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toms752
07-07-2010, 02:42 PM
been working with very thick gray pvc lately. i'm having a hell of a hard time finding drills/feeds/speeds that are any good in this stuff. it mills incredibly easily and for the most part drills fairly easily too, except during deep hole drilling(anything deeper than an inch or so). the drills just gum up and end up splitting the part.

i've played around with feeds and speeds but i'm not having much luck. so far it seems like the drills i should be using are highly polished, with a fairly sharp point.

any ideas?

bwprice100
07-07-2010, 05:01 PM
Hi

Are you using a drill with a quicker than normal spiral?

Brian

Kipper
07-07-2010, 05:06 PM
been working with very thick gray pvc lately. i'm having a hell of a hard time finding drills/feeds/speeds that are any good in this stuff. it mills incredibly easily and for the most part drills fairly easily too, except during deep hole drilling(anything deeper than an inch or so). the drills just gum up and end up splitting the part.

i've played around with feeds and speeds but i'm not having much luck. so far it seems like the drills i should be using are highly polished, with a fairly sharp point.

any ideas? You could try keeping it cool?

toms752
07-07-2010, 08:04 PM
it's flooded with coolant and the drills are standard helix and spiral 118* point. there just seems to be nothing i can do to keep the stuff from melting

brunog
07-07-2010, 08:17 PM
Try drilling a small thickness at a time and retract the drill bit out of teh piece after each "peck". This will permit the part to cool off.

Best regards

Bruno

toms752
07-08-2010, 12:00 PM
that's what i'm doing right now and it still doesn't seem to help

brunog
07-08-2010, 01:04 PM
What diameter hole are you drilling?
What RPM are you drilling at?
Are you drilling on a drillpress or CNC mill?

Best regards

Bruno

bwprice100
07-08-2010, 04:15 PM
.
I would suggest a drill with a larger helix angle to increase the effective rake angle. This require less cutting force and thus less heat generated.

Also a sharper point angle will help along with higher feedrate.
Inconjuction with this an increased lip relief angle will help with the higher feed rate.

Lightly buffing the cutting edges will help produce a sharper edge.

Spray the drill with PTFE spray and use an air blast instead of coolant.

Worth a try:)

Brian