How to print POM (acetal Delrin) on a Core One
I was experimenting with replacing a worn-out brash bushing on an old telescope mount with a 3D printed version. I was struggling to find a filament that had low sliding friction on a metal shaft. Whilst I was assembling my Core One kit, I wondered what kind of plastic the Z-axis trapezoidal nuts were made out of and whether or not I could print it (the trapezoidal nuts are machined and I'll get to that). Google search yielded that they are made from Delrin or POM. Went on Amazon and found it in filament form: Gizmo Dorks 1.75mm Acetal Delrin The reason why it's generally machined is it's extremely difficult to print.
The spool arrived, I picked a PETG profile and tried to print a Benchy. POM is interesting material, it highly crystalline, shrinks a lot and consequently warps a lot. It also doesn't stick to any regular build surface and there is no adhesive that bonds to it easily. So... lots of failed prints. Tried different print surfaces, glues, tapes. Finally got it to stick to dry wall tape but it was not easy to prepare the surface.
I then stumbled onto a obscure thread that mentioned using Garolite G10 that was lightly sanded with the bed at 110° To my surprise, that worked
I also needed a very large brim to keep the part attached to the print bed. Here I've got the bed at 120° and the chamber at 58° to control warping. It also needs to be printed very slowly. I'm using a max flow rate of 2mm^3/s which works out to around 20mm/s with 0.4mm nozzle. The fans need to be off to keep warping under control. It means small features like a Benchy smokestack can be a challenge:
The other caveat is that you can't print it above 240° or it can give off formaldehyde gas. So the printer needs to be well ventilated and the nozzle at 230°. I've attached my PrusaSlicer config for a 0.4mm nozzle.
RE: How to print POM (acetal Delrin) on a Core One
"ugly as sin, fast as hell" (no racing Benchy has lower friction)
RE: How to print POM (acetal Delrin) on a Core One
This is filament is really interesting. The prints are super strong, layer adhesion is insane. It also feels like soap. But... is it challenging to print. The largest object I can successfully print is around 120mm square. It will only stick to scuffed G10 and paper. I might pick up a square of Delrin and see if it sticks to itself.
RE: How to print POM (acetal Delrin) on a Core One
I swung by the local plastics shop, bought a square of 250x220 Delrin and can confirm... No... It doesn't stick to itself... at all. At least my wife has a new cutting board.
RE: How to print POM (acetal Delrin) on a Core One
...At least my wife has a new cutting board.
Perfect for competitive benchy racing!
RE: How to print POM (acetal Delrin) on a Core One
Gave me an idea. I might actually try that. I have PA6, Igus i150, PETG-PTFE and POM. Print a Benchy in the other 4 and slide them around on my new POM surface.
RE: How to print POM (acetal Delrin) on a Core One
This is filament is really interesting. The prints are super strong, layer adhesion is insane. It also feels like soap. But... is it challenging to print. The largest object I can successfully print is around 120mm square. It will only stick to scuffed G10 and paper. I might pick up a square of Delrin and see if it sticks to itself.
So, do you think it will be useful in practice -- e.g. will you be able to print a working bearing? It seems that the low friction may be offset by the bad surface quality?
RE:
Working bushings yes, but not complex bearings. I did attempt one but the shrinkage made it hard to control dimensional accuracy. May attempt gears.
RE: How to print POM (acetal Delrin) on a Core One
Working bushings yes, but not complex bearings. I did attempt one but the shrinkage made it hard to control dimensional accuracy. May attempt gears.
Thanks! Sleeve bearings (= bushings?) are what I was thinking of. Good to know that you consider that a realistic application for 3D-printed POM; that's a good option to have in one's back pocket for repairs.
Ball bearings are a tall order for most 3D printed materials, I would assume. They probably don't benefit too much from low surface friction, since the surfaces are not meant to slide vs. each other. I would rather focus on dimensional accuracy and wear resistance -- and realistically would search for a suitable off-the-shelf bearing.
RE: How to print POM (acetal Delrin) on a Core One
Working bushings yes, but not complex bearings. I did attempt one but the shrinkage made it hard to control dimensional accuracy. May attempt gears.
Thanks! Sleeve bearings (= bushings?) are what I was thinking of. Good to know that you consider that a realistic application for 3D-printed POM; that's a good option to have in one's back pocket for repairs.
Ball bearings are a tall order for most 3D printed materials, I would assume. They probably don't benefit too much from low surface friction, since the surfaces are not meant to slide vs. each other. I would rather focus on dimensional accuracy and wear resistance -- and realistically would search for a suitable off-the-shelf bearing.
I've been using it for telescope repairs. I had a PTFE joint on one of my telescopes that failed and I was able to print a usable replacement with POM. It's very niche for sure. It has extremely low moisture absorption so I can just throw the spool in a drawer.
RE: How to print POM (acetal Delrin) on a Core One
If you decide to pick up a roll, it must be printed on either a scuffed G10 surface or on dry wall joint tape (coarse paper). It will not stick to anything else.
RE: How to print POM (acetal Delrin) on a Core One
If you decide to pick up a roll, it must be printed on either a scuffed G10 surface or on dry wall joint tape (coarse paper). It will not stick to anything else.
Which, one might argue, is the whole point. 😊
I will probably hold off on buying POM filament & G10 for now; saving my 3D tinkering energy for the INDX... But many thanks for the tips, I will make a note of them!
RE: How to print POM (acetal Delrin) on a Core One
I will probably hold off on buying POM filament & G10 for now; saving my 3D tinkering energy for the INDX... But many thanks for the tips, I will make a note of them!
I've found a G10 plate is handy for other materials as well. Works really well with PA, PC and ASA. With PC especially I can get aggressive with adhesive so I get zero warping without ripping the sheet apart. I can also clean it with acetone (as long as I don't go overboard with it).
RE: How to print POM (acetal Delrin) on a Core One
For some work I have been doing, I purchased 3Dlac. I find that it is a pain to get stuff off of. A bit of IPA helps.
Printing with Delrin. Now that is something I need to try. Have used Delrin machined parts at work and they are expensive to get made. 3D printing them may be cheaper.
RE: How to print POM (acetal Delrin) on a Core One
For some work I have been doing, I purchased 3Dlac. I find that it is a pain to get stuff off of. A bit of IPA helps.
Printing with Delrin. Now that is something I need to try. Have used Delrin machined parts at work and they are expensive to get made. 3D printing them may be cheaper.
Depends on the size of the part. There is a reason why it's machined instead of printed. It's very challenging.
RE: How to print POM (acetal Delrin) on a Core One
I agree. No shit.
In R&D, many times, time is the most important factor. I have worked on projects where $8K was a low cost to get a stainless steel part in our hands in a few days. We were looking at a $200K metal printing system to save money from contracting out machining, on a regular basis. Some of our projects were in the $100s of thousands on a daily basis. $10K, in one day, was a low cost to the project.
When you are looking at people that make 30 to 50 an hour for design work, to get the correct drawings, too an outside manufacturer, that is a question that needs to be addressed. When you can do it in-house, you save thousands of dollars. In-house doesn't need detailed drawings. Outside work needs detailed drawings that add extra work and adds hours to the work, and the final bill. Lived it and expensed the price. Time is MONEY.