I found the excellent threads discussing the Kenjig and Dutchman tables. It seems the discussions and Dutchman's tables were developed for the knife jig.
I would like to develop some quick-set jigs for plane irons and chisels. I have the old-style square jig, if that matters.
I don't see any reason why I could not use Dutchman's equations to develop settings for my purpose, but I thought I would throw this out to more experienced users first.
Thanks.
Steve
Excellent question, Steve.
I don't see why Dutchman's tables would not work. In my case, I started what would evolve iinto the kenjig sharpening my chisels and plane blades. This was before Dutchman posted his tables. My goal at the time was to avoid having to measure each blade using the Anglemaster. By keeping the Distance and Projection constant, I could sharpen chisels and plane blades all day without having to remeasure.
I used the two holes in the TTS-100 to set a constant Distance. With this Distance set, I used the Anglemaster to set the appropriate Projection. I then marked this projection (from the front of the square edge jig) on a piece of blank label tape placed in one of the three slots of the TTS-100. I made a mark at the end of the blade in the slot and labeled it (eg. "25 degrees"). Adjusting the Projection instead of the Distance is a bit clumsy, however, I only needed to do it once.
You might have to compensate to use Dutchman's tables with the square edge jig. I have not tried this, however, I don't think it would be omplicated. Hopefully Dutchman will post. He is the authority on this. I will email him.
Ken
Thanks Ken.
I thought about using some trial and error to set the projection (and make a jig), using a fixed support distance from the wheel surface. However, I know that over time this relationship would change. Of course, I don't know how long that will take.
My thought was possibly to develop a spreadsheet using Dutchman's equations, specifically for use with the square grind jig. As you know, there would be a different range of "S" and "A" values with the square grind jig vs the knife jig. Also, I thought I may as well use the spreadsheet for the range of wheel diameter I will be working in for the realistic future (which is 230 mm to 240 mm). I could run the spreadsheet for each 1 mm change in wheel diameter. At this time, I don't know how sensitive cutting bevel is to a slight change in wheel diameter. But for the level of sharp we all like to chase, I suppose it would be sensitive. I guess if I get it really close with the set-up, I can do a slight adjustment using the sharpie method before grinding.
I have a lot of ideas floating through my mind right now about how to implement this. One of them would be to develop an adjustable projection jig, which would allow the projection to be set to the spreadsheet projection values - which would ALL be established for the SAME distance between the support and wheel surface "S). I could use a spacer block to set the support bar.
I hope that makes sense. I have to think through the details a bit more.
I don't have much experience with the machine, so I could be chasing a bad idea.
Steve
Steve,
I think you are overthinking this. Most bench chisels are sharpened with a 25° bevel. Paring chisels normally get 20°. If you happen to use mortise chisels, they get 35°. Plane blades normally get 25°.
One of the reasons I used the TTS-100 is that the two small wheels are Tormek's patented means to auto correct for wheel diameter changes. (The 250mm T8 wheels and the 200mm T4 wheels use the same TTS-100 with no adjustments.) A plane blade or chisel back is a large enough surface to work well with the Anglemaster. Either the tape mark in the slot or wooden stop blocks work well to set the Protraction.
You have good creative instincts. I just think another project would be better for them.
Keep thinking!
Ken
Arnman, Dutchman tables do not work for the square edge jig because the geometry of this jig is substantially different from the knife jig.
Nevertheless you can use the Dutchman's approach and equations to calculate tables for square edge jig. I have a simple calculator for it, so I can verify your results. Let me know.
Jan
P.S. Important guidance resulting from recently closed discussion on this forum: the set up does not depend on the chisel thickness!
Thanks Jan. I understand Dutchman's tables are outside the range of the square edge jig.
I developed a calculator for use with the square edge jig. Here is my input:
Wheel diameter = 237.0 mm
Surface of wheel to center of support bar = 19.0 mm
Grinding bevel angle = 25.0 degrees
Here is my output:
Back of support bar to wheel surface = 41.78 mm
The blade projection from the front of jig will have to be determined after I get a good measurement directly from the jig.
As I said earlier, I would hope that I can make a sliding jig that will allow a changing blade projection setting as the wheel diameter changes. I have a simple prototype in mind that is just a couple of wood blocks with slots and a screw to tighten. Of course, I don't know how quickly the wheel diameter will change, as I am expecting the original wheel to last many more years.
Thanks for your help. I can attach my Excel file if you would like.
Steve
Arnman,
For D=237 mm, chisel/plain iron protrusion 50 mm and target angle 25⁰ the distance between USB centre and stone surface should be 27.8 mm. The spacer block USB/stone would be by 6 mm shorter i.e. 21.8 mm.
Jan
Jan,
Can you please clarify what you mean by "protrusion"?
Is that the distance from the back of the USB to the stone, or the distance from FRONT of square jig to stone?
Thanks.
Arnman, the protrusion is measured from the front of the square edge jig to the stone surface. My calculations are for the SE-76 jig. I hope it will work for the jig SE-77 also, but cannot guarantee it because I do not have it.
The angle 25⁰ is at the tip of the plane iron. If you measure it with protractor you get slightly larger angle because you measure chord angle between the back, tip and the heel. For plane iron which is 4 mm thick the chord angle is some 27⁰ in this case.
Jan
Quote from: Jan on November 14, 2019, 09:10:27 PM
Arnman, Dutchman tables do not work for the square edge jig because the geometry of this jig is substantially different from the knife jig.
...
The equations in "More math ..." can be used ;)
Arnman,
the attached graph can answer some of your questions concerning stone wear. Chisels and plane irons are handled in the same way.
Jan
Jan's graph says a lot. When I designed the kenjig, I decided to leave the Projection constant (at 139mm, although the 140mm used by others is just as valid). I wanted to incorporate the self correcting double wheels of the TTS-100. Although Tormek only uses this patented feature for turning tools, it can just as easily be used for woodworking tools and knives.
Jan's graph, like Dutchman's tables, uses diameter changes of ten millimeters. I constructed the kenjig using the 15° line on Dutchman's 250mm diameter chart. Going across to 139mm Projection, I went up to 80mm Distance. At first I debated between making a set of kenjigs for ten millimeter diameter wear reduction or dedicating the kenjig to that particular grinding wheel and modifying the jig as needed for wear. Kenjigs cost almost nothing to make, and they are quickly made. Either option would work. A professional sharpener might prefer to make a set.
At the risk of sounding like a heretic, I do not believe that home shop sharpeners, the majority of us, need to be concerned about wheel wear. Wheel wear of ten millimeters (diameter) will change the bevel angle by about one degree. (2° with the double bevel). I can see where that amount of change might make some of us nervous. If so, it's time for a new kenjig. I make the wooden kenjigs using my table saw and bandsaw. The set up is what takes the time. I think it is wise to make up several spare blanks. With a diameter change of one millimeter, a change of 1/10° will happen. Yes, this is noticeable with the math. Can we accurately measure this change, or, more importantly, can we detect a difference in cutting?
How long will it take the average home sharpener to wear off ten millimeters from his wheel diameter? How many longtime Tormek users are still using their original grinding wheels. For most of us, wheel wear is glacial.
As constant diameter diamond and CBN wheels become more commonly used, I see wheel wear becoming increasingly less important.
Several years ago, I was particularly impressed with the comment Jan made pointing out the error in my kenjig. Jan is enough of a highly skilled mathematician to notice the error and a practical and honest enough sharpener to also note that the error was not significant.
We need both skilled mathematicians and practical sharpeners.
Ken
Ken, I think that the protrusion 53 mm used in the graph above and below resulted from some discussion with you. But because it is already some three years ago I have forgotten what was the reason for this unusual dimension. Nevertheless the graph is still useful.
I am attaching another graph which shows the situation for 30⁰ edge angle used for chiselling in hard wood.
Jan
Thanks for this discussion. I hope to have time to review some of your comments this weekend.
One thing I did notice - I made my own spreadsheet based on Dutchman's calculations and assumptions, and I match the numbers in his tables exactly.
I found another website app (from one of the Tormek site members) called Sharpening Handbook. The math is basically the same as Dutchman's, but there are some slightly different assumptions involved - such as the distance from the top of the USB to the center of jig.
I found that these differences result in minor changes in the results. I don't really mind the slight difference - I am more concerned with jig settings for repeatability.
Steve
Steve,
I'm the creator of the Sharpening Handbook. I truly believe I will never be the font of all wisdom (though I've had plenty of learning mistakes), and this tool can only get better with others' help. And since most of the information came from others, it will stay free to use.
So if you find there are errors in my assumptions or calculations, please do elaborate. I'll be grateful, and happy to fix it,
Kind regards,
Rich
Quote from: RichColvin on November 16, 2019, 03:40:27 PM
Steve,
So if you find there are errors in my assumptions or calculations, please do elaborate. I'll be grateful, and happy to fix it,
Kind regards,
Rich
Rich,
Thank you for responding and making that app available. Sorry I could not recall your name when I referred to this in my post. I was looking for your name on the website app, but did not see it.
One minor comment on the calculations you shown at the bottom of the diagram - I believe there is a typo. It seems there is a "2" missing in equation 1, just in front of the parentheses. I think the quick calculator is using the "2" in that equation.
Once again, I really appreciate the discussion on this topic. There have been many more responses than I expected. Great discussion on the effects of wheel wear. I am hoping to dedicate some time this weekend to dive in.
Steve
Quote from: RichColvin on November 16, 2019, 03:40:27 PM
...
I'm the creator of the Sharpening Handbook.
...
Rich
On your website I miss my second publication "More math for the Tormek grinder".
The following reference comes from the topic of the link in my signature.
20180702
At the request of "cbwx34" I developed mathematics for use with its robust "jig-fix" as published on https://forum.tormek.com/index.php?topic=3570.msg22912#msg22912 (https://forum.tormek.com/index.php?topic=3570.msg22912#msg22912)
The new formulas can also be used to choose a different reference point for the distances than the center of the jig's stem, which is unclear and inconvenient.
As a result, the setting of the sharpening angle can be determined more accurately.
Some measurements were also made from which possible sources of error appeared.
The new document is titled "More math for the Tormek grinder"
You will find the documents in the public folder "Tormek-T7 grinder":
https://bit.ly/2lHaR3m (https://bit.ly/2lHaR3m) on DropBox
https://bit.ly/2KpROFg (https://bit.ly/2KpROFg) on OneDrive
The new documents are:
• "More math for the Tormek grinder A5 serial.pdf", serial version for tablet
• "More math for the Tormek grinder booklet.pdf", A5 booklet to print on A4
• "USB adjustment table.ods", spreadsheet to generate the new table
Ton,
Thank you for letting me know of the missing document. I will add these later today.
Kind regards,
Rich
Quote from: Dutchman on November 15, 2019, 10:28:47 AM
Quote from: Jan on November 14, 2019, 09:10:27 PM
Arnman, Dutchman tables do not work for the square edge jig because the geometry of this jig is substantially different from the knife jig.
...
The equations in "More math ..." can be used ;)
Dutchman, Thank you for your excellent work, and sharing this information. I did not understand immediately what you meant by your comment about "More math...". Then I realized this was a reference to an update of your original document. I have now spent some time studying the "More math" document.
I am pursuing the use of these concepts for chisels and plane irons, with the SE-76 square edge jig. My question is how to establish the distance JC for this jig - which is for a single bevel blade.
Please confirm if my method is correct, or point out where I am wrong.
Distance from the jig bedding surface/bottom of blade to the bottom of USB = 23.5 mm.
Subtract 6 mm (radius of USB) from this value = 17.5 mm.
Add the full thickness of the blade (3.0 mm).
JG = 20.5 mm.
Thanks again.
Steve
Quote from: arnman on November 19, 2019, 04:19:15 AM
...
Please confirm if my method is correct, or point out where I am wrong.
Distance from the jig bedding surface/bottom of blade to the bottom of USB = 23.5 mm.
Subtract 6 mm (radius of USB) from this value = 17.5 mm.
Add the full thickness of the blade (3.0 mm).
JG = 20.5 mm.
Thanks again.
Steve
Steve,
Please add a figure, a rough sketch is sufficient.
So as I understand now, only half the blade thickness should be added.
Arnman,
For SE-76 use the distance 23.7 mm.
In my understanding the square edge jig SE-76 geometry is complicated by the small raised edge in the rear part of the jig base which tilts the tool upwards by some 1.3⁰5. For sure I take this into account in my calculations. ;)
Jan
Quote from: Dutchman on November 19, 2019, 10:03:52 AM
Quote from: arnman on November 19, 2019, 04:19:15 AM
...
Please confirm if my method is correct, or point out where I am wrong.
Distance from the jig bedding surface/bottom of blade to the bottom of USB = 23.5 mm.
Subtract 6 mm (radius of USB) from this value = 17.5 mm.
Add the full thickness of the blade (3.0 mm).
JG = 20.5 mm.
Thanks again.
Steve
Steve,
Please add a figure, a rough sketch is sufficient.
So as I understand now, only half the blade thickness should be added.
I think he's right to use full thickness... since it's a single bevel? (But yeah, sketch would help). :)
Jan,
I'm just curious about the annotated angle of 91.5⁰ in your sketch as I would have just assumed it to be 90.0⁰.
Did you derive this angle mathematically or did you measure it using an AngleCube or such like?
Thanks, Andrew
Andrew, you are welcome! :)
I got the value by measuring the height of the protruding edge (0.75 mm) and the width of the jig base (33.3 mm). The arctan of the ratio 0.75/33.3 gives the angle 1.3⁰. It is also directly measurable with a protractor.
In both cases the accuracy is limited to some +/- 0.3⁰.
Jan
Oops : missed Jan's sketch... pretty much nails it! 👍🏼👍🏼
Thanks for the clarification Jan.
I don't have a SE-76 but do have the SE-77 so can now determine the 'right' angle. That said if you have already done the calculation and can share it that will save me and others the effort of doing so :)
Unfortunately, I am unable to load photos small enough for the forum.
I have attached a crude sketch that shows my measurement from the bottom of USB to bedding surface. I am interpreting Dutchman's "More math" sketches to calculate JC as shown.
It is my understanding that for a blade already ground (approximately), then the "sinking" effect could probably be neglected, and the full thickness of the (single-bevel) blade should be used for calculations, as this is the line to the tip of the blade at the grinding wheel.
If I am interpreting Dutchman's sketches correctly, the JG measurement is from the tip of blade contact with the stone to the back face of the USB as shown. I would appreciate confirmation that I am calculating JC correctly, and interpreting the JG dimension correctly.
Jan, apparently my jig dimensions do not match yours. Maybe I do not have an SE-76. Also, mine does not have a notch inside to affect the bedding angle. I guess this is why my calculations were not matching the ones you posted earlier.
More comments are welcome. I really appreciate the discussion on this.
Steve
Quote from: arnman on November 20, 2019, 01:40:31 AM
...
If I am interpreting Dutchman's sketches correctly, the JG measurement is from the tip of blade contact with the stone to the back face of the USB as shown.
...
It also depends on where on the arc, caused by the round stone, the grinding angle must match.
That is of academic interest, but I am not concerned about that. ;)
Quote from: smurfs on November 19, 2019, 09:46:56 PM
Thanks for the clarification Jan.
I don't have a SE-76 but do have the SE-77 so can now determine the 'right' angle. That said if you have already done the calculation and can share it that will save me and others the effort of doing so :)
Andrew,
I have posted only some guidance here because in my understanding Arnman intends to develop his own calculator.
I have done my calculations some three years ago, so it can take some time for me to prepare a script suitable for sharing on this forum. Evermore I am not a good Excel programmer because I have grown up with IBM FORTRAN which I still use in a DOS window. ;)
Jan
Quote from: arnman on November 20, 2019, 01:40:31 AM
...
If I am interpreting Dutchman's sketches correctly, the JG measurement is from the tip of blade contact with the stone to the back face of the USB as shown. I would appreciate confirmation that I am calculating JC correctly, and interpreting the JG dimension correctly.
...
Steve
I guess it depends on how you write your formula, but I believe JG should be from the tip of the blade to the
center of the USB.
(https://forum.tormek.com/index.php?action=dlattach;topic=4116.0;attach=3960)
Quote from: cbwx34 on November 20, 2019, 01:33:52 PM
but I believe JG should be from the tip of the blade to the center of the USB.
That actually makes the most sense to me, but it seems that all the diagrams for the knife sharpening jigs illustrate this dimension being measured from the back face of the USB - and it seemed that the only dimension that differentiated the knife sharpening jig from any other jig was the diameter of that jig.
Maybe I missed it in the "More math" document, but I did not see a note that 6 mm should be added to the JG measurement for jig setting. The 6 mm additional correction to reach the back of USB was clearly depicted in the original Dutchman document (A vs K).
I don't mean to obsess about this too much, and I appreciate everyone's patience. After looking into this so much, having a clear understanding of the setting parameters and relationships has become very important to me.
I was not able to download a
working copy of Dutchman's spreadsheet for some reason, so I duplicated it myself and I match every one of Dutchman's values. I would be glad to post the Excel spreadsheet somewhere, but I am not sure it is mine to disseminate without Dutchman's approval.
Quote from: arnman on November 20, 2019, 03:15:53 PM
That actually makes the most sense to me, but it seems that all the diagrams for the knife sharpening jigs illustrate this dimension being measured from the back face of the USB - and it seemed that the only dimension that differentiated the knife sharpening jig from any other jig was the diameter of that jig.
Maybe I missed it in the "More math" document, but I did not see a note that 6 mm should be added to the JG measurement for jig setting. The 6 mm additional correction to reach the back of USB was clearly depicted in the original Dutchman document (A vs K).
...
The way I understand it, both Dutchman's new formula, and Jan's formula, "move" the point to the center of the USB, then adjustments can be made to where you measure to set the position of the USB in relation to the wheel (or casing), so in my case, in the formula I use (for the knife jig), since I measure from the top of the USB to the wheel, I add 6mm to obtain the final answer.
The quote in blue (from p.12 of Dutchman's book) and the referenced figures is how I interpret it...
(https://forum.tormek.com/index.php?action=dlattach;topic=4116.0;attach=3962)
Quote from: cbwx34 on November 20, 2019, 03:36:58 PM
The quote in blue (from p.12 of Dutchman's book) and the referenced figures is how I interpret it...
cbwx34,
Thank you for pointing that out. I don't know how I missed that. It makes much more sense now.
Steve
Just out of curiosity. :)
Some four years ago Ken inspired me to think about the usage of TTS-100 for setting the edge angle of a tool mounted in the square edge jig SE-76. The old thread, read more than 2000 times, was entitled "Setting 25 degree edge angle with TTS-100" and you can find it here
https://forum.tormek.com/index.php?topic=2731.msg14578#msg14578
I have reinserted the disappeared original pictures.
Jan
Thanks Jan, I will definitely read that thread.
Over the past few days, I have discovered old threads that cover some of the things I have been inquiring about. I can see that I am dragging you, Dutchman, cbwx34, Ken, and others through topics that have already been hashed out!
I am not sure if you noticed in my earlier post - my square edge jig does not resemble yours at all. I tried to post a picture, but I cannot shrink it enough for the forum to accept.
Steve
Steve, you are welcome. Old threads are also for authors interesting reminders of thoughts in the past. It is a good feeling, when in hindsight, the results are still valid.
I have noticed your post concerning different form of your jig. It is geometrically simpler when the jig angle is 90⁰. The usage of my angle 91.3⁰ instead the 90⁰ changes the tool edge angle by some 0.5⁰ only.
Let me know if you need another working example, for 90⁰ jig angle, for testing you calculator.
Jan
Quote from: arnman on November 21, 2019, 05:13:53 PM
...
I am not sure if you noticed in my earlier post - my square edge jig does not resemble yours at all. I tried to post a picture, but I cannot shrink it enough for the forum to accept.
Steve
I had him email me the pics... they are attached for reference. 8)
cbwx34,
Thanks for posting my pictures!
Jan,
I read the thread that you linked above. That is very informative, and it sure looks simple (and repeatable). I think if I had read that a week ago, I would have already adopted that method. And I will certainly keep it in mind.
BUT - now that I have started down this path I have noticed the possibility of elevating my results.
For example, switching over to the honing wheel, which will require me to re-set the USB on that side and try to achieve the same angle.
Or even jumping to another machine...I noticed that wootz has paper wheels in his collection. I happen to have 8-inch diameter paper wheels (which I have never used) and a spare bench grinder. I was thinking about setting up a USB mount on that system.
The idea would be to be able to achieve the same grinding (or honing) angle on the second wheel. I may be chasing diminishing returns, but I don't know that yet. So many ideas, so little time.
I will follow up when I have time to try my ideas out.
Steve
Steve, you have Straight edge jig SVH-60 which was produced from 1992 to 2002 than replaced with SE-76 and later with SE-77.
Jan
Thanks Jan. That is good to know. It seems to have worked okay so far, but sometimes small chisels are hard to set square. I am hoping my setting jig will eliminate that issue.
Steve
Steve, the newer jigs SE-76 and SE-77 are significantly different from your SVH-60. These jigs have machined edge to align the tool in the jig. Nevertheless to get small chisels square still may be challenging. Overtightening one of the knobs can skews the chisel.
For deriving a calculator for your SVH-60 its simpler design is an advantage.
Jan
Quote from: arnman on November 21, 2019, 07:50:39 PM
For example, switching over to the honing wheel, which will require me to re-set the USB on that side and try to achieve the same angle.
Or even jumping to another machine...I noticed that wootz has paper wheels in his collection. I happen to have 8-inch diameter paper wheels (which I have never used) and a spare bench grinder. I was thinking about setting up a USB mount on that system.
The idea would be to be able to achieve the same grinding (or honing) angle on the second wheel. I may be chasing diminishing returns, but I don't know that yet. So many ideas, so little time.
Hi arnman / Steve
I don't know if you are aware but jvh has developed an Excel spreadsheet which does what you want and more and is available via this post https://forum.tormek.com/index.php?topic=3919.msg26587#msg26587. No need to reinvent the wheel (no pun intended) :)
Even if you are developing your own solution it provides an excellent reference point to check your own results.
Steve, I agree with smurfs. The Excel spreadsheet developed by jvh and entitled TormekCalc is an excellent tool for set up of Tormek machines. It is free and offers much more than some commercial apps! It is suitable for your jig.
Jan
P.S.: In my understanding TormekCalc assumes that the internal jig angle is exactly 90⁰. Ton Nillesen also assumes 90⁰ angle. It is true e.g. for knife jigs and straight edge jig SVH-60. It is not exactly true for my SE-76 which has the internal angle ca 91.3⁰. I do not have the SE-77 so I do not know its internal angle. I would be happy if somebody could measure it for me. ;)
Thanks smurfs! That is a great resource. I am very encouraged that the spreadsheet that I wrote, which was based on Dutchman's spreadsheet, matches the results of TormekCalc.
I am going to keep both handy!
Steve
I experimented with TormekCalc a bit more. It is really nice.
It seems that all of the calculators are geared toward knife sharpening, and the variable "jig diameter" accommodates knife jigs.
I have had to establish an artificial diameter to accommodate my SVH-60 straight edge jig to use those calculators.
Not a big deal, but I might have to establish several variations of the SVH-60 jig properties in TormekCalc to accommodate different thicknesses of chisels and plane irons.
Steve, I am happy to read that your spreadsheet matches the results of TormekCalc. It means that your spreadsheet works correctly and that you use exact formulas. Congratulations! :)
It was my feeling from the beginning of this thread that you intend to develop your own calculator. It is usually challenging but also rewarding. ;)
Jan
I have the Tormek Supergrind. I would like to try to use the USB elevation/position settings from jvh's TormekCalc spreadsheet.
Can anyone tell me if the geometry of the Supergrind will be compatible with TormekCalc? I don't know if updated Tormek models shifted the location of the center of wheel, or the location of the USB supports that could affect USB settings.
Thanks.
Quote from: arnman on November 25, 2019, 06:10:28 PM
I have the Tormek Supergrind. I would like to try to use the USB elevation/position settings from jvh's TormekCalc spreadsheet.
Can anyone tell me if the geometry of the Supergrind will be compatible with TormekCalc? I don't know if updated Tormek models shifted the location of the center of wheel, or the location of the USB supports that could affect USB settings.
Thanks.
I measured a "Supergrind 2000" a while back... and the horizontal and vertical measuremens from the wheel center to the vertical USB are within .5mm of what he's showing in the TormekCalc measurements... so I'm thinking not much has changed. (Always double check). :)