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Engine boring bar inserts

Larry Dickman

Titanium
Joined
Jan 30, 2014
Location
Temecula, Ca
Im not sure, I am not that familiar with inserts.

Neither am I. This has nothing to do with engine work, but we run a couple parts that are very abrasive cast aluminum. Carbide inserts would wear, so we had to constantly adjust size (+/-.0002)
Then I tried using PCD inserts. No comparison. Finish like a mirror, haven't had to adjust for size in a couple years.

FWIW, the inserts I'm using are Sumitomo.
 

CarbideBob

Diamond
Joined
Jan 14, 2007
Location
Flushing/Flint, Michigan
Hi Bob, those numbers are pretty close to what I'd expect for a 1/4" I.C. and a 1/32 corner radius. And he's already confirmed the I.C. and thickness (3/32")
Perhaps your definition of close and mine are different in the insert world. .. I might be too picky about such.:)
Numbers work out to .260 IC and .037 corner rad.
Why strange? That is outside the world of even poop "M" inserts. It is at the low end of a "R" which means somebody forgot to grind the IC.
It is near a 21.52, this a common brake drum/disc insert.
Looking for in stock somewhere on the planet with a 3 or 4 in the rad shows nothing. I'm still searching.

This rad should in a perfect world should only leave less than a tenth peak to valley. Given the unground and holder layout a .001/.002 back side burr would not be unexpected.
Options: Try a C or P insert. Note that the back wall of the holder is zero so care when loading.
Send me some used or new inserts to me and I can grind the IC and some different rad sizes to try. I can do this....OP will have to pay shipping costs.

I expect that is steel sleeved two strokes. If so PCD is not going to work. The interruption on the ports another problem for tool edge.
T land helps this but still the added and released tool pressure not so good for roundness.
Bob
 
Last edited:

jl1132

Plastic
Joined
Jun 22, 2019
Perhaps your definition of close and mine are different in the insert world. .. I might be too picky about such.:)
Numbers work out to .260 IC and .037 corner rad.
Why strange? That is outside the world of even poop "M" inserts. It is at the low end of a "R" which means somebody forgot to grind the IC.
It is near a 21.52, this a common brake drum/disc insert.
Looking for in stock somewhere on the planet with a 3 or 4 in the rad shows nothing. I'm still searching.

This rad should in a perfect world should only leave less than a tenth peak to valley. Given the unground and holder layout a .001/.002 back side burr would not be unexpected.
Options: Try a C or P insert. Note that the back wall of the holder is zero so care when loading.
Send me some used or new inserts to me and I can grind the IC and some different rad sizes to try. I can do this....OP will have to pay shipping costs.

I expect that is steel sleeved two strokes. If so PCD is not going to work. The interruption on the ports another problem for tool edge.
T land helps this but still the added and released tool pressure not so good for roundness.
Bob

Thank you, I'll send you a PM as to where I could send you some of these.
 








 
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