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13" Clutch Disassembly

ChipMeister

Plastic
Joined
Jul 14, 2016
My apologies in advance if this post seems all too familiar but I just could not find a solution to my problem in previous postings.

Background is I am refurbishing my 1950's-vintage 13" x 6' SB lathe. Got through the reversing gear system (seized bearing) and refurbished the QCGB; am presently working on the apron. I am using the ILION Refurbishment Guide that does have some pretty good guidelines and photographs.

My SB lathe has the star knob configuration for the clutch, but it does not have the center screw, the one that has left-hand threads, so there's the first apparent difference. The star knob freely spins off to reveal the shaft and hex nut that secures the shaft to the apron.

However, there is a special nut inside the hex nut that appears to require a special tool to remove it. That is the second difference from other descriptions. In fact, the ILION guide makes no mention whatsoever of this feature and merely states to 'grasp the clutch gear and loosen the hex nut.' or words to that effect. I may have overlooked the obvious but it seems to me there really is nothing to grab onto that will keep the clutch assembly from turning.

I've read other posts that imply a special bushing or similar adapter might be used beneath the star knob to lock down the shaft and I can kind of see that as an approach, but what of the special nut inside the hex nut? I don't understand how that factors into this configuration. And with there being no description in the manual/guide I am at a loss.

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That is not a nut inside a nut. It is a slot in the end of the clutch body. You need to remove the worm, and the clutch will slide out.

allan
 
I believe there is a pin through the drawbar shaft in that slot. Remove that outer nut and the clutch will come out. Once the nut is off, you will be able to get the pin out and break the clutch assembly down into as many pieces as you want. You do have to remove the worm as well, like Alan said.
 
Well, the worm is already out; the hex nut spins the clutch shaft but does not come loose from that shaft and I can find nothing to hold the shaft to break the nut free.
Plus, since this is not the lever-type clutch but the star knob variety, there is no pin holding a draw bar to the shaft.
It's that darned hex nut that is holding up the show.
 
Put the star wheel on and tighten it by hand. Hold the clutch gear with something soft like a strap wrench and break the nut loose. Then remove the star wheel to get the nut the rest of the way off. Once the clutch assembly is out, clean the slot. There is a pin there, that the inside face of the nut keeps from sliding out of the drawbar shaft. You will not get the assembly apart, until you get the pin out of the drawbar shaft and you won't remove the pin without removing the nut. There is another set up used that doesn't use a pin to hold the drawbar shaft in, but it would be able to slide right out at the stage you are in. The slot is the giveaway to the style you have. The Illion book is helpful, but I have found a few mistakes on the larger lathes, that can cause you some grief. The book is a huge help, but it is geared toward a smaller lathe and is only a guideline to the larger ones.
 
Well, the worm is already out; the hex nut spins the clutch shaft but does not come loose from that shaft and I can find nothing to hold the shaft to break the nut free.
Plus, since this is not the lever-type clutch but the star knob variety, there is no pin holding a draw bar to the shaft.
It's that darned hex nut that is holding up the show.

Ok, so the pictures you showed are not your apron :)

Put the clutch back together, tighten it down, and wedge the clutch gear. You should then be able to loosen the nut.

allan
 
Thanks for that feedback. I'll give it a try today and report back.
Yes, the guidebook is pretty good but obviously is not completely comprehensive regarding the possible variants.
Keeping my gears crossed!
 
Appreciate the reply, Allan, but I'm puzzled about the pictures 'not being the apron.' I'm obviously no expert but the descriptions I've read in books and manuals all indicate the apron is what I'm working on. What am I confusing this with? ��
 
I'm not questioning the fact that it is an apron pictured, only that it was yours. I guess you removed the worm since you took those shots?

allan
 
I'm not questioning the fact that it is an apron pictured, only that it was yours. I guess you removed the worm since you took those shots?

allan

Oh, it's mine and you're right... the worm was removed. But the good news is that the combined advice provided on this forum helped me to solve the problem of releasing that hex nut- A strap wrench on the clutch gear, plus tightening the star knob onto the shaft did the trick. That, and the driving out of that little pin and the assembly is free and clear of the casting. Aside from the snap ring for which I need a different tool than the ones I have and everything will be down to their component parts.

Lots of caked and baked oil and debris and dirt, but no significant scoring or erosion of any bearing surfaces (so far). Gear teeth look good and so do the clutch plates. Now it's off to a parts bath!

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My thanks to everyone who replied with advice and suggestions.
I appreciate to support!
 
I worked my backside off to get that snapring out of the bottom of the clutch body. I suggest you don't waste you time, unless it feels gritty or something.

allan
 
I worked my backside off to get that snapring out of the bottom of the clutch body. I suggest you don't waste you time, unless it feels gritty or something.

allan

Yeah, that thought certainly crossed my mind. Why the design didn't include a snap ring with eyes I can't fathom. There seems to be enough room for that type ring but that's my opinion.
I'm going to put all these parts into a bath and hopefully this last assembly will look and feel clean and smooth without needing to break it down further. I know, it's not a very professional approach but good enough is... well, good enough.
 
Put the star wheel on and tighten it by hand. Hold the clutch gear with something soft like a strap wrench and break the nut loose. Then remove the star wheel to get the nut the rest of the way off. Once the clutch assembly is out, clean the slot. There is a pin there, that the inside face of the nut keeps from sliding out of the drawbar shaft. You will not get the assembly apart, until you get the pin out of the drawbar shaft and you won't remove the pin without removing the nut. There is another set up used that doesn't use a pin to hold the drawbar shaft in, but it would be able to slide right out at the stage you are in. The slot is the giveaway to the style you have. The Illion book is helpful, but I have found a few mistakes on the larger lathes, that can cause you some grief. The book is a huge help, but it is geared toward a smaller lathe and is only a guideline to the larger ones.
Extremely helpful, thank you! Actually had no confidence in this method, as neither driving a hard wood wedge between the clutch gear and apron housing nor binding 2 3/8"-16 nuts against each other on the shaft would allow me to loosen that 1" nut holding the clutch assembly in the apron. And I was SURE that the worm gear would shred my rubber strap wrench with the nut being so tight. I put the star knob back on firmly, held the worm gear just by HAND, put a 1" box wrench on the nut and gave it a whack with a hammer and PRESTO, loose. Done Job. Thanks again!
 








 
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