Matte finish on ABS and Delrin?

Maybe bead blast? You might try:

supply spray coatings for various thermoplastics. They have specific grades of matte and eggshell finishes. It does work pretty well, and you can request a sample.

Bead blasted? (glass beads)

put an ad in the local paper for any former employees of the shop to contact you.. they might have a home shop and work on the side also.. they would know what he did or they did....

Just a long shot, Spencer, but it's possible the components were run in a tumbler with plastic media. You might be able to tell by looking closely with a loupe. You'll see a perfectly random matt finish, but any tight corners may not be touched at all, and that would tell the tale. Plastic media often has very fine abrasive particles in its makeup, which would account for the cleaning, deburring and blending it does.

Harold

Greetings Spencer, You can get a matte finish on delrin by tumbling. I know because I did this inadvertently. After tumbling to deburr all the parts had a matte finish. The biggest problem was polishing the parts in the tumbler after I ruined the finish by tumbling them in the first place. I seem to recall that I used a plastic media, little triangles, to achieve the matte in the first place. You can experiment fairly cheaply by buying a small tumbler from a gun supply and small bags of different media to match. Then, buy a big tumbler and large bags of media. Cheers, Eric

Hi Harold,

Thanks very much for the advice. I hadn't thought to do this. Upon close inspection with a high power loupe, I see fine structure all in a tangential direction. It certainly seems to be a surface finish produced on a lathe, with *possibly* some post-turning ...something ... done to it. The inside surface of the cylinders have a different finish, more like what I'm used to seeing from fresh cut delrin. Maybe the outside surface is just a cut surface, but with great care taken with tooling, angles, lubricant, etc. I don't cut delrin with any kind of fluid, I just go slow.

Thanks as well to everyone else who responded. The Chem-Pak site was a revelation. Not useful for this particular application, but I'll certainly be getting a sample and maybe incorporating it into other stuff. Thanks, Billy!

Spencer

I turned a piece of ABS and then blasted it with glass beads. Looks matte to me, see what you think:

Try "polishing" with Scotch Brite Pads.

snip---.

Hey Spencer,

Just a little tip on cutting Delrin. The faster you run it, the better it performs. If you keep your tool nice and sharp, the finish is superb. Delrin does not get gummy from heat like many other plastics. I've had chips coming off in a continuous ribbon that shot over my shoulder and piled up on the floor in a nice heap. It is one of the nicest of all the plastics to machine, the only problem with it is it has considerable stress and moves about a great deal as you rough it. Be certain to rough parts before finishing, leaving a reasonable amount so you can remove the error generated by the movement. I've often done it in three phases to get parts straight. I used to make telescopic blowpipes for bagpipes, which is where I learned of the tremendous movement it displays.

Regards,

Harold

for auto work. Fantastic on brass, copper, steel and the like.

I haven't looked, I suspect it is a chunk of Dover Cliff :-) IIRC, diatamacious (sp) earth. Martin

Once again, thanks to everyone who responded! Great stuff.

BTW: Harold, it's funny you should mention delrin bagpipe blowpipes. A couple years ago someone gave me a chanter as a gift. (I'm a big Corries fan and they figured it kind of, sort of fit. Alas, I've developed no talent for it. They were wise to leave it at just the chanter.) At any rate, I've also suspected this was made from delrin. I know that "African blackwood" (ebony) is the traditional high quality material, but could this cheap chanter be delrin?

Spencer

Actually, Blackwood is not the same as ebony. It is another very dark wood, but quite a different species.

It's incredibly rare in larger sizes these days, too.

CJ

Spencer wrote:

Hey Spencer,

Yep! The plastic models I've seen have all been made from Delrin.

Interesting you should mention your lack of talent. Unlike you, I jumped in with both feet, purchased a beautiful set of pipes, ordered directly from Sinclair in Scotland. Silver and ivory, in fact (all legal, done under proper license for the ivory at that time, mid 80's). They sit unused. I still screw around with the chanter, though, and have two of them, one a Delrin model, the other blackwood. A musician I am not.

I think if you'll check a little closer you'll find that the blackwood used in pipes is not ebony. The color of the wood in pipes is a rich dark brown color whereas ebony is truly black. Unfortunately I do not recall what the wood is, but it is commonly called (African) blackwood. I've machined a small amount of it and I'd liken it almost to machining a plastic. It's quite nice to work with, unlike so many of the woods we see with coarser grain. It is also rather difficult to obtain according to the pipe major of the Salt Lake Scots (he's engaged in pipe building), where I struggled to gain some semblance of skill at the pipes. Didn't happen! :-(

Harold

Should have read your post first, CJ, would have saved me repeating that which you had already stated. :-)

Harold