dusty wrote:I have played with this for about four days now and I am convinced that what I experienced was/is a fluke. A self induced fluke maybe but none the less a fluke.
I can reproduce the failure mode but in normal operation the conditions required to do so are not likely to exist.
When the trunnion bolts are loose, if the trunnions are pulled apart (by whatever force) and the tilt lock is then applied, the front brake will secure itself on the trunnion while the rear brake will close some but will not fully lock (thus the illustrated gap). It is my conjecture that the gap is the sole cause of the tilt lock slipping.
On the bench, pushing the trunnions inward tight against both spindles before applying the tilt lock eliminates the propensity for slippage of the tilt lock. The gap is gone!
At this point, securing the trunnions to the table and performing a table alignment is all that remains. Once that is done, I believe that the slippage problem is eliminated and can not reoccur unless the trunnion bolts are loosened and the table tilt lock is released both at the same time. Only under this condition will the trunnions be able to move apart.
I am currently performing some verification tests but I am satisfied that this issue is resolved.
I have a floating table mounted to the main table and extended as far from the main table as the extension tubes allow. This simulates the typical load condition for the table tilt lock.
Good news!! Let us know the rest of the story.
Since the lock slippage has been plaguing you for a while and since you've been through many, many alignments, I continue to suspect there is something unusual about your machine that makes it particularly prone to having the relatively large rear trunnion gap when normal alignment procedures are used. But if you can with care get alignment and no slippage, it is a non-issue.
All of this has made me curious whether this may be part of the reason for table flatness issues we discussed in the past. Back in August we discussed how your table flatness readings were different depending on whether the table was mounted vs on the bench. I hypothesized the reason you got different flatness readings on the bench versus mounted was because, with the trunnion lock engaged, the trunnions were pushed inward to the table bar assembly and either the table or trunnions had to flex. My money was on table flex then and still is. http://shopsmith.net/forums/showpost.htm?p=174114&postcount=23 At the time I didn't know about the relatively large gap between your rear trunnion and the table bar assembly. With your trunnions properly mounted flush, or very close, to the triple pad on the table bar assembly, there should be a lot less flexing.
