Can you identify this carbide insert?

Dynahoe Dave

Dynahoe Dave

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Carbide Insert 01.jpg

I got it with a bunch of misc. cutters somewhere. Long before I got my Bridgport. Made the holder out of 1/2" diameter bar stock and bored a hole. It works. But the insert won't last forever... I looked on ebay, but they are all listed by part numbers, and I have no idea what the thing is, other than carbide, and small. I used a #4-40 screw to hold it on the bar. The width at the bottom is about .480". The visible face is slightly bigger all the way around than the back face.
 
Doesn't look like a cutting insert, looks like an insert anvil to me.
 
I did notice there are triangle ones that have 3 equal sides. Yes, this one has 2 points ground off - The grind marks look pretty much like the other faces. I can look up TPG 3 and see if it looks like it started as one of those.
 
As darkzero pointed out, it could also be an anvil, if you set a TPU or G 300 series insert on top of it, and the tapers matched at the interface, you could probably think of it as an anvil, but some inserts also have the countersunk hole in the center as well.
 
TPG inserts don't have a screw hole for mounting. If it was a cutting insert, if it has a countersink hole for a screw it could be TCMT. TCMT would have a 7° relief angle edges. TNMG also has a hole but it's not for a screw mount (no countersink) & has 0° relief. May not mean much though if that was a modified insert.

If that was a cutting insert it has been heavily modified, doubt you will find an exact replacement for it. Would need to measure the inscribed circle to figure out the size. 1/4" IC is size 2, 3/8" IC is size 3, 1/2" IC is 4.

I still think it looks more like an insert anvil, like for TNMG inserts, but modified as benmychree pointed out. Anvils are also made of carbide & some people have tried to use them as cutters not knowing.
 
I will measure it and udate. It does have a #4 clearance hole, and it is countersunk. The edges are ground at an angle, so the front face is bigger than the back. It's small, but I'll attempt to measure the angle also. An unmodified triangle one would work for most of the stuff I figure I'll be doing anyway.
 
OK... It's marked SM-42 on the face opposite the picture, but that gets me all sorts of carbide bits, not just inserts...
On that same face, the reverse of the one in the picture, the 2 unmodified parts of the edges, there is a small [not sure what to call it] hollow grind. Like the inverse of a fillet, making a sharp edge on the edge, like I have seen on pictures of inserts that are ground that way.
The 2 longer edges are ground at 90 degrees from the faces. The 2 short edges are ground at 7 degrees, and the "bottom"edge is at 8 degrees.These faces are just planes with sharp corners. It did the cutting I wanted to do yesterday. It's kind of hard to determine the inscribed circle, but it looks close to 3/8"
 
Come to think of it, maybe it's not anvil (aka seats). Insert anvils are usually used on larger tools, 1/2" IC negative inserts (not screw down type). Well some 3/8" IC threading tools have anvils but they're for changing helix angle.

I'm not sure what SM-42 means but a search came up with this pic of Kennametal inserts.

sm-42.jpg
 
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