Power grinding primary bevel: What do you use?

[Gary Focht]

I have the Lee Valley rest for my grinder and the jig it uses, but I really don’t like the jig much and am free-handing it with regular checks with a square. I’m still fairly new to this all, but it isn’t that hard to free-hand the grind. I’m not that picky about the angle - as long as it is close to 25 degrees, I figure that is good enough.

[Gary Focht]

Unfortunate you can’t get all your strength back. I read if carpal tunnel goes on too long, the damage could be permanent, so I got surgery in a relatively timely manner.

I swear I gave myself the carpal tunnel in one day installing crown molding. My fingertips were numb at the end of the day and it never really came back. No issues before that.

[Curt Putnam]

Based on David Weaver's Unicorn method and the recommendation of Derek Cohen, I am slowly migrating from a Worksharp 3000 to a Rikon 8" 1725 rpm grinder with a CBN wheel and a Tormek rest. I say slowly because learning how to grind efficiently takes some effort. I bought a couple of Tormek jigs and that takes care of the square part of grinding. I also bought 2 angle setting jigs - but I do not yet fully trust that I am using them correctly, and therefore, the results are suspect.

As far as your coarse grinder wheels go, the general advice I've read is to use the coarsest wheels you can get. The most useful advice I've gotten is that all one is trying to do with a grinder is to get metal out of the way so you can hone at the angle you want.

[William Fretwell]

I have a generic ‘Tormek’, far less money. A lot of plane blades nowadays are much thicker, this has some benefits with stiffness but sharpening at the primary 25 degree bevel is a lot of metal area. On water stones this is huge work.
I simply grind with the ‘Tormek’ to produce a concave grind between the blade edge and the inside edge. This retains the two reference edges to rest on but at least halves the metal contact on the water stones. The full support is still there as the concave is slight.
Two important points, the quality of the ‘Tormek’ grind matters not a damn as it does nothing, just gets steel out of the way! You have at least halved the work to restore the primary bevel, yes at least half the time!
The other huge benefit is it keeps you away from secondary bevels, I feel the appeal of a secondary bevel is just to get back to wood work however as the secondary bevel grows you have to re-grind the primary bevel so no time is really saved.
The only secondary bevel on my blades is from the leather strop.

Yes it’s an added expense but a huge time saver and the cheapest water wheel will do the job. Use the grinding support, keep it even and that ‘middle concave area’ will last quite some time.

[Andrew Seemann]

I have a generic ‘Tormek’, far less money. A lot of plane blades nowadays are much thicker, this has some benefits with stiffness but sharpening at the primary 25 degree bevel is a lot of metal area. On water stones this is huge work.
I simply grind with the ‘Tormek’ to produce a concave grind between the blade edge and the inside edge. This retains the two reference edges to rest on but at least halves the metal contact on the water stones. The full support is still there as the concave is slight.
Two important points, the quality of the ‘Tormek’ grind matters not a damn as it does nothing, just gets steel out of the way! You have at least halved the work to restore the primary bevel, yes at least half the time!
The other huge benefit is it keeps you away from secondary bevels, I feel the appeal of a secondary bevel is just to get back to wood work however as the secondary bevel grows you have to re-grind the primary bevel so no time is really saved.
The only secondary bevel on my blades is from the leather strop.

Yes it’s an added expense but a huge time saver and the cheapest water wheel will do the job. Use the grinding support, keep it even and that ‘middle concave area’ will last quite some time.

Actually in this system (which is basically what I use) the hollow grind from the grinding wheel is the primary bevel, and the water stone puts on a secondary bevel. It is very slight, but it is just a little bit steeper than the primary bevel of the hollow grind, which makes it a secondary bevel.

Secondary bevels are great for most things. They do reduce the amount of metal you need to remove which makes for many quick touch ups before you need to regrind the primary bevel. Because they are steeper, they make the actual cutting edge a little stronger, yet because they are so small, they don't appreciably make the tool harder to drive like a steeper primary bevel would. Kind of the best of both worlds, stronger edge yet easy to drive, all while being quicker to sharpen.

[William Fretwell]

So Andrew you take the concave grind all the way to the edge then the very small real edge you add at the normal flat angle you call secondary. The only problem is restoring the primary bevel consistently on a grind wheel is very difficult. That is why, on the thick blades I keep some primary bevel either side of the grind, I only think of it as removing work.
Yes small secondary bevels get you back to work faster but the typical 1 or 2 degrees dialled in on the honing jig will make little to no difference in edge strength.
I have used small secondary bevels in the past but they just grow bigger as the job progresses, now you have a primary bevel 2 degrees less than before and have to grind back. With my method now I can keep the primary bevel easily all the time, no need to remember which blade needs more work down the road.
The little knob on my Lee Valley honing guide stays put!
The wear bevel on the back of the blade needs monitoring as you try and keep it flat, that can encourage grinding back the primary bevel even sooner!

[Jim Matthews]

I have an appreciation for hand pain and how it can afflict your daily life in unexpected ways. First and foremost - do the physical therapy.


*****


For me the difficulty is securely holding things for extended periods. I built the "swing arm" grinding set up as designed by JSK Koubou.


Really rough blades or regrinding bevels are done on a handcranked grinder with a Norton White wheel.

[Jim Koepke]

That looks like it would put a camber on every blade whether you want to or not.

jtk

[Jim Matthews]

That looks like it would put a camber on every blade whether you want to or not.

jtk

It puts an even flat on blades from 1/4" to 2 1/2". The fixed point of rotation and positive registration between the blade and the "swing arm" means the blade stays flat through the arc it travels.

If the plate (or stone) is flat, the steel always maintains the same angle.

You *could* get a camber by twisting the swing arm, but I can do that free hand.

[Don Parker]

Robert Sorby ProEdge. Expensive, but to me, worth every penny.

[Kevin Adams]

Robert Sorby ProEdge. Expensive, but to me, worth every penny.

I also like the Proedge. You can use jigs or freehand, just rough grind or go up to 3000 grit. I typically like a flat bevel and this makes it easy to repeat and then move to a guide on stones or even freehand on stones.

Thanks.
Kevin

[Dan Grano]

First, I'm sorry to hear about the ongoing limits with your hand, Thomas. This thread is interesting timing for me personally. I am having carpal tunnel and cubital tunnel surgeries today (both on the right side, though I am also having trouble on my left side). And, I spent some time on the grinder yesterday repairing a damaged plane blade.

I have a Rikon 80-805 grinder and I've been pretty happy with it. It goes on sale somewhat frequently, and isn't too costly. I also got a Wolverine tool rest (just the plain rest, without the attachments for turning tools). That combination has worked pretty well for me. The wolverine rest is big enough that it helps with stability and serves as a good heat sink.

The Rikon comes with a 60 grit white friable wheel on one side and that's the one I've been using. It's the main thing I am going to look at changing, either for a CBN wheel or maybe a Norton 46 grit (blue super-cool wheel), something that will speed the process. With numbness and pain plus loss of dexterity I think that speed is at a premium, as things start to fall apart (both accuracy and patience) the longer I am working at the wheel.

[James Pallas]

I have always used a standard 6” grinder with a 46 grit wheel. Unless you have unusual damage little metal is being removed. A light touch, the baby bird thing, is plenty. Water to dip in, just in case. I did purchase a CBN wheel last year. It’s nice because less work on the stones. I use it more for metal cutting tools than woodwork tools. I guess practice is good. I have to intentionally do it in order to blue a tool nowadays. Keep the wheel dressed, coarse wheels better than fine for heat. Accuracy to me is not a problem. I can tell the difference between 20 and 25 degrees in use but not 20 and 22 degrees for instance.

[Bill White]

Thomas, glad to hear about your use of the Makita. I have it, and use it often. I kinda think that it is the unsung hero of the sharpening world.

[Thomas Wilson]

Thomas, glad to hear about your use of the Makita. I have it, and use it often. I kinda think that it is the unsung hero of the sharpening world.

Yes. it is, Bill. I have used it for years. I bought mine before the Tormek came out and never felt the need to upgrade. I am on my second green wheel. I sharpen everything on it. I use the tool rest and holders for plane blades and chisels. I sharpen kitchen knives and lathe lathe tools freehand. I think my only objection is the mud that comes off sometimes.