Thursday, October 31, 2019

Grinder Improvement

It's been almost three years since I got my hand-crank grinder.  Its clamp doesn't open wide enough for me to attach it to my workbench, so I clamp it to a chunk of wood and clamp the wood in a vise.
My grinder, clamped to a 2x8, clamped in the end vise
The original tool rest is an "L" bracket bolted to the side of the gear box.
See the bolt?
The tool rest is fairly flimsy, so early on I made a new tool rest from a few pieces of oak and pine.
My first homemade tool rest
The adjustable rest is bolted to the gear box on one side and to a pine upright on the other
In use, I held the tool flat to the surface of the rest and brought it to the wheel
There were some problems with this.  First, it took a bit of practice before I got good at using it.  Second, if was never as accurate as I wanted it to be.  I wasn't getting an even grind across the width of the chisel or plane iron.
Here's an example: this chisel had been sharpened a few times after being ground,
but you can still see that the grind marks were not consistent
A while back I saw a grinder attachment that someone made and I'd been wanting to make something similar.  It's basically a platform with a movable stop that will hold the butt end of the chisel or iron a fixed distance from the wheel.  I can move the stop to get the grind angle I desire.

Half inch plywood extension screwed to the bottom of the 2x8, with a slot
down the middle for the movable stop
The stop keeps the chisel a consistent distance from the wheel
(the ruler is laid in front of the stop to keep the chisel from getting stuck in the slot)
Another view - see the sparks?  Ooohh!
And another view, in line with the wheel showing the alignment of tool to wheel
This is a far more even grind than I've ever gotten
The stop does double duty.  One side is straight so that I can slide chisels side to side, and the other side has a "V" groove for grinding gouges.  I've had much more difficulty grinding gouges in the past.  With this helper, the gouge's butt end stays seated in the groove while I twist the gouge to grind the entire bevel.
Bird's eye view of a gouge on the grinder
This allowed me to get an almost perfectly consistent grind all across the curved bevel.
Now that came out great!!
For plane blades, I can use it just as I did for chisels.  But it looks like the iron is held at a weird angle.  So I made a riser to hold a plane iron at a much more reasonable angle.
Plane iron in the jig
Plane iron on the riser
As it turns out, the riser isn't necessary and I quit using it.  That upright angle of the iron doesn't matter - what matters is the angle that the wheel grinds on the bevel.

This was an easy project to make.  It just took a little thought about how to do it.  And it works fantastically well.  I'll still need the other tool rest I made for other kinds of grinding work, but fortunately the two jigs are removable.

I'd seen another variation on this somewhere, possibly made for a powered grinder.  In that one, rather than have an adjustable stop, the whole platform was adjustable, sliding in and out through a slot under the grinder.

4 comments:

  1. Pretty cool.
    On your frame #11 you show a freshly ground bevel with the edge honed. If you have honed that with a guide after grinding then the rest of the comment won't apply.

    If you grind each time so that the honed edge is preserved but the heel of the bevel is consumed the bevel angle is going more acute with each grinding. Ideally the remaining honed surface left behind would be even on each side of the grind and then the bevel would stay the same.

    It's a nice guide that seems especially suited to a hand powered grinder. A challenge is that grinding 10 tools of slightly different length will require 10 setups. I would think there is some sort of gauge that would take the wheel center and bevel angle to give a quick location of the fixture block.

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    1. Thanks for the comment, Steve. I'm honing freehand after grinding. During setup, I check the grinding angle by eye and also with a little angle block. The setup takes a short time. I try to grind at about 27° +/-, but I'm not too concerned with the exact angle, then I hone at about 30°.

      If I figure out some angle setting guide that is easy to use and allows me to set the stop more quickly, I'll write about it.

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  2. I'm having a front head slapping moment! Doh!
    I have the One-Way Wolverine grinder attachment with the Vari grind jig for sharpening my turning gouges. Works in same principle, with one glaring exception. Mine sit in front of the power grinder, hence sticking out. Long enough to handle long handled turning gouges, so it is adj and removable. I have yet to set it up here. I long thought of doing something similar for my hand grinder setup, but never thought of making it in your orientation, my crank grinder sit at the RH end of my catch all bench, which meant jig would be sticking out. Now if I rotate mine like yours.. Slap on the forehead! :-)

    Bob, who was staring at it the whole time thinking... :-)

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    1. Glad that something I've done can inspire a solution for your shop, Bob. I don't recall my reasoning for putting my hand grinder in the orientation it's in, but it might have been simply due to the length of 2x8 I had to clamp it to, while clamping the board in the vise. Whatever the reason, it works fine.

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