In the Shop > Wood Turning

Why is skew chisel taking soooo long to sharpen?

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GGee:
Hi everyone I am new to the forum and to Tormek.  Hope you can help.  Have been trying to sharpen an oval, angled skew chisel (HSS).  It was taking ages (about 2 hours) and still nowhere near.  We realised we needed to shape it first, so we got bench grinder with Tormek BGM-100.  Did all that, got it into shape, all looking promising.  Transferred skew over to the Tormek (black silicone) and once again it is barely touching it (we put black pen on both sides and even after 40mins much of it it was still visible, with only tiny areas removed).  As far as I can tell we've been doing everything 100% correct.  But maybe not!  Any suggestions please?  Is the differential between the diameter of the bench grinder and larger Tormek wheels a material factor?
Thanks for your help
G

Twisted Trees:
Yes the different diameters will be a major factor on a skew as the bevel is so long. Avoid using smaller wheels in future...

but back to the problem in hand, I take it you are using the skew jig, be certain that the wheel is dressed flat and that you have used the course side of the grader more than once to get the best cutting surface, being oval be sure that it is sat flat in the jig.

If it has taken more than 30 minuets then you are doing it wrong, if it has taken more than 2 minutes then you are not doing it often enough

RichColvin:
Gareth,

I probably have the same one :  a Robert Sorby oval skew. 

This is not uncommon.  The reason is this :  there is a lot of surface area to be ground, especially for shallow included angles like 30° (vs. a bowl gouge).  And this large surface area is what takes so long.

What I have found to accelerate getting it to the next level is holding the gouge against the grindstone (using my right hand) whilst also holding the stone grader (SP-650) against the grindstone (in my left hand).  That keeps the grindstone's surface rough and makes for this process happening faster.  It will sound like you are adding sand to the process.

But, once you get a smooth surface across the whole area, you'll need to set the stone grader down and go from there.


Of course, there is always the option to use the course grit diamond grindstone ... but that is a very different cost option.

Kind regards,
Rich

Ken S:
I took the liberty of moving this topic to the woodturning section. Gareth, you ask very good questions. If by chance, you do not already have the Tormek Woodturner's Information Box, I recommend it highly. It is, in my opinion, Tormek's best video and well worth the cost. Here is a link:

https://www.tormek.com/usa/en/accessories/other-accessories/tnt-300-woodturners-instruction-box/

In addition to being an expert with the Tormek, Jeff Farris is also a very experienced turner. Jeff worked exclusively with the SG-250. (The other wheels were not available when he left Tormek.) One of Jeff's pearls of wisdom from the DVD is to reshape gradually. By that I mean if your skew left the factory not matching any of the Tormek presets with skew and bevel angles, do not try to regrind the whole change in one session. Just do it partway and leave the skew sharp. Get continually closer during the next sharpenings. You will soon be where you want to be and only need Twisted Tree's fabled less than two minute sharpening.

Twisted Trees and Rich Colvin both have much more extensive turning experience than I do. I would make only two suggestions. The first is the gradual change I just described. I have experienced what you are going through. An interminally long sharpening time is totally frustrating. Even a small amount of reshaping can be frustrating. Do it in small bites. Do not be afraid to use lots of pressure with your SG wheel.
The second suggestion is to keep your TT-50 convenient. It will make your grinding wheel cut faster than just your stone grader. Use the TT-50 and when the stone starts to slow down, switch to the stone grader. Go back and forth as needed.

Once you have the shape duplicated, TT hit the nail on the head.Sharpen often.......

Keep posting.

Ken

PS Jeff's other pearl of wisdom was if the shape you want is radically different than your present tool, buy a tool shaped as you want it. This is especially good advice if you decide you really prefer the original shape.  :)

GGee:
Many thanks all for your detailed and prompt responses.  The two most encouraging things are (1) we are not alone and not going mad(!) this is a known issue experienced by others; and (2) there is a solution!  One thing I did forget to mention is that we don't own a DVD player, having got rid of it when we went 'digital' a long time ago and started streaming everything!  Would be good if Tormek could make the DVDs available digitally.  Anyway we'll try the suggestions. Thanks again.
G

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