Best way to hold drill in VN 12 ?

[stoneaxe]

Looking for suggestions- I was running 3/4" bit with 1/2" shank in a collet and had it slip-

Should I use a 1/2 " end mill holder, and grind a flat on the drill shank ?

I could make a VN 5v to JT taper arbor, to hold a chuck, but that burns a lot of Z travel.

Or maybe a 5v to MT2 and use MT shank drills? It would need to be MT2, not enough room for MT3.
Naturally, all my taper shank drills are MT3.....

Or maybe just pay closer attention to getting every last trace of oil off the drill shank, and increase torque on the drawbar? I tightened it the same way as any end mill- Guessing about 20 ft lbs? 2 -10" wrenches with a moderate pull. I have no idea what a collet torque should normally be.
BTW, the spindle taper, collet and drill bit shank are in new condition.
?

 

[plastikdreams]

What are you drilling that you are slipping in a collet.

 

[stoneaxe]

What are you drilling that you are slipping in a collet.

3/8" mild steel. It just slipped for 1/2 second, I backed off the feed (manual crank) and it resumed drilling.

 

[plastikdreams]

Maybe a sharpened drill

 

[stoneaxe]

Maybe a sharpened drill

Brand new- first holes it ever drilled-and it cut well to.

 

[plastikdreams]

Sucks when that happens lol. Damn thing tries to take your arm off.

 

[Ohio Mike]

3/8" mild steel. It just slipped for 1/2 second, I backed off the feed (manual crank) and it resumed drilling.

That is the bad thing about a machine like the VN12 as the lack of quill makes it difficult to feel the feed pressure. That said the lack of a quill is also its strong point since it makes it a more rigid mill. So maybe you were just pushing the drill to hard?

 

[stoneaxe]

That is the bad thing about a machine like the VN12 as the lack of quill makes it difficult to feel the feed pressure. That said the lack of a quill is also its strong point since it makes it a more rigid mill. So maybe you were just pushing the drill to hard?

Could be- I suspect I just did not pay enough attention to a clean dry shank and torque- thinking about it, a 3/4" drill must have a much higher load on it than a 1/2" end mill.
Maybe an end mill holder with a flat ground on the drill bit would be better.

 

[reggie_obe]

Van Norman did make adapters for the 5V spindle taper, 5V to MT2 was available as well as 5V to B&S.
They do appear for sale every so often.

 

[stoneaxe]

Van Norman did make adapters for the 5V spindle taper, 5V to MT2 was available as well as 5V to B&S.
They do appear for sale every so often.

I may have a 5V to B+S around- don't know where I would find a drill with that taper though.
Usually I use a 1/2" shank Silver and Deming drill, so maybe I will just grind flats on them and use an end mill holder.

 

[svs]

I may have a 5V to B+S around- don't know where I would find a drill with that taper though.
Usually I use a 1/2" shank Silver and Deming drill, so maybe I will just grind flats on them and use an end mill holder.

Tighten the draw bar a bit. 20ft.-lbs sounds light to me.

I use S&D bits up to 1 1/2” with R-8 collets. “Snug” isn’t enough. “Firm” is.

 

[Rick Hand]

I have a 5V to MT2 adapter that I use the drill chuck from my lathe tailstock in. Some people talk about modifying R8 tooling to fit 5V. I have intended to order a collet holder to modify for some time now and maybe a shell mill arbor.