Kgorden wrote:
Hello All:

I have machined UHMW,NYLON,DELRIN,HDPE,POLYCARBONATE every day for 15 years.
It is not uncommon for UHMW to come from the factory with a little warpage,
especially close to the edge of the sheet. UHMW sheets come to us from 1/8
thk thru 4" thk and are either 48 x 120 or 60 x 120 size.

We cut it with a CNC Schelling panel saw 18" dia blade 32 hp. I buy the
blades from Woodworker Supply and order Freud heavy body wood rip blades ,
actually P/N LM71M 16" dia 28 teeth works very well and are dirt cheap at
80.00 ea..


Eric - If you're going to be ripping a lot of this stuff, I suggest
thin-kerf blades. I use 10" 24-tooth Freud red blades for thin
material. Above an inch in thickness, you'll want to be getting
flat-top teeth and get as agressive a ripping profile as you can find.




If you use a fine tooth blade on UHMW the shavings will be very stringy and
get wraped around things. Blade or cutters must be very sharp or any plastic
material will heat and induce some warpage possible closing behind the blade
as you cut it.

UHMW can kick back out of a saw worse than wood, before we got the CNC saw
workers would get hit from pcs coming out of the UNISAW at warp speed usally
hitting them in the family jewles. Never bring the cut pc over the saw blade
because if you drop it (very slippery material)on the blade UHMW is soft and
the blade grabs it very well and throws it back at you, Stand slightly to
the left so when this happens to you it will miss you and just put a hole in
the wall instead of you.

Eric - He's absolutely right about UHMW getting thrown by saws. I used
to get it thrown at me all the time (Usually in the gut). I have found
the best way to beat that is to cover the entire saw face with a sheet
of UHMW (I use 3/4") and I have designed sleds and special fences that
sit on top of the sheet. Since then the number of times the saw has
thrown pieces back to me is down near zero.




Use coarse tooth blade for UHMW use sharp blades or you could get hurt.

I'm rambling again sorry
UHMW has a tolerance of +/- 10% for thickness . This means .75 thk material
can vary +.075 to -.075 from the stated .75 anywhere in this sheet. I
rarely see a sht that is perfictley flat we use the next higher thickness
and mill or route the surface on CNC routers and CNC mills to get flat
parts.

Eric - I have noticed a lot of material benefits from being surface
planed. We surface plane thicker materials if they have scratches or
imperfections.



We only sell to commercial accounts unfortunately and we throw cutoffs of
this material in the garbage each and every day. We have collected 4ft x 4ft
x 4ft containers of it and tried to sell it to recyclers it but its not
worth the freight cost ,it would cost us more than they will pay per pound
to send it to them.

If your using it for a fence liner on the table saw you could joint and
plane it to get it flat. It does joint and plane very well, again use sharp
blades. The chips tend to get stuck in the jointer so have the compressed
air gun handy and have someone blow on the cutter head while you push the pc
over the jointer. USE a push block and take light cuts.



Eric - That brings up a good point - We only use surface planers that
have back chip ejection ports. If your planer has a side ejection port
it could get clogged very quickly. I find that you have to check the
spaces beside the rollers frequently, as some of the material can get
caught there.
As far as jointers go, it's going to help if your jointer has a
clear, straight path to eject the chips. I've recently bought a Jet
jointer with a stand and I'm going to have to remove the stand and make
another one because this thing has a little 4" hole to eject chips off
the side. Sucker's going to clog in about 10 seconds.



I will sign off now as this has stretched out longer than I intended.

Thanks
Kevin


wrote in message
oups.com...
For the past 10 years or so, I have been sorcing UHMW polyethylene from
manufacturers, packaging the pieces in assortments and selling them
through woodworking distributors like Lee Valley and Woodcraft.
I have noticed that the sales at Woodcraft don't seem to be on a
par with the sales in Canada (they're lower) and I wonder why that is.
I have some huge new supplies available of UHMW and I'm looking
to expand sales.
I have noticed that some of the other woodworking distributors
either don't sell UHMW and those that do don't seem to carry much of
it.
I have noticed that Ebay and Amazon.com have sellers of UHMW on
them.


My questions are - Those of you that buy UHMW, where do you get
it?
- If you could get offcuts of UHMW at a
good price on Ebay, would you buy it there?

Thanx.