Using Dutchman Tables with Square-Edge Jig for Plane Irons?

[arnman]

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.

[cbwx34]

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...

[arnman]

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

[Jan]

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

[arnman]

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

[Jan]

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

[cbwx34]

...
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. 

[arnman]

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

[Jan]

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

[arnman]

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

[Jan]

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

[smurfs]

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.

[Jan]

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. 

[arnman]

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

[arnman]

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.