Different angle without changing universal support height...

[dadinthegarageww]

So...

I've been practicing sharpening some cheap chisels. I started by grinding the SG wheel to coarse, then ground a 30 degree angle. I then changed the grit of the wheel to fine using the grinding stone that comes with the T8. I put the chisel back on the wheel without changing anything else than mentioned above. When I looked at the wheel and it's interface with the chisel, the angle seemed off. I had to adjust the universal support a bit to get the same angle back.

Does the angle change so much while changing grit on the stone? Did I do something wrong or didn't do something correctly?

Thank you for the feedback!

A

[cbwx34]

So...

I've been practicing sharpening some cheap chisels. I started by grinding the SG wheel to coarse, then ground a 30 degree angle. I then changed the grit of the wheel to fine using the grinding stone that comes with the T8. I put the chisel back on the wheel without changing anything else than mentioned above. When I looked at the wheel and it's interface with the chisel, the angle seemed off. I had to adjust the universal support a bit to get the same angle back.

Does the angle change so much while changing grit on the stone? Did I do something wrong or didn't do something correctly?

Thank you for the feedback!

A

How much is "a bit"? 

Easiest way to check would be to mark the bevel with a Sharpie and see where the stone is removing metal.

Angle change should be negligible grading the stone. 

I'd try again, and see what happens.

[Ken S]

I agree with CB.

What puzzles me is how much coarse grinding you had to do to establish the bevel. Normally, this would not be a concern, however, if the amount was excessive, it could change your bevel angle slightly. I suggest that you check your angle with your Anglemaster again after doing the coarse grinding. If you get a different reading, use the microadjust to reset your chisel back to the original angle.

Out of curiosity, your 30° bevel seems steep to me for a bench chisel.I would normally use 25°, although I am open to other possibilities.

Keep us posted.

Ken

[dadinthegarageww]

Thank you both.

I did 30 degrees because I planned to use this chisel on hardwood.

When I was done with coarse grinding, the bevel was flat on the stone. When I changed the stone coarseness to fine, only couple mm of the tip of the chisel touched the stone, the heel of the bevel was off the stone by couple degrees. I used the stone grater for about 20 seconds on the stone to change the grit.

I didn't use the sharpie, what I did (accidentally) was that I was looking for the light between the chisel bevel and the stone and adjusted it until the gap disappeared. Worked just as good. Can't say the same about my back

[cbwx34]

...
When I was done with coarse grinding, the bevel was flat on the stone. When I changed the stone coarseness to fine, only couple mm of the tip of the chisel touched the stone, the heel of the bevel was off the stone by couple degrees. I used the stone grater for about 20 seconds on the stone to change the grit.

I didn't use the sharpie, what I did (accidentally) was that I was looking for the light between the chisel bevel and the stone and adjusted it until the gap disappeared. Worked just as good. Can't say the same about my back

Perhaps take a look at Rich's page on chisel sharpening... it doesn't directly answer this question, but has a lot of reference material.  (Also might want to watch the Tormek video on the subject.)

Again I'd probably just try again... if it continues, I'd be interested in how much change there is.

[Ken S]

Dad,

Your reasoning for using 30° for hardwood seems logical, especially if you are using a mallet with your chisel. The "recommended settings" are only general guidelines, rather than gospel.

I do not mean to minimize your problem, although your situation presents interesting possibilities. I do not limit my study of sharpness to just Tormek. One of my favorite resources is Lie-Nielsen. L-N produces some excellent you tubes. The low angle jack plane is designed to use several blades with different angles. The different angles are produced by secondary microbevels. Normally, I don't use microbevels. This might be an unusual situation. I would just start two or three degrees lower (27 or 28°) and end up at 30°. The only critical angle is at the very edge.

The real long term answer may be to sharpen more frequently while less metal needs to be removed.

Keep us posted.

Ken

[cbwx34]

This made me think of something... if chisels are normally sharpened at a lower angle, did you change the angle, and if so, is it possible there was a "gap" that you didn't notice until you graded the stone fine?  (IOW, was the entire bevel ground when the stone was coarse?)

Just a thought... 

[dadinthegarageww]

Good thought. I didn't change anything except the grit of the stone from fine to coarse since I was removing material.

That is the only thing that was different. Unless I took out a lot of material and didn't realize it?! But still, the bevel should be in the same place unless I took off a lot of stone while changing it from fine to coarse...

I'm a bit afraid to try it out on my expensive chisels. Looking around if I can find some cheap ones on CL to experiment with..