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By andrewgcook
#855379
I haven't used the tormek T7 in my workshop for some time but it has been getting some use from the lads. I went to true up the stone to do some sharpening and found both honing wheel and grinding stone running out vertically (bobbing up and down) by about a millimetre.

Upon inspection, it appears that the nylon bushings have worn and play has been introduced causing the motion but I'm not positive that this is the case.

Can anyone shed any light on this?

My observation is that nylon bearings are a pretty poor choice for this application. I am seriously considering replacing them with bronze oilite bushings such as these (the dimensions are not the right ones, the link is for information only):

http://www.bearingboys.co.uk/OBF142014_Flanged_Oilite_Bearing_Bush-6199-p

Anyone got any opinions?

Thanks.
By Spindle
#855428
Hi

I can't see how worn bearings would give that type of run out - have a look at the spindle to see if there is corrosion on it from water wicking up through the wheel.

The wet stone may have distorted due to absorbtion caused by being left in the water bath, (I've never had this happen to mine but others have reported it), - does the spindle exhibit run out when viewed from the side of the wheel? if not it's the stone that's distorted, if it does I'd suspect corrosion per above.

Regards Mick
By srp
#855577
The chromed steel shaft goes rusty, and the rusty shaft wears the plastic bearings. It's an utterly rubbish bit of design - water is bound to go everywhere in use especiallt when sharpening plane irons and planer blades, and if I'd known about it beforehand I definitely wouldn't have bought one. I turned a new brass shaft and acetal bearings but if you don't have access to a metal turning lathe then I think Tormak sell an over-priced repair kit (they really should give them away as it's obviously their fault that this happens).
By Random Orbital Bob
#855586
if maintained properly ie detaching water bath after use, particularly when the machine will be left the rusty shaft can be avoided. The problem is the wheel wicks up water and drips it slowly onto the shaft causing the rust. It takes a long time to happen (years) and can be avoided by the simple housekeeping of removing the bath. You should anyway in order to use clean water before the next session or you just introduce slough'd off bits of ceramic and tool steel to the stone which helps to prevent it cutting.

Having said that, new models come with a shaft that doesn't rust so its a known issue.
By srp
#855594
I have always emptied the water bath after I've used it, but that doesn't remove the water that has dripped down onto the shaft and (inevitably) into the bearing itself. Because it is behind the wheel and impossible to get at, and combined with the slurry of abrasive from grinding it is bound to wear. The stainless shafts fitted to later models will at least not rust, but they will still wear at an accelerated rate.
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By misterfish
#855659
When I bought my old Tormek on Ebay it had this problem - worn nylon bearings and corroded shaft. I purchased spares from Tormek which seemed a reasonable cost at the time. However I did pay a bit extra for the stainless steel shaft and since fitting the parts it has run smoothly.

Misterfish
By andrewgcook
#856910
Gentlemen, thank you for your input.

I think I have a compounded problem. There is definitely play in the bushings. I am fortunate in that I have a newer model with a stainless shaft so the play is not caused by corrosion, however, the nylon bushings are definitely worn. To remedy this, I have decided not to buy replacement Tormek bushings and, as I mentioned previously, have ordered flanged Oilite sintered-bronze bushings in the correct size. These should ensure a long-life with no need for lubrication and lovely smooth running.

If anyone is interested, the dimensions measured from my machine are as follows:

Inside Diameter (shaft diameter): 15.98mm
Outside diameter (bushing mount hole): 22.33mm
Flange diameter: 28.00mm (rounded off as non-critical)
Flange thickness: 3.00mm (rounded off also)

All measurements were taken with Mitutoyo dial calipers.

Using this information I have ordered these bushings:

http://www.bearingboys.co.uk/OBF162212_Flanged_Oilite_Bearing_Bush-6233-p

The shaft should be a fairly tight fit at that tolerance and I'm hoping the bushings should fit without significant play in the mounting hole. I'll use some medium-strength bearing compound to seat them.

The second problem, as mentioned by Spindle, is a distorted wheel from long-term, asymmetrical immersion in the water bath. The shaft shows no discernible run-out. I have the diamond truing tool, so after I install the upgraded bushings and everything is aligned and locked down, I'll re-true the wheel.

I suppose I expected the lads to look after the Tormek (as I would) and empty the water bath after every use as I requested. They have often scoffed at the slow speed ("Bloody gimmick", "Cheap toy" etc) so I think it will be back to the old bench grinder for them and the T7 will return to the garage for my use.
By Glynne
#1145504
That's a shame because I had exactly the same problem. I replaced the shaft & nylon bushes (not exactly cheap) and whilst I've flattened the grinding surface, the side of the stone does wobble. Haven't left in the water or anything like that and it is annoying when grinding across the whole surface i.e. plane blades.
By Rorschach
#1145521
Truing the wheels of a Tormek is difficult because they run so slowly, their own truing tool does ok but still isn't perfect because of flex in the bar. I have trued mine up on the lathe which does work very well but it doesn't take long for them to go out again and the play in the shafts and casing doesn't help. One day I will get around to building my own from scratch but for now I just live with it.
By Glynne
#1145526
Never thought about truing the wheel on a lathe, not a bad idea.
What about flattening the sides? Obviously you need to be really careful not to shatter the wheel but something like a scraper just brought in very gently?
By andrewgcook
#1150414
Hi guys,

I took a break from woodworking due to a long term illness. Back at it now with renewed vigour.

As an update, the Oilite bushings work a treat. Quieter and smoother. Part of the problem solved!

There was still a little runout which I cured by soaking the whole stone in water for 48 hours, mounting it on the machine and taking very shallow truing passes with the diamond truing tool. I took the wheel off the machine and left it in the workshop to dry out for 4-5 days. To allow good airflow I laid it flat on two pieces of 2mm square hardwood.

When I remounted it and ran it the runout was barely perceptible. One more fast shallow pass and there was none.

Since doing this I have made sure that the water trough is empty afer use. Haven't had a problem since.

I think I often overthink things and the run-out was probably not an issue really but I do have obsessive tendencies and like my tools to be just so.

Thanks for everyone's input. I hope mine, although two years later, helps someone!

Regards,

Andrew