Thread: Tomonagura confusion

Alex has videos on prepping, modifying and using nagura. Round off all the corners and edges, I round at least one corner to about the radius of a dime or more and smooth the surface. Cut grooves with a hack saw if you have sticking issues while using a flat side. I don’t cut grooves and just use rounded edges so you are using a smaller surface area and use a rocking motion so you are not creating a flat on the nagura.

Try all 8 edges before giving up on the Tomo. I would also switch to a diamond plate if you are still having issues.

When trouble shooting a problem, begin by eliminating the most likely suspects.

Just few thoughts from my experience, as they say YMMV.
Both tomo and base stone seem hard, much easier to raise slurry with a softer tomo.
Deep visible scratches are usually caused by a sharp corner or too much pressure. When using a hard tomo/base stone combo you have to resist applying pressure and just keep rubbing.
When I round my tomo, I dont just work it at 45 degrees but I do a continuous motion on the atoma, back and forth while I lift and then again lower the tomo. It gives it this shape. Sort of like rocking it.
Then you just lift few degrees and rub away

I would use a diamond plate slurry after my highest progression synthetic. And see where you are. I would make the slurry about the size of a quarter to start. Dilute one, don't dilute the other. Try them both. And then see. I would use ONE slurry only. The last one. Make it simple.

Originally Posted by Bill31521

I would use a diamond plate slurry after my highest progression synthetic. And see where you are. I would make the slurry about the size of a quarter to start. Dilute one, don't dilute the other. Try them both. And then see. I would use ONE slurry only. The last one. Make it simple.

I would do the same. Keeping it simple and minimizing variables is the key when learning a Jnat.
Honestly when I test a new stone I always use DN slurry because I dont want the variable of the tomo. Start with that and then you can experiment but at least you have some basic info about your stone. Speed, power - how much can it do after synthetic etc. Each stone is different. Some are pure finishers and cant handle quickly 1k scratches. I occasionally find one that can take you all the way but that's not the norm in my house testing plenty of stones.
Theoretically you will have have to work the DN slurry a bit longer since it "should" be coarser than a tomo slurry.

Originally Posted by ffourteen

The little white scratches along the edge were not there before I took the tomo to the base stone. They seem to correspond to black flecks in the tomo, and look a lot like the scratches in the base stone. Could those be toxic inclusions? Attachment 301540

You may want to drill the suspected culprit black flecks out and see what happens.

There are definitely too many black spots to remove.

Just to update, I moved on to a different side of the tomo and worked it into a kind of pillow shape. I practiced making slurries with it for a while and got to where, if I apply zero pressure and just drag it lightly for five minutes or so it works up a nice slurry with only a couple light scratches (and those usually appearing when I start getting tired; I can feel/hear them). It does still scuff the surface of the base stone (kind of looks like I’ve run an eraser over it), though at a deep angle the mirror finish looks undisturbed. The tomo itself is developing a mirror finish that is unscratched or scuffed.

My guess is that it’s a really hard tomo, combined with me still getting the technique down, that was causing the scratches. I’ll keep practicing and hopefully will get better. That being said, the edges I’m getting are superb! Those really sharp, really smooth Jnat edges… I still want to improve them a little but I think I just need more time put in with only water.

I do also kind of want to pursue a little bit softer of a tomo. Where are some places I might look to pick those up?

Thanks for all the advice!

Here is a good video on how to shape and polish a Tomo Nagura by Keith Johnson.

Tomo Nagura Lapping 101

Yep. I've told him about Keith in private since I didn't know what's allowed. I've used ones made by him.