Grinding a square edge on Plane Irons?

[MIGNAL]

Why not just seat the blade in the plane, allow it to project a mm or so and simply pull the plane backwards over a sheet of wet/dry.
This is how jig makers think.

 

[Eric The Viking]

I agree with Zeddhead that the tool rest - the long bar and its mounting - is the prime suspect.

I don't have a genuine Tormek, I have a Dakota one*. Those tool rests (identical to Jet et al, too) have exactly the same problem - cheapskateness - only a threaded nut on one shaft, not both. So I have a process that works:

1. Check the side of the wheel is running true (disengage drive shaft by taking the rubber-tyred wheel off & check wobble with something like a pencil clamped in the tool rest). If this is wrong you're stuffed as you can't do the rest of the process!

2. Check rim of wheel is square to the side (engineer's square).

3. Set tool rest bar to also be square to the side.

4. If necessary, true-up wheel with diamond thingy.

Then you're good to go (and apart from (4) that lot takes longer to read than to do, honestly).

I have a couple of "Smoothcut" Japanese laminated plane irons, and although they're really, really wonderful, THEY TAPER slightly across the width. So you can't trust the indexing blocks on the plane iron holder and have to eyeball it. I often end up with the skew lever on my planes pushed quite far over, but it's not the end of the world - as long as I end up with a good finish (and squareness) life is way too short to lose sleep over the squareness of the pointy end.

I take Jacob's point, but the same machine gets used for all sorts of things from chisels through to the garden shears, electrical screwdrivers (which I am fairly anal about being square and true, and yes I can square-up those!) and kitchen scissors. My hands shake sometimes; I have trouble holding certain shapes of object, and having a Tormek-style jigged system takes out a lot of the potential for cock-ups.

It's only a slow grinder though - I have once or twice succeeded in getting chisels dry-shave sharp with it, but not consistently, so I use it for re-grinding, not for final honing. I don't love it, I just use it - a tool to help do what for me is an awkward job otherwise.

E.

* "My name is Eric and I have been a Rutlands Customer." (sits back down in the ring of chairs, to half-hearted applause).

 

[Mike-W]

Eric your not on your own I was once a Rutland customer…. many years ago!
Thanks for your post it’s got me thinking and doing a bit more testing with my Tormek 2000.

• I checked if there is any run out in my stone, yes there is a bit- about 0.3mm measured with a pencil and a feeler gauge on the inside edge of the wheel, this could be down to how the wheel was mounted on the axel at manufacture or down to me occasionally using the side of the stone for grinding.
• I set the tool post at the optimum height from the grinding face of the stone for the truing and dressing tool (TT-50) to do its work about 12mm.
• I changed the tightening knobs on the tool rest for Allen head machine screws that I could nip up more tightly so there is no chance of the tool rest moving after prolonged use.
•I made several slow and shallow passes across the stone taking just under 0.5mm in total off the overall diameter of the stone. I did notice when ‘planning’ the stone with the TT-50 the cut sounded and felt like it was removing more (i.e. taking a deeper cut) on the unsupported side (outside) of the tool rest. Could this be the tool rest flexing on its unsupported end?
• I did check if the stone side was square to the grinding face and also the stone side square to the tool rest (it was) but because of the 0.3mm run out I thought a better check of accuracy between the tool rest and stone would be to check the gap between the top of the stone and the underside of the tool rest. Both the inboard side and outboard side measured 12.8mm with a feeler gauge, however under the middle I could only get a 12.7mm feeler gauge in. Close examination with a 6” steel ruler indicates a slight bend in the middle of the tool rest!. Note the unsupported end (over the stone) of the tool rest is about 8” long, so the 6” ruler exaggerates the bend in the tool rest however different jigs run on different parts of the tool rest, this could cause problems.
•I then took a piece of mild steel plate to replicate sharpening a 2” Plane iron,
I set it in my Tormek Square Edge Jig (SE-76) with the RH side of the 'Iron' set against the square edge shoulder in the jig and with a projection to grind a 30 degree bevel.
The Tech Bulletin that Zeddedhed provided a link to suggest the primary cause of out of square grinding was down to uneven clamping pressure with the chisel iron in the SVH-60, as I said I was aware of this problem but I still check the saddle clamp on my jig is tightened up evenly by sighting through it for any ***** of light on either side between the back of the iron and saddle.

Because the ‘iron’ was the same width as the wheel I had no need to move the jig from side to side on the tool rest, I was also able to keep my finger pressure in the middle of the ‘iron’ meaning there should be no likelihood of uneven pressure while grinding.

After I ‘raised a burr’ I checked how square the cutting edge to the side was.

Its out by about 0.25mm over 44mm. Not sure what that is in degrees, but it sure ain’t square.
I’m inclined to agree with Zeddedhed’s first post - its poorly designed/manufactured jig support which the likes of Jet and Triton have copied that fails this system of 'precision' sharpening.
I think I’ll stick to using the grinder freehand from now on!

BW
Mike

 

[Jacob]

Er - you could have squared the ends of a dozen chisels and plane irons freehand, in less time than it took you to write the above!
It really is very easy to do, unless you do it the Tormek way when it obviously verges on the impossible.

 

[iNewbie]

There was a tech note using the svh60 jig, online.

http://www.sharptoolsusa.com/squareedgeweb.pdf

 

[RogerP]

... and here's the way to grind and hone the curved edge of a fore plane’s iron. Same technique is used for a straight iron. No jiggery-pokery required.
http://www.popularwoodworking.com/woodw ... fore-plane

Looking at the grinding article you posted, the tool rest which is also a guard is way, way, too far away from the wheel, should be 3-4mm away from the grinding wheel to prevent any snatch or even getting jammed with the object being shaped or sharpened.
Regards Rodders

I agree! This is the problem with all this easily available material particularly from a cross the pond. It's all too easy to assume dangerous practices are acceptable if you have no proper training.
Like rodder says that's asking for trouble
I can envision that causing a wheel shatter, people have lost their sight when that happens
Swartz should know better

Perhaps I didn't pick on a good illustration - but don't get sidetracked - freehand squaring of the end of planes or chisels is so easy it doesn't need jigs.

 

[AJB Temple]

Interesting thread. I have a Tormek T7 and conventional grinding wheels. I rarely bother with jigs and grind by eye, engineers square and angle template if I am feeling fussy. As I am extremely used to freehand sharpening Japanese knives on water stones (every couple of days) I always produce the secondary bevel by eye and then strop. The stones are frequently flattened. My experience is that the jigs and guides take too long to set up and do not improve the results.

Are you sure the wheel itself on the Tormek is not out of true? I have seen these slow wheels (not just Tormek) ground very one sided though slightly improper use. Maybe true up the wheel.