main shaft out of round

[cpevey]

A friend loaned me his tormek t-7 because he got a divorce and wanted someone to be able to use it while he figures out his life. Anyway I've been trying to sharpen with the t-7 with little success. I've noticed the grinding wheel seemed to have a oscillation/wobble and searching the forum found that any wobble is a problem.  So I took it all apart and brought the shaft to a machinist who chucked it in a lathe and it looks like the shaft is bent to the tune of 0.008. On a ten inch wheel this might account for the probably 1/16-1/32 inch of oscillation that I'm observing? Is this enough to thwart my sharpening efforts or do I just suck at using this thing?  I've been trying to sharpen chisels 3/4 inch chisels with little success, just cant get a good edge.
Thanks Casey

[Elden]

Casey, welcome to the forum.
   I purchased a used Supergrind that arrived with a bent shaft. As the grinding wheel was rust bonded to the shaft, I have used the unit after bringing the grinding wheel into round perspective to the Universal Support with the TT-50 truing tool. This may cause the grinding wheel to wear faster than it would otherwise, but in my situation it didn't matter that it did.
   The grinding wheel costs significantly more than the shaft does. In your situation if you have it for long term usage, it may be more practical to replace the shaft.
   I actually believe you should be able to get a decent edge with it as it is, however. Check out the following thread:

http://forum.tormek.com/index.php?topic=1565.0

[cpevey]

thanks for the reply. I'll just keep trying. I kinda thought this would be foolproof but apparently this fool has a learning curve.

[Elden]

Casey, first of all you are not a fool. There IS a learning curve for all. Start with reading the thread I posted. It has good information in it. It is fairly lengthy and will hopefully trimmed down in the future. There have been many have trouble getting desired cutting edge. Do you have the truing tool and stone grader? Be sure to watch the tutorial videos put out by Tormek.

[Herman Trivilino]

On a ten inch wheel this might account for the probably 1/16-1/32 inch of oscillation that I'm observing?

That much side-to-side oscillation shouldn't affect the sharpening of a chisel or knife. However, if it's rising and falling that much it can be corrected with the truing tool. A necessary tool that hopefully you have.

My guess is that the surface of the grindstone is glazed over with steel particles. Apply the coarse side of the stone grader with lots of force. Use the corner. Change the water.

[jeffs55]

.008 inches is only discernible with some kind of gauge I would think. Do you have a glass table? Put it on there and roll it. You may be able to find the bend. If so, fastent the shaft in something immovable, attach a piece of pipe or something 3 feet or longer to the free end and bend that thing back into straightness. The longer your attachment the more power you have and therefore the more control you have. Attach the shaft to your immovable object as close to the bend as possible so that the straightening occurs at the bend. Last idea, get that machinist to straighten it, shouldn't cost more than one hours work time.

[Ken S]

i agree with Jeff's suggestion to have a machine shop straighten the shaft. A machine shop would have equipment like an arbor press which is capable of applying several tone of controlled force to the shaft and proper tools to support the shaft.

However, if the shaft is not the new EZYlock design, I think you would be better off upgrading.

Ken

[cpevey]

I appreciate everyone's comments. I trued the stone aggressively last night with the included tt50 and there is no real discernible up and down oscillation It seemed to cut very well and then I graded the wheel using the grading stone. I notice that I get a nice wire on the back of my chisels, and after honing the edge is sharp but not "scary" sharp. Maybe I am dulling the edge on the leather wheel? I am using headlight lens polishing compound until a tube of honing compound arrives in the mail. I suppose it the learning curve I am up against. All in all I think I can work with this bent shaft for the time being and just improve my technique. How sharp are you guys getting your chisels?

[Elden]

This sharp is possible by you, Casey. All it takes is practice.
http://tormek.com/en/videos/jeff_farris/jeff_farris_demo.php
Oh, did I mention, it requires practice?   

[Herman Trivilino]

I notice that I get a nice wire on the back of my chisels, and after honing the edge is sharp but not "scary" sharp.

Well, that's significant progress. It takes time to develop the skills. The pros like Steve and Jeff make it look easy, but then that's the nature of any skill.

My first guess is that you're not spending enough time with the fine side of the stone grader. You have to apply a lot of force and spend a lot of time to properly prepare the grindstone in the fine state. The grindstone should feel smooth as glass. You need this step in between the coarse grindstone and the leather wheel just like like a woodworker needs a medium grade sanding in between the coarse and fine.

Examining your edges under good light helps, as does magnification. My skills developed greatly when I started examining my edges under a 40X dissecting microscope. But just good light and a decent magnifying lens is more than good enough.

[jeffs55]

You have to be careful not to "round over" the edge with the honing wheel or leather strop if that is what you were using. You place the chisel on the honing wheel flatly so that the ground edge is just touching the wheel and the cutting edge is 180 degrees to the wheel. In other words, the cutting edge touches the wheel but still remains 180 degrees to it. Imagine a circle with two parallel lines. One line is at the top of the circle and one is at the bottom. The chisel edge is one of the lines. The ground edge always remains parallel to the bottom line even though only a tiny fraction of it is touching the honing wheel. Then, the back of the chisel is another parallel line to be treated in the same way. You just never "roll" the cutting edge on the wheel.

[Ken S]

Well stated, guys. your advice hits the high spots. 1) a good source of information 2)proper use of the stone grader 3) proper use of the leather honing wheel. A lot of good advice in a small space.

The only small thing I would add is to make sure you raise a burr before moving from coarse to fine. No burr=no sharpness. (with most steel).

Ken

[Ken S]

Casey, I suggest you have your friend (the registered owner) contact Tormek support (support.tormek.se) or your national importer. Please see my new topic on Tormek malfunctions. Support or the importer can advise you about warranty coverage.

Ken