WM-200 Angle Master Accuracy

[GIPPER]

Hi Herman
You're right.  It doesn't make sense but it's a fact.  On the right side of the chisel, it measured 45 degrees (edge to heel) while on the left side of the chisel, it measured 30 degrees (edge to heal).  Obviously, either the wheel was not square or somebody sharpened it by an unsteady hand.  In any case, I decided to reshape the chisel so it would have a 30 degree bevel (and would be square to the shank).  It seemed to work pretty good and I now think I have a pretty good chisel to work with.  Gipper

[ionut]

Hi Gipper,

How wide is the chisel you are working with? 15 degrees difference is humongous that would lead to a very large degree of un-square edge compared to the sides of the chisel. Is the chisel body badly twisted? At that degree the un-squareness of the wheel would be more than obvious and your side to side movements would be wavy, I mean the chisel would not be moving in the same plane as you would move it side to side. How did you measure the bevel angle?
Is the universal support securely tight at the time when you start sharpening?

Thanks,
Ionut

[GIPPER]

Hi ionut.
Not sure how to address the questions you pose so let me first try to answer your questions directly.
A. the chisel is 1" wide
B. the chisel is not twisted as best as I can tell
C. I measured the angles using the WM200
D. The Universal Support was tight.

Please understand this was my second attempt at sharpening a chisel with my new Tormek T-7.

The Set Up
1. Used the Square Jig in the horizontal position
2. Protrusion was by hand and the max. allowed by the jig and the tool length.  Actual protrusion unknown
3. Black Ink marker on bevel surface
4. Measurement with WM200 left and right side by adjusting USupport. Until scratch ink off bevel surface each side then measure angle with WM200
5. Different bevel angles obvious by sight on each side
6. Chisel was snugly secured in the Jig

Final Set Up
A. Maximum protrusion allowed by jig and chisel shaft length to lock in place squarely
B. Set Chisel bevel to 30 degrees using the WM200
C. Reshaped and sharpened chisel.
D. Did not change grit on grinder
E. Did hone with flat honing wheel by hand
F. Results Good
Gipper

[ionut]

I understand you but this Tormek machine is a very simple machine and very effective, you do not have to know anything about sharpening and still be able to get good results first time. When it comes to edge square difference of a  1 -2 degrees than the complication comes up too, but 15 degrees difference between the left corner of 1 inch chisel compared with the right corner is far too much or I do miss something.  If I would try to replicate that difference just by adjusting the height of the universal support and using the WM I would have to make a big change. Does the chisel stay approximately in the same plane while grinding and moving it left –right over the stone? Was this chisel grinded before on a dry grinder and is possible to have lost its tamper? If that happen differentially it may be an explanation  of the angle difference but you should still see a plane change of the chisel while moving it left to right over the stone.
There may be another cause but still would not explain such a difference. The back side of the chisel is not flatten, and the area you clamp it in the SE-76 is not in the same plane with the cutting edge but even then the first thing you will see would be a very un-square cutting edge in relation with the sides of the chisels.

Ionut

[Herman Trivilino]

On the right side of the chisel, it measured 45 degrees (edge to heel) while on the left side of the chisel, it measured 30 degrees (edge to heal). 

Ok.  When you put it that way, it makes sense.  I helped frame a roof once that was shaped like that.  The thing is, if the back or your chisel forms a flat plane, the edge that's been machined cannot be a flat plane.  The surface has to be concave, like a magnifying mirror.  Someone perhaps did this on purpose.

Anyway, you can confirm these angles by using the v-shaped notches on the edge of the WM-200.

[GIPPER]

Incidentally or Coincidentally, the Angle formed on the TTS-100, between the two moving disks and the center of a grindstone whose radius is 125 mm, is 17.5 degrees.  No coincident for sure.  That explains why a WM-200 AngleMaster shows the same degree angle on a flat surface.  Now I can sleep tonight in piece.  LOL.
Gipper