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T8 wire edge frustrations for gouges: SJ-250 the solution?

Started by Jof, April 04, 2020, 11:44:36 AM

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Jof

Hi all.

After a couple of weeks with the Tormek T8 and the stock SG-250 wheel I'm finding there to be one frustration I didn't have with the Work Sharp 3000 and that's the wire edge.

On the T8 I sharpen my gouges with the direction of rotation which gives is a substantial (>0.5mm) edge that's super hard to detect by hand until I use the gouge and it chips within a few cuts. Looking at this http://bessex.com/forum/showthread.php?tid=372 amazing thread has helped me understand the problem much better, but I still have some questions.

Currently I'm finding that to finish a gouge I'm regularly alternating between fine metal removal with the 1000 grit and power stropping (with my homemade tool as the leather on the Tormek is too slow) the inside and outside edge at 1-2 degrees to get rid of that wire. This works well, but I feel I'm not gaining maximal sharpness here due to the very slight rounding of the edge you get with a strop.

On the WS 3000 my trick was to raise the blade at about 2 degrees and hone with a 3000 grit perpendicular to the direction of rotation. This achieved an extremely small but incredibly sharp micro-bevel that subsequently didn't need stropping with the leather and so kept its wedge profile. So I wonder:


  • Could I (should I?) add this micro-bevel with the SJ-250 as my final finishing operation (as well as using it to polish the rest of the edge as the smoother the surface the better for carving gouges)
  • would the DE-250 be an alternative or is it too coarse?

Ken S

Jof,

Good questions. Would you please clarify some things for me. Are the gouges you are sharpening wood turning gouges or carving gouges? HSS turning gouges and carbon steel carving gouges are very different steels and uses.
What bevel angle are you using?

In the past ten years, I do not recall other posts with chipping gouges. I do recall somewhat frequent edge rounding problems with the leather honing wheel. I watched a very experienced Tormek rep honing a chisel while we were having an in depth discussion about rounding. Watching him work skillfully, I am convinced that the rounding problem is primarily due to not knowing how to use the leather honing wheel. Incidentally, using the stone grader is not just "220" and "1000" grit. It can also be graded to "600 grit", meaning an approximate in between grit. I have never been able to duplicate the grit of a freshly trued wheel. I tried using the fine side for longer time periods and was able to get an even smoother finish. In my opinion, the grit numbers are just indications of more coarse and more fine.

I am just trying to establish the full picture, not to be critical. Edge chipping and edge rounding seem like two different problems.
Do you have the same problem if you use the Tormek leather honing wheel with PA-70 compound?
Do you have a second gouge for cutting comparison which you have sharpened with your Worksharp?

I would not recommend purchasing an SJ wheel until you have worked more with the SG and have become convinced that it will not do what you want. Two weeks seems like a very short trial period.

We will work through this.

Ken

Jof

Thanks for the reply, Ken. I'm always glad and grateful to see your replies :)

These are steel woodcarving gouges, typically around 58 Rockwell. For the gouges I use with mallets or hard woods they have a 20-25 degrees bevel angle and all the rest have 17.5.

I'm afraid I'm not sure which of the tools were sharpened by the WS and which by the T8; they are all the same mirror finish now.

Re chipping versus rounding I couldn't say which is happening for sure as my eyesight even with a 8x lens isn't amazing. What is clear, however, is that if I do the following process they will be astonishingly sharp but fragile and chip/round after a few cuts of end grain:

1) Shape with coarse
2) Finish with fine (ending with a very light touch to reduce scratches)
3) Remove burr and polish on leather wheel with PA-70

What's notable about the surface using that process is that the blade is continuous right up to the edge as if it were a perfect infinitely-sharp bevel. But weak. Doing some further stropping with the tool at about 1-2 degrees solves that but often results in an unexpected edge shape as this fragile region of material gets removed in unexpected ways - especially for curved gouges above a #5. If instead I go back and forth between the strop and the fine graded stone for a few minutes at the end I can ensure my edge is robust, sharp and the correct shape.

My ideal outcome would, of course, be that wonderful edge for without the fragility!

(Side note: I only use my own power strop with PA-70 because it's much faster than the Tormek wheel. The results are identical though)

RichColvin

Jof,

I compiled this regarding the sharpening and honing of wood carving tools.

      https://sharpeninghandbook.info/Info-WoodCarvingTools.html

I hope that helps.

Kind regards,
Rich
---------------------------
Rich Colvin
www.SharpeningHandbook.info - a reference guide for sharpening

You are born weak & frail, and you die weak & frail.  What you do between those is up to you.

Ken S