# Rotary Table Woes



## OlCatBob (Mar 17, 2015)

Hey Guys,

When I bought my Nichols Mill, the accessories that came with it were few; but it did come with a D60 Kurt and a Troyke 9" rotary table.
I had to clean 'em up of course, but hey! they were valuable pieces. Anyway, I thought I could use the rotary table for a project I was working on, so I took it apart to clean and paint it. When I took it apart, the nut underneath was a lot looser than I thought it should be, but I figured I could adjust it when reassembling. Well, upon reassembly, I tightened it up to what I thought would be good, and when I went to try turning the table with the crank knob the table turned until it just tightened itself up. It was then that I determined that a prior owner must have dropped it at some point. I put an indicator on it, and sure enough, it's bent at the spindle.
Does anyone know how to get it back square to the table?

Any help would be appreciated.
Bob


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## JimDawson (Mar 17, 2015)

Loosen the nut, shim up the low side, and smack the high side with a big hammer?  It might work, it's about the only way I can think of the straighten it out, short of making a new spindle.


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## randyc (Mar 17, 2015)

Might be easier to make a new one rather than attempting to straighten.  You're a lucky guy - that Troyke is a real score as you clearly know and well worth investing some TLC !


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## OlCatBob (Mar 17, 2015)

Jim, I never even thought of that approach; that just MAY work, and I really don't have a lot to lose by trying it. What about "tightening the bolt" it may help pull it into position better... it would also be easier to check, just start turning the handle, it would tell me something immediately.
I'll give it a try this weekend, and report back.
Bob


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## JimDawson (Mar 18, 2015)

I should note here that when smacking with a hammer, you need to protect the table with a chunk of oak or hickory if you have it, a chunk of 1/2 inch thick aluminum or steel would work too.  Or use a big dead-blow hammer.  Another option might be a press rather than a hammer.


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## ARKnack (Mar 18, 2015)

You could try heat to straighten it. keith Rucker on YouTube had a good video on it.


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## RJSakowski (Mar 18, 2015)

OlCatBob said:


> Jim, I never even thought of that approach; that just MAY work, and I really don't have a lot to lose by trying it. What about "tightening the bolt" it may help pull it into position better... it would also be easier to check, just start turning the handle, it would tell me something immediately.
> I'll give it a try this weekend, and report back.
> Bob


Years ago, I purchased a 12" Enco rotary table which also had a bent shaft but it was the worm shaft.  As you rotated the dial, it would bind up at a particular spot and the interference was visible.  To use the table, I had to loosen the nut on the shaft.  I unsuccessfully tried straightening it by the method described in earlier posts and finally just shimmed the dial so it wouldn't touch when rotated.
While I have never straightened a rotary table spindle, I have straightened bent crankshafts  on B&S lawnmower engines after running into immovable objects.  It is important to try to duplicate in reverse the conditions that caused the bend.  Otherwise you end up with an "S" bend which may have zero runout at one position but will not at any other position.
I made a fixture to support the far end of the shaft and a split bearing to clamp the shaft at the same point as the lower mower bearing.  This was all set up on a long piece of I beam.  A long piece of pipe was placed over the end of the shaft and leverage applied to straighten the shaft.  A dial indicator was used to check for runout.  The process allowed putting the shaft back into service.  I would think a similar process using a hydraulic press and properly located supports would work for you.


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## OlCatBob (Mar 18, 2015)

JD, yeah: that goes without saying. I would likely place the RT on a solid surface, place a piece of hardwood on top of RT to protect it from the blow. My initial thoughts were in fact to use a press, just couldn't think of a way to accomplish it.
Arknack, do you have a URL for the Keith Rucker piece? I'm open to anything, although I'm not sure if there would be a way to utilize it.

thanks to all so far, still open to other suggestions though.
Bob


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## george wilson (Mar 18, 2015)

Sakowski,congratulations on straightening the bent crank shafts if you really got them accurate!!!


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## RJSakowski (Mar 18, 2015)

george wilson said:


> Sakowski,congratulations on straightening the bent crank shafts if you really got them accurate!!!


They were serviceable to the point of eliminating vibration.  As I recall, I couldn't get them totally straight but stopped "adjusting" when I was down to a thousandth runout.

I have also done some archery in the past and found out how hard it is to remove a bend in and arrow by visually sighting straightening.  Invariably, you would end up with the "S" curve rather than a straight arrow.  As I recall, I past times, the blacksmiths who could properly straighten shafts were at the top of their profession.  It is a true art and one I have not yet mastered.


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## george wilson (Mar 18, 2015)

Have you tried using heat to help straighten arrows? Violin bows are re curved over a pot of hot charcoal.


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## RJSakowski (Mar 18, 2015)

george wilson said:


> Have you tried using heat to help straighten arrows? Violin bows are re curved over a pot of hot charcoal.


The arrows were 7075 aluminum, unknown heat treatment.  I would be afraid that heating would destroy the temper in the shaft.  The problem was not with being able to bend the shaft but that the bend usually happened when the arrow tried to go around some object.  There was a gradual curve in the shaft which was induced as the arrow slid around the offending object.  The momentum of the arrow provided the bending force.  Ideally, the bend would be removed by drawing the shaft past a fulcrum point while applying the correct amount of restoring force.  Practically, this can't be done.  What I would do was to place the arrow in the lathe with a small amount protruding and measure runout.  Straighten that portion and pull out another half inch and repeat the process.  Continue until the entire shaft has been straightened.  Because the process is done in discrete steps, there are little wobbles in the shaft.  It would be OK for nutzing around but I would not use it for anything serious again.


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