually makes the prints take longer do to travel moves. it is only good to do with very small parts.

5

You want stiffness, not necessarily sheer strength. I am not sure how much it actually matters especially at high infills but every bit counts. PLA is great for us, the only downside is the said low temp resistance and isn’t forgiving when it comes to over tightening.

What kind of printer is this? If it can do abs, why not PETG or PLA? Both can be printed and are somewhat preferable to be printed on heated beds and enclosures. Another thing to be noted as that if you print too many parts at once, your layer adhesion might suffer. The layers may cool off too soon if there is a ton of geometry to cover in just 1 layer. Fast machines don’t have this issue

6

If it only prints in abs it’s probably a SLS machine. I don’t think we’ve seen a mpcnc made with those kinds of parts.

7

I didn’t think of that. $$$, but cool to see!

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8

I confirmed the ABS printer specs (Fortus 900 or 400), they can’t use PLA:


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9

Have you asked for a price yet? We had the same model at my school. It was about $500/12hours. Not sure if the rates have gone down in the last 3 years.

10

Holy! It’s like a Fanuc of the 3D printer world.

On the other end we have MPCNC and Snappy, lol.

If we can scale Snappy up to 200x200 so it can print a MPCNC…

11

Sorry, what is Snappy ?

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13

Hi

I was looking at what material to print my MP CNC and stumbled upon this thread. I am thinking to print some parts in ABS for it’s heat resistance.
I understand that PLA is recommended for it’s rigidity, but I am worried about the motor mounts melting. Glass transition temperature of PLA is 60c, motors can easily get to 80c.

Has anyone had any issues with part touching motors melting ?

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14

We keep the motors below them below 50C by adjusting the current. ABS is less rigid, so we still recommend PLA first, PETG second.

15

Keeping the current low will reduce the torque of the motors. In your experience reduced torque is less of an issue than difference in rigidity between PLA and ABS ?

16

The motors still have a lot of torque.

The advice here is keep them under 50C, and use PLA.

17

I went against advice and printed with PETG CF, in order to run 48V to steppers to achieve 10000mm/sec on z with a 1-start leadscrew, with a 2200W watercooled spindle, and in a shop that gets to 105F often (so motors get up to 70C). If any of that sounds familiar and you also plan to use such high feedrates, you’ll likely need PETG at least… the CF makes up for the lower stiffness vs PLA… more than makes up if you get high quality filament like CarbonX.

I wouldn’t use ABS… way more flexible than PETG, and PETG can handle any temps a stepper will give it.

edit: Wanted to add that… high feedrate like that really only helps when doing 3d carves, for things like relief art. PLA and stock setups are perfectly OK for running endmills through wood in general. It’s just the rapid z moves when relief carving that requires all the extra torque. Only other thing might be production milling… having the faster travels will up the parts per day significantly. That said, no idea how long an mpcnc would last in production work.

18

The way I think about these choices is:

  • The main trail through the forest (the yellow brick road) is covered in the docs.
  • If someone gets off the trail, the people in the forums are the rangers, helping you find your way
  • If you are someone who wants to go your own way, we won’t stop you.

It is definitely possible to do what Kev did. But you do not have to do that to find success. The documented way to build an MPCNC works, and it works well. It may not be your way though, and we are fine with that.

Suggesting PETG instead of ABS is a good ranger move. Suggesting you have to use PLA is not.

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19

@jeffeb3 and @truglodite thank you for taking the time to share this information with me. You make a good case against ABS. PLA seems to be the simplest one, but I will be looking into CFPETG.

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