Shopsmith Forums

dusty wrote:I still have not resolved the table tilt issue but I do believe I am making progress. I do believe that when a table slips it is because the brake shows have not fully engaged (the gap). What is preventing that engagement is still to be determined.

The circled areas in the attached images may (repeat may) be an issue or at least an indicator of the issue.

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[ATTACH]26771[/ATTACH]

I must have looked at these photos a dozen times since you posted them. I cannot figure how the circled ledges can be interfering with anything since the lock wedge is not wide enough to make contact out there and the trunnions don't hang down that far.

dusty wrote:I still have not resolved the table tilt issue but I do believe I am making progress. I do believe that when a table slips it is because the brake shows have not fully engaged (the gap). What is preventing that engagement is still to be determined.

The circled areas in the attached images may (repeat may) be an issue or at least an indicator of the issue.

[ATTACH]26770[/ATTACH]

[ATTACH]26771[/ATTACH]

I've studied this and can't figure out how the circled ledges can be interfering with either the wedges or the trunnions or how they are indicative of the problem.

algale wrote:I've studied this and can't figure out how the circled ledges can be interfering with either the wedges or the trunnions or how they are indicative of the problem.

Me neither.

algale wrote:I've studied this and can't figure out how the circled ledges can be interfering with either the wedges or the trunnions or how they are indicative of the problem.

Maybe the orientation of the image is confusing. Is that not the point labeled "possible interference point" in post #10 this thread?

dusty wrote:Maybe the orientation of the image is confusing. Is that not the point labeled "possible interference point" in post #10 this thread?

I originally thought so and posted that but deleted the post because I think not. The interference is with the travel of the lock wedge so only the ledge in the path of travel is relevant. What you have circled is outside of the path of travel because the lock wedge is only as wide as the large machined flat in your photo. Now, the ledge at the end of that machined flat is a stop and if it wasn't machined to the proper spec it may be the problem.

algale wrote:I originally thought so and posted that but deleted the post because I think not. The interference is with the travel of the lock wedge so only the ledge in the path of travel is relevant. What you have circled is outside of the path of travel because the lock wedge is only as wide as the large machined flat in your photo. Now, the ledge at the end of that machined flat is a stop and if it wasn't machined to the proper spec it may be the problem.

You are absolutely correct. Those wear marks are definitely not part of this discussion. They are curious but not related to the tilt lock issue.

My curiosity got the best of me and I tore into another table bar and tube assembly for a comparison.

There are differences. These differences tell me nothing about my tilt lock issue but it does alert me to the fact that two interchangeable Shopsmith parts are not necessarily the same.

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Shopsmith has milled off the area that I encircled in post #58. There is no ledge. Note that I do not know which version came first.

dusty wrote:You are absolutely correct. Those wear marks are definitely not part of this discussion. They are curious but not related to the tilt lock issue.

My curiosity got the best of me and I tore into another table bar and tube assembly for a comparison.

There are differences. These differences tell me nothing about my tilt lock issue but it does alert me to the fact that two interchangeable Shopsmith parts are not necessarily the same.

[ATTACH]26783[/ATTACH]

[ATTACH]26784[/ATTACH]

Shopsmith has milled off the area that I encircled in post #58. There is no ledge. Note that I do not know which version came first.

Did Shopsmith mill off the area shown in your post #58 or did they create the ledges shown in #58 by milling lower/deeper into the pad area where the lock wedge sits/travels. If it is the latter, the wedge would sit lower relative to the trunnion and the wedge would need to travel further in order to apply the same amount of contact force as a lock wedge sitting on a higher pad. Does that make sense?

dusty wrote:This gap was created by deliberately sliding the trunnions apart as far as they would go (with the four trunnion bolts loose) and then securing the tilt lock. The front shoe is making contact with the trunnion while the gap remains as shown on the rear trunnion.

Why the rear shoe is not pulled into place is now the question.

I see no reason to expect that the brake shoe (clamp wedge) should draw the trunnion up against the table bar.

If you look at the angle of the wedge, it is pushes the trunnion upward even harder than it draws it in sideways. This forces the trunnion upward, against the axle on the table bar, creating friction that will tend to lock it up. Likewise, the opposing vertical force will tend to lock the wedge against the surface that it slides on.

A complete analysis of the force vectors would require knowing the coefficients of friction at the various mating surfaces, which we don't. But from the basic geometry, it's reasonable that the brake shoe and trunnion would lock into place before the trunnion is drawn fully against the side of the table bar.

If you imagine that the brake shoe had an extremely acute angle, like a wooden framing shim, you'll see what I mean.

BuckeyeDennis wrote:I see no reason to expect that the brake shoe (clamp wedge) should draw the trunnion up against the table bar.

If you look at the angle of the wedge, it is pushes the trunnion upward even harder than it draws it in sideways. This forces the trunnion upward, against the axle on the table bar, creating friction that will tend to lock it up. Likewise, the opposing vertical force will tend to lock the wedge against the surface that it slides on.

A complete analysis of the force vectors would require knowing the coefficients of friction at the various mating surfaces, which we don't. But from the basic geometry, it's reasonable that the brake shoe and trunnion would lock into place before the trunnion is drawn fully against the side of the table bar.

If you imagine that the brake shoe had an extremely acute angle, like a wooden framing shim, you'll see what I mean.

You apparently have a much better understanding of vector forces than I do so I am not totally understanding what is being conveyed. However, I do believe you are telling me that the the table tilt lock was not designed to pull the trunnions and wedge locks into proper relationship when locking the table tilt.

I think I get it. I will ponder what you have said some more. I may even have to go back to the books. I even enjoy doing that because sometimes I actually understand those lessons that confused me when in school.

dusty wrote:
There are differences. These differences tell me nothing about my tilt lock issue but it does alert me to the fact that two interchangeable Shopsmith parts are not necessarily the same.

This is one of several reasons why I used different color schemes on the SS's that I restored. While there are a zillion ways to swap stuff around in making set-ups when it comes to using table assemblies I color match as the "brown" table was sat-up on the "brown" Shopsmith etc. The same applies to the tail-stocks which are matched center to center to the particular machine. Pretty much everything else accessory wise will swap except for certain 510 stuff and old Mark VII stuff which is easy to tell apart.
Now if I am just using one as an extra in-feed or out-feed support I might grab any old table and stick on any machine but not on the one doing the cutting.


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