Bushing material question

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John Evans
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Re: Bushing material question

Post by John Evans » Thu Jul 14, 2022 10:58 pm

Part it it off using the lathe.
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seal killer
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Re: Bushing material question

Post by seal killer » Fri Jul 15, 2022 12:40 pm

Harold and All--

[Note to All: This is taking a long time because I am not in a hurry and my primary objective is to continue learning, especially as I've been away from my shop for years. I appreciate you sticking with me and all the help you give.]

I took your advice on ditching the insert-based tool. I found tool I had either bought or ground long ago that looked right to me. I tried it on the face of the phosphor bronze work piece with good results . . .
much better face finish.jpg
Next I tried it on the diameter of the workpiece with very poor results . . .
no better diameter finish.jpg
Here is a closeup of the cutter (I can take far better pictures of all, if needed) . . .
cutter.jpg
Can you tell where I've gone wrong on improving the finish on the diameter?

Thank you.
--Bill
You are what you write.

Harold_V
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Re: Bushing material question

Post by Harold_V » Fri Jul 15, 2022 3:49 pm

I see a couple things with the tool that may be an issue. First is that the chip breaker appears to have yielded negative rake. That may or may not be an illusion, however. A photo of the end of the tool taken in line with the tool would reveal the actual geometry. The second thing is obvious---the tool has no radius, and that's important if you hope to achieve a fine finish. Simply honing the tool to improve surface finish should make a difference, and the recommended radius could then be created. It doesn't take a lot, even ten thou makes a huge difference.

A second look gives me cause to ask----is there any relief on the end of the tool? It has a tendency to look as if there is not. A square end will not perform well.

H
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seal killer
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Re: Bushing material question

Post by seal killer » Fri Jul 22, 2022 2:03 pm

Harold and All--

Sorry for taking so long to get back to this issue. I brush hogged a few acres for a neighbor and graded the road and . . .

Harold, do these pictures tell you what you need to know? The cutter has no visible radius, but it does have clearance.

No radius . . .
radius.jpg
Clearance . . .
Clearance.jpg
--Bill
You are what you write.

Harold_V
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Re: Bushing material question

Post by Harold_V » Fri Jul 22, 2022 3:48 pm

If I can safely assume that the tool has an equal amount of relief on the side, then that issue is likely moot, but I am troubled by the chip breaker, which appears to turn negative all too quickly. This material will respond better to being shorn than it will to being pushed by negative rake, although excessive positive rake can create its own issues. A balance of positive rake and limited relief will generally prevent self feeding, however. Here's a picture of what I'd suggest is acceptable in chip breaker form:
Boring tool3.jpg
A sharp corner will rarely provide a decent finish, but with any top rake on a cutting tool one must limit the amount of radius, as the cutting edge moves away from center rapidly. At a minimum, the tool should be honed on both the front and cutting side, then a minimal radius stoned on. If the tool geometry is correct, the top and bottom edges will provide a guide for stoning, so the cutting edge isn't rounded beyond being useful. I'm talking about rounding that removes relief in this instance, not the size of the radius. Ten thou would be an acceptable tip radius in this case, but maintaining the necessary relief.

H
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seal killer
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Re: Bushing material question

Post by seal killer » Thu Aug 04, 2022 2:31 pm

Harold and All--

I'm back. I have been grading the road and other stuff. My internet connection has been worthless. (Hughesnet.) Another reason is that it has been over a hundred here. The shop is not air conditioned, yet.

I followed Harold's advice about the clearances and bit radius with great results. My photo could be better. I was lazy and used my V60 ThinQ which is supposed to have a great camera. It does. Maybe not for closeup work, though. I should have got the Nikon out with the closeup lens. Next time.

Anyway, take a look . . .
Better finish.jpg
--Bill
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Bill Shields
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Re: Bushing material question

Post by Bill Shields » Thu Aug 04, 2022 3:29 pm

:mrgreen:
Too many things going on to bother listing them.

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seal killer
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Re: Bushing material question

Post by seal killer » Thu Aug 04, 2022 4:28 pm

All and Bill--

Better pictures . . .
better finish resized.jpg


I increased the clearance on the indicated faces and increased the radius . . .
radius resized and text.jpg
--Bill
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GlennW
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Re: Bushing material question

Post by GlennW » Thu Aug 04, 2022 5:15 pm

Excellent!
Glenn

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John Evans
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Re: Bushing material question

Post by John Evans » Thu Aug 04, 2022 10:53 pm

Seal Killer : Check your PM in box.
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