[Newbie] How To Repair Slot In Van Norman Collets

[Bob V]

Hi,
I just bought a Van Norman 16 mill, and in going over the tooling that came with it, I found that 10 out of 20 or so collets that came with the machine have damaged key slots in the collets. I'm pretty sure this happened because someone cranked the drawbar up with the key in the spindle resting on the side of the keyway (not in the keyway). I found out this is very easy to do!
Anyways, these collets are very expensive since they have the Van Norman 5V (or "C") external taper-- so I want to repair these collets with the mill AFTER I get some experience with the machine--maybe in a month or so.
I found a drawing of the 5V collet (attached).
Questions:
Can someone tell me what tool hardness is needed to clean up these slots? (I really have no idea what steel the collets are made of).

Do I just order a "slot cutter" from say, Niagra, with a diameter of .5 inches and a slot cutting width of .188"? (I'll take the next month to figure out beginner horizontal milling, layout, etc etc.)

Thanks in advance,
Bob

 

[JimDawson]

Do the file test, if you can cut it with a file, you can cut it with a HSS cutter.

 

[T Bredehoft]

If you can't cut it with a file, it's probably too hard (springy) for you to be able to have much influence on it. Sorry, bad news.

 

[brino]

...and if they are hard possibly clean up the slots with a thin grinding/cut-off wheel. Even one from a little dremel tool could be used. You could try free hand, or with the dremel mounted. If you do any grinding on lathe or mill be sure to cover the ways, bearings, spindles, etc. First.

 

[Karl_T]

Yep, those collets will be harder than a hooker's heart.

I wouldn't worry too much. Carefully grind away the high spots, maybe by just using a stone. the dents won't hurt.

Karl

 

[Bob V]

Thanks for all the help-- I have a Dremel--I'll have at it!

 

[Ebel440]

I've used a file on r8 collets so it may work on yours but I've never seen one so I'm not sure. You should check the key in the spindle as well. I have somebody at my work who likes to put the collet in wrong and when he does it the pin in the spindle has gotten crushed causing it to damage other collets.

 

[Bob V]

I've used a file on r8 collets so it may work on yours but I've never seen one so I'm not sure. You should check the key in the spindle as well. I have somebody at my work who likes to put the collet in wrong and when he does it the pin in the spindle has gotten crushed causing it to damage other collets.

I think that's exactly what happened to damage the 10 or so damaged collets on my machine!

 

[Ebel440]

If that's the case blue up a good collet and stick it in the spindle but don't tighten the drawbar. Take it out and see where the blurring was removed. I needed the machine in a hurry once I just went in with a needle file and narrowed the pin so it fit again. But the spindle was harder then the file so it couldn't damage the bore.