5 replies to this topic

[mreibman]

I was cutting some arms yesterday and getting some really subpar results.

 

I determined the cause had to be something with the bit, since all else seemed fine. So I looked at it with a 25x magnifier, and lo and behold it's chipped.

 

Here's a picture of the chip at max magnification from my camera (like 8x):

 

 

I don't know whether the bit is carbide or diamond.

 

Is there a recommended way to repair the bit (probably by grinding)? Is there a service to repair the bits? Or will I just have to bite the bullet and buy a new bit?

 

Any suggestions or advice would be appreciated.

[wbugenis]

The  1/4" polycrystalline diamond turning tool  (E-4) from J & M Diamond is the one to get. 

 

It has a 60-degree tip which is enough clearance even for capped commutators.

 

You can order from them yourself or have your raceway stock them.

 

Hudy replacements are way too expensive

[havlicek]

What Bill said (as usual). I use the ones he suggested in my XiPP, and they cut nicely and last and last.

 

Diamond bits are subject to chipping even more than solid carbide which is a really brittle material also. With proper care, these bits last for hundreds of cuts.

[John Streisguth]

We go through hundreds of PCD tips every year.  Unless you do volume, relaps are hardly worth it, especially in the case of a big chip like that.  As John said, they last a long time but they are very brittle, almost like glass. 

[mreibman]

Thanks a bunch! That's $54.50 for the bit and another $10 to ship it.
 
I am gathering that's PCD as opposed to CBN on the option?
 
PCD - CBN - Natural Diamond Turning Tools
 
But the shape of the bit also makes more sense from a cutting standpoint as it's made to go both directions.

[Phil Hackett]

CBN is used on hardened steel and is almost as expensive as a monolithic diamond tool. Not sure how it would work for copper with interrupted cutting.