roughing scraper carbide bits?

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metalmagpie

Titanium

Joined

May 22, 2006

Location

Seattle

• Apr 17, 2020

• #1

I haven't heard this question before.

Suppose I have a Biax tool or two that clamp carbide inserts. Further, suppose I buy one or more inserts that are basically square, but actually have two of their edges ground with a radius.

I have heard people here suggest that you should sharpen such an insert on all 4 sides so that you have 8 cutting surfaces.

Here comes my question - I have a tool grinder with 100 grit CBN wheels in good condition. Would this be suitable for roughing out a radius on a carbide insert? I don't have any green wheels, and the only diamond wheel I have is pretty much for lapping. It would take forever to form a radius.

Thanks!

metalmagpie

 

sfriedberg

Diamond

Joined

Oct 14, 2010

Location

Oregon, USA

• Apr 17, 2020

• #2

I have reshaped a carbide scraper on a plated diamond wheel. Don't know the grit, but maybe 220 or 320 effective. You have to be a bit patient, but it's much faster than lapping. Maybe 5-10 minutes from a completely new radius. The resulting edge is not ready for scraping. It needs lots of attention on a lapping wheel to remove the scratches and establish a consistent 95 degree (or thereabouts) included angle on each face edge.

 

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metalmagpie

Titanium

Joined

May 22, 2006

Location

Seattle

• Apr 17, 2020

• #3

sfriedberg said:

I have reshaped a carbide scraper on a plated diamond wheel. Don't know the grit, but maybe 220 or 320 effective. You have to be a bit patient, but it's much faster than lapping. Maybe 5-10 minutes from a completely new radius. The resulting edge is not ready for scraping. It needs lots of attention on a lapping wheel to remove the scratches and establish a consistent 95 degree (or thereabouts) included angle on each face edge.

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Thank you, and that agrees with my experience. The present question, however, is can I grind carbide with a CBN wheel?

metalmagpie

 

gbent

Diamond

Joined

Mar 14, 2005

Location

Kansas

• Apr 18, 2020

• #4

metalmagpie said:

Thank you, and that agrees with my experience. The present question, however, is can I grind carbide with a CBN wheel?

metalmagpie

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NO have to have 16 chars now.

 

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DennisCA

Hot Rolled

Joined

Oct 20, 2017

• Apr 18, 2020

• #5

I used a 1000 grit diamond wheel and went from 100 to 60 mm radius on my scraper blade today, took 5 minutes. Then I swapped to a 3000 grit wheel and it was ready to use.

My simple (and temporary) setup:

 

ironsmith89

Aluminum

Joined

Aug 29, 2014

Location

lennox, sd, USA

• Apr 18, 2020

• #6

Yes CBN will grind carbide or steel.

 

eKretz

Diamond; Mod Squad

Joined

Mar 27, 2005

Location

Northwest Indiana, USA

• Apr 18, 2020

• #7

CBN will grind carbide but nowhere near as well as diamond. It will rapidly require more pressure and dull/wear out faster also. DAMHIKT. There's a reason it hasn't just universally replaced diamond.

 

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lucky7

Titanium

Joined

Sep 6, 2008

Location

Canada

• Apr 18, 2020

• #8

My slow speed Accufinish with a 120 diamond grit wheel roughs out carbide blanks very quickly. A quick touch up with the 1200 grit and it’s good to go. Imho, having tried a green wheel and a few other dodges, this is the way to go for carbide scrapers. Don’t forget, you’re also going to be resharpening every half hour in use, so why not get/make a system that is quick?

Btw, big thanks to PM member Other Brother, who noted in a youtube how often he resharpens. I was wasting time not resharpening often enough..

L7

 

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dian

Titanium

Joined

Feb 22, 2010

Location

ch

• Apr 29, 2020

• #9

this will rough out a biax bit in 5 seonds. its about 10 grit. i have a radius contraption for it.

 

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rimcanyon

Diamond

Joined

Sep 28, 2002

Location

Salinas, CA USA

• Apr 29, 2020

• #10

lucky7 said:

Btw, big thanks to PM member Other Brother, who noted in a youtube how often he resharpens. I was wasting time not resharpening often enough..

L7

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How often do you resharpen?

 

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CarbideBob

Diamond

Joined

Jan 14, 2007

Location

Flushing/Flint, Michigan

• Apr 29, 2020

• #11

Yes it will work if not a lot to be removed, some spray coolant will help
Better than a green wheel by miles.
100 grit is not a finishing wheel. Look at the edge under 300 to 500x magnification.
At this grit in diamond or CBN expect .0005 to .002 or much worse edge chips or grain grooves when grinding carbide.
Bob

 

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lucky7

Titanium

Joined

Sep 6, 2008

Location

Canada

• Apr 29, 2020

• #12

Rimcanyon, sharpen every 20-30 minutes of cutting time. Cuts nicer and has helped me become way more consistent in scraping depth and scraping straight down. Note, I’m not a pro scraper!

L7