Downcut bit question.

[nodnerb]

Hello all.

I was wondering if I should be using the same feeds and speeds with a downcut bit as an upcut, or if a downcut bit is even appropriate for what I am doing.

I am cutting two sheets stuck together of polycarbonate totaling 0.134" thick. I have run the job before with an upcut and while it worked out ok, the poly was lifting throughout any of the 2d profiling and was pretty close to turning catastrophic.

So is a downcut bit my best option here?

Thanks in advance for any help.

[dana_swift]

The difference between an up and down spiral is less than the difference between a new and old bit of either type. Either type of bit leaves a channel behind as it cuts and many of the chips seem to "ride around the fluting" until they reach the open channel and exit, some ride up and exit above the channel.

If you have any doubt try to make some test cuts in your scrap. I suspect you will like down-spiral more as it helps hold the material down.

Good luck- and keep us "posted"-

D

[nodnerb]

Great! Thanks for the help.
I still have a hard time wrapping my head around the whole "downcut" concept though. It just seems wrong. lol

[bleeth]

A downcutter can hold warm plastic in the cut which can weld back on. You are probably best with an o-flute straightcutter.

[knight_toolworks]

yes upcut will make edge cleaning work. a single or 2f straight bit will work great I run them around 8k. I have been using a 1/8" bit for the job and I can cut 5 hours on a bit. I just use amana or whiteside they are 14.00 or less each.