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Shaping an oval skew chisel

Started by John55410, March 08, 2014, 04:06:49 AM

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Rob

Excellent advice as usual from the Grand Master Ken :-)

One question Ken, I understand intuitively that its a good idea to first blunt the end when you're shaping but now that I think of it I cant think why exactly??  Is it so you can then make sure you grind evenly to the "shape" left by the blunt end?  In other words its like using a coping saw when you cut skirting to match a profile?  You blunt the end and then grind down to that profile on both sides of the bevel till its gone...then you know its sharp?
Best.    Rob.

Wybrook

I'd assumed it was to minimise the contact area between the chisel and the grindstone, thereby maximising the pressure and giving you some chance of finishing before Christmas ....

Rob

Another man who gets sarcasm.  Thank goodness. I've been so alone for so long :-)
Best.    Rob.

John55410

The blunting question seems to be something of a Rorschach.  My guess would be it's to keep the edge from getting too hot.

Anyway, with your encouragement, I finally reshaped my skew chisel.  My original aim was to put a curve on the skew as suggested in the T manual.  So, more questions:

1) Is this a good idea as suggested in the manual?  Any down side?
2) Will this take a long time?
3) I assume I should continue to use the fastest grinding technique (frequent use of the truing tool, universal support in the upright position), right?
4) Then switch to finer grinding surfaces and finally to honing?

Thanks.

Rob

correct on all counts with respect to the Tormek.  The only thing I cant answer is whether or not you should make a curved skew in the first place.  I only use traditional square edge myself.  Presumably its to remove the wings so you get less catches when cutting beads?
Best.    Rob.

Ken S

Wybrook, you may have waited too late for Christmas this year. :)

Rob, a line from Leonard Lee's sharpening book comes to mind.  He was talking about mortising chisels.  He happened to be talking with a shop foreman, presumably in Sheffield.  He asked why the mortising chisels has a radius ground in the top.  The foreman looked puzzled and answered that ever since he could remember, everyone, man and boy, ground the radius.  Lee noticed soon after that the new mortising chisels did not have the radius any longer.  The radius was actually a beneficial design feature which helped levering out the waste.  Unfortunately, over the years the reason for it had been forgotten.

In that spirit, I don't remember the reason for blunting the edge before regrinding. 

As I recall, Ernie Conover, one of my teachers, prefers flat ground skews without a radius.

Ken

Rob

Isn't it funny how these things get obscured with time.  When you're turning wood between centres as opposed to a bowl the skew is one of those chisels that causes much frustration and anguish.  It's a technique that can't be "bluffed" because if those sharp corners come into contact with the work piece, "boom" you have an ugly catch which badly dents the work and usually scare the willies out of the operator as the tool slams down on to the rest (or your fingers if held incorrectly).  So it has a certain cache and fear surrounding it.  Its the chisel that everyone is both scared of at the start and yet want to master because the benefits are huge.  Beautiful beads, slicing cuts in end grain leaving a near perfect finish, crisp details with fine edges, or crude but efficient massive stock removal with long wasting off cuts.  Finally, the planing cut, where you literally angle the skew in such a way as to "plane" the spinning work and get a fabulous finish and quite fine tolerances of trueness for the diameter of the cylinder you're creating.  In all an immensely useful and satisfying chisel to master....and a pig to tame the beast.  Envy and dread of the new wood turner in equal measure.

I'm sure why your teacher liked the corner design (as do I) is because you have a crisp, sharp edge with which to present to the work.  It's a proper, old fashioned style skill that really needs mastering before you get it.  It doesn't come over night and I'm by no means there yet myself.  But I'm well on the journey and its a very worth while one.
Best.    Rob.