Author Topic: CBN WHEEL & story  (Read 214 times)

Offline Petergreycat

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CBN WHEEL & story
« on: September 30, 2021, 04:20:51 pm »
Hello everyone, I would be very interested in your comments on this:-
I had an old 8” bench grinder, it needed a new stone & I ended up buying a 180 GRIT CBN.
Mainly my research was by watching YouTube’s, Stumpy Nubs & Rob Cosman etc
After turning bushes for it & mounting it on the 2880 rpm grinder, two things rapidly occurred to me.
1, my grinder shaft was probably not straight
And
2  it took 11 minutes 17 seconds to stop.
I stripped it down & renewed the bearings, tried it again, re-mounted my original grind stone & gave the machine away.
This left me with an 8” CBN wheel.
I tried to buy a 1440 rpm bench grinder, but these days in the UK, after Brexit and COVID, there are none to be had.
So.
I bought a Tormek T4
And am very very pleased with it.
I find the Tormek wet wheel very nice indeed for exactly what’s it is supposed to be for, and when my CBN is mounted, that one is extremely good at much faster material removal than the Tormek wheel.
The CBN also is superb at sharpening metal working lathe tools both HSS and tungsten carbide. (I made a quite crude tool rest for grinding the lathe tools)
I know Tormek do not advise the use of CBN, preferring diamond, but as you see, I was painted into a corner and found a pretty decent solution I think?
Anyway, does anyone have any advice on this?
I use Hone Rite gold in the water for all grinding & am hoping that won’t destroy the beautiful Tormek stone.
I could also mention I always hone finish my cutting tools on 8000 grit whetstones by hand, I can’t for the life of me get any feeling for the honing wheel on the T4!
Regards
Peter

Offline Ken S

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Re: CBN WHEEL & story
« Reply #1 on: October 02, 2021, 08:44:01 am »
Peter,

Being practical, I would say that the CBN wheel you already have is the ideal wheel for you. From your post, it fulfills your needs sharpening both hss and carbide metal lathe tools. That's a tall order.

The practical part is that you already own it; no further expense is necessary.

Superabrasives like CBN or diamond last longer with light grinding pressure. With light grinding pressure, I do not see any advantage with the larger wattage T8 motor. With a smaller circumference wheel and a higher RPM motor, the Surface Feet per Minute of the T4 and T8 are essentially equal.

I have both CBN and diamond wheels. Both do the job. Should you eventually wish to add another grit wheel, you are not locked into one type of wheel.

I started using Honerite Gold with my CBN wheels before Tormek introduced its diamond wheels and Anti Corrosion Concentrate. I use it with my CBN wheels and ACC with my diamond wheels. Cost is comparable and reasonable. I have not used Honerite Gold with my original Tormek wheels; however, I would be surprised if it would cause any damage. Rob Cosman uses it with his bench stones.

Keep us posted.

Ken

Offline Petergreycat

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Re: CBN WHEEL & story
« Reply #2 on: October 09, 2021, 02:42:57 pm »
Thank you for your reply Ken.

It is very reassuring to know that someone with a huge amount of knowledge and experience with Tormek is positive regarding my situation.
Regards
Peter

Offline Ken S

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Re: CBN WHEEL & story
« Reply #3 on: October 09, 2021, 07:48:57 pm »
Peter,

Like the rest of us, I am still learning. You are off to a great start.

Sharpening metal lathe tools is a fertile area for growth with the Tormek. In the past, the aluminum oxide SG wheels performed better with carbon steel than with hss. The newer grinding wheels (silicon carbide SB blackstone and, especially, the superabrasive diamond and CBN wheels) have made sharpening and even reshaping hss practical. Not lightning fast, but doable. Since the superabrasives work better with light grinding pressure, the larger motor of the T8 would offer no advantage.

I believe several members have homebuilt jigs for sharpening metal lathe bits. Check with Rich Colvin's Sharpening Handbook. It is a useful online reference he patterned after the venerable Machinery's Handbook.

You have a useful set up for your sharpening needs. Keep using it and keep posting. I have no doubt that we will be seeing innovations from you!

Ken