Universal support bar add-on modification.

[Kok]

Hey I'm a new T8 user and new to the forum.

I've been having a hard time feeling precise with my brand new and expensive machine, I already made my own FVB, after watching videos from Knife Grinders on YouTube.

That yielded much better results, from simply being able to hone at a guided angle.

However I found to much inconsistency in mounting and adjusting the universal support bar, simply pressing down over the adjustment knob doesn't really do the trick for me.

So I made a stainless sleeve that fits very snuck, making it easy to square up the universal support bar.

https://vimeo.com/531154090

[Ken S]

Welcome to the forum, Kok.

I am somewhat puzzled by your looseness problem with the universal support bar. Tormek has incorporated their patented Torlock into the sleeves which guide and hold the support bar. The holes are not round. Like the platform jig, the  holes have a wedging action which grasps the support bar very tightly with minimal pressure. In your vimeo, I noticed you had the sleeve screws loose. Tightening them should solve your problem.

Also, adjusting the support bar height with the microadjust works better if you are adjusting by raising the bar. This keeps an even tension on the screw threads.

An FVB is a convenient tool for honing with a jig. It is not the only way to do this. Substituting 12mm long M6 thread socket set ("grub") screws for the large plastic locking screws on your knife jig and sleeves and filing just a little of the back of the knife jig will let the knife jig clear the support bar and allow you to use the knife jig with the leather honing wheel (either T4 or T8).

Ken

[Kok]

Thank you Ken S.

I am somewhat puzzled by your looseness problem with the universal support bar. Tormek has incorporated their patented Torlock into the sleeves which guide and hold the support bar. The holes are not round. Like the platform jig, the  holes have a wedging action which grasps the support bar very tightly with minimal pressure. In your vimeo, I noticed you had the sleeve screws loose. Tightening them should solve your problem.

My sleeves seem very round.


And this is the wedge profile on my SVX-150 scissor platform.



Do I have a bad model? Since obviously I wouldn't have the same issue with looseness, if the sleeves on my T8 were profiled like on the platform jig.

[micha]

Hi Kok,

no, your T8 is perfectly ok.
I'm afraid that was just Ken's wishful thinking. Or an April fools' hoax. 
But it would probably make a great improvement for future T-models.

Mike

[Ken S]

Stig once told me that he learned to say, "You're wrong" to some Tormek customers. In this case, I was wrong. It was not an April Fools joke. I believe more use of the Torlock would benefit the Tormek; however that was not my intention.

I must have incorrectly remembered a long ago conversation. The sleeve holes are indeed round.

In my defense, I rarely use the microadjust. I sharpen mostly chisels, plane blades, and knives. I set up my Tormek for chisels and plane blades using the TNT-100 holes for the Distance (almost exclusively hole B). I placed a blank piece of label tape in one of the three TNT-100 slots. Using the Anglemaster, I drew a line for 25° to establish the Projection. For knives, I use the kenjig and rarely have to use the microadjust. My primary use of the microadjust is when using the TT-50 truing tool.

In one of the online classes, Wolfgang Hess noted that the preferred way to adjust the height of the support bar was to raise it using the microadjust. Using the threads to raise the support bar is more controlled than tapping on the top.

Your stainless steel spacer is a clever idea. I would suggest making it the same length as the spacer to hold the shaft in place when transporting your Tormek with the grinding wheel removed. It can do double duty.

Ken

[Stickan]

Happy Easter!
If you look at the opening of the sleeves, the one next to the honing wheel has an oval shape. The one next to the stone is round. The sleeve size on the T-8 and T-4 are improved in size compared to the T-7/T-3 and precision is much better. The oval-shaped hole makes the support bar run down and up more freely than if both holes had the same diameter. The "drawer" effect is minimal.
In the search for the perfect edge, there are many ideas and sometimes I do think that practice and get experience is left out. The extra sleeve is a good idea and seems to work even If I personally never felt I needed it.

Best,
Stig

[RickKrung]

Very ingenious.  I watched the video and am struggling to figure out how or why it works.  Per Stickan's comments, I've not noticed that the sleeve next to the honing wheel is oval, but will look.  I conceptually get how that would work, providing looseness while still providing a positive positioning when locked.  I think this could explain the looseness you experience and have sought to rectify.  I have not had this problem, but am curious enough to check it out. 

It would be interesting if you could explore whether/how much difference there is between "with" and "without" the sleeve in terms of parallel-ness and consistency of position of the USB to the machine/stone - once both locking screws are tight.  I would measure this by measuring the distance from the tip (top or bottom surface) of the USB to the workbench when using and not using your sleeve. In locking down the USB, use the same procedure, of pressing down on the threaded bar when locking that knob and then only locking the other knob, without further contact with the USB.  At least 10 measurements by each method would be an appropriate sample. 

Rick

[Kok]

Well this has been a bit of a rollercoaster so far.
And yes, I did just move my machine to a more dedicated spot

I did some testing as suggested and my findings are somewhat surprising.

The measurements were taken from the top of the USB and down to the piece of solid bar steel. With both locking screws tightened.
- repeated test measurements with no altering of the USB, showed repeatability to within 0,05mm accuracy.


Results:

Pressing down on the threaded bar when locking it in, showed a max deviation of 0,8mm. (I didn't touch the nut, although I wrote it like that in my notes on my phone, it was done like in the Tormek manual/handbook)
Placing the USB freely before locking it in without touching it further, showed a max deviation of 0,15mm.
Using the sleeve and applying downwards pressure and spin to only the sleeve itself, while locking in the USB, showed a max deviation of 0,2mm.

I would say that 0,8mm deviation is too much for my liking, this corresponds with my observations truing the stone with the TT-50, where I noticed that from one pass to another, suddenly I would only be removing material from about half the stone, when taking away material in ½ increments of the micro adjust.
But I will also admit, that it isn't as bad as I thought it would be and I'm nowhere near experienced enough to really tell how much of an impact it might have on the final results.

Using the sleeve I made, I do also get the USB to be more square to the wheel, this is clearly visible when holding a square to the stone and USB.
If we say that 83,2 (rough average of test #3) is truly square, you could potentially get the USB locked in at 84,2 (test result 4 in test #1) which would put the USB 1mm out of square at the end of the bar.
- I guess this doesn't really matter, since you would be truing the stone to the USB, but then the pesky deviation of 0,8mm comes into play.

Conclusion:
Make a sleeve or stop touching the universal support bar, when locking it in? 

[micha]

What an interesting observation. Thanks for sharing.
Now that one is surely out for the peer review.

I'll definitely give your various methods a try and will perform some measurements. Hopefully some others will do the same.

Mike

[Artis]

Well this has been a bit of a rollercoaster so far.

To make things more complicated for you, what I discovered was that universal supports are not square, they are bent down I would guess from welding forces. Same issue with small and large universal supports.

While it might be okay for stone you can true, I use only diamond wheels and can not true them but I did bent them back straight as possible as well as I had to file down welds as they were in the way for fvb honing.

https://forum.tormek.com/index.php?topic=4619.msg33096

[Hannsi1957]

I think your biggest source of error is your caliper.
with a caliper like the one shown in the picture, you will always have deviations. this starts with the fact that you are not sitting in the center of the toolbar. the range of the depth gauge is too small for this.
so you should, if you already make the effort, use a pure depth gauge. by the way, deviations of 0.8 mm in the angle are less than 0.5 degrees. you will not realize these. other error rates weigh much more heavily.