New Tormek T-4 with wobbly grindstone

[Schmart]

Hi everyone,

I'm a hobbyist woodworker and knife enthousiast from the Netherlands, and long-time lurker of this forum. After years of deliberation, I've finally decided to invest in a Tormek T-4 and the HTK-706 hand tool kit, and have already beautifully sharpened some chisels and knives.

However, I'm dealing with huge wobble and eccentricity of the grindstone 19 out of 20 times after taking it off and attaching it again. The axle seems straight and the bushings are fine and well lubricated with the white lithium EP2 grease I purchased.

I've already read a lot about possible issues and beginner mistakes and resolutions. For example, I marked the position of the washer, stone and axle when I get nearly perfect behavior. However, I'm not able to repeat this success with everything aligned identically. I've dressed the stone and even flattened the stone on the washer-side using the grading stone, but I still run into issues. The problem was less noticible in the beginning and while the stone was still factory-dry, but after having used the machine and taken the stone off for a couple of times, I'm afraid the problem is getting worse. I'm afraid the cause might be the arbor hole that is too large.

Below is a OneDrive link of a video of me demonstrating the problem as it was when I just got the machine. Notice that where I tightened the wheel an extra bit by hand, it caused much less wobble in this instance. Increasingly, I'm not that lucky anymore...

https://1drv.ms/v/s!Au1g8fW6BaQzh8YFPyS_NRI9mXKh_A

I would appreciate your insight and opinions on this!

[jeffs55]

I am going to jump in and say to rotate the wheel less and then retighten lock nut. It looks like you even rotated and then went back to a previous setting to me. Try a little less rotation. Once again I looked and it looks like you are not loosening the lock nut before you rotate the stone. Loosen nut, rotate stone, hold stone and tighten lock nut making sure the leather wheel does not move which would indicate the drive shaft turning. Rotate stone 1/8 turn or less.

[Elden]

Interesting. I am surmising that when you tightened the nut by turning the wheel, that it added more pressure than when using your fingers.  I imagine Ken or someone will soon be along with an answer. Is the flange washer flat?

[Schmart]

Both of you, thank you so much for your response!

It is an interesting phenomenon for sure.

I realise from viewing the video myself again that it may not entirely be clear what I'm doing to demonstrate the issue, so I'll try to explain the steps. My first attempt is fastening the nut per the instruction manual, hand tight and the torque of the motor should do the rest. The second attempt includes loosening the nut by turning the stone slightly, but not much, and then using much more force trying to hand-tighten the nut again. The third attempt also includes a slight turn of the wheel in order to loosen the nut, but in addition to hand-tightening the nut again, after that I also turn the wheel to apply extra force indeed. I tried to keep washer, wheel and axle in the same position in all attempts as much as possible. In later attempts (not recorded on video) I ensured even much better alignment (marked the three components) with same results.

What seems to be happening over and over again is that the stone is clamped firmly between the washer and nut in an already slanted position, which is sometimes only corrected with applying more force by turning the wheel. This is however absolutely not a guaranteed way to prevent the issue from happening.

I checked the washer for potential small debris sticking to it, but found nothing there. It also appears nice and flat when checked with an engineer's straight edge. Maybe I'll run the washer over a Japanese water stone to see if there are low or high spots, but I wouldn't expect variances in that order to be able to cause such a big wobble to be honest.

[jeffs55]

What seems to be happening over and over again is that the stone is clamped firmly between the washer and nut in an already slanted position Can you affix a "square" to the shaft and align the wheel to that and then tighten? Or does the act of tightening slant the wheel? Sounds like the shaft hole is too large but even that should not necessarily cause a wobble. Rather an elliptical rotational wobble in the vertical rather than horizontal plane. Do you have another round object to attach to the shaft to compare the grinding wheel to? Such as a grinding disk for a grinder, just something with the appropriate size arbor hole.

[Schmart]

Hi jeffs55, I like your suggestions! Did you mean that I remove the axle/shaft from the machine and affix the wheel then? I probably could also use the USB as a reference for the square. I'm also curious if the slant is caused by tightening the nut, or that the slant is already present.

Please allow me to further follow up on your suggestions tomorrow, it's almost bedtime for me.

[jeffs55]

Do not remove the drive shaft but attach/ place onto a known 90 degree object such as a square to the shaft or as you suggested the USB. However, if the USB is not parallel to the drive shaft then you have another problem. Place the T4 on the edge of your bench with the end of the shaft overhanging the edge of the table and tie a plumb line to it. The plumb line will be 90 degrees to the drive shaft. Place the grinding stone next to the line with the tightening nut just barely on the shaft just to keep the stone from falling off the shaft. Notice the edge of the stone as you manually turn it on the shaft. Is it wobbling? If so, the stone is at fault. You can buy a new stone or try and repair the wobbling one. How to do that? I have never done this but if you could locate some bedding compound like that used in the bedding of a rifle action into a stock I have an idea. When you mix the compound it is a thick liquid, very thick. Plug one side of the stone and pour/force the bedding compound into the hole. Take a 12 mm piece of metal, not the drive shaft and coat it with release compound and place into the hole. This will force out the compound but will leave enough in the hole to perhaps fill the void causing the wheel to wobble. It must have a void/ flaw in the stone to allow the wobble.  The piece of metal must of course be 90 degrees to the hole you are forcing it into. If no bedding compound can be found, something like epoxy might work or a product known as JB Weld. The JB is often used to repair cracks in metal or stripped threads in stuff. A simpler idea would be to line the hole with something like a copper tube that is 12 mm in diameter. You might need a metal reamer to make the hole just the right size though. Remember, these are just random thoughts and if you have a bad wheel; you have nothing to lose.

[RichColvin]

On my T-2000, I just let it wobble.

[Ken S]

Welcome to the forum, Schmart.

The first thing you should do is to email Tormek support (support@tormek.se). Describe the problem for them and ask what you should do. The T4 was introduced in 2014, so all T4s in home use are still under warranty. If you have not already registered your T4, support can help you to register it.

When you say that you dressed your grinding wheel, do you mean with the TT-50?

You are entitled to have a Tormek which works properly and to your satisfaction. I have always found Tormek warranty service to be outstanding. You must make Tormek aware of your problem.

Please post your results working with support.

Ken

[Elden]

If there is indeed a faulty stone, one should contact support instead of trying to repair it. The machine did come with a warrantee. Support is reported to be excellent.
Actually a plumb line attached to the shaft does not assure a 90° angle to the shaft. It is 90° to the source of gravity. One could affix a plumb to a shaft that is oriented at a 45 degree angle to the gravity source. The plumb line would still maintain a 90° angle to the gravity source. This situation would thus produce the plumb line angle of 45° in reference to the shaft.

Ken glad to see you in here. You posted before I got the above submitted.

[jeffs55]

One could affix a plumb to a shaft that is oriented at a 45 degree angle to the gravity source You are totally correct, I never considered that. He could in fact have his machine attached to the steeply angled roof of a house and my idea would never work. Maybe he has it on a more level surface.

[Ken S]

If Schmart had purchased an older, out of warranty Tormek, these would be valuokable suggestions. However, he has a Tormek which is still under warranty. Correcting the problem is Tormek's responsibility. In almost ten years on the forum, I have never seen an incident where Tormek failed to deliver outstanding service. I assume Tormek service is global, and the same in the Netherlands as in the US. If the needed correction is not user maintenance, Tormek will send him a prepaid shipping label. Tormek will repair or replace his Tormek as needed and return it promptly to him at no charge.

The customer must inform Tormek that there is a problem. I have always encouraged members with a warranty issue to post their service results, positive or negative. Follow up posts have always been positive, and I would never delete a negative post.

Ken

[Ken S]

Elden,

You and I have been involved with this forum for enough years to see problems come and go. I would say that the major problem was the rusted shaft. The straight stainless steel shaft in 2006 and the EZYlock stainless shaft ended that problem with new Tormeks, and also with older Tormeks with upgraded shafts.

The universal support bar with microadjust made fine adjustments easier and more controlled. The TT-50 truing tool made truing more precise. The 2019 redesign eliminated bouncing problems.

The water trough of the T8 made it easy to keep the grinding wheel out of the water when not in active use.

I think we still have occasional wheel wobble problems. This needs to be addressed. I am confident that wheel wobble will eventually go the way of the rusted shaft. We are still striving for perfection.

Ken

[Schmart]

First of all, thanks for all your help and comments!

@Ken S: Correct, I used the TT-50 to dress/true the grinding wheel to remove an up/down wobble. I did this when I finally managed to mount the wheel with acceptable left/right wobble.

Fortunately, this evening, I finally had some quiet time to really take a good look at the problem and establish what is happening by measuring the stone's position on the axle as (sort of) suggested, and I think I know now for sure what's going on. Since I could not find my plumb line or a true level surface, I settled for relative measuring of the stone's angle using a square resting on the USB.

I started with a known good position with minimal left/right wobble, and put the long end of the square against the side of the wheel. There was a very small gap between the square and the bottom of the stone, but rotating the wheel did not cause any change, so this told me that my USB is almost parallel to the axle.

Then I took the EZYLock nut off the axle. With the stone against the washer but free on the axle, it turns out that the stone tilts to the right quite a bit. There was now a significant gap between the long end of the square and the bottom of the stone. I tightened the EZYLock nut again per the manual. This did not correct or change the tilt of the stone at all. When I rotated the wheel, I immediately faced a massive left/right wobble. I repeated taking off the nut and fastening it again a couple of times, each time with the washer, axle and stone in different positions, each attempt resulting in the same severe wobble (which is ~2.0mm left + 2.0mm right of the centerline).

This confirmed my hunch that the washer and EZYLock nut (maybe especially the grabby plastic one) are very good at what they do, clamping the stone, even when it's not 90 degrees to the axle; they don't care! This inspired me to try wiggling the stone from the left to the right while simultaneously tightening the EZYLock nut. This makes all the difference. I can tighten the nut ~10-15 degrees further until I can no longer wiggle the wheel, and this approach completely corrects the tilt of the wheel on the axle. I can get consistent results regardless of the position of the wheel, axle and washer, and the stone runs without significant left to right wobble, probably as little as 0.1-0.2mm, which is well within Tormek's tolerances I believe.

So based on the above, if the general experience here is that your stones are square to the axle before tightening the EZYLock nut, I think the stone's arbor hole must indeed have some defect and is too wide overall or widens towards the label side. This may be amplified because the SG-200 stone is 37.5mm wide and the machined part of the axle supporting the stone is only 32.5mm long before the threading starts, I don't know. It may also be amplified if the working surface is not perfectly level. Even the difference between the T-8 and T-4 nut could be a factor, where perhaps the small plastic ledge of the T-4 nut grabs the stone more aggressively compared to the solid and smooth surface of the stainless steel T-8 nut. Other components are just not suspect, the thickness of the axle of my machine is dead-on 12.0mm and the washer is perfectly flat (I checked).

Since my T-4 is only two weeks old, I will avoid implementing measures that might void the warranty. I've had one excellent experience with Tormek support in Sweden already, and I'm confident either Tormek or the reseller in my country will resolve any justifiable issue. I'll probably contact my reseller first and support my case with this thread.

[Schmart]

Hello all, I wanted to let you know that my trusted Tormek reseller (a premium web shop with a brick-and-mortar visiting location) has investigated the grind stone thoroughly in my presence.

They performed various tests including multiple runs of my stone on a brand new T-4 machine, running a brand new stone on my machine, evaluated left-to-right wobble on a new T-4 machine with another new stone and looked at the wobble on a known-good T-7.

Admittedly, no machine was entirely without wobble, but it was apparent that the wobble I experienced was out of spec, that getting the stone to mount right was not the intended care-free operation, and also that the arbor hole in my stone was significantly larger compared to the other stones.

In short, they found my stone to be defective, and exchanged it for a new one that sits much more snug on the axle. I'm happy with the service and the result!