Chisel length

[flyer]

What is the minimum length that a chisel must protude from the SE-76 Square Edge Jig in order to grind properly?  I seem to be unable to get a 90 degree grind by inserting the tool per instructions.  I was wondering if the the length has anything to do with that?

Thanks.

[ionut]

Hi Larry,

I am able  to get a square edge on the Japanese chisels I have and their protrusion is less than 2 inches, the suggested length in the manual. What is the bevel angle that you are grinding on the chisel? Is it the edge at 90 degrese to the side that rested on the stop? If yes then the sides of the chisel are not parallel,
Try to clamp the chisel in the middle of the SE-76 and before completely tightening the knobs make sure one side is square to the SE-78 base with a small square. Clamping the chisel in the middle will allow you to tighten the knobs equally so there is no way for the chisel to slide sideways in the clamp from too much pressure, If at the end of the grinding the edge is square in relation to the side to which you applied the first measurement then it is fine. Of course before everything make sure your grinding  surface of the stone is parallel to the universal support first, if it is not you will have to true the stone. Also when you grind you dong have to move the chisels corners outside of the stone more than a couple of milimeters.

Ionut

[ionut]

... If the blade protrusion is too short you can always try to grind away from you by mounting the universal support in the horizontal position. You have to be aware though that the grinding action is less aggressive in that position but it may give you more control.

Ionut

[flyer]

Thanks for the suggestions!  I will try them out.

[flyer]

bevel angle is 25 degrees.  I tried putting the chisel in the middle and squaring it up.  It worked ok but took a long time.  I had to work the high side by spending more time grinding it.  I notices that my wheel now has a high spot a little off centere of the middle.  I had trued it up yesterday for another tool.  What causes the grinding wheel to be high in the middle.  I seem to have to true it quite often.  Also I have a hard time getting rid of the streaks with the rough side of the grading wheel.

[ionut]

Hi Larry, it took longer because probably the chisel was already out of square or maybe the stone got glazed. When you coarse grind if you have more to grind that usual you can regrade with the coarse side the stone, that will clean the stone and allow fresh crystals to do the work. Sometimes during the same grinding session if I have to change the bevel angle or the tool is in bad condition is not uncommon for me to clean the stone a number of times. When using on woodworking tools I ALWAYS check and true the stone in between tools if it is the case. The stone wears off immediately after you start grinding, and also depends a lot on how you apply pressure. I sometime have the tendency to apply more pressure on  right side for example and I try to compensate that, and if you have to square a bad edge you will definitely end with a high spot somewhere. For edges smaller than the grinding stone width do not move the corner of the tool more than 2 milimeters out of the stone. . If you apply constant force on the tool the grinding action depends on the contact surface between the tool and the stone. If the surface is smaller the grinding action is more aggressive also the stone wears faster in that area. That's why maybe you have a high spot in the middle. BTW how long did the grinding took for that chisel and how much out of square it was before you started?
If after truing the stone was perfectly flat and parallel with the universal support, then the grinding action  changed the shape of the stone which is  normal. When you are trying you have to take the minimum possible until the stone gets flat.

Ionut

[ionut]

You will also have to check the grading stone, it wears off too and it may not get to touch the grinding stone on all the surface. Look for an unworn area of the grading stone and use that. You may also have to try the edge of the grading stone.
My grading stone is useless now, it has no more  usable flat surface or hollow one that can be used successful on the stone. It also happened to bring my grinding stone out of flatness of square-ness with the grading stone so I stopped using it. And because I have a 1000 grinding stone I do not grade anymore the 220 one, I use that for coarse grinding. If you have a 220 DMT diamond bench stone you can try this. Clamp it in the SE-76 and start cleaning the stone but be careful, the grit is not the best one you must not apply much pressure at all, it will knock out the diamond crystals. It would be perfect if you would have a 120 grit diamond stone and use it that way, the stone will get flat and clean of streaks fast. And more than that this action will maintain the parallelism between the universal support and the grinding surface of the stone. If you don;t have a diamond stone and you want to try this get a 120 grit from the beginning but again, do not get crazy on the stone with the pressure, diamond does not need a lot of pressure to do its job. The DMT 8 by 3 inches on 120 has enough weight to not apply any extra pressure, you just have to move it sideways while dressing the stone. This does not eliminate the need to use the TT-50, but does not have to be done so often only when the grinding stone is out of round or the surface is in a very bad shape. Using this method between my tools keeps my stone always in great condition.

[Jeff Farris]

Please take a look at some of the other posts on here regarding stone grader use. It is not necessary, in fact it isn't even advised, that the stone grader be flat to be effective.