Jack shaft overheats.

Thinking over the speed thing.

I found a larger pulley that would slow down the jackshaft speed. Need to get a belt.

I did check out the tension on the original belt and I probably had 1” or so of easy play on each side of the belt. Not a lot of tension. In fact when the VFD break engages the belts slipped.

If this does not work then I really struggle to see how to reconfigure the motor and keep the stock jackshaft arrangement with the belt tensioner/swapping system. I know I do not need that any more with the VFD. Wonder if Direct drive may be better but I fear loosing low end torque.

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I have a couple of questions:

How did you decide to fit a 3 HP motor? I would think a 1/2 HP motor would be about right. Do you have all the parts to return
the belts and tensioning system to stock, or would you have to buy parts? That pulley looks like the original Logan part: If nothing
else, you can use it and just get a new belt. Belts are easy.

Your VFD doesn't have enough speed range to replace the pulley system.
 
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Fit i do not recall exactly but was with-in .0005" if the shaft OD.

Your bearing fit might be too tight. As the shaft warms up your clearance goes to zero. With oil I'd go .001 to .0015 clearance, for grease you need at least .005 or you can't pump it into the space.

Greg
 
Nogoingback. 3HP because it became available. I made two VFD at the same time. One for my mill and one for the lather. I found the motor used and since i was working on the mill way before the lather i just grabbed both as they were priced to move. I do have all the parts to return to stock somewhere... I have not given up on this yet thought...

Greg. You may be right. I foresee the system coming apart soon and i will re-check things.

Here is my plan of action.

- first get a belt for the larger pulley. That will drop by shaft RPM's. See what happens. I suspect i will still run hot.
- Since i do not see a way to shift the motor over so the overhang is less i will look at making a support bearing and place it just inside the pulley. Attaching it to the motor mount to take the moment load from the belt.
- If i am still experiencing issues then i will look to switch to ball bearings. I think there is enough material to get bearings in there. Shaft is 3/4". I should be able to get a 1" OD bearing set in there with material left. Maybe even a little bigger but not much. Not as large as i would like but not alot of casting there to work with.

I am having fun but man i wish Grandpa bought a 9B or a 200 back in the day. The 200 probably would not have fit in my garage but the 9B would have saved me all the upgrades i have done to this little 400. :)
 
I had the same issue, I swapped out my yoke for one with Gitz oil cups and bronze bushings. Of which my original had neither. No longer an issue
 
I think your plan is a good one. The pulley change should help with the bushings, as well as bringing your spindle RPM's down into
the design range. Instead of making up a bearing support, how about switching out the 3 HP motor for a 1/2 HP that will fit in the
space a bit better? A 3 HP Baldor is worth enough, I would think you could sell it and buy a smaller motor without spending more in
the end. Then you could locate the pulley next to the support bracket and eliminate the overhang on the shaft.

Richard's suggestion on oil cups is a good one. You could also just drill a couple of holes down from the top and drip some oil in every time
you use the lathe. The jackshaft on my Atlas 618 is like that.

As for the upgrades, all these old lathes seem to require work. Once you get it sorted, it will be worth it. :)
 
I would bet the tension with all that overhang was much more then you think that shaft will flex ,,, bend ,,, easily with barely any real tension. I'd bet money on that. If you mount an indicator on top near the end and put your tension on the belt it will bend down an125 thou. It's hard to realise but no support near the end is part of the problem. You could add a frame with ball bearing carriers fairly easy and about $50 in cost.
 
I agree that 0.0005" clearance is much too tight even if the shafter weren't bending. And that this is aggravated by the shaft bending a lot so that it is jammed in the hole at an angle and has zero clearance. And that with a 3 HP motor, sooner or later you are going to seriously break something.
 
3 hp with proper vfd should have great torque Down in low rpm range so consider keeping it.

Another option is to add another mid shaft to both offset the alignment(motor under bench) then you also can reduce speed by offsetting pulley sizes.

Flip motor 180 degrees then have output pulley in correct place.

The motor and new shaft are mounted under the bench out of the way.



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An update.

First some info.

The motor i have is a 2HP Baldor Motor. Model CM3558. 13.23" long. I would need to reduce that OAL by 3-4" to shorten the assy back to what the old Dayton motor was.
http://www.baldor.com/catalog/CM3558

I cannot easily run the motor from below the lathe and turning it around to stick the motor pulley in the middle of the jackshaft would not work either as the belt angles are wrong.

Direct drive to the head stock is interesting but this motor would still not work. It is too long since my lathe is tucked into a very particular corner of my much too small garage. (I know... no one has a garage big enough...)

Seems like i am officially looking for a new motor now...

Pulled it all apart last night and something went very wrong. I will place my bets for the initial problem being the bushings were too tight which was compounded by running too fast. Anyways, things got nasty and both the shaft and the bushings are shot.

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So where do i go from here.

I located an alternate 3PH Baldor motor (3/4HP, 4 pole, 230VAC) that would fit but it is only face mount. (10.25" long) I have located a few with side mounts that are in the 11.5" range that would work with a external bearing support.

As far as external support my thought is to come off the back side of the jackshaft structure but it is not the best surface. Doable but not going to be fun.

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Guidance and ideas are welcomed.

A few questions.

What is your guy's opinion on running bearings in the assy? I have a 3/4" shaft and could likely get 1" OD needle bearings in there. Note sure there is enough material for a 1-1/4" bearing.

What material would you suggest for the new jackshaft?

Thanks
 
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