S B angle gauge

[Albert Cwirko]

Hello does anyone have an aluminum S B angle gauge? Mine has been checked for accuracy, but when I use it to grind my gouges, the gouges are 3 degrees off. Has anyone had this problem? I know the grind is 3 degrees off as I have checked the angle with a professional protractor. Has anyone ran across a similar problem? Thanks, Al

 

[Robert D Evans]

It probably has something to do with the height of your tool rest. That would affect where the tool intersects with the round grinding wheel. As long as the angle is repeatable, 3 degrees shouldn't make much difference on your tool.

 

[robo hippy]

Well, not positive, but I ran into the same thing with my robo rest platform. If the height is off a bit, that can make a difference. I set mine to be even with the center of the axle on the grinder motor. If you are higher, the angles will get more acute, if you are lower, the angles get more blunt. You will also get slightly different angles if you sharpen a 1/4 inch gouge compared to a 5/8 inch gouge.

robo hippy

 

[Dennis Weiner]

The Sb gauge measures the angle at the base of the gouge. @robo hippy is correct that the angle actually formed varies based on gouge size. The top part of the gouge gets a different amount of metal removed due to the arch in the wheel, therefore the top angle is slightly different. The flute angle is a measurement of both and varies slightly from the 40 degrees. The larger the gouge, the larger the variance. The smaller your grinding wheels radius, the larger the variance. This effect does not happen with a belt sander which is flat. What you set, is what you get.

According to Stuart Batty, as long as your gouge is plus or minus 5 degrees, your gouge will perform like a 40/40. Like the others, I wouldn’t worry about it.
If you really are set in getting exactly 40 degrees, you can try using a spacer that is half the diameter of your gouge. Place it on the platform and readjust its angle with the SB. This will set the 40 degrees at the center of the tangent cutting line and may help with balance the error.

 

[robo hippy]

Hmm, with my grinder platform, when I tried the 40 degree setting, the gouge just didn't 'feel' right, and I went to the 45 degree setting. That 5 degrees made a big difference. More acute, I am guessing would make more of a difference than more blunt. I did figure out once, that a 1/2 inch piece of plywood on my platform made about a 5 degree difference, more acute.

robo hippy