Best method for sanding/smoothing PLA jewelry

Hey, so I'm using my 3D printer to creat jewelry, and it is a bit of a pain to sandpaper smooth, any ideas on the best way firstly get the layer lines/resolution removed, then to polish it up to a shine?

Could I use a dremel with a fine abrasive tip? Any ideas on what sort of part I'd need?

I'm considering purchasing a tumbler to polish my metal pieces, but it would be great if I could use the tumbler for polishing my PLA stuff. Any ideas on the best one? I did a brief search and came up with this, I guess it's some kind of hint that you can polish plastic with a tumbler I just don't know how PLA would fare...

Cheers!

I have no idea. But I would love to know what you come up with!

Use ABS, then acetone vapor with a crockpot.

Lol @ acetone vapor - that sounds either very highly toxic or flammable... can you give more detail?

I'm using a Replicator 2 (I know wrong place, but you guys have a bit more activity) so not sure if I can use ABS..

Oh another question, when I cast in metal using lost wax will the infill percentage translate the same into metal? Like will the center of the cast have air pockets or will it be completely solid?

All the fine jewelry models I've seen were created using resin printers. So if it justifies the cost, you might want to switch to that.

i spoke with faberdashery about smoothing out PLA and they dont know of any chemical which will do it.

Iv tried acetone but it doesnt attack PLA as much and also leaves a nasty white shine over the print.

Heat seems to smooth it off quite nice and give it a very nice shine. but as for getting rid of Z Lines i dont know.

Tumbler might work would love to see the results of PLA in it as PLA is a very hard plastic

What about coating in water-based polyurethane such as Varathane? If you try it please let us know how it turns out. It's been on my list of things to try for a while.

Andy

I agree with the idea of using a tumbler for many parts, although it may take some experimentation to find the right ablative (sanding medium) and tumbler time for a particular detail level. Nice thing is that you can probably make your own tumbler, if you've been able to produce your own reprap printer...

In terms of manual tactics, I'm a big fan of riffler files for detail cleanup. And although really really nice sets are often very expensive, a set of inexpensive rifflers will cost you about $25 or ebay and elsewhere. Rifflers are a nice tool to have for cleanup because they have shapes conducive to otherwise difficult profiles. They can be purchased with standard profiles or as rasps. Both are nice to have in hand.

fwiw

I run a business making complex sculptures etc in fibreglass for the entertainment business etc, we use a wonderful material to help make our patterns smooth.
It's called "Reface" It's polyester based and it's a bit like thick emulsion paint. You mix catalyst with it and either paint or spray it on ( we spray it) it cures quickly and you can put more coats on top. When set you can rub it down easily. It works well on 3 d models . We are uk based but I'm sur it's available elsewhere
Steve www.articolestudios.co.uk

Can you post some photos/videos of before/after? I assume it sticks on PLA and ABS just fine, no peeling or anything.

kug Wrote:
-------------------------------------------------------
> Oh another question, when I cast in metal using
> lost wax will the infill percentage translate the
> same into metal? Like will the center of the cast
> have air pockets or will it be completely solid?

Umm, no. Not a chance. If you use the lost wax method to cast a hollow cube (one with 6 sides, completely sealed), you should get a solid cube out of the cast. Of course, if there's a hole in 1 if the cube walls, then the mold material would go into that hole, but you'd still have to fill the center of the hollow cube with molding material, and then take it out after making the mold. Way more trouble than it's worth.

The center of the cast will be completely solid, as long as it is not exposed to the outside at all.

The only issue you have to worry about with infill is whether the mold material you put around the print will deform the print and produce a deformed metal object. Use just enough infill to stop deformation - anything else is wasted material and time. Consider structural partitions inside if this is an issue.

Good luck with it.

Regards,
aeronaut

Hey,

Actually for me I found out that a high speed polishing tool such as a dremel cotton buffing wheel of any variety works really well for polishing /smoothing PLA. Sandpaper on a dremel tends to melt/destroy the plastic however a cotton wheel seems to remove Z lines very well.

Just keep the object cooled with a fan while doing this and ensure you have printed with 2+ walls so that you have room for error. Cotton seems to eat the plastic away very rapidly if you are not careful. Also without the cooling I once got a wheel coated in melted PLA by accident.

cannonpr Wrote:
-------------------------------------------------------
> Hey,
>
> Actually for me I found out that a high speed
> polishing tool such as a dremel cotton buffing
> wheel of any variety works really well for
> polishing /smoothing PLA. Sandpaper on a dremel
> tends to melt/destroy the plastic however a cotton
> wheel seems to remove Z lines very well.
Could you please post some photos of the results?

Edited 1 time(s). Last edit at 02/11/2013 11:20AM by MPower.

cannonpr Wrote:
-------------------------------------------------------
> Hey,
>
> Actually for me I found out that a high speed
> polishing tool such as a dremel cotton buffing
> wheel of any variety works really well for
> polishing /smoothing PLA. Sandpaper on a dremel
> tends to melt/destroy the plastic however a cotton
> wheel seems to remove Z lines very well.
>
> Just keep the object cooled with a fan while doing
> this and ensure you have printed with 2+ walls so
> that you have room for error. Cotton seems to eat
> the plastic away very rapidly if you are not
> careful. Also without the cooling I once got a
> wheel coated in melted PLA by accident.

Yeah, I suspected that would be right, I've done that with sculpey, although it's annoying for curves because it does as you say eat it quite quickly leaving a sort of uneven surface. Not sure if that's the case with PLA?

Ukrobotman Wrote:
-------------------------------------------------------
> I run a business making complex sculptures etc in
> fibreglass for the entertainment business etc, we
> use a wonderful material to help make our patterns
> smooth.
> It's called "Reface" It's polyester based and
> it's a bit like thick emulsion paint. You mix
> catalyst with it and either paint or spray it on (
> we spray it) it cures quickly and you can put more
> coats on top. When set you can rub it down easily.
> It works well on 3 d models . We are uk based but
> I'm sur it's available elsewhere
> Steve www.articolestudios.co.uk

Does it evenly take away a few layers or something?

xiando Wrote:
-------------------------------------------------------
> I agree with the idea of using a tumbler for many
> parts, although it may take some experimentation
> to find the right ablative (sanding medium) and
> tumbler time for a particular detail level. Nice
> thing is that you can probably make your own
> tumbler, if you've been able to produce your own
> reprap printer...
>
> In terms of manual tactics, I'm a big fan of
> riffler files for detail cleanup. And although
> really really nice sets are often very expensive,
> a set of inexpensive rifflers will cost you about
> $25 or ebay and elsewhere. Rifflers are a nice
> tool to have for cleanup because they have shapes
> conducive to otherwise difficult profiles. They
> can be purchased with standard profiles or as
> rasps. Both are nice to have in hand.
>
> fwiw


LOL, noo I have not built a 3D printer. Any suggestions on a tumbler to try for plastics? Vibratory, Rotary or Magnetic?

I'd think a rotary can be made at home pretty easily using a motor, a coffee can, and a few other items prettily easily. People have been making tumblers for decades. I believe the first plans I saw for one were in a cubscout manual when I was a boy, over 40 years ago.

Not so sure about the others, or even if they are examples of tumblers. In any case, doing a search for the terms "tumbler, polisher" will probably yield more than few hits worth reading.

Edited 2 time(s). Last edit at 02/12/2013 10:06PM by xiando.

No it's just a paintable body filler that can be sprayed as well
Steve

kug,
Just a hint: I built a coffee can tumbler a couple of decades ago with several beads of silicone for ribs to make the stuff tumble inside to clean brass casings. I used it for years and still have it. I would suggest using a plastic can in stead as the abrasive medium continually abrades the metal can surface and discolors the medium and may add unwanted color (contamination) to the fine cracks/grooves in the plastic surface features. I used nut shells or corn cob bits mostly.

Folger's ground coffee (32oz size) comes in plastic "tins" now, so that might be a good candidate. The only problem with the plastic canisters is that they don't have quite as much rigidity as a metal coffee can, although I suppose it'd be easy enough to print and apply some reinforcing brackets.

I am looking into doing the same type of thing. You might find this interesting:
Tumbler Finishing

I have a mini-sandblaster that I bought from my local auto discount store. I haven't tried it yet but it seems like it might have some possibilities for this purpose....gets into nooks and crannies really well and very gentle controlled abrasion.

PLA turns white-ish as soon as you bend it (unless it snaps). Same for the areas where it was filed. So you will probably need a paint job even after mini-sand-blasting. Worth a try though, you already have the equipment anyway.

ABS is much better for sanding and also the acetone works well. It also paints better than PLA.

PLA dust is bad enough that you need a respirator to sand it. You should read the MSDS for it.

In general, if you want to do post-processing, then use ABS.

---

[www.matter-replicator.com]

Hi Steve,
so the REFACE you mentioned work well on PLA? can you share some photos before/after...

huge thanks..
Justin