I need some advice on cutting some Lexan Lenses.

[daniel]

Hey guys, I got a job cutting some lenes down to smaller lenses. There are no extra's for me to experiment with so I wanted to talk to you guys first. Here is what I've got,
(1) Lexan material 1/8" thick
(2) Jig that uses vacuum and cotter pins to hold part and scrap (See Picture)
(3) 1/4' Onsrude upcut spiral O flute on a colombo spindle.

I'm looking for advice on, feed, speed, cut depth, final pass allowance(full depth clean up cut).

Any advise is much appreciated. I have attached a picture of the jig.

http://ioiopi.com/?attachment_id=184
http://ioiopi.com/?attachment_id=184

[bleeth]

You should be able to do this in one go if your vac is good. Ramp in at a slow plunge (.25-.50), keep the feed fairly low (1.5) and spin around 8/12K. Might be worth picking up a scrap and experimenting first.
I actually prefer a straight single flute o-flute for a lot of plastic work as it keeps material from hopping, and as long as I don't cut too fast have very little cleanup other than normal edge finishing.

[Nate Zellmer]

I second the 1/8" straight bit. I did a similar project for cutting notches into lenses. The Aspire file shows 1 ips at 14000 rpm. The Onsrud 61-040 was like a hot knife through butter.

Nate

[knight_toolworks]

might cost less to buy new material so you don't have to battle hold down and making a jig.

[bleeth]

To clarify: My suggestion was for a 1/4" bit.

[daniel]

might cost less to buy new material so you don't have to battle hold down and making a jig.

The Job doesn't pay enough for it, plus I like the idea of recycling the wrong ones so that I don't just throw them in the garbage/land fill, plus I already have the jig made.

I would like to try the straight o flute but I'm not sure if I can obtain one in time, but I'm going to try.

Thanks guys!

[knight_toolworks]

lexan is pretty grabby and wants to lift up. I use as small of a bit as I can 1/8" would be plenty a 2f straight bit will work fine.