Author Topic: Another idea for pivoting the knife jigs  (Read 6655 times)

Offline GKC

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Another idea for pivoting the knife jigs
« on: November 11, 2018, 11:39:12 pm »
While I am not convinced that I am good enough on the Tormek yet to improve my results by pivoting (rather than just lifting), I am impressed by the enthusiasm of those more experienced members who like to pivot.  I have made the “four stop collars” pivoting mechanism and quite like it.  I have one of Rick’s collar-and-pin mechanisms on order and comments like Wootz’s tell me it will be brilliant.  But a postal strike in Canada has delayed Rick’s jig getting to me, so I made one of my own that seems to do the job very well.  You might call it a wedge collar.

The governing factor in this design was simplicity in fabrication: I am no machinist and I wanted something that could be made by anyone with a hack saw and file (and drill press, for the holes).  Also, I wanted to design something that someone could make out of plastic, either by shaping it or by using a 3D printer, and so it had to have more reinforcing bulk than Rick’s pin collar.

I find this wedge collar very easy to use.  The fingers (of the hand you are using to hold the knife jig) can slide up comfortably behind the wedge; you can leave off the disc supplied with the SVM-45 and SVM-140.  The pivoting is very fluid, and the range of pivoting is more than sufficient for the knives I have tried it on.

As I said, I wanted this to be easy to make.  It is made from a 2” length of a 1” square bar of aluminium, which I drilled and then cut to a triangular shape. 

Stainless steel would be better than aluminium: less friction and wear, but I haven’t noticed the friction from the aluminum, and machining stainless steel would require tools I don’t have.  A block of UHMW plastic should work, and might be nicely slippery on the USB.  I don’t know much about 3D printing, but the wedge seems like a simple project, perhaps with the holes being done after.  Of course, wood would be easiest, but there are drawbacks when wood is used around water.

Gord

Offline RickKrung

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Re: Another idea for pivoting the knife jigs
« Reply #1 on: November 12, 2018, 05:11:55 am »
Absolutely stunningly brilliant, Gord.  I love it.  I especially love that it can be fabricated by anyone with basic tools and skills.  And that it can be made from just about any material.  I have a block of UHMW that I can use to make one from and will try it.  I think Delrin would work very well also.  Thumb screw for locking it frees one from having to keep a hex key handy. 

Bravo!

(You can return the PPC for a full refund if you like ;D   I had a request for one that I could not fill.  8)

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Offline Plekter

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Re: Another idea for pivoting the knife jigs
« Reply #2 on: November 12, 2018, 11:38:16 pm »
What a brilliant idea. Well thought out :-)
Tormek T-8...(and some whetstones)

Offline wanderingwhittler

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Re: Another idea for pivoting the knife jigs
« Reply #3 on: November 14, 2018, 03:29:28 am »
Hey Gord, that’s really slick! Thanks for sharing the idea and instructions.
Greg
Joy is a sharp knife and a block of wood.

Offline Drilon

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Re: Another idea for pivoting the knife jigs
« Reply #4 on: November 17, 2018, 06:34:25 pm »
Just a short info about my economy version of the pin pivot collar.
 
I used a flat washer, glued on it two tubes with a high strength epoxy glue (cured at 90°C for two hours). This device I fixed on the standard collar with strong double sided sticky tape.

Works great – and can be removed if needed!

Best regards
Drilon



Offline RickKrung

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Re: Another idea for pivoting the knife jigs
« Reply #5 on: November 17, 2018, 08:28:13 pm »
...snip...
This device I fixed on the standard collar with strong double sided sticky tape.
...snip...

I love innovation.  How does it work with the rotation of the standard collar?  Do you just set the projection in increments of half-turns and go from there? 

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

GeoTech

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Re: Another idea for pivoting the knife jigs
« Reply #6 on: November 18, 2018, 03:07:28 am »
Now that is clever.

Offline Drilon

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Re: Another idea for pivoting the knife jigs
« Reply #7 on: November 18, 2018, 10:47:45 am »
...snip...
This device I fixed on the standard collar with strong double sided sticky tape.
...snip...

I love innovation.  How does it work with the rotation of the standard collar?  Do you just set the projection in increments of half-turns and go from there? 

Rick

Yes, the increments are half-turns.

Drilon

Offline Drilon

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Re: Another idea for pivoting the knife jigs
« Reply #8 on: November 18, 2018, 11:44:23 am »
...snip...
This device I fixed on the standard collar with strong double sided sticky tape.
...snip...


I love innovation.  How does it work with the rotation of the standard collar?  Do you just set the projection in increments of half-turns and go from there? 

Rick

Rick, after seeing your great tool I was looking for a way that I can test this method. That was my intention to make the cheap copy. If I come to the conclusion that I like it and use it often I most probably will purchase your professional tool as now offered by Knife Grinders, Australia.

Thank you!
Drilon

Offline Ken S

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Re: Another idea for pivoting the knife jigs
« Reply #9 on: November 18, 2018, 12:47:06 pm »
Drilon,

I like your simplistic approach. Have an idea, and make up a working prototype. Work with it. I would love to visit Tormek in Sweden. Many years ago, I visited the Leitz (Leica camera) factory in Wetzlar, Germany. I was not allowed to tour the factory, however, I was allowed to visit something much more meaningful. The Leitz Museum Director gave me a personal tour of the museum. Every Leica model ever made was on display. He then opened the safe and let me handle the Ur Leica (the Ancestor Leica),the first prototype hand made by the inventor, Oscar Barnack. It is unique, and among Leicaphiles it is certainly the Holy Grail.

The Ur Leica was made from a piece of 75mm brass pipe which Oscar Barnack flattened into what has become a camera shape. I have been told that the Tormek factory has several odd bits of plywood and other prototype material used by Torgny Jansson in developing the Tormek. I think it would be fascinating to learn more about the nuts and bolts development of the Tormek. I do believe that Torgny's spirit of innovation continues, both with the Tormek design team in Sweden and globally through the forum. I am proud to be a member of this group.

Ken

Offline GKC

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Re: Another idea for pivoting the knife jigs
« Reply #10 on: November 19, 2018, 03:55:24 pm »
Like Drilon, I like the simple way of putting something on the SVM-45 collar; I tried a flattened section of 1/2" aluminium bar, stuck on with double-sided tape.  It works just fine, and one of these in-front-of-the-collar approaches is quick and easy for someone who wants to see whether they like pivoting.  One limitation, as Rick mentioned, is that you have to work in 1/2 turn-of-the-collar increments.  Another is that when you mount something in front of the SVM-45 collar, you have to move the collar back by its depth, and probably adjust the USB height.  You end up with the collar a bit further back on the SVM-45 shaft than you prefer.  But it works and it is easy.  Here are some pics.

Offline Ken S

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Re: Another idea for pivoting the knife jigs
« Reply #11 on: November 19, 2018, 04:41:00 pm »
I think we have two issus to settle:

First, and in my opinion the more important, is getting a smooth pivoting action. I think these jigs do this well.

Second, and of lesser importance, is obtaining a specific bevel angle. The projection of the knife blade in the jig is only one of two adjustments for this. Adjusting the Distance of the support bar from the grinding wheel is the second and probably easier method.

I would just set orient the pivot jig vertically and measure the the projection. The macimum deviation is limited to plus or minus a quarter screw thread. I would check with Dutchman's tables. The slight difference could be easily compensated with another kenjig or tweaking the microadjust. (or, dare I say, ignored)

Either way, I don't see the vertical orientation as much of a problem. Good thought, however, and something to be aware of.

Ken

Offline RickKrung

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Re: Another idea for pivoting the knife jigs
« Reply #12 on: November 19, 2018, 08:03:53 pm »
...snip...
One limitation, as Rick mentioned, is that you have to work in 1/2 turn-of-the-collar increments.  Another is that when you mount something in front of the SVM-45 collar, you have to move the collar back by its depth, and probably adjust the USB height.  You end up with the collar a bit further back on the SVM-45 shaft than you prefer...snip...

If using pivots attached to the front of a standard collar (and using the O-ring on the shaft), I don't see what the collar's position has to do with anything.  I am assuming the projection is set based on the front "pivot point" surface.  The USB height is then set according to the projection (or visa versa?).  Until the collar falls off the O-ring, moving it back has no bearing on anything, as far as I can see it.  Similarly, if using the old style collar with the locking screw, it would be - "until the set screw falls off the end of the shaft". 

If one is using a Pin Pivot Collar (PPC) or some brilliant alternative such as Gord's "Triangular Pivot Stop" (TPS), as I use it, the standard collar is not used at all.  As Wootz uses the PPC, the collar is there but the projection is set as above and the collar is just to preserve the "feel" and muscle memory motions he uses so well.

...snip...
I would just set orient the pivot jig vertically and measure the the projection. The macimum deviation is limited to plus or minus a quarter screw thread. I would check with Dutchman's tables. The slight difference could be easily compensated with another kenjig or tweaking the microadjust. (or, dare I say, ignored)

Either way, I don't see the vertical orientation as much of a problem. Good thought, however, and something to be aware of.

Ken

In my view, it is effectively only about 1/8 turn from vertical.  Past that and the closer to a full 1/4 turn, the pivot point is too horizontal.  Within that 1/8 turn range, I think it could definitely be ignored.  The lost portion of the rotation, from 1/8 to 3/8 is 1/4 turn, but the threads on the collar are very coarse, so if only 2mm per turn, that up to 0.5mm of "error".  I think that would be a personal choice about whether it could be ignored. 

Rick
Quality is like buying oats.  If you want nice clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Offline GKC

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Re: Another idea for pivoting the knife jigs
« Reply #13 on: November 19, 2018, 09:13:50 pm »
Rick you say (I can't figure out the "quote" function in posting) "Until the collar falls off the O-ring, moving it back has no bearing on anything, as far as I can see it.  Similarly, if using the old style collar with the locking screw, it would be - "until the set screw falls off the end of the shaft"."

That was my only point--and it is a minor one--about having to move the collar back: I found that with mounting things in front of the SVM-45 collar, and to keep my 139mm projection, I had to move the collar back enough that I was very close to the O ring, where the collar has more play.  It was just a bit further back than I prefer it.  You could move up the collar and lower the USB, it all still works well.

Gord
« Last Edit: November 19, 2018, 09:15:22 pm by GKC »

Offline Dutchman

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Re: Another idea for pivoting the knife jigs
« Reply #14 on: November 20, 2018, 09:52:45 am »
In order to match the jig to the curvature of the knife tip, the length of the jig should be variable, equa; to the radius of the curvature, and in any case longer than it is now. ;)