Shopsmith Forums

A number of us have reported a problem with locking the Table Tilt tight enough to secure the table when under pressure.

What I would like to know is whether anyone has eliminated that problem by replacing either the Front Clamp Shoe (514104) or the Rod and Shoe Assembly (514634) or both.

These two components lock against the trunnions.

I have had a perpetual tilt lock problem and have cleaned the shoes and the trunnions to no avail. The parts in question do not appear to be excessively worn or otherwise damaged.

I have resolved my table tilt problem by utilizing other means but would like to avoid having to do that. The Mark V was designed to lock and it seems that most everyone's does. I want mine to lock too!:(

Dusty,

Since no one else has responded, I will.

I have not encountered this problem with my table lock but perhaps we use our tables differently and I put them under less stress than you. If you would give an example or two of the conditions and operations where you have had the table lock fail, I will see if I can duplicate them with my 520 table.

A couple of thoughts on things other than wear and tear that might contribute to loose table locks. I recall reading a post where you said that you wax your trunnions. I have never waxed mine. Could that be part of the issue?

Also, do you use Nick's $20 bill trick? I have not found that the $20 bill trick makes a difference in how freely my table pivots and so I do not use it any more. Could that extra space (caused by the $20 bill trick) contribute to inadequate clamping pressure?

Al

I wanted to get my eyeballs on my own before responding, Dusty. I've never had a problem with it slipping, unless I forgot to tighten it. And it doesn't take much torque on the locking lever to lock it up good and tight.

The thing is a friction lock. So if it doesn't lock, the immediate cause has to be either 1) an inadequate coefficient of friction, or 2) inadequate normal force on the clamping surfaces.

#1: You said that you have cleaned it, to no avail. And I doubt that even JPW would reduce the friction enough to keep it from locking, so my hunch is that #2 is the problem.

#2: If something else is stopping the brake travel before it locks down on the trunnion, you won't get the proper force applied. But it must be darned close in your case, or it wouldn't clamp at all.

The photo below shows my front trunnion brake in the locked position. I noticed that there is a ledge in the casting just to the right of the clamp shoe. The inside bottom corner of my front shoe is less than 1/8" from hitting that ledge, and the back is about the same. Any chance that yours is hitting it?


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algale wrote:Dusty,

Since no one else has responded, I will.

I have not encountered this problem with my table lock but perhaps we use our tables differently and I put them under less stress than you. If you would give an example or two of the conditions and operations where you have had the table lock fail, I will see if I can duplicate them with my 520 table.

A couple of thoughts on things other than wear and tear that might contribute to loose table locks. I recall reading a post where you said that you wax your trunnions. I have never waxed mine. Could that be part of the issue?

Also, do you use Nick's $20 bill trick? I have not found that the $20 bill trick makes a difference in how freely my table pivots and so I do not use it any more. Could that extra space (caused by the $20 bill trick) contribute to inadequate clamping pressure?

Al

With no extension tubes installed, downward pressure on either the left or right edge of the main table will overcome the lock. The pressure does not have to be significant; you don't have to "lean into it".

This does not happen as a result of just the weight of a work piece. It has happened most of as a result of my adding downward pressure to the table.

I wax the trunnions but not the surfaces where the brake shoes contact the trunnions. I will, however, reassemble this time with the trunnions clean and wax free.

Yes, I use the dollar bill and I think that it forks per the Sawdust Session video. I would say that if it is not needed, don't do it.

Thanks for the response and since no one else has responded I will just assume that I am the "odd ball" on this one.

BuckeyeDennis wrote:I wanted to get my eyeballs on my own before responding, Dusty. I've never had a problem with it slipping, unless I forgot to tighten it. And it doesn't take much torque on the locking lever to lock it up good and tight.

The thing is a friction lock. So if it doesn't lock, the immediate cause has to be either 1) an inadequate coefficient of friction, or 2) inadequate normal force on the clamping surfaces.

#1: You said that you have cleaned it, to no avail. And I doubt that even JPW would reduce the friction enough to keep it from locking, so my hunch is that #2 is the problem.

#2: If something else is stopping the brake travel before it locks down on the trunnion, you won't get the proper force applied. But it must be darned close in your case, or it wouldn't clamp at all.

The photo below shows my front trunnion brake in the locked position. I noticed that there is a ledge in the casting just to the right of the clamp shoe. The inside bottom corner of my front shoe is less than 1/8" from hitting that ledge, and the back is about the same. Any chance that yours is hitting it?


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I don't think so. That is where the dollar bill is installed and after I have completed the alignments I simply release the locking pressure and pull the dollar bill out. That particular surface has nothing to do with the locking pressure (if I am assembled correctly).

I'll double check.

Thanks for the feedback.

Dusty
Is it possible that the brake shoe is not contacting the trunnion properly? Do they wear like the locking wedges on the headstock? Maybe they just have to be filed to make full contact like the other locking wedges.
Bill V

Sure wish I could offer some help Dusty. But, that's never happened with either of mine.

wa2crk wrote:Dusty
Is it possible that the brake shoe is not contacting the trunnion properly? Do they wear like the locking wedges on the headstock? Maybe they just have to be filed to make full contact like the other locking wedges.
Bill V

Yes, that is possible and since I work quit a bit with the table tilted mine may wear faster than others. Just guessing! I have nothing to substantiate that theory.

I did not want to do this but I may have to disassemble the tilt lock on a couple of machines for comparison of the wear pattern.

Gene Howe wrote:Sure wish I could offer some help Dusty. But, that's never happened with either of mine.

Good! I am glad for that and I hope no one else has the problem either.:)

I'm hijacking and annotating Buckeye's excellent picture to make a point about this mechanism.

My understanding of how the table lock mechanism works is that
when the table lock is engaged, a wedge (one on each trunnion) are driven against the bottom beveled edge of the trunnion which creates friction at that point. In addition, the wedges force the trunnions inward toward the center of the table a fraction of an inch until the flat, backside of the trunnions contact part of the table bar/tube assembly which creates additional friction at that point. (When I used the dollar bill trick, the dollar bill went between the flat, back part of the trunnion and the table/bar tube assembly creating additional clearance).

If I am correct, wax on the flat back part of the trunnion would decrease friction that is needed to lock the table. In addition, the dollar bill trick means the trunnion starts further away from the table/bar tube assembly and the wedge must drive the trunnion a greater distance to make contact there. In that case, I see that ledge or lip in BuckeyDennis' photo (the ledge near the bottom right angle of the wedge) as a potential stop/source of interference.

This should be clearer in the the following picture:
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