Machining Plastics

[burnrider]

Any one have advice on best plastic selection for making low impact spacers, or washers with regard to a clean measurable finish. Of the following which would be decent for threading?

Most available stock in my area are rem stock pieces of ABS, Teflon, or HDPE plastic.

Tx, in advance

 

[Rbeckett]

Burn,
Online metals has a good selection of different plastics and other machineable soft materials. You can also make your own machineable wax if heat iis not part of the equation. Using ultra sharp diamond honed tool bits will yeild the best surface finishes, or you could spin them and wipe with a solvent to remove the album lines from the surfaces. If you need help with machineable wax, let me know and I will get the formula for it again. Just some thoughts...
Bob

 

[burnrider]

Thanks Bob,
News to me. Just looking for options other than aluminum, in some cases.

Did treatment at home work out for you?

 

[GaryK]

Delrin works and cuts great.

 

[darkzero]

+1 on Delrin/acetal, it machines & threads very nice! But if you are looking for something less expensive than Delrin or just because you have the materials available as you mentioned, as someone else mentioned, be sure to use very sharp tools. I only use high positive ground inserts for alumnium on plastics instead of negative inserts. Only other plastics I've machined is ABS & nylon. They can get quite messy & if you feed too fast or hard they will melt unlike Delrin. Acetal is dirt cheap from Enco, I get em in 4' lengths & they are almost always on sale.

 

[Tom Griffin]

Delrin or acetal does machine very well, but it's not a high impact plastic like Teflon, ABS or polyethylene. A good high impact plastic that still machines well is Nylon 6/6. It's inexpensive, it comes in white or black and can even be obtained blended with lubricants like molybdenum disulfide.

Tom

 

[cwkelley75]

Ultem is a great plastic to work with and its very durable. It's a little more pricey but it's an option depending on the what you need.

 

[Harvey Melvin Richards]

If I'm trying to hold a tolerance, of the plastics mentioned, I would choose Ultem first, and Delrin second. Teflon is the easiest to machine, but its like butter. UHMW is also easy to machine if you use sharp HSS. It can be difficult on tolerances and it creates very tough strings on the lathe. I've haven't machined much ABS, although I've fabricated a lot of enclosures using sheet stock and solvent welding. It's also a nice plastic to work with. Another one not mentioned is PVC. It machines better than UHMW and can also be solvent welded.