What Does It Matter If The Stone Is Out-Of-Round A Little?

[cbwx34]

I like that model.

So, if a wheel is slightly out of round, will it offset the hollow grind, and produce a flat grind? (Not that the hollow grind really matters)...

My stepson just brought me his knife set for sharpening, Henckels or Wusthoff. Guess what? My wheel is egg shaped again. I have an aftermarket "truer" that has worked before, guess it will have to work again. I sure have not used it much for this to happen.

Maybe your stone wears faster in certain areas?  What about marking either the high or low spots... and see if they reappear in the same area?  (And if it's a bent shaft like Ken suggests, you could rotate it 90° on the shaft, and see if it changes anything).

[AKMike]

Are you taking the wheel off your Tormek after you have trued it and made it round again? If so, you may want to try marking the wheel and the Tormek so that you always replace the wheel in the same orientation.

Mike

[Grizz]

good idea AKMIKE  !

[Jan]

I like that model.

So, if a wheel is slightly out of round, will it offset the hollow grind, and produce a flat grind? (Not that the hollow grind really matters)...

CB, I do not expect a flat grind.
Jan

[Ken S]

Jeff Farris and I had a private joke to describe this kind of debates: "How many angels can dance on the head of a pin?" At one time the way you answered questions like these could put your life in peril with the Inquisition. 

I predict we will have another resurgency of the old flat vs hollow ground debate when the new diamond wheels arrive. Having a flat grind option will be new for Tormek. The diamond wheels still have the same large 250mm Tormek diameter. While my logical side recognizes this as hollow ground, my eyes have difficulty seeing it.  It will be an interesting debate.

Ken.

[RickKrung]

Jeff,

I wonder if your shaft might have become bent. I remember Jeff Farris posting that he always removed the grinding wheel(s?) of his Tormek(s?) whenever he traveled. At one time he was traveling thirty four weeks a year. And, that was before the left hand thread EZYlock when you needed a hammer and a wrench to loosen or tighten the nut.

Machinery rebuilder Robert Vaughn wrote an article for Fine Woodworking where he routinely checked the straightness of drill press shafts with a dial indicator. He would hit the shaft with a hammer until it was straight.

A dial indicator would quickly check your shaft. If you do not have one, a local machinist, auto machine shop or motor repair could easily do it. ...snip...

Straightening a shaft with clamping pressure is no big deal. (This is another example of the value of knowing a good machinist.)

Plan B would be to just replace the shaft. It you have a pre EZYlock SuperGrind or T7and have been thinking of upgrading to a stainless steel EZYlock, this might be a good time to do it. The EZYlock also includes a new set of bushings. I converted my first T7. It is not difficult. The hardest part was reprogramming my brain  to think left hand thread.
...snip...
Do keep us posted. I think your solving the egg shaped wheel problem will benefit many readers.

Ken
...snip...

I'm having a hard time with some of this. 

First, it is difficult for me to imagine how a shaft could become bent through merely transporting it with one of the grinding wheels on it without the machine/stone being dropped.  Did Jeff Farris ever say why it was that he removed the wheels for transport?  I remove the stones from the machine when transporting to make handling of each easier as much if not more than being concerned about the shaft.  I am much more concerned about the stone being damaged through hitting it while lifting/moving it, or if it shifted in the vehicle during transport.

In order for the shaft to become bent in a drop, I would think there would be such substantial damage to the case and probably the wheel, that much more than the shaft would need replacing. 

Second, I have a very serious problem with the notion that whacking the exposed part of a drill press spindle with a hammer can straighten it, especially without causing serious damage to other parts of the spindle, in particular the spindle bearings.  I put it this way because the image I got from your statement about Robert Vaughn's method is of him hitting either the drill chuck or the spindle taper with a hammer while the spindle is still installed in the quill in the drill press.  Please tell me this is not how he does it. If I saw someone treating my drill press like that, I would immediately separate the two by substantial distance and never let that person near any of my machines or tools again. 

The right way to straighten a shaft, such as a drill press spindle is with it removed from the machine and with it supported on either side on precision blocks and slowly bent in a hydraulic press using a dial indicator to show the amount of bending.  Followed by rotating the shaft under a dial indicator, again supported on precision blocks ("Vee blocks"), to show the extent of straightening achieved and followed by bending again, as necessary, with the same setup. 

I did this once when restoring my pre-WWII Rivet 1020 metal lathe that had helical bevel gears mounted on counter-rotating shafts in the headstock which controlled the direction of travel of the carriage. I did not have a hydraulic press so I used the quill of my vertical mill. 

Indicating the runout.  Numerals on the indicator are 0.001".  Hash marks between the numerals are 0.0001". 


Shaft straightened and headstock workings reassembled. 


The restored lathe is my Avatar photo.  Here it is before we started the restoration.


And when it was finished.


A lot more than shaft straightening when into that.  Took two years.  It was my pride and joy, home shop machinist's dream machine.  A few commented that it belonged in the Smithsonian. 

Rick

[Ken S]

Rick,

Considering that I read the article over twenty five years ago, I might not have all the details correct. I will leave the reply posted, but will add a caveat that the soirce may be misquoted.

Ken

[RickKrung]

Rick,

Considering that I read the article over twenty five years ago, I might not have all the details correct. I will leave the reply posted, but will add a caveat that the soirce may be misquoted.

Ken

I looked at Fine Woodworking.  I had to re-up to get access to the whole article, but here is a quote from what I'd say is probably that article:

Correcting wobble with a smack

Rather than replacing your machine's most expensive parts (quill,
spindle and chuck), you may be able to smack wobble out (see the
bottom photo). Since a shock force knocked things out of alignment,
an equal-and-opposite blow (within reason) can line things
up again. Move the arm of the indicator out of the way, and then
mount a hefty steel rod in the chuck and put on your safety glasses.
Position the chuck so you can smack the rod directly opposite
your mark, Your first tap should be a light one-similar to driving
a 3/8-in. brad into soft pine. Chuck your precision rod, reposition
the plunger and rotate the spindle to observe any change. Repeat
until you've got less than .002-in. wobble.


Not an unreasonable approach.  And not the horror that I imagined.  No surprise.  I think this would only work with modest amounts of runout.  I'd still take the spindle apart and figure out just where along it the bend is and work on fixing that more directly. 

I downloaded some of his other articles.  I am particularly interested in the one on fine tuning a bandsaw as I've just installed Carter precision guides on mine and am interested in all the info I can get. 

[RichColvin]

Rick,

That is an AWESOME restoration! Looks great.

Kind regards,
Rich

[RickKrung]

Rick,

That is an AWESOME restoration! Looks great.

Kind regards,
Rich

If you are interested, more photos of it here: 
http://users.easystreet.com/krugerr/Machining/Rivett/Restored/

Rick

[Wyo6050]

Wow Rick-  Like others have said, sweet restoration on that lathe!

This thread interested me since my stone too seems to end up getting out of round.  I was going to post a thread about it but haven't had the time. so thank you for this one.

My T4 is only a few months old and I figure I have 10-12 hours on it.  I've had to redress the SG-200 three times now because it started to get egg shaped.  Is that normal or is my technique causing it to go humpty dumpty?   

When you folks put it away for storage- as in wont be using it for several weeks to longer, do you take off the wheel? I have avoided taking the wheel off since it was trued to its current position and I don't want to take more wheel off if I don't have to.

The last truing I did, I noticed that the TT-50 slanted the wheels grinding surface.  I'm at a loss for what to call it so I'll just say it didnt square it up to the sides of the wheel and there is a little sliver of light when the USB is up against the wheel.  I need to figure what caused that but I have my suspicion that I didn't set the USB correctly.  I discovered there is a slight play in the usb going into the locking holes.  Next time I bring it out I'll look at it closer.

[RickKrung]

Wow Rick-  Like others have said, sweet restoration on that lathe!

This thread interested me since my stone too seems to end up getting out of round.  I was going to post a thread about it but haven't had the time. so thank you for this one.

It might behove you to start a new thread with your questions, as this thread may be "worn out" and guys aren't paying much attention anymore.  There is a tremendous collective knowledge here and it would be good for your questions to be seen by as many as possible.  I will speak to what I think I know.

My T4 is only a few months old and I figure I have 10-12 hours on it.  I've had to redress the SG-200 three times now because it started to get egg shaped.  Is that normal or is my technique causing it to go humpty dumpty?

I wouldn't think getting egg shaped that quickly is normal.  Hard to comment on whether your technique is causing it.  I've not actually had problems with my stones going egg shaped.  My original post in this thread, my SJ wheel was only about 1mm out of round, which I would not characterize as egg shaped.  I have trued them more to refresh their surface than remove egg shaped-ness.

When you folks put it away for storage- as in wont be using it for several weeks to longer, do you take off the wheel? I have avoided taking the wheel off since it was trued to its current position and I don't want to take more wheel off if I don't have to.

I do both, take a stone off and sometimes leave it on.  I sometimes leave a stone on the machine so it will dry.   

I change stones between SB, SG and SJ, so stone changes are a regular thing.  I've marked all the components to help with aligning them as they were when last trued.  I have marked the end of the shaft and the backing washer with center-punches. I've used white paint marker on the inside surface of the leather honing wheel and marked a "vertical" position on the labels of each stone.  I align these all went putting a stone on, for use or truing. 

The last truing I did, I noticed that the TT-50 slanted the wheels grinding surface.  I'm at a loss for what to call it so I'll just say it didnt square it up to the sides of the wheel and there is a little sliver of light when the USB is up against the wheel.  I need to figure what caused that but I have my suspicion that I didn't set the USB correctly.  I discovered there is a slight play in the usb going into the locking holes.  Next time I bring it out I'll look at it closer.

First, I believe I've read and/or viewed how we should set the USB height by tightening the threaded upright with downward pressure on the top of the USB above the upright.  Then tighten the other upright without pressure anywhere.  I do this, but I also check that the USB is perpendicular with the sides of the stone using a machinist's square (but any good square will do) before truing.  I'd do that too with the square edge jig and others that rely on being square, but I haven't used them that much. 

Second, you didn't specify which side of the stone surface had the light shining through, left/inside or right/outside.  If it was the left/inside, then you may have a problem with the USB not lining up properly in the clamps.  If it was the right/outside, it is possible you put pressure on the outboard side of the truing tool/USB during truing.  I think the proper technique is to touch/rotate only the thumb screws when truing, avoiding resting your hands so as to avoid pressing down on the unsupported outside-side.  This is part of the reason I developed a motorized truing tool.  Both rely on a properly aligned USB. 

Hopefully, you will hear from several others.

Rick

[Ken S]

I am starting to wonderif I havemisinterpreted "egg shaped". I would interpret egg shaped to mean not having a consistent radius if a compass was laid flat on the grinding wheel. I would interpret crowned to be if the grinding wheel had a high spot in the middle and tapered if one side was lower than the other.

I think it is good practice to regularly eliminate any of these problems.

Ken

[cbwx34]

...
This thread interested me since my stone too seems to end up getting out of round.  I was going to post a thread about it but haven't had the time. so thank you for this one.

My T4 is only a few months old and I figure I have 10-12 hours on it.  I've had to redress the SG-200 three times now because it started to get egg shaped.  Is that normal or is my technique causing it to go humpty dumpty?   

When you folks put it away for storage- as in wont be using it for several weeks to longer, do you take off the wheel? I have avoided taking the wheel off since it was trued to its current position and I don't want to take more wheel off if I don't have to.

The last truing I did, I noticed that the TT-50 slanted the wheels grinding surface.  I'm at a loss for what to call it so I'll just say it didnt square it up to the sides of the wheel and there is a little sliver of light when the USB is up against the wheel.  I need to figure what caused that but I have my suspicion that I didn't set the USB correctly.  I discovered there is a slight play in the usb going into the locking holes.  Next time I bring it out I'll look at it closer.

I think a lot more info would be needed... what do you sharpen, do you make repairs on tools, do you grade between coarse/fine often... etc.  Also, what do you consider "egg-shaped"... something you notice obviously, or something you have to, for example, compare against the USB to see it?

To answer at least one question... I rarely remove the stone... and it has sat on my older machine for years with no problems that I could tell.  I suspect that most leave the machine stored with the wheel mounted... considering Tormek makes a cover to store the machine, I would think this is the norm?

BTW, I happened to notice the other day that the holes for the horizontal USB position, don't have the "play" that the vertical holes do.  Has anyone else noticed this?... and any thoughts on truing the stone from the horizontal position?  (I haven't tried this yet).  Kinda weird that there is a difference in shape between the two positions... 

[cbwx34]

Rick,

That is an AWESOME restoration! Looks great.

Kind regards,
Rich

I agree.... that restoration looks amazing!!!