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Ph Horn inserts have incomplete nose radius. Is this acceptable?

guythatbrews

Titanium
Joined
Dec 14, 2017
Location
MO, USA
I've seen this condition on PH Horn tools before. Mitsubishi as well so not junk stuff. I brought this to the attention of Mitsubishi talking heads at IMTS but for once they did not talk, and nothing ever came of it.

20230504_115146.jpg

Here you can see the radius is not tangent to the tool flanks.

20230504_115134.jpg

In this shot the R.008 is offset both ways .008. It looks better along the X axis than the Y. The Y axis end of the radius is actually slightly short of .008.

This is a 3mm minimum bore boring bar. The part radius is functional and I routinely must cut about .015 radii with +-.002 tolerance tangent to the face and bore. I can't seem to detect any defect at the tangent points with a cast of the part, and disregarding the slight shortness of the TNR in Y that is what I would expect. But the sharp at the point of tangency has to affect the surface finish along face and bore. The finish required is usually 32 max but sometimes 16 max. I've never been rejected for surface finish or size and this is a 30 year customer. Full disclosure neither I nor my customer can actually check the finish on the radius we can check the face and bore. The longstanding agreement is a close visual inspection of the radius. I really can't detect any problems with this flawed condition.

But the inserts do cost $30 each. Should I be expecting a better tangency condition on the insert? Should I complain? We used to have a very good PH Horn salesman that would come by but he retired. He would have been great to talk to. But I've seen nobody from PH Horn in probably 10 years so phone support is likely my only resource.
 
Good questions, I'd go ahead and contact Horn and see what they say. For that money you should be getting a geometrically correct insert.

It may require a change of boring setup, but I used to get custom inserts from Thinbit that were always to spec and consistent. If there's no help from Horn, perhaps check out Thin.

 
That is a sort of bad part but likely still within spec.
We call this a chopped radius. Flanks are in the right spot, tip in the right spot but ugly blend.
It is only a .008 rad so the mismatch here from ugly to good is only a few tenths.
I should not say so but at an .008 rad I would likely ship this or a bit worse as okay limit. Then adjust, dress whatever to try to make it better.
People expect perfect but will not pay the price for "A" tolerance inserts.
I know it looks poopy and you expect better.
Would you rather the rad was smeared into the sides by a tenth or two? Then users will complain that the sides do not end where they should.

I think it is okay. You may be wanting too much for $30
 
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Would you rather the rad was smeared into the sides by a tenth or two? Then users will complain that the sides do not end where they should.

Bob, wouldn't that be better in a facing application, as during a finish pass from minor to major you'd just be cutting on the radius, and the "smear" would never be in contact with the face?

And I do think for a relatively small commercial insert that doing a better job than what's shown should be expected for $30. But I've never done this work myself, so perhaps that's not reasonable?
 
If we know the application a "smear" can be better as it sort of a wiper.
Other times this is never to be done due to loading/chatter problems behind the rad where the heel clear is poop and a point is better.
These are catalog tools.
This thing is within .001 true to form..... But yes ugly and oh-my. We chase this a lot.
For sure I understand the OP not liking it and during a batch grind I would not like it either and make that know rather firmly to all involved.
But tiny rads on a carbide tool can be .... nightmares at 100 or 300x.
 
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Huh, I interpretted "smear" as an over-rotation of the insert fixture so the radius blend cuts into the flank a bit, not being a flat (which is what I interpret as a wiper), but again, no experience in your biz.
 
Huh, I interpretted "smear" as an over-rotation of the insert fixture so the radius blend cuts into the flank a bit, not being a flat (which is what I interpret as a wiper), but again, no experience in your biz.
No not an over rotate. The smear is still a radius of sorts. Just that it's tail is not where it should be. To me a wiper is also a radius maybe 3 to 6 inch radius.
This tool would normally be done on a swing style or maybe an IC grinder.
On both you get micron level grooves in the wheel or axis loading things between the side and rad.
Thing here is that we are dealing with a .008 rad. Lay this out in your CAD and see how much room you have to work inside between perfect and the 5-10 degree line of not tangent.
I will always agree with the customer as that is who you really need make happy.
On the other side there is sort of a limit for a price tag.
30 bucks and he may have bought 5 or ten? Do not come knocking on my door.
Maybe this tool has a chipbreaker on top. In this case a perfect blend is just this side of impossible.

On this tip is it bad or good to all you out there?
I would really like to see feedback so lets do it.
Thanks to the OP... good call.
 
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The pics are 50x. No chipbreaker. I only bought two of these @ $30 each but my guess is Horn has a couple hundred in stock and likely make them in big production lots, not a few at a time. I've bought custom tools made on standard blanks from Horn before and they are not cheap. I think the minimum is 10 and from past experience I'd expect to pay about $100 each for one like this if it was very custom.

I know zero about making these inserts. How does the process differ from making say a cdcd51 ground insert? I use a bunch of kennametal (formerly circle) inserts and I've never seen this defect on them. Maybe it's because they are easier to grind. I sure don't know.

It does bug me a little if I sent my customer turned parts that showed this defect I'd hear about it, and they might even be rejected. And the parts are nowhere near $30 each. The radius is functional and they are picky about it.
 
The Ph bit was fun BUT neutral is 7, so 6 is just a touch acidic. I always enjoy seeing a bit of Chemistry here. :-) Don't know a thing about ball players.
...lew...
 








 
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