8” diamond wheel? Flatten chisel backs

[Leeroy]

Wondering if any one knows if tormek are going to release an 8" diamond wheel?? I know there is one for the t2 but I want to be able to flatten the back of chisels and plane irons which rules the t2 style out. I have used the SG wheel to flatten plane irons which worked quite well but I see tormek don't recommend this (under the mb-100) so once I groove the Sg stone I'm out of luck.
Like most of us, I have a fair bit invested in my t3 so would rather not drop the 2k for a t8 and diamond wheel, just to do the back.

[Ken S]

Leeroy,

The Tormek can do many things well. In my opinion, flattening chisel backs is not one of them. I follow Leonard Lee's advice with chisel backs. If the back is concave, I don't worry about it. If the back is convex (if it has a belly), if the chisel is new, I would return it as defective. Most of my chisels are old. I do work on a number of Irwin 3/4" Blue Chip chisels (my learning chisels). These are almost always a little concave, so I just polish the ends.

For plane blades, do a search of David Charlesworth's Ruler Trick. He flattens and polishes only a small fraction of an inch at the tip of the blade.

I have a very nice old Buck chisel which had a belly. Checking the back with a straightedge ruler. I ground away most of the belly by holding the back against the edge of my Tormek wheel (NOT the side). I did the final flattening and polishing using my waterstones.

Most of us have too many chisels. Flattening the backs (if necessary) of the three or four chisels you use regularly is not as daunting as trying to flatten all twenty sizes. Beyond the three or four, only flatten the backs individually right before you actually need to use one. Stick with your SG.

Ken

Edit: I have received a suggestion from a sharpener I respect suggesting that I might want to review my initial tests flattening chisel backs. I will do so and post my results.

[dhansmeyer64@gmail.com]

I have a general question about some chisels I bought years ago when I was in Taiwan. All of these chisels have a short flat back and then the back is concave, seriously concave. After sharpening some of them many times I am sharpening into the concave part so the chisel does not have a flat back. Anyone have any experience with this problem?

[ega]

I have no direct experience.
However, if your chisel is Japanese then according to Toshio Odate the remedy is to hammer the bevel and thereby force more of the hard lamination into the concavity. He emphasises the danger of cracking the chisel!
If you are interested and will PM your email address I can send the relevant extract from his book, Japanese Woodworking Tools.

[RichColvin]

Ega is probably right.  Andrew Hunter has this article/video on the same :  https://www.finewoodworking.com/2017/02/02/tapping-japanese-plane-blade-andrew-hunter

I have some information here :  https://sharpeninghandbook.info/WW-Chisels-Japanese.html

Kind regards,
Rich

[Ken S]

David,
Reading your post,I had the same thought as Ega and Rich. Designing the hollow in the back is clever. It greatly reduces the work of flattening the back of the chisel. Japanese chisels are very hard and traditionally used with native soft wood. They hold a keen edge for a long time.

I have read about the hammering technique. My only Japanese chisel is flared on both sides. It is designed to excavate inside corners of half blind dovetails. With this light duty, I will probably never need to sharpen it and will never have any direct experience hammering a back.

Please keep us posted.

Ken

ps If I was still in the tool acquisition phase of life, I think I would purchase a good quality Japanese chisel (my most used size). This would both give me a chance to decide if I wanted to acquire more of them and also have another sharp chisel in reserve if I wanted to keep working rather than stop to sharpen. (No, the idea is not mine; I read it in a book by Chris Schwarz.)

[ega]

Useful links from RichColvin. The Japanese have semi-automated the process with a tool:

[dhansmeyer64@gmail.com]

I tried the tapping chisel procedure on the end grain of a 4 x 4. Surprisingly very simple and effective.  I hit it fairly hard with a ball peen hammer using both sides and it did not damage the chisel but flattened the end.  One chisel is still giving me troubles because the entire chisel is concave. It must be an old chisel that came in a box of purchased item at an auction. I will still work on it and let you know.

[dhansmeyer64@gmail.com]

Well I continued to tap the chisel and it developed some cracks. I hope they will come out when I sharpen it. You can see the cracks if you increase the size of the picture.

[John_B]

Well I continued to tap the chisel and it developed some cracks. I hope they will come out when I sharpen it. You can see the cracks if you increase the size of the picture.

I wonder if those cracks were initiated when the chisel sustained the damage to the cutting edge and the flattening you did caused them to expand. Micro cracks from in a lot of metals and are normally not visible to the naked eye. A whole segment of industry focuses on finding these flaws before the material fails. This is one of the primary methods used when jet engines are periodically disassembled and inspected. I worked at the industry leader in this field.

https://www.magnaflux.com/Magnaflux