SJ-250 truing

[Commonzense]

Hi there. I am new to the Forum. Over a decade living in Belgium now. Professionally occupied as interior renovator and cabinet maker for about three years now. I have a couple of kids, play volleyball, shoot airguns for fun, etc.

Currently I use a Tormek T8 from a friend of mine. I bought the Japanese stone in addition to the SG on the machine to achieve mirror sharp chisels.
With the TT50 I trued the SG stone parallel tot the USB. Is this something one does with the SJ too? Or is this a no-go?

A second question. I read about the JS having a brittle/ chippy edge. I found sometimes it's advised to round up the edge a bit.
Is this really required and how would one advise practically rounding up the edge?

[RichColvin]

Bastiaan,


You probably should not need to true the SJ grindstone, but if you do, watch this video.  The boys from Tormek show you how to do so:


       https://youtu.be/_9izVW7g6uo


Typically, I use a Nagura stone to clean up mine.  The only time I've had to do that was when I accidentally put a gouge into the surface.


Rich

[cbwx34]

The video Rich linked to shows specific tips for truing the SJ stone (around the 10min. mark), in particular, not letting the diamond tip run off the edge, if needed.  (He's right, it shouldn't need it).

This video shows how to round the edge... 

https://youtu.be/7eCDSZ2PHU0?t=565

... I always do it at least a little bit... helps prevent the edge from digging into a knife.

I use a rust eraser to clean mine (similar to using a Nagura)... here's some other tips...  https://forum.tormek.com/index.php?topic=3374.0

[Commonzense]

Thanks for the links to the both of you. Will have a look them later today.

I have a 1000grid diamant plate, all the way from PRC, in my kitchen draw. Can I use that instead of the nagura stone.
I think I saw someone doing this in a video that I came across while ago.

[Ken S]

Welcome to the forum, Commonzense.

Some of us have been using diamond cards and stones for several years. The two forum pioneers were Ionut and Wootz. Sadly, neither of them are still active on the forum.

I think there is also a place for the nagura stone and rubber rust erasers. Fortunately all of these options are inexpensive and readily available.

I purchased a set of three DMT diamond file cards. In my opinion, where they really excel is in keeping the grinding wheel true. Wootz used a plane blade to back up the diamond card. I epoxied the three diamond cards on to eight inch pieces of 2" x 24" x 1/16" (or 1/8") aluminum stock from the local hardware store. The epoxied card is placed in a square edge and laid flat on the grinding wheel.

I found that the coarse diamond card worked no better than the coarse side of the stone grader with the SG. The1000 grit card seemed to make the surface smoother than the fine side of the stone grader. I don't use the SJ much. I would suggest starting with a rust eraser of nagura stone. I would move to the diamond card only if you wanted to be more aggressive.

Don't forget to grind a small radius on the sharp corners of the wheel. 

Ken

[RichColvin]

Thanks for the links to the both of you. Will have a look them later today.

I have a 1000grid diamant plate, all the way from PRC, in my kitchen draw. Can I use that instead of the nagura stone.
I think I saw someone doing this in a video that I came across while ago.

Bastiaan,


With the SJ stone, there is no operation for regrading it (as with the SG stone).  It is not rough or smooth.


So the operations that make sense for it are:

   
• Changing the shape of the stone (rounding over the edges, or re-flattening the surface), and
• Cleaning the surface

As for #1, you can use the TT-50 or a diamond plate as you showed.  Both will probably rough up the surface and you will have to use the stone a little bit longer to get it back to the flat smooth surface for which it is so well known.


As for #2, you can remove some rust erasing product or a Nagura stone.  I prefer the Nagura stone as it I also cleans up some minor changes I've made to the SJ grindstone.


Hope that helps to explain.


Rich