Grinding Wheel for Thin Plane Irons?

[Steve H Graham]

Today I watched a video about hollow-grinding plane irons and chisels. The guy in the video ground a very thick plane iron. Obviously, a Stanley iron about 3/32" thick is going to be tougher to put a hollow grind on.

I felt like the video was a bit on the snobby side.

The video guy used a 6" grinder. If I want to hollow-grind a thin plane iron, will 6" work, or am I better off getting a crappy little Chinese grinder with a smaller wheel?

[Chris Parks]

I don't see any problems, I grind Stanley blades on an 8" wheel. I would say that a CBN wheel on any size will give better results but it is not necessary by any means.

[Steve H Graham]

Thanks for the reply. Just to be sure I'm understood, I want to shape the edges so they will only touch flat stones at the back and front, to make final sharpening faster. You can do that with 8"?

I used to have an 1800 RPM 6" Baldor, and I stupidly sold it to a wood guy who was going to put CBN on it. I should have kept it.

[Chris Parks]

Steve, you can't get faster than a CBN wheel on a high speed grinder, it simply is not possible. From there it takes less than 5 minutes to put a bevel on the blade with stones of your choice. I must admit I am not quite following what you mean here >I want to shape the edges so they will only touch flat stones at the back and front<

[Steve H Graham]

It's hard for me to explain without a photo.

Say I'm working on a chisel. I would start out with a hollow grind that goes all the way from the heel of the cutting surface to the very edge. Then I would finish the tool on a flat stone. Because the grind is hollow, when you first put it on a flat stone, the scooped out part of the grind won't touch the stone. The very edge will touch, and the heel will touch. As you sharpen the tool, you get a small bevel at the very edge and a small flat area on the heel. It saves you the aggravation of wearing away metal in the area between the heel and edge.

I didn't know CBN would work well at high speed. I have tried power tools on blades before, and it was hard to avoid burning them. I have never used CBN, so I don't know how it behaves.

[Chris Parks]

Put the blade down to contact the heel and toe then lift it slightly so the heel no longer contacts the stone holding that angle to begin sharpening. This obviously begins to form a bevel at the toe of the blade, when a wire edge happens proceed to the next stone. I go from the wheel to a 2000 > 8000 > hone with green paste on a piece of MDF. I am going to cop a lot of flak for what I am going to say next so be prepared for it. The bevel formed is so small that holding an absolute precise angle is not necessary, depending on the chisel the bevel is so small the angle becomes a non event. Muscle memory will come as you do it more and more and if you stuff up the first couple of goes the time to do it is so short that going back to square one is no big deal. See Derek Cohen's site for some photos and a better explanation of the process. Without doubt this is the simpilist and quickest way to sharpen a blade.

https://www.inthewoodshop.com/WoodworkTechniques/UltimateGrindingSharpeningSetUp.html

[steven c newman]

Grinder I use...
394235
And OLD 6" Craftsman dual wheel. Changed the one tool rest to that block of wood.....added a notch with the wheel..zero clearence?
Also, I used to use a jig, to hold the irons straight..
394236
Couple c clamps to hold the iron to a straight stick....slide the jig back and forth to grind the edge..
394237
Then I sharpened to 2,500 grit, then a strop....
394238
Key to the grinder..have a cup of water, sitting right beside where you are working...couple passes, dunk, couple passes, dunk...repeat as needed.

I just have a "Fine grit" 6" wheel on the grinder, now a days..other end has a wire wheel...

[Tom Stenzel]

I put a hollow grind on my planes and chisels using the same method as Steven's. Except I clamp the plane iron to a piece of angle iron that acts as a jig.

When I clamp I use a square to make sure the iron is perpendicular to the jig. Steven might do it by eye but I would have a trifocal failure and make a mess of it.

Full confession: I did blue the corner of the iron from my #7 grinding it. Still ticked off I did that.

-Tom

[Derek Cohen]

Today I watched a video about hollow-grinding plane irons and chisels. The guy in the video ground a very thick plane iron. Obviously, a Stanley iron about 3/32" thick is going to be tougher to put a hollow grind on.

I felt like the video was a bit on the snobby side.

The video guy used a 6" grinder. If I want to hollow-grind a thin plane iron, will 6" work, or am I better off getting a crappy little Chinese grinder with a smaller wheel?

Steve, the issue with grinding is not so much the thinness of the blade for the hollow, but rather the heat generated by the wheel, and whether you have the steel type or the skills to prevent the edge burning.

The most safe grinder, that is, one that generates the least heat, is a water cooled type, such as the Tormek. The next coolest is a CBN wheel, then a white Norton 28 grit wheel. Grinder speed also factors in here: the slower the turning and surface speed, the lower the heat. The Tormek turns at 110 rpm, a half-speed 8" at about 1450 rpm, a 8" full speed at 2900 rpm. The 6" wheel is about midway between the two 8" wheels mentioned. It is a good compromise, especially when adding a CBN wheel. If you go for one, then 180 grit is recommended.

Whatever you get, grinding requires a light touch to keep heat down.

The hollow from a 6" wheel will be deeper than an 8" wheel, and probably better suited for thin Stanley blades. Hollow grinding these is no issue - it has been done for at least 100 years.

Regards from Perth

Derek

[Steve H Graham]

The thing that concerns me about a big wheel is the radius, not the heat. A small wheel will cut deeper into a short bevel. A thick iron has a bevel maybe 3/8" long, so an 8" wheel can cut deeply into it without touching the heel or edge.

[Vincent Tai]

The thing that concerns me about a big wheel is the radius, not the heat. A small wheel will cut deeper into a short bevel. A thick iron has a bevel maybe 3/8" long, so an 8" wheel can cut deeply into it without touching the heel or edge.

Steve, you can hollow grind a Stanley blade just fine with an 8 inch wheel. Accurately with all sorts of different angles. Perhaps if you have access to a CAD program (there are a free ones out there) you can quickly draw it out and prove to yourself it is fine. While the radius produced is shallower and yes you will return to the grinder a bit sooner if you insist on using the hollow grind as the jigging and angle mechanism. I use the hollow grind this way on irons that are a bit thicker, but for the Stanley ones I just grind a 25 ish and hone at 30.

[Bruce Haugen]

I have used a Delta 3500 rpm grinder and a 100 grit white wheel for all my grinding, which has includes thin Stanley blades, for more than 30 years. At first I burned my share of blades but I learned to use a very light touch and to dunk the tool when it gets warm. I don’t have deep pockets, and this grinder has been good enough for my needs.

[lowell holmes]

The only time I will put and edge on a grinder is to establish a bevel. Then I hone the edge on a diamond hone.

One example, but only one of many is following.

https://www.homedepot.com/p/Chef-sChoice-Diamond-Whetstone-4002601/203742472?cm_mmc=Shopping%7CG%7CDD%7CD29B%7C29-29_HOUSEWARES%7CNA%7CNA%7c71700000032305523%7c5870 0003835510657%7c92700036895454620%7cpla-523791893221-51166497102&gclid=Cj0KCQjwi8fdBRCVARIsAEkDvnId8__cSvA7ZLv5XUhH 72v5MF7jCjdBBLcCq7lJN-zLgR4HW_Qw4U4aAk8sEALw_wcB&gclsrc=aw.ds&dclid=CKbwm7Tm5d0CFUbCwAodstoCyg

[Tom M King]

I mostly only use the old, thin irons. Since I have a couple of helpers that would be close to hopeless honing by hand, and worrying about resulting damage to fairly soft, fast waterstones, I went back to using a guide, with some foolproof setting jigs, and honing the full bevel. It's really a very fast process. Time saved with a hollow grind by only having to knock down the cutting, and heel edges is not a noticeable time savings with this type of iron.

I understand what you are wanting to do with the hollow grind. Almost any grinder can do it. I can tell you from experience that an 8" CBN wheel will do it just fine. The only time I use a grinder is if an edge has some damage, which is fairly rare. I don't worry about it being a hollow grind, although it is, because I grind it to a little shallower angle than I want the cutting edge, and the honed edge gradually takes over the whole bevel, unless it needs to visit the grinder again.

Yes, no microbevels.

[Steve H Graham]

I was planning to use the grinder for correcting screwed up irons and chisels (i.e. virtually every one I buy) and then putting a hollow grind on them. I intended to keep using flat stones for sharpening. I don't really care, though. I'll use anything that works.

I bought a Millers Falls #14 the other day. About 1/16" needed to come off the blade because of a chip. I used a DMT XX-coarse stone. I'm still not finished. I don't want to spend the rest of my life putting in that kind of time on every messed-up blade.

I am strongly considering getting CBN now, even after all the aggravation and expense of locating white aluminum oxide. I see Woodturner's Wonders sells a pair of wheels that look neat. One is very square, and the other has a big radius on each side. I think that would be great. One of the most annoying things about bench grinders is that you can't use the sides of the wheels. These CBN jobs would open up a lot of possibilities.

I got white aluminum oxide because it was recommended for HSS, but it's very touchy with tool steel.

[Tom M King]

I bought the radius edged CBN wheel several years ago, and don't remember using the edges. Derek had trouble with one, and went to square edged wheels. If I had it to do over again, I would have gotten square wheels, even though I have not had any trouble with the one I have for several years. I can't dry grind in the houses I work on, so I'm going back to a wet grinder as soon as I see some first hand reviews on the Tormek diamond wheels. I'll walk outside to use the CBN wheel before I'll go back to friable grinding wheels though.

I don't understand why using the grinder for correcting screwed up edges doesn't put a hollow grind on the edge in the process.

[Steve H Graham]

I don't understand why using the grinder for correcting screwed up edges doesn't put a hollow grind on the edge in the process.

It would, but I've been using flat stones on my tool steel.

[bridger berdel]

A big part of the advantage of thin irons is that they hone quickly with minimal grinding needed. Just develop the muscle memory to freehand hone at an angle within the range of usefulness for your plane. Exact angles aren't necessary.

[Jim Koepke]

Perhaps if you have access to a CAD program (there are a free ones out there) you can quickly draw it out and prove to yourself it is fine.

If you are not into CAD, a compass and a ruler can do the same thing.


I was planning to use the grinder for correcting screwed up irons and chisels (i.e. virtually every one I buy) and then putting a hollow grind on them.

A hollow grind is nice, but it isn't the end of the world not having one. Especially if you are stocking up your shop buying a lot of tools in the wild. In my sharpening a hollow grind isn't any less work than a flat bevel. It is easier to register the bevel with a hollow grind. A hollow grind kind of makes the blade 'click' into place on a stone.

What makes freehand easy for some is a secondary bevel.

My electric sharpening is done with a Veritas Mk.II Power Sharpening System (http://www.leevalley.com/us/Wood/page.aspx?p=48435&cat=1,43072). One of the reasons it was chosen is for being a flat disk which comes in handy working the backs of blades.

There has been one for sale for a while in the Classified section. It may have drifted down a couple of pages.

jtk