Depending on the desired app., acrylic (PMMA) has the added advantage
that it can be compression moulded into complex shapes rather than
always machining a part from a block.

bob g.

Koz wrote:

Because UHMW is quite soft and the molecular chains are 4 to 6 million
molecules long, sanding produces a hairy surface. There are ways to get
what you want from it but you'll never get a polished surface. Machining
can give a fairly good surface that looks "shiny" but will have tool
marks to some extent.

Delrin....well, sort of. If you are looking for polished surface,
probably not. Delrin can be a little soft so polishing can go like a
dream or go bad really quickly if you happen to overheat a section.
However you can get a good surface with hand tools and sanding that
might be acceptable.
Maybe if you elaborate on what you are trying to do? Your description
sounds more like you want acrylic or similar.
Koz

Richard Ferguson wrote:

I was answering a neighbor's question today, and went back and looked
up Delrin and UHMW on the web, and found that I did not know what I
thought I knew. ;-) Apparently Delrin can be sanded and polished,
while UHMW is not good for sanding, according to what I found on a
couple of websites.

So which plastics are good for sanding and filing? Is Delrin a good
choice? I am talking basically hand work, or perhaps using a belt
sander. I want something that can take a smooth finish, preferably is
food and dishwasher safe.

Thanks in advance.

Richard