Author Topic: Manual touch up of chisels between sharpening and angle issues  (Read 6231 times)

Offline Chris B

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Manual touch up of chisels between sharpening and angle issues
« on: September 15, 2019, 11:23:52 pm »
Hi all. New forum member here. I'm reasonably new to this. See there is a lot of experience and expertise on here.

My question relates to touching up chisels by hand when they get a little blunt and some observations on an issue I found when trying to match sharpening angles between the Tormek and a manual honing guide.

My garage doubles as my workshop - so there is not a lot of space and I can't leave my Tormek permanently set up. It lives in a cupboard. Rather than setting up the Tormek each time I need to do a quick blade touch up, I figure I can give chisels a few swipes on my waterstones.

Originally I was planning to use my eclipse-style honing guide to do this. I have a jig when allows me to set the blade at a precise 30 degree (or whatever) sharpening angle. But that's when I noticed a problem. I was sharpening a decent size firmer chisel  (30mm or 1 1/4") and I found that even though I had set my grinding angle on the Tormek to 30 degrees using the angle master, it didn't nearly match the (precise) 30 degree angle on the honing guide. So I scratched my head a bit and realised that, in fact, the 30 degree sharpening angle on the Tormek only applies to the very leading edge of the chisel bevel. Since the sharpening wheel is round, the bevel is obviously ground concave. So the angle on the leading edge is 30 degrees but the grinding angle somewhat higher on the trailing edge of the chisel bevel. In fact, when I use the bevel angle gauges on the angle master side to check the Tormek ground angle, the bevel angle didn't really match the 30 degree gauge at all.

I played around with the angle master to give me a grinding angle which would match the precise 30 degrees of my manual jig. The easiest way to do this was to change the stone diameter setting in the angle master. I found that if I set the stone diameter to just over 200mm (whatever that is in inches) I got a match with the 30 degree bevel achieved with my manual honing guide. Clearly the Tormek bevel is concave and the manual bevel flat. But it would be good to easily set up an angle on a manual honing guide to add a very small microbevel to the Tormek edge.

And then I did a bit of reading and see that some people touch up (or finish sharpening) their Tormek sharpened chisel blades by free hand with a few strokes on a waterstone using the concave chisel bevel surface as an angle guide. This gives you a very small microbevel - essentially coplanar with the ground bevel edge. So I figure it is too hard to match a manual honing guide jig angle to a Tormek angle.

So this was a long way of getting to my question. I'm about to try using the freehand manual approach. Is this the best way of touching up my blades rather than setting up the Tormek each time?


Offline RichColvin

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #1 on: September 16, 2019, 04:39:30 am »
Chris,

The concavity of the grind on a 250mm wheel is quite small, barely noticeable.  But, it is common to do just what you are saying. 

Indeed, I’ve read some woodworkers will sharpen on a Tormek, and then hone on flat stones to 13,000 grit or so.  They’ve said that honing is easy as the blade’s edge is balanced on the two edges.  To outline this, see the picture on the right of this page :  http://sharpeninghandbook.info/WW-Chisels.html

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

Offline Ken S

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #2 on: September 16, 2019, 04:47:25 am »
Welcome to the forum, Chris. Some thoughts:

I worked out of my garage for many years. I know moving my Tormek very well. In temperate weather, you might try setting up a Workmate just outside your garage while you are working for your Tormek. This worked for me. One side benefit was the natural daylight was fantastic for seeing. Even the Anglemaster worked amazingly well in the bright light!

I remember handcutting dovetails for a class project (a Shaker candle box). I could gradually feel my chisel losing its sharpness. In the middle of an operation, I believe the most practical solution is to have a second chisel available. If you use one size chisel extensively, say in cutting dovetails, you will probably get more use from a second chisel of the same size than from most of your hardly used sizes. Or, you can use the next size smaller as your second.

Regarding hollow grinding, I realize the round Tormek wheel produces a hollow grind in theory. This is more pronounced with a traditional high speed six inch dry grinder. When I hold a straightedge up against a Tormek ground chisel bevel, I have trouble seeing much hollow grind. If this theoretical hollow grind bothers you, I would just set the Anglemaster three degrees higher. I would not suggest fiddling with the wheel diameter setting; you are not altering the wheel diameter.

I suggest making simple wooden setting blocks for your chisels. Use one block for setting the Distance between the support bar and your grinding wheel. The second gage block is for setting the Projection of your chisel from your square edge jig. Using these properly, you only set your Distance once. Keep the Projection the same for all the chisels you grind at the same angle. When switching chisels, all you have to do is use the stop block. No fiddling or measuring, and your angles are consistent. Make a second Distance block to compensate for the smaller diameter of the leather honing wheel. You can use the same Projection.

Personally, I think it can be as fast to efficiently touch up your chisels using just your Tormek. Whichever method of finishing your chisels is entirely up to you. My suggestion would be to really learn the full operation with your Tormek. Once you are very fluent with your Tormek technique, feel free to try other methods and things like secondary bevels.

This has been a stop and start day. I will close now. Chisels are my favorite tools to sharpen with the Tormek. Persist.

Ken

Offline Ken S

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #3 on: September 16, 2019, 04:56:39 am »
Rich,

The traditional two point hollow grind technique predates the Tormek. In my opinion, it was more useful with the typical six inch dry grinders of the day than with the large diameter Tormek wheel. The secondary micro bevel lessened the hand sharpening labor. I don't see the advantage when the work is done by the Tormek machine.

My opinion......

Ken

Offline Twisted Trees

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #4 on: September 16, 2019, 12:45:28 pm »
As Ken said, the hollow is a hangover from smaller grind wheel diameter, a 10" is almost though obviously not quite flat.

Even my wood turning tools get touched up with a diamond card between sharpening, can just add that edge for the final pass cut before sharpening properly again.

Offline Jan

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #5 on: September 16, 2019, 03:29:37 pm »
Chris B, in the attached drawing you can see that for a thick chisel the heel angle can be by 6 degrees larger than the edge angle grinded by a 250 mm diameter stone.

Jan

Offline MikeK

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #6 on: September 16, 2019, 04:20:43 pm »
I think if you ask five people how to sharpen chisels and plane irons, you'll receive eight answers...and they are all correct if the results work for the user.  For fine woodworking, such as dovetails, I would never use the Tormek to sharpen my chisels or plane irons, but might use it to sharpen a chisel used for carpentry.  I use the Tormek to establish the primary bevel angle, but then use the Lie-Nielsen honing guide on either water stones or DMT diamond plates for the secondary bevel and honing bevel.

The first 25-degree primary bevel will usually last seven to eight sharpenings before I have to go back to the Tormek and re-grind.  Each touch-up widens the secondary bevel a bit, and this adds to the amount of time on the stones. The slight hollow grind from the Tormek ensures I'm not wasting time sharpening and honing the part of the chisel that doesn't do any cutting.

All of my bench chisels are Lie-Nielsen and Blue Spruce, and they get at 25-degree primary bevel using the Tormek.  The exact amount isn't important, since I put all of my effort on the next operations.  When grinding on the Tormek, I'll leave the final 0.5mm of the edge since I'm going to address that part on the stones.  A Sharpie (or any permanent marker) on the bevel gives me a clear indication of the grinding process and when to stop.

The next operations are on the stones, starting with the 800-grit water stone.  I set the projection of the chisel at 30mm, which gives me a 30-degree bevel with respect to the back of the chisel.  A few swipes on the stone are all that is required for a wire edge to form for a fresh grind.  The number of swipes increases with each sharpening, and when I get to the point where it takes 20 to 25 swipes for the edge to form, it's time for a fresh grind.  By that time, the 30-dgree secondary bevel is large and dominates the cutting edge.

I then change the projection to 25mm for a 35-degree bevel for the honing.  I use a 10,000 grit water stone and it takes no more than four swipes for the wire edge to fall off.  One swipe on the back of the chisel holding it flat against the stone, and I'm done.  The four swipes on the honing is constant during the touch-ups, and I don't remember ever having to do more.

I don't strop my chisels and have never seen a reason to do this.  However, others recommend touching up only by stropping.  My chisels are razor sharp (maybe sharper  ;D) and the A2 steel at RC60 takes a beating while retaining an edge for a long time.  I have a couple of new Two Cherries chisels that seem to lose an edge just by moving through air.  I can use them on ash for a couple of minutes before the edge is gone, while the LN and BS chisels last much longer.

Find the rhythm and process that works for you and have fun.

Offline Ken S

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #7 on: September 16, 2019, 09:31:33 pm »
Mike,

I agree with you about receiving  eight answer, all correct. As an old hand  with oil and water stones, you have found a very workable method. You are happy with it; I would not change. You have premium tools and a method I would not hesitate to use with fine woodworking like cutting
dovetails.

The only area where we think differently is that I would also feel just as comfortable sharpening my plane blades and chisels for fine woodworking, including dovetails, using only the Tormek.

Leaving a .5mm blunt edge is a wise precaution with a high speed dry grinder. That last very thin .5mm is where the edge is most likely to overheat. With the water cooled Tormek, this precaution is unnecessary.

Secondary micro bevels are a labor saving shortcut for hand sharpening. They are efficient with bench stones. Using a Tormek for the heavy lifting makes them unnecessary. Once the bevel is ground with the coarse graded SG, honing with the SG graded fine goes quickly. Having a preset second support bar for the leather honing wheel makes accurate stropping fast. If one is concerned about rounding the edge, using a flat ultra fine ceramic stone for the back lets the tool stay in the jig.

If the small hollow grind is a concern, set the angle three degrees higher.

PA-70 honing breaks down with use and becomes finer grit. Well used, it should be as fine as a fine waterstone.

As you say, there are many answers. I would include Tormek as an option for fine woodworking with chisels and planes.

Ken
« Last Edit: September 16, 2019, 10:12:10 pm by Ken S »

Offline smurfs

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #8 on: September 16, 2019, 10:40:26 pm »
Chris B, in the attached drawing you can see that for a thick chisel the heel angle can be by 6 degrees larger than the edge angle grinded by a 250 mm diameter stone.

Thanks for the diagram Jan. Up until now I had only thought in terms of the bevel angle formed by the angle of the chord and hadn't considered that the angles at the heel and edge are different. I have learned something new! 

Offline Chris B

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #9 on: September 16, 2019, 10:51:00 pm »
Thanks for all of your very useful comments guys. I clearly need to do some more experimentation to perfect my technique.

This whole sharpening thing can become a bit of an obsession to find that perfect edge. But then I guess a lot of folks on here can identify with that! I don't have a Japanese waterwheel for the Tormek and indeed can't justify the cost or the hassle of changing wheels for my hobbyist situation. (In fact I have already spent far more on sharpening gear than I could ever rationally justify  :)). So hence the thought about whether I could use my 6000 grit bench Japanese waterstone to finish off chisels etc and give me that sharper edge.

Yes I have done a lot of reading and see that there are many opinions on how to best sharpen! I need to do some more experimentation to see what works best for me in my situation. Mike I was thinking of doing just what you say. But spending all that money on a sharpener only to use it to grind the primary bevel is hard to justify to myself! I need more practice with the Tormek. What I haven't been doing very well is resetting the wheel grit from coarse to fine to finish off the edge. Also, I've been using the honing wheel freehand which may have rounded off the edge somewhat.

I do like the idea of the blocks/jigs Ken. Great to have a way of setting a repeatable edge angle. I have done something similar for my manual sharpening setup to give me the correct honing angles for chisels and plane irons. I have downloaded your very informative and useful notes on the Kenjig and am intending to make something up. I have also read the excellent paper from Dutchman on how to work out the jig dimensions needed for various angles. Both of these are very useful resources.

So thanks again all for your help. Now to keep practicing my technique!

Offline Chris B

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #10 on: September 16, 2019, 11:02:59 pm »
Chris B, in the attached drawing you can see that for a thick chisel the heel angle can be by 6 degrees larger than the edge angle grinded by a 250 mm diameter stone.

Jan

Thanks Jan. Yes this what I figured out in my experiments. I was going to try and draw something similar to work it out - but you've already done it! Hence the difficulty in taking say a 30 degree angle from the Tormek and translating it to a 30 degree angle on a manual honing guide. When I tried to do this I ended up just sharpening one edge of the bevel. I guess you could make up jigs if you wanted to combine Tormek with manual sharpening at a very similar angle. Or maybe just use freehand would be a lot easier using the Tormek grind bevel as the guide.

Offline Ken S

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #11 on: September 16, 2019, 11:56:41 pm »
Chris, I am pleased that you like the gage block idea. Please note that I did not say "my" gage block idea. I believe I contributed to it, however, these ideas pop up in the turning video that Jeff Farris did many years ago. The TTS-100 turning tool setter echoes them as well. (My original setting jig for setting plane blades and chisels was an adaptation of the TTS-100.)

The Tormek has a reputation for being slow. Setting tools are like a good pit crew in an automobile race; they don't make the car go faster, however, they reduce the down time.

There is room for much more innovation. I hope you will join in and enjoy the journey.

Ken

Offline RichColvin

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #12 on: September 17, 2019, 04:42:59 am »
Rich,

The traditional two point hollow grind technique predates the Tormek. In my opinion, it was more useful with the typical six inch dry grinders of the day than with the large diameter Tormek wheel. The secondary micro bevel lessened the hand sharpening labor. I don't see the advantage when the work is done by the Tormek machine.

My opinion......

Ken

Not my preference.  Just wanted to note that it is relatively common with high end furniture makers, even when they sharpen on the Tormek.

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

Offline MikeK

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #13 on: September 17, 2019, 10:26:42 am »
Leaving a .5mm blunt edge is a wise precaution with a high speed dry grinder. That last very thin .5mm is where the edge is most likely to overheat. With the water cooled Tormek, this precaution is unnecessary.

I've never used a high speed grinder for my chisels because I was never good enough to judge when to quench in order to retain the hardness.  My few trial and error efforts were not good and resulted in discolored edges, much to the dismay of my instructors.  Prior to the Tormek, I created the primary bevel using a honing guide on various grades of paper on a flat glass or granite surface.  This was especially time consuming when reconditioning used chisels or plane irons with edges that had been abused and had to have fresh metal on the cutting edge.  The Tormek reduced this time considerably and was well worth the purchase.

I stop at the 0.5mm edge with the Tormek not because of heat, but because there is no return on time investment in taking the primary bevel to the edge.  I'm going to put two more steeper angles on it anyway, and doing this with stones is much faster for me.  If the edge is chipped, or otherwise not square, then I will continue to the edge with the Tormek.

Offline Ken S

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Re: Manual touch up of chisels between sharpening and angle issues
« Reply #14 on: September 17, 2019, 01:03:55 pm »
Mike, you state your thoughts well, and I certainly do not disagree with you. Like you, I was no stranger to blued edges with my grinder. I have since learned that crowning the wheel may help prevent overheating, however, I have not used my dry grinder in several years. I detect the influence of David Charlesworth, a craftsman I hold in high regard, in your thoughts. Yes?

I would just set the Tormek to grind at the desired final bevel angle and grind. Secondary bevels are fine; I just don't find them necessary when the work is being done by my Tormek instead of my hands.

Ken