sharpening a skew chisel

[Ken S]

After reading several horror stories about sharpening high speed skew chisels, I decided to take the plunge. I have the loan of a one inch (25mm) Bodger Tool skew chisel. The Highland Hardware website says this tool is high speed steel hardened to 60 Rockwell. It was sharp when I began. I ground the sharp edge to a flat 1/16" (1.5mm). That would certainly rival the dullness of any skew on the forum. It should resemble reshaping.

Two hours later I learned some things. The job is not complete. I used the recommended settings on the TTS-100. The skew was reasonably close to these settings, but not exactly. At this point, I have reground the skew to the new profile, although the flat is still there. So what have I learned so far?

When I sharpen carbon steel chisels, I pay attention to the sound of the grinding. I was not hearing much with the skew and either the SG or the SB. I get the best grinding sound (and most metal removal) right after using the TT-50 truing tool. I ground until I was not hearing the grinding sound. Then I used the truing tool again. I eventually switched to two universal supports, one for use with the multijig, the other with the TTS-50 in placed. It made switching back and forth more efficient.

There may be better ways.

I am glad I tried this project. I would not do it again. I have resisted the urge to switch to the much faster Norton 3X wheels.  I don't feel I have mastered the SB wheel, but I am starting to feel more fluent with it.

Ken

[RichColvin]

Ken,

I've found that when I are removing a good bit of metal on the skew (HSS), I have to touch up the wheel with the stone grader quite often.  I also noticed a real difference in the sound after grading.

Rich

[Ken S]

Thanks, Rich.

I will keep with it.

Ken

[Ken S]

Day two with the skew:

There is an English idiom, "twenty-twenty hindsight". The twenty-twenty refers to the projected letter test at the optometrist, twenty-twenty being normal good vision. Twenty-twenty hindsight means clearly understanding something after the fact as opposed to before doing it.

Here is some twenty-twenty hindsight on yesterday's marathon sharpening:

I neglected to measure the skew chisel before grinding. If I had been wise enough to have done that, I would have realized that the skew had been sharpened differently than the TTS-100 settings. Both the skew angle and the bevel angles were different. A quick check with the built in angles of the TTS-100 would have told the story with the bevel angles. Looking at the mounted skew, I could tell the skew angle was different. I did not need to grind the flat to simulate reshaping, the tool itself provided all the reshaping I needed. I would have had two choices:

1) Using the black marker set the skew angle to be perpendicular with the grindstone and match the bevel angle. If the sharpening was a one time or occasional situation, this would have been logical. The grinding would only be resharpening.

2) Use the TTS-100 settings without grinding the flat. No need for the flat to simulate reshaping. Without the flat, the project would still have involved most of the two hours. However, at the end of that time, it would have been finished and the skew configured wuth the TTS-100 for quick touch ups later. This would have been the logical choice for a regularly used tool.

Note to self: always remember to measure the tool first.

After checking the magnifier on my DBS-22 for AndrewLee, I will continue grinding the skew. The shape is cow matched with the TTS-100. I just need to grind out the flat. I will focus on use of the stone grader and post my results.

Ken

[Ken S]

Day Three and Success.

As part of my preparation for the third and hopefully last day of my skew chisel reshaping project, I did a forum search on "blackstone". Among many suggestions, I found one posted by Rob on April 29. Rob mentioned that he has been using a diamond T dresser to keep his SB-250 working well with his turning gouges. I thought I would try it, as well as continuing to work with the TT-50 and the stone grader.

I set up my Tormek in the horizontal position with the SB-250 grinding wheel. As per Rob's suggestion, I moved the support bar within a millimeter of the grinding wheel. I held the T dresser on the support bar and dressed the wheel. It went well and quickly.

The SB cut better than at any time in the project. I had allotted an hour to hopefully finish up. In under five minutes, the grinding was done. I was amazed. The old grinding sound had returned!
As per Rob's caveat, for critical work, I would true the grinding wheel with the TT-50 before making a light final pass.

Conclusion: The SB -250 works well with high speed steel. I have had good results using it with knives. I am pleased that it also works well removing more steel. If I had this experience earlier, I probably would not have done my Norton 3X tests. The Norton wheels definitely cut faster, however, they seem less necessary when the SB is working well.

I still do not fully understand the stone grader. I am working on it and will post my findings when I am successful. Others use the stone grader proficiently, so I must conclude that my problems relate to my technique rather than to the stone grader itself.

I did pick up some good tricks along the way. I became much more fluent with the TT-50 truing tool. My set up time improved when I left the truing tool mounted on a separate universal support. Switching back and forth involved only minor tweaking of the micro adjust.

Using a separate universal support for the T diamond dresser helped, too. As it is only set up close to the grinding wheel, an older, non microadjust universal support works fine for this.

Using one of the setting holes, in this case, B, on the TTS-100 really speeds things and is very repeatable. I have found the TTS-100 an essential tool, even though I am not an active turner.

I was discouraged initially, but am pleased I did the project. I learned a lot and hope it has benefitted other members of the forum.

Ken

[AndrewLee]

Would you say reshaping/sharpening a skew chisel one of the hardest things to do on the tormek?

I've tried to regrind the shape of mine from a flat skew to a rounded chisel. The result was less than satisfactory for me. 

[Ken S]

I would say that for me it was very difficult. I want to clarify that statement. I started the project to get a better understanding of what several forum members had encountered. I have stated before that I am not an active turner. This was the first time I had ever sharpened a skew chisel.

My original intention was just to grind a flat surface about 1/16" or 1.5 mm from the sharp edge to simulate a very dull tool. I foolishly did not take the time to verify that the skew was ground to the Tormek profile. It was not, although it was close. Matching the profile required much more work than the resharpening. I had inadvertently made the project much more involved than I realized.

Here is how, with the benefit of hindsight, I would redo the project: After carefully measuring the skew and realizing that both the bevel angle and skew angle differed from the Tormek profile, I would have partially adjusted both angles and sharpened. The resharpened skew still would not match the Tormek progile, however, it would be closet to matching. I would gradually bring the skew to the Tormek profile through several sharpenings. Once the profiles matched, further sharpenings would be quick and easy for the life of the tool.

I have long believed that mastering a few basic skills on the Tormek places one in the last lap of mastering the Tormek. Before this project, I felt adequate with the truing tool, which is one of the basic skills. I now feel fluent with the truing tool. Acquiring that mastery alone was worth the struggle of the project.

I became more fluid in the use of several universal supports for different functions. I became quick with the TTS-100, which I consider the most advanced set up tool.

I still have work to do with reaching that level with the stone grader. With directed practice and study, I will achieve that goal. Please keep in mind that as a Tormek demonstrator, I require a deeper understanding than a home shop used would need. As I approach that goal, I will share any insights with the forum. I welcome insights from the forum; I am a member, not a guru.

Ken

[Rob]

Interesting Ken.  Your experience was clearly the same as mine which is to say it's a bit of a "grind"!

Although the steel removal does become possible by frequently dressing the wheel (whether using a T bar or the diamond truing tool), it comes at the price of an unacceptable loss of stone diameter in my view.  With the benefit of 2020 hindsight, I would switch to a Norton wheel or similarly more aggressive medium for fast HSS removal.  The SB or the SG for that matter are not inexpensive and personally I think their forte is in sharpening rather than shaping because the toll on the diameter is too great a price to pay when reshaping.

Having said that, I've literally just come in from the workshop having been turning bud vases all evening and what a pleasure it is using a Robert Sorby 3/8" spindle gouge after a quick touch n turn using the new SVD 186.  I have to share this tip with the forum because it works a treat.

I now mount the gouge in the jig with the usb in the horizontal position using Hole A.  I always, on both spindle and bowl gouges, grind off the heel leaving the primary bevel occupying only about half of the facet on the entire bevel.  This can be done with zero setup change by loosening the gnarled black plastic knob at the base of the SVD 186 jig and sliding it all the way out then locking.  You don't even need to take the jig off the usb or the tool out of the jig. Simply regrind the bevel and it will now do the heel. This leaves you with a secondary bevel which is a single facet in its own right.  The purpose is that when you come to grind the primary bevel, there's so little metal that literally one pass will resharpen it.  I'm not exaggerating, I promise on my deceased Mother's grave....one pass will completely renew the metal on the primary bevel.  If you then flip it upside down and just polish the flute freehand, you'll have a gouge so sharp the cut will seem like it was done with the long point of the skew.  It is a joy to use. 

But the tip that people might not know (the above stuff should be reasonably well known) is I leave the tool in the jig while turning with it.  Only if it is way over the rest does the jig interfere with the proper use of the gouge.  For all simple coves and general sweeping cuts, including shallow hollowing like cutting the inner rim of a bud vase into end grain, it works a charm. Then when you need to touch it up for a finishing cut, zero setup time.  The usb is already setup with Hole A and the gouge has the correct protrusion because its still locked in the SVD 186.  All you do is slide it on the usb, hit go, one pass and you're done :-)  If you're being really fussy, one quick pass with the profiled hone to polish the flute.  If that takes more than 10 seconds then I'm a monkey's uncle!

Frankly, that method is faster than freehanding because there is zero margin for error.  What I'm improving on now is where to hold the gouge/jig combo for maximum effect while turning and even that has some advantages because the gnurled black knob is up top and provides rather a handy substrate to grab hold of in some cuts.

So just to cycle back to the original topic.  What I'm describing (just) above is the diametric opposite from where we started.  This is what the Tormek really excels at doing ie removing an almost immeasurable, gossamer layer of metal it's so fine.  Earlier, we talked about shaping and in that regard...the Tormek....not so much :-)

The combo of the SVD 186 and a spindle gouge.... never to be parted now that's nice :-)

[Ken S]

Excellent post, Rob. I believe you have discovered a "and Bob's your uncle" sweet spot for your turning.

More later.

Ken

[Ken S]

The handbook lists a useful tip on the last page of the turning skew section:

   "If the geometry does not differ too much from the shapes the TTS-100 offers, you should consider changing the shape to the TTS-100 shape for easier replication in the future."

I followed this advice for my skew chisel project, however, it would have been more logical to have modified the tip to "if the geometry does not differ too much from the shapes the TTS-100 offers, change the shape gradually over several sharpening/reshaping sessions".

In my case, the skew had a different shape than the TTS-100 profile and I tried to match the TTS-100 profile in one reshaping session. In hindsight, this was foolish and wasted both time and tool steel. My initial error, not measuring the skew and bevel angles was compounded by "bull moosing" ahead and matching the TTS-100 profile.  The original tool profile was just as functional for turning as the TTS-100 profile; it just did not match the TTS-100. A more logical course would have been to have gradually altered the profile to match the TTS-100.  This would have converted a very long reshaping session to several much shorter resharpening sessions with a bit of reshaping. It would have also produced much less wasted tool steel.

Logistically, I would have placed the same three function Tormek label on the ferrule with the desired end settings written in. I would have also placed a piece of blue masking tape on the handle to indicate temporary "manual" settings.

I would use the same procedure with a turning gouge.

Ken

[Hatchcanyon]

For me straight skew chisels are pretty easy to do independent of the angle they are grinded to. They work more or less like other irons except that they need to be worked on both sides. The SVS-50 is the right jig for the job. Normally I do not use the TTS-100 but color the bevel and look how a first removal of material is positioned. If the edge only is touched the universal tool rest needs to be positioned alittle bit nearer to the stone, if only the heel is touched a little bit farther.

Oval skews are more difficult due to the fact that they have a larger contact area substantially slowing grinding down. Without the SB stone grinding is annoying slow. The first one I did with the SG took me an hour to grind it - at last it felt like that. This was the trigger for buying the black stone.

Rolf