Printing POM/Delrin/Acetal - anyone with experience or suggestions?

3D Printing
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Printing POM/Delrin/Acetal - anyone with experience or suggestions?

Just got in this rather lovely looking POM filament that I’ve put up for sale tagged as an experimental filament.
http://e3d-online.com/Filament/Interesting-Filament/POM-Natural-175

Maybe I should look at creating an “experimental filaments” section, we have a bunch of weird stuff kicking around that people might want a crack at.

@Joshua_Rowley and I have been having a crack at printing it, as I’m really interested in using it for plain bearings and the like. It’s really nice looking stuff, very shiny, nicely extruded filament, extrudes beautifully at 250C or so, bonds to itself very effectively.

However, big issue is that it doesn’t stick to anything very well. First port of call was to go for UHU Stic, which works for ABS/PLA/Bridge/PS/NinjaFlex/PC - nearly everything I’ve thrown at it. However adhesion was quite poor and I barely managed to finish a very small object with a lot of warp. Bed was at 125C

Next up - following on from what I gleaned from Tony Lock at T3DP3D:

I tried some Tufnol. No joy on new tufnol, worse than UHU Stic, even at 130C.
Next I got out some 400Grit paper and had a good go at the surface to really rough it up and expose the fibres to get the stuff to bite. This was the most promising approach and I managed to print @nop_head s cal.stl from the M90 Repo with what I would call “mediocre adhesion” and warp that was “pretty awful”. Could do with some more quantifiable terms here, but you get the idea. This was on a bed at 135C now, but Tufnol is a poor conductor so the top surface was probably cooler.

Next steps are to really really rough up that Tufnol and use a big old raft/brim. Then perhaps look at heated chambers to combat warp.

I’ve also some Delrin/Acetal 30mm thick sheet that will be my last resort, I expect the print will weld to the sheet effectively. Perhaps careful use of a sparse raft will even allow separation of the print from the sheet.

I’m all ears to suggestions on how to print this as it really is promising in terms of extrusion and properties, but without a surface it’s a non-starter.

If anybody with some experience or a good idea wants some to experiment with then do chime in and I’ll look at getting out samples.

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If you can’t find anything else it sticks to then yes you will need to use a sheet of itself clamped around the edge as I did with HDPE, see http://hydraraptor.blogspot.co.uk/2008/08/back-to-black.html.

Doesn’t POM give off toxic fumes?

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@nop_head I’ve got some 3mm Acetal sheet on order.

And yes, if you really cook it you can get a bit of formaldehyde out of it, but much like Nylon and the HCN risk it’s a bit of a boogeyman that only comes out when you’re really going crazy with the stuff.

Chatted with some guys who do large volume IM parts in a fairly small UK facility. Their H&S officer was pretty up on his stuff and the only concerns he had were actually regarding styrenes from HIPS/ABS. Apparently Nylons, Acetals, etc are really quite benign unless seriously temperature abused, the volumes we’re processing and the slow rate at which we’re melting things almost entirely obviates offgassing hazards as the concentrations are so low and the dissipation times so high. None of this applies to fluoropolymers however, and if you’re melting fluoropolymers you should sure as hell be taking serious precautions.

With all the above said, I’m going to add a bit of a warning to the product page regarding all this so people are aware of what they are playing with.

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Why not glue a piece of sandpaper to the glass plate, print real slow with bed at 60 C, as I find some warp energy is released when you print at 20 mm/s. My theory is that shrink [causing warp] is less if given a chance to cool more quickly than the print move. I found the slow print effective with nylon warping. Never tried printing on sand paper though …

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@nop_head Just read through your post, really good info. Especially like the concept of a raft with the temperature tuned such that the print can weld, but also detach. Thanks again for your awesome blog, E3D wouldn’t exist without it.

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Thanks for posting, I’ve been wanting to try this. Ordered.

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POM is chemically and mechanically fairly similar to PE-UHMW (and PE-HD). Maybe try a sheet of that and see if it sticks well enough?

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Have you considered perforated board a la UP! Printers and Zortrax?

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@Tim_Rastall Yes for sure, I think a raft arranged such that the holes function to make a mechanical attachment for the print as opposed to conventional adhesion is a good idea, I just need to get some perfboard.

@Thomas_Sanladerer I did not know that - I have some UHMWPE kicking around, and it might even be worth trying out some HDPE to see if adhesion works with that too.

@Whosa_whatsis Glad you’re on board for some - do get in touch if you want to order stuff in the future, happy to give you a considerable discount.

Overall I think my next port of call will be some 3mm Acetal sheet that will be heated, and then a raft extruded at a temperature such that it adheres enough to resist warp but should hopefully be detachable with a craft knife/spatula type object. Then print the object on top of that at full temperature. Hopefully this will be reusable to an extent. Worst case scenario I have to print parts where the sheet becomes a permanent part of the object - for the applications I have in mind this is fine. After that I’ll look into more reusable methods.

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If it behaves anything like HDPE you cannot eliminate warping just be holding it flat. I think it would need a heated chamber just below the melting point.

HDPE has a relatively high thermal contraction coefficient, but just as importantly it solidifies just below its melting point, so it contracts a lot between that point and room temperature. The opposite to PLA which remains like jelly until it cools all the way to 55C so there is very little contraction after it has hardened.

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@Sanjay_Mortimer once you have a sheet of the same material to print on, you could apply a thin layer of something else on top of it (e.g. a tiny film of heat resistant lithium grease?). This way you can reduce the adhesion level down to your taste.

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@Sanjay_Mortimer Ordered a spool. Any updates on a suitable build surface?

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Just finished cutting up some POM sheet, which will certainly bond with the POM prints. Remaining challenges would be getting the raft to detach, and also combatting warp.

As @nop_head said you can’t just rely on holding it down, it’s going to want a heated chamber really but some serious bed heat might do the trick in a pinch.

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Have you come across the information of Acetal here:

http://www.stratum3d.com/collections/acetal-613/products/acetal-613

They seem to be using a pcb board as a print surface