T4 SG200 out of round

[Scotty]

Hello,
New to the forum and first post.
A few years ago a friend gave me a T4.
I have read the manual, watched numerous UTube demos, practiced on old knives and think that I do a relatively nice job of knife sharpening - mainly kitchen, utility, EDC and sporting.
My SG200 stone is now about 190mm and after a recent sharpening period, has a pronounced "bulge", as in out of round.
I am not sure how this happened as I consciously keep even pressure on the blades and stone (when dressing).
When I attempted to use the diamond dressing jig it was a disaster, not removing the "bulge" and cutting irregular grooves on the wheel.
Fortunately I had a spare SG200 and have had no issues, but would not want to replicate the previous experience.
Has anyone else had this issue?
Causes?
Technique?
Thanks.

[John_B]

Hi Scotty and welcome to the forum.

When wheels are manufactured there will be minor variations in density within the wheel. This is unavoidable but I think the better wheel manufacturers have found ways to minimize this. The small difference in density results in part of the wheel not wearing at the same rate as the surrounding area. There is really nothing one can do to alter the wear pattern on a given stone.

My recommendation is to use the TT-50 Truing Tool on a regular basis. Time between uses will depend on your sharpening volume. Using it regularly with a light touch you will keep the wheel round. At this point all you can really do is to true the wheel slowly to remove the bump. Don't try and fix it too quickly make more shallow passes.

https://www.tormek.com/international/en/accessories/other-accessories/tt-50-truing-tool/

[Ken S]

Welcome to the forum, Scotty.

An out of round grinding wheel can easily sneak up on you. (unfortunately, I speak from personal experience, more than once. 

What I have learned to do is to use the TT-50 Truing Tool, very gingerly with very light and slow passes. Your first pass should barely touch only the highest spots on your grinding wheel. Move very slowly across the wheel; ninety seconds is not too long. Lower the microadjust only a fraction of one number. Yes, this is a slow procedure. Yes, it is also very safe and effective.

Keep making very light passes until you have a pass which lightly touches the entire wheel. At that point, stop. There is no extra credit for "one more for good measure".

In the future, true your wheel frequently and lightly. Your Tormek will work better.

Ken

[Ken S]

I second John's recommendation. (John's reply came in while I was typing.)

Ken

[Elden]

https://forum.tormek.com/index.php?topic=3053.0

Consider reading or reading this thread again. It contains excellent material.


Rick Krung,
Do you use your motorized truing attachment every time you true a wheel with the TT-50?

[Scotty]

All good advice.
Thanks.
I have tried the truing tool (TT-50) very (excruciatingly) slow and I thought very lightly - maybe not light enough.
I will practice on the old wheel.

[Scotty]

Not familiar with a motorized truing attachment.
Would be interested in any additional info.
Thanks

[Ken S]

Scott,
I realize the truing method I suggest may seem excruciatingly slow. That is by design. If "Dead Slow" works, the     TT-50 works. Once you know it works, you can gradually increase the depth of cut. Make sure it works first.

All I know is that it works for me.

Keep us posted.

Ken

[Elden]

Scotty said: "Not familiar with a motorized truing attachment.
Would be interested in any additional info. "

https://forum.tormek.com/index.php?topic=3339.0

I don't remember if there was more than this thread. Maybe  Rick can clue you in.

[RickKrung]

...snip...

Rick Krung,
Do you use your motorized truing attachment every time you true a wheel with the TT-50?

Yes, I do use it every time.  Partly because I have no other option.  My TT-50 has been modified in a way that it cannot be used manually.  The drive motor is "hard" connected to the shaft and I did not install the hand knob on the non-drive end. Earlier versions, of which I probably posted photos of, show a knob on that end, but the final version does NOT have that knob.  I think this is because, initially, I did not include a modified threaded shaft with associated changes to the cutter head  housing. 

If I were to do the motorization mod again, I would opt to use a timing belt drive mechanism, which would be much simpler to implement and could provide for the option of using it manually.  I cannot imagine WHY I would ever do it manually, as the motorized method works so much better, but, it would not be hard to do. 

Please keep in mind that the mods I made to the truing tool were a fair bit more involved that just putting a drive motor on the shaft - aimed at reducing the slop in the drive train the resultant vibrations that can cause chatter and rippling of the stone surface.  I've not had the new version of the truing tool in my hands to determine whether the changes adequately reduce the slop and vibrations to know whether it could be modified to only add the drive mechanism. 

Rick

[Elden]

Thanks for the update and explanation, Rick.