Blowing out edge of SG wheel when trueing

[Antz]

Has this happened to anyone before? I was trueing my SG wheel and it was going perfectly until I reached the far edge of the stone, right when the trueing tooth was leaving the wheel it blew out the edge leaving some pretty massive chips. I'm pretty upset about it because I can't use that edge of the stone for small curves now unless I true off a lot more material. Did I do something wrong?? Any advice is appreciated.

Thanks,
Antz

[Elden]

Antz,

How heavy of a cut were you using? Ken talks about using light cuts with the truing tool. It could have been a weak spot in the wheel as well.

[RichColvin]

Antz,

I did that on my SJ wheel as I was being too aggressive when truing the grindstone.  Good news is that it didn't affect the way it works.  Just looks bad (and reminds me to be more patient).

Kind regards,
Rich

[Antz]

Rich, Elden,

It was a semi aggressive true. I'm guessing a little over half a millimeter. What I normally do is lower the usb until the tooth touches the wheel, then slide it off to the side and lower the bar a little over one number on the micro adjust then true. I've done it before without that happening. Next time I'll practice a little more patience and see if it has a better result. Good to know though Rich that it's most likely cosmetic and won't affect function. I was thinking the chipped areas might catch a knife blade and nick it. Heres a photo of the chips.

Thanks,
Antz

Ps: still figuring out the photo attachment function. Sorry for the giant picture.

[RickKrung]

Rich, Elden,

It was a semi aggressive true. I'm guessing a little over half a millimeter. What I normally do is lower the usb until the tooth touches the wheel, then slide it off to the side and lower the bar a little over one number on the micro adjust then true. I've done it before without that happening. Next time I'll practice a little more patience and see if it has a better result. Good to know though Rich that it's most likely cosmetic and won't affect function. I was thinking the chipped areas might catch a knife blade and nick it. Heres a photo of the chips.

Thanks,
Antz

Ps: still figuring out the photo attachment function. Sorry for the giant picture.

Antz,

As others have commented, the depth of cut was likely too deep.  I use about 1/4 of a number on the micro adjust dial per pass.  It is painfully slow, but works much better and does not waste much stone taking too much off.  Going SLOOOOOWWWW really helps also.  I have motorized my truing tool and can go as slow as about 4 min. per pass.  I don't do it that slow, but I can do it.  Two minutes per pass is more like what I typically use. 

I agree with Rich that the chips should not really affect its use.  To make the edge more useable for curved edges, you could chamfer that edge (both, even).  A flat bevel on the edge would get rid of the chips cleanly but a more radiused chamfer will likely be better suited to the curved edges. 

I think the truing tool is NOT the tool to use, nor would I use the grading stone, but the latter would be the better of the two.  The truing tool would be just too awkward and the stone grader I think is not meant to take off material the way you need to for chamfering. 

I have a grinding stone dressing tool that I use for refreshing the Norton 3X grindstone.  It has diamonds on the surface.  I used it to chamfer my SJ stone last fall after it fell and was terribly cracked from falling as my folding table did just that, before everything was removed and packed away.  I got this tool from Lee Valley.

I'm not at home now to go look at my repaired SJ stone, but the first photo below is of the really big chip on the edge.  That is what I'd call "blown out". 

Rick

PS, also included is a cropped and resized version of your photo. 

[jeffs55]

Adjust the truing tool over the stone and lower it till it touches a revolving stone. Back the tool off and turn the stone until the tool does not touch. Now bring the tool into contact with the stone until it just touches over the entire circumference. Make sure it is barely touching the highest point on the wheel. It should skim over the valleys and touch the hilltops When it touches the highest point on the stone, bring it into the stone about 1/4 turn. Proceed from there 1/4 turn at a time until you get a complete circumferential cut and go at it.

[Ken S]

Antz,

You are starting ahead of the way many of us started. That includes me. In fact, I would like to say "most" instead of many. I do not remember the first time I used my truing tool. Whenever it was, it was not early enough. Like most of us, I suffered from the "Precious Tormek Grinding Wheel" syndrome. I did not want to "waste" my precious grinding wheel with the truing tool.

Keeping the wheel trued and dressed is only one side of the benefit of truing. Frequent light truing helps keep the operator's skills trued and fresh. I contend that such frequent, light truing causes no more wheel wear than infrequent, heavy truing. It also increases the accuracy of your work.

I once took out a nasty gouge from the center edge of my SG while truing. It was my fault entirely. It was not a bad wheel; I had inadvertently forgotten to tighten the TT-50 to the support bar. I thought I had ruined the diamond cluster and even purchased a replacement. Several days later, with a cooler, calmer head, I began what has become my very light truing cut technique, hoping to resuscitate my diamond cluster. It was a most valuable learning experience.

I think you probably made too deep of a cut. In my opinion, Tormek marketing is held hostage by today's speed culture. Most people watching a real time video of me truing my grinding wheel would conclude that it was too slow and spend several hundred dollars in the quest for more speed.

Often my first slow pass does not remove any material. The second pass, usually half a microadjust number OR LESS, barely kisses the high spot. I continue at this snail's pace until the cutter just touches the entire wheel. At this point, the wheel is true. Any more passes just wears down the wheel.

Yes, my light, frequent truing method is slow, however, the surface of my freshly trued wheel is pristine. I have never had edge blow out on my SG, SB, or SJ.

A violinist always loosens the tension on his bow before putting his instrument away. A sharpener would be wise to true his wheel after each sharpening session.

I predict that your experiences with your first grinding wheel will result in longer life from future wheels. Do not become discouraged.

Ken

[John_B]

Antz,

You are starting ahead of the way many of us started. That includes me. In fact, I would like to say "most" instead of many. I do not remember the first time I used my truing tool. Whenever it was, it was not early enough. Like most of us, I suffered from the "Precious Tormek Grinding Wheel" syndrome. I did not want to "waste" my precious grinding wheel with the truing tool.

I should set up a foundation for those afflicted with this syndrome. I too seem to have it. I use multiple light passes periodically on my wheel and found that it works very well. Mine does not seem to go out of true by very much. I also use more passes with a fairly light touch when sharpening.

[wootz]

By the way, do you know why Tormek stone wheels never run round out of the box, even if they are perfectly round in shape?

Yesterday we were measuring the arbor hole (bore) in the wheels, using a Telescopic Gauge Micrometer.
The stone wheel hole diameter showed 12.11 mm.
While the Tormek shaft diameter, measured with a micrometer, is within 12 - 12.01 mm.
The SG, SB and SJ wheel arbor hole is made a bit wider on purpose, for the ease of mounting and so that the wheel won't get stuck on the shaft if left sitting on it for prolonged period.

You see now why you have to true every new wheel?
When you mount the wheel, it will sit on the shaft a little off its center, and because of that will be rotating out of round.
To make the wheel run round, when truing the new wheel, we are to mark the wheel and then always mount it in the same position.

[RickKrung]

...snip...
To make the wheel run round, when truing the new wheel, we are to mark the wheel and then always mount it in the same position.

This came up a long time ago (for me that is just under 2 yrs as a forum member) and it was generally agreed that using a consistent procedure during mounting of the stones would be good practice. 

To this end, I have put centerpunch marks on the end of the shaft and on the OD of the spacer between the machine and the stone and line them up vertically, they are at the top.  And then mount the wheels with the label up and horizontal, effectively mounting them in the same position each time they are changed. 

At the point of tightening the stone using the EZ-Lock nut, I press the stone against the washer to "capture" it and rotate the assembly 1/8-1/4 turn clockwise to take up the "backlash" when the nut is tightened (holding the honing wheel so the shaft doesn't turn also).  I run the nut up to the stone and snug it a little, then rotate the spacer/stone/nut counterclockwise to lock it all in place.  All this being an attempt to get the stone tight and in the right location. 

Rick

[Antz]

Ken,

I always thought of the SG wheel as a consumable and never really was afraid of trueing for fear of wasting my stone. I recently been doing a decent amount of work on my tormeks and have probably trued them about 5-6 times combined in the last 2-3 weeks.

Wootz,

Good advice about always mounting the stone in the same position when removing/replacing. An easy way for me is just using label on the wheel itself and making sure it's completely horizontal. (Not as accurate as your method Rick, but works well for me)

Just wanted to mention the reason I was doing a deeper than usual cut with the trueing tool. I started off my first couple trueing sessions with really light passes and lower the bar about a quarter of a number at a time. But I noticed if I don't make a deep enough cut the trueing tool vibrates like crazy to the point of vibrating the whole tormek and the result is a wavy/hilly stone surface which requires more trueing to remove with a deeper cut.

To me it seems like there is a sweet spot with the depth of cut. Not enough and the tooth skates on the surface. Just a little past that and it vibrates like crazy leaving a horrible finish. And if you go too deep it blows out the edge of the stone. Seems like you have to cut just deep enough for the tooth to bite but not deep enough to damage the edge of the stone. I also find my trueing tool to have more play than I would like. Why they designed it like that is beyond me. Wouldn't it be better if the tooth was almost static to the jig?

Thank you all for your reply's,
Antz

PS: Rick I'll start marking the shaft and spacer location as well. Thanks for that tip.

[wootz]

We reduce the TT-50 play with cable ties - please see this thread:
https://forum.tormek.com/index.php?topic=3053.msg16372#msg16372

[Antz]

Thank you Wootz, I shall try that.

Thanks,
Antz

[Ken S]

Ken,

I always thought of the SG wheel as a consumable and never really was afraid of trueing for fear of wasting my stone. I recently been doing a decent amount of work on my tormeks and have probably trued them about 5-6 times combined in the last 2-3 weeks.

Antz,
I make the best guesses I can about other members. I am always delighted to be wrong.
Keep up the good work!
Ken
ps The electrical ties work well with the pre 2019 TT-50.

[Antz]

Ken,

Just out of curiosity, is there a way I can tell if my TT-50 is pre or post 2019? I ordered my tormek in 2019 but it's possible the dealer had from 2018 (Grainger).

Thanks,
Antz