Leather honing wheel out of true

[arnman]

I posted a few weeks ago that I am the new owner of a Tormek Supergrind 2000.  I got it cleaned up, got the truing jig and a new usb and a new horizontal support base, and a few other jigs.  I wish I remembered to get the honing compound also.  It will be here Tuesday.

The grinding stone was out of true by about 1/8".  It took a while to get it round.

I took a test run on the grinding stone with an old chisel and I am amazed at how fast I have a nice new bevel!

I could also see that the leather honing wheel was out of true - by about 1/8".  I assumed the high spot was at the seam, but it is not.  The trouble spot is about 5 inches along the circumference of the wheel.  I tried using a piece of sandpaper on a piece of wood (supported by the SVD-110 support) to true the wheel with the machine running.  I think it helped, but not much.

The axle that supports the honing wheel is not the culprit.  It is not machined perfectly, but it is not the cause of this issue.

My efforts to search for past threads did not turn up much as far as solutions.

Any ideas?  Do I need to order a new honing wheel?  This thing was not heavily used before I bought it.

Thanks.

Steve

[grepper]

Are you really saying that a 5" long section of the surface of the honing wheel is 1/8" ,(3.2mm), higher than the rest of the wheel?  That's odd, and a lot higher!

Does the leather on the wheel just look a lot thicker there?  Is the wheel itself deformed?  Seems like you would be able to tell what's going on with some careful examination.

[arnman]

Grepper,

I measured the length of the trouble spot by holding a marker on the tool rest and moving it very slowly into the spinning wheel.  As soon as I could tell that contact was made and I saw the mark on the wheel, I stopped moving the marker.  I shut off the machine and observed the mark - it was about 5 inches long.  Low tech, but that was how I did it.

The increase in thickness is not sudden.  It seems that the thickness increases gradually to a maximum of about 1/8 inch.  The 1/8 inch can be observed by comparing the spinning wheel to the stationary usb or a work support.

I can take another shot at some more aggressive and targeted sanding if this is a normal procedure.

I would appreciate any additional comments.  Thanks.

Steve

[grepper]

Hi Steve,

I have a T7, so I don't know if mine is comparable to yours.  But, I just looked at the T7 and it's a plastic wheel with leather glued to it.  The leather looks the same thickness all of the way around the wheel.

I suspect yours is similar.  So, if the shaft is not bent, it seems like one of two things has to be:

1.   The wheel itself is not round or the hole for the shaft is off center.
2.   The leather is thicker at some points than others.

If you hold a pointed object, say a knife tip, against the side of the wheel at a fixed height just below where the leather is and spin the wheel, does the wheel itself look round?  Can you spin the wheel and scribe a line on the wheel with a knife tip?

I think it unlikely the wheel itself is not round or off center.  So, if the leather is the same thickness all around the wheel and the wheel is not oddly warped, what's left?  What else could it be?  This seems pretty simple.  A shaft and a wheel with some leather glued to it.  I suppose however a plastic wheel could warp with heat or something.  Sure seems like we should be able to figure this out.

Are you sure the shaft is not bent?

I must say however that it's getting late and I've enjoyed a few shots of Old Crow, so I may be operating with slightly less than a fully functional brain.

Mark

[grepper]

I was just about to call it a night when I had a thought.  So, and considering what I mentioned above...

I just pulled the wheel off mine.  The hole in the center of the wheel is larger than the diameter of the shaft.  The wheel has posts on the inside that locate it against a wheel on the machine.  If those are not located correctly I suppose it would be possible to screw the wheel down off center from the shaft.  That would do it!

Pull the wheel.  Run the machine and watch the end of the shaft.  It should be obvious if the shaft is straight.

I don't know how the Supergrind wheel attaches.  But after the wheel is off, examine it.  Does is look ok?  Is there any way it could be mounted off center?

[arnman]

Thanks for your comments Grepper.

I also thought I had found the solution as you described in #4, but it was installed with the pins aligned.

Your ideas in #3 should help me get to the bottom of this.  I really hate to keep sanding the leather.  I will report back.

Thanks!

[Ken S]

Steve,

If you put your universal support bar in the horizontal position and bring the bar against the leather honing wheel, you can turn the wheel by hand and determine the high spot. Note that spot with a small piece of masking tape on the outside of the honing wheel. Comparing your honing wheel with the face of a clock, designate the noted high spot as twelve o'clock.

If you remove the honing wheel you will notice three nubs on the inside of the plastic wheel. They correspond with three holes on the  outside of the driven wheel. Place small pieces of the masking tape on one of the nubs and its corresponding hole.

If, by chance, your honing wheel does not have these nubs, that may be your problem. There is some play in the shaft hole, however, the three nubs fitting securely into the three holes should accurately center the honing wheel.

If you do have the three nubs and holes, try rotating the honing wheel one hundred twenty degrees so that the original marked nub fits into the next hole. Tighten the honing wheel and see if the honing wheel rubs against the universal support bar in the same spot. Try the same thing with the third nub/hole combination. If the high spot changes, you may be able to determine which of the three possible alignments has the least run out.

You can use the same method of placing the universal support bar against the driven wheel without the honing wheel. You will need a piece of wood for this, as the bar itself can't get close enough to rub the driven wheel. If the honing wheel has the 1/8" run out and the driven wheel runs true, the problem is with the honing wheel.

If the driven wheel runs untrue, use the same technique but clamp a piece of wood to the bar and have it rub against the shaft. Do the same test. This will rule in or rule out the driven wheel.

If the driven wheel is not the problem, I would order a replacement EZYLock shaft. The shaft kit comes with new nylon bearings. Installation should take around ten minutes. The shaft is a real improvement over the original.

Start by testing the honing wheel and work your way in. My gut feeling is that the nubs may be missing from the honing wheel. If that is the case, replace it.

Good luck, and please post your results, successful or not.

Ken

[jeffs55]

Ken S, it seems to me that you are trying to correct a run out problem. The original post addressed a "high spot", this is not the same thing.

[gwelsby]

Steve,
  I'm no expert at all in this field.  However, a grinding wheel 1/8" out of true and a honing wheel 1/8" out of true on the opposite side bespeaks a shaft out of true to me.  Are the two high spots at 180 degrees to each other on the shaft?
G.

[Ken S]

If your wheel is now running true, try loosening the nut slightly and rotating just the wheel one  hundred eighty degrees. Tighten and see if the wheel is still reasonably true. If the out of round  condition returns, the shaft is probably bent. If the grinding wheel is still true, we are back to looking at the honing end.

Ken

[arnman]

I checked everything in the chain.  First, I took better measurements of the honing wheel "oscillations."  They were a just shy of 3/32".

The plastic wheel that the leather is mounted to is not too bad, probably as good as can be expected for a molded plastic piece.  I did not measure the out of round of that piece, but I would guess under 0.010".

The axle is pretty good in my opinion.  Using a dial indicator, I measured 0.003".

It appears that the culprit is really the leather strip.  I tried shaving the wheel down, using the SVD-110 support and a straight scraper blade held perpendicular to the wheel, with the machine running.  This is difficult to achieve good results because the leather yields when it contacts sandpaper or a blade.  After almost 45 minutes of this, I still measure the out of round to be a strong 1/32".

I tried rotating the wheel in 120 degree increments - that really did not change the results.

It probably would not hurt to try honing with this wheel as-is.  But I have read that honing can be tricky, and this could be working against me from the get-go.  I will try honing when the compound gets delivered later this week.

My rubber drive tire seems to be degrading, and it has a bad divot from siting in one spot for a few years.  I might have to replace that soon.

I appreciate everyone's thoughtful comments.  I will report back after I try honing.

Steve

[grepper]

Steve,

You originally said, "The axle that supports the honing wheel is not the culprit."

Did you really verify that?  The last few posts about 180 off are correct about indicating a bent shaft.  1/8" should be pretty obvious.

Hey everybody-  If the shaft is bent, wouldn't you be able to see it just by pulling the wheel and looking at the end of the shaft with the machine running?  With a 1/8" (3mm) deflection, it sure seems to me that the center of the shaft would be obviously wobbling around center.

[arnman]

Grepper,

I am sure the axle is not the problem.  I used a dial indicator to measure only 0.003" runout.

Steve

[grepper]

Huh.  Cool!  You have a dial indicator.  Well, the reason that a bunch of folks posted about the 180 degrees off thing was that you said that the grinding wheel was also off by the same amount as the honing wheel.  Unless the axle had two bends, that would make perfect sense and it is an odd coincidence.

But because you are only showing .003" runout, it sure seems to me that there is something funky with the wheel or it's mounted off center.   What do you think?

Wheel deformed?  Off center mounting?  Leather considerably thicker on one section?

It will be interesting to hear what you discover the problem to be.

Are we missing something?  Anybody else have any ideas?

[Herman Trivilino]

My guess: There's a bad spot on the surface of the leather wheel, just as there's a bad spot on the surface of the driving wheel. The machine was probably left in one position for years with the honing wheel resting against something. Maybe the USB.

You might trying mounting the honing wheel in a high speed grinder and then try to grind away the high spot in the leather with sandpaper or a file. You may end up buying a new honing wheel, but this might be worth a try first.