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Toolbit offhand grinding - which wheel?

leeko

Stainless
Joined
Jun 30, 2012
Location
Chicago, USA
Hi all,

I picked up a bench grinder with a diamond cup wheel and toolrest on one side, and a straight diamond wheel with no rest on the other side.

I'm planning to use this for grinding brazed carbide bits, or retouching the occasional insert.

Can anyone explain what the straight wheel is needed for, that the cup wheel can't do? The only thing i can think of would be grinding a chip breaker on the sharp corner of the wheel....

Thanks,

Lee

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Good to diamond by hand on the rest so to make a straight edge. Is the cup wheel flat-faced or perhaps 1/16 or 1/8" diamond.
Wet is so much better, can you grind wet?
Great idea regrinding single point inserts as the cutting angle is not important for simple turning, but do at the edge that still allows to set in the holder so supported to the back of the pocket.

Grind so going across the wheel to not put any groves in the wheel.

I guess a photo would be good.

Good to try to grind away all steel and braze so none touched the diamond wheel. it eats away a diamond wheel.
 
Hi Buck,

Wet grinding isn't an option, yet, but I may add a drip tray and/or small pump in the future.

I've added a few pictures of the grinder. It's a bit weird - I think whoever made it used either a spindle or a spindle cartridge from a surface grinder. The straight wheel is on a Sopko style arbor. I haven't had it apart yet, but I'm hoping it's a straight swap for my surface grinder wheels.

Any reason I'd want to add a toolrest to the left side too?

Thanks,

Lee
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looks like a very decent grinder.
Adding coolant would be tough with the motor down under.

Guess I would add a protractor off the out edge of the table (yes make that edge flat).

With having that you can travel the grinding across the wheel trying to create a flat surface on the cup wheel.

just a homemade protractor with no number would be OK..you can protractor set it if you need a certain angle.

I think it is good to wear a mask for such grinding.

Putting a fresh wheel in the cup position you put shims behind the wheel to make it run .001/.002 at the start. just shims made of paper are Ok.

Make or buy a decent wheel pull wrench so you don't need hammer on the spindle.
 
The narrow wheel was probably originally used on a surface grinder. I used to use an 1/8" wide one with a round profile for doing exactly what you surmised - grinding chip breakers or high positive tops. I'd add at least a hand rest to the narrow wheel side to help support and steady your hand when offhand grinding.
 
Guess I would add a protractor off the out edge of the table (yes make that edge flat).

Yup. I was thinking I might weld some 1/2" plate to the top of the table, with a parallel slot to accept a little mitre gauges for that purpose.

Hey Eric, good to hear I wasn't far off! I'll likely do just as you suggested, and hang a toolrest on that side too :)

Thanks guys

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You might math out the RPM and note that on the spindle. Such diamond wheels ok/good with 6,000 (many/some to 10K) but if you should put on a 7" aluminum oxide wheel at over 3400 it may not be safe.
All grinders should have the RPM posted on the machine.. (also that is the law)

3400 for such diamond wheel is not best but OK.

Motor x pulleys minus a couple hundred is pretty close.
 
I still use my first bench grinder, now very old, with a green SiC wheel on one end for rough shaping brazed carbide tools and undercutting the steel below the carbide. The other end has a gray alox face wheel that I bought for drill grinding and seldom use any more. I do a lot of steel grinding with my 1 x 42 belt sander, which I like better than a standard bench grinder.

I do touch up TPU and TPG carbide inserts, still in their lathe holders, when the tip wears and get a little more use out of them. For several years, I have been using my Glendo Accu-Finish grinder for almost all my carbide grinding. The slow RPM plated diamond face wheels work fine dry and can even safely touch up the edge on HSS tools. The Baldor carbide grinder seldom gets plugged in and the Leonard cool grind slow oscillating diamond lap grinder has not been used in ages.

Larry
 
i assume the diamond is on the periphery of the flat wheel. then you can use it to put a hollow grind on brazed tools so they can be honed easily.
 
So the cup for normal flank grinding and the OD off hand wheel for everything else.
Examples could be simple flat or hooked top grinds, chipbreakers or funny side clearance.
If you need to make a trepan tool you need a secondary clearance. Not real fussy and not part of the cutting edge but it needs to be there.
Same secondary also needed sometimes on a boring tool. Here one needs to just knock off the bottom of the insert rather than have a straight side rake.

Wet and pump perhaps not a option but a leftover spray bottle from the home may help.
Pure water, 409 and even glass cleaner works but ..... rust. So coolant mix in the bottle.
If no coolant mixed blow off and spray everything with a good coat of WD-40 when done.
Why not use WD-40 the whole time as a coolant/lube? Because the grinding comes to a crawl.
Do you have wheel sticks for your diamond wheels? If not you will want some.

The picture shows your tool sitting on what would be the upwards side of the grind, Assuming clockwise wheel rotation ....NO, No, no.
Carbide likes compression into the material when being ground.
In such a case when when one has to go exit (sometimes no choice) a much finer grit wheel has to be used so to control the edge chippage.
Bob
 
Thanks for the pointers Dian and Bob. I'll definitely have a spray bottle on hand. Any suggestions for a mix that doesn't go rancid with only occasional use?

The direction of wheel rotation is counter clockwise as viewed from the toolrest, so the left side of the wheel should be correct.

Thanks again

Lee



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I still use my first bench grinder, now very old, with a green SiC wheel on one end for rough shaping brazed carbide tools and undercutting the steel below the carbide. The other end has a gray alox face wheel that I bought for drill grinding and seldom use any more. I do a lot of steel grinding with my 1 x 42 belt sander, which I like better than a standard bench grinder.

I do touch up TPU and TPG carbide inserts, still in their lathe holders, when the tip wears and get a little more use out of them. For several years, I have been using my Glendo Accu-Finish grinder for almost all my carbide grinding. The slow RPM plated diamond face wheels work fine dry and can even safely touch up the edge on HSS tools. The Baldor carbide grinder seldom gets plugged in and the Leonard cool grind slow oscillating diamond lap grinder has not been used in ages.

Larry
Larry,

If you don't mind me asking, what does the accufinish do that the Cool Grind doesn't? I have a Leonard, and I like it for putting a fine finish on the carbide. I've no experience with the Glendo though - what makes it better?

Thanks!

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