[martinw]

Dear Geof,

That advice is brilliant!

Yes, I can get PCB carbide 2.0mm drills, but from memory, the cutting thread may be a
a "bit" short for 10mm stock.

The strange thing was that even the first hole I drilled with the 2.0mm HSS stubby was tight. I blew out all the swarf with an air duster before trying the first press fit. No luck.
I then tried going down the original hole again , just hand centreing, and the hole was still too small.

Anyway, I'll try and get a 2mm carbit bit and see what happens.

Thanks,

Best wishes,

Martin

[Geof]

....I then tried going down the original hole again , just hand centreing, and the hole was still too small.

Anyway, I'll try and get a 2mm carbit bit and see what happens.

Thanks,

Best wishes,

Martin

What happens here, at least this is my hypothesis for which I only have my own knowledge of the properties of plastics to fall back upon, is that the plastic simply flows around the cutting edge. You are getting a lot of rubbing, in an acrylic or polycarbonate, you would get melting as well; epoxy has a higher melting point, actually I think it starts to char before it melts, and you have the filler, so you don't see melting.

Even if you went in with a brand new carbide drill you may still be unable to enlarge the hole.

[martinw]

Dear Geof,

Hmmm...

Now you come to mention it, there was a bit of a stink when I drilled the holes. As you suggest, that could indicate too high rpms and melting. I really hate plastics!

Anyway, I will try the carbide bit/ solvent cooling/ slow speed route. It does so happen that I have a 250 ml container of IPA in the van.

Thanks again,

Best wishes,

Martin

[Mitsui Seiki]

Did somebody say BRONZE ! HMMMM lol

I have not cut any of Stellite products, thanks for the info.

http://en.wikipedia.org/wiki/Stellite paints a different picture of this material.

Is this the same stuff ? http://www.stellite.com/

Nope says nothing about Bonze!

Yes, I think it's the same material.

[dapoling]

Yes, I think it's the same material.

Sounds like pretty nasty stuff, off hand do you know what SFPM you were using for HHS and Carbide and chip load?

[Mitsui Seiki]

Sounds like pretty nasty stuff, off hand do you know what SFPM you were using for HHS and Carbide and chip load?

It's been a while since I ran these parts but I believe the face mill (Coromill 390,Gc1025 inserts) had 80m/min 0,05 chip load and 4 inserts. S800 F160.

[RICHARD ZASTROW]

Bob, Well said, particularly not giving them your time.

Dick Z

[lerman]

when you could use a Forstner bit?

Works just fine in aluminum. Although it works better in a milling machine than in a drill press. I don't want to know how it works in a hand drill. :-)

Ken