Hollow grind not square?

[Monte Milanuk]

So... dug out the old Veritas grinder tool rest to regrind a chisel that got bunged up.

It's been a looooong while since I used it; I *thought* it was fairly goof-proof... but maybe not.

I indexed the chisel against the left side brass screw, and the brass pin of the Veritas grinding jig. I set the jig in the Veritas tool rest, and started the grinder at its lowest speed, using a 6" Norton white wheel. I'd also used a small square to check the chisel square to the face of the grinding jig.

Imagine my surprise when the edge came out almost rounded to one side. I thought maybe I had inadvertently put pressure on it somehow, and tried a few more times. About all I managed was to achieve a fairly ugly camber on a 1" chisel

I'm kinda of at a loss here. Any suggestions?

[Robert LaPlaca]

Sure the grinding wheel is dressed parellel to the tool rest?

[Monte Milanuk]

It's been quite literally years since I fired this thing up last... took me a while just to dig out my honing guides, etc. Not sure of much of anything at this point.

[andrew whicker]

photos of the chisel?

[Jim Andrew]

Sounds like the chisel handle was wobbling in and out as you sharpened it.

[Monte Milanuk]

So, I ordered a single point diamond wheel dresser, and got it today. Clamped it in the Veritas jig, and ran it over the wheel. Took a bit off the wheel, and then mounted the chisel in the jig again. its better - not cambered, but definitely not square.
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[Matt Day]

When you go back and forth Make sure to speed up while approaching and leaving each edge. When only the edge is being ground there is less blade being ground therefore will be ground faster. That can cause camber and possibly what you're seeing.

[Brian Holcombe]

I set the tool rest for the angle that I want, but otherwise grind freehand that way I can take more material where I want to and keep the grind even.

[Prashun Patel]

Like Brian I find freehand is the easiest way to get a square edge. The platform holds the bevel angle only. You maintain the perpendicular path freehand.

Also, radius the edges of your wheel so you are not using the entire edge. This also makes the process much easier to control.

[Ted Reischl]

Is your tool rest square to the wheel? No way to tell from the pics.

[Monte Milanuk]

I had laid a straight edge (blade from my 12" Starrett combo square) along the wheel and it *looks* square... but I'm considering loosening the mounting bolts for the rest and tweaking it a bit to see if that squares things up a bit.

About the free-handing suggestions... I can (apparently) screw this up with a big and a rest. I really don't think free-hand is a good idea at the moment. I appreciate that it works for you, but for right now I want to get this straightened out without throwing something else into the mix.

[Brian Holcombe]

You should take my above advice, as I've learned from doing and sharpen blades practically every day, but feel free to do as you please.

wheel squareness has no effect on blade squareness in a situation like this where the blade is being moved across the wheel. If the wheel is skewed then only the high spots will touch.

I pointed this out earlier and I'll point to it again once more. The blade is obviously not square in the holder, adjust it until the edge is square to the track, those are the only two things that really matter in this setup.

[Monte Milanuk]

The blade *was* square to the from edge of the holder. I also clamped a straight edge in there and ran it out alongside the wheel - no gap.

Finally did end up free-handing it... and had to (from my perspective) skew the chisel a bit (3-5 degrees) to get a square edge on it. Then the bloody bevel angle was off when I went to hone it... ended up saying screw it and dug out the 220 grit water stone. It's almost done now, in far less time than I've spent screwing around with that tool rest & grinder.

[Brian Holcombe]

The purpose of hollow grinding is not to sharpen the blade, it makes a ragged edge. Instead it is to facilitate ease of sharpening. So it basically allows you to make a very thin land at the edge which sharpens easily. Many will grind at an angle more acute than they hone at. So grind at 25 and hone at 30.

220 grit is rough, a typical regimen for sharpening would be to remove wear with a 1k stone, hollow grind, then hone with an 8, 10 or 12k stone then remove the wire edge also with the fine stone.