I have wondered about this for some years now

[algale]

I still think the movement would be 1/16th in any any/all directions, not just due north, due south, due east, due west.

I think the dynamic that is not being taken into consideration is what happens at all four locations when something moves.

Oh, I'm taking it into consideration. I just may be wrong!

[dusty]

Table moved 1/16" and rotated .45 degrees. Yes, ther maximum movement at any of the four holes is 1/16" If the table is simultaneous "rotated" the movement is slightly less. I think Ed's disclosure will be the same (1/16" in all directions about the axis of rotation). Like an eccentric with 1/16" offset.

A 1/8" dot.

AFour Trunnion Bolts and Holes with Movement.jpg (74.26 KiB) Viewed 794 times

[dusty]

Is this not a math question?

The trunnion holes are 1/2" and the trunnion bolts are 3/8". Based on that, I would say that the table can be moved 1/16" in all directions; thus the maximum travel from one extreme to the other is 1/8".

Yes, there might be some vary slight deviations brought about by component tolerances but is that really going to be significant.

I agree. Deviation up or down from that value could have multiple causes, but that's the nominal.

I'm scratching my head about the earlier Nick post. I've seen a couple of Marks with undersized holes and IIRC it is one specific hole on one specific trunnion.(?) And I always believed it to be deliberate, kind of acting as a hinge point for aligning the table. Sometimes unsuccessful, but deliberate. With two undersized holes the table would be essentially un-adjustable.

The rear trunnions are the ones I redrilled and I redrilled both holes. I think that was the jest of Nick's post (not just one hole). May be wrong.

- David

When this trunnion hole size discussion first came up, I jumped on the band wagon and redrilled all of my trunnions to have 1/2 inch holes. To this day I regret that. Now, whenever I have had the trunnion bolts loose, I reposition the table by pushing the main table firmly to the left against the trunnion bolts and finger tighten the bolts. I then double check and/or tweak the table position using a dial indicator. At this point we are talking about movement in the thousandths of an inch.

[DLB]

When this trunnion hole size discussion first came up, I jumped on the band wagon and redrilled all of my trunnions to have 1/2 inch holes. To this day I regret that. Now, whenever I have had the trunnion bolts loose, I reposition the table by pushing the main table firmly to the left against the trunnion bolts and finger tighten the bolts. I then double check and/or tweak the table position using a dial indicator. At this point we are talking about movement in the thousandths of an inch.

Clarity for the reader: most of the detail in this discussion is specific to 510 and on.

IMO one snug trunnion hole will greatly reduce table movement when the bolts are loose, the snug fit basically working like a point on a compass and everything swinging around that in an arc. That seems like a good thing as long as the range of rotation includes the angle you want, miter slot parallel to the blade, disc, or alignment plate. More than one small hole would reduce movement to near zero, still okay if it includes the angle you want, but it starts to seem less likely to be the case.

This alignment step is more of a struggle for me than most. I want it near perfect because I know whatever I'm aligning to isn't perfect. Throw in the $20 bill trick, inconsistent holes, two bolts you can't tighten without tilting the table. Not exactly a recipe for success. A single snug hole acting as a hinge on one of the bolts I can't get to with the tilt at 0 strikes me as an improvement.

- David

[dusty]

When this trunnion hole size discussion first came up, I jumped on the band wagon and redrilled all of my trunnions to have 1/2 inch holes. To this day I regret that. Now, whenever I have had the trunnion bolts loose, I reposition the table by pushing the main table firmly to the left against the trunnion bolts and finger tighten the bolts. I then double check and/or tweak the table position using a dial indicator. At this point we are talking about movement in the thousandths of an inch.

Clarity for the reader: most of the detail in this discussion is specific to 510 and on.

IMO one snug trunnion hole will greatly reduce table movement when the bolts are loose, the snug fit basically working like a point on a compass and everything swinging around that in an arc. That seems like a good thing as long as the range of rotation includes the angle you want, miter slot parallel to the blade, disc, or alignment plate. More than one small hole would reduce movement to near zero, still okay if it includes the angle you want, but it starts to seem less likely to be the case.

This alignment step is more of a struggle for me than most. I want it near perfect because I know whatever I'm aligning to isn't perfect. Throw in the $20 bill trick, inconsistent holes, two bolts you can't tighten without tilting the table. Not exactly a recipe for success. A single snug hole acting as a hinge on one of the bolts I can't get to with the tilt at 0 strikes me as an improvement.

- David

But the trunnion bolts are in a line that is parallel to the blade, There should, by design, be very little need for movement What movement that is needed is for tweaking (fine tuning). I contend that the Shopsmith was not designed to be aligned to within .005" (like I used to strive to achieve) and that it does not need to be to produce excellent wood working results.

I can hardly wait for Ed to reveal his findings on the subject of this thread. Ed presents some very interesting and most often educational conclusions with these mind teasers. I am curious about what this one does reveal.

[DLB]

I think this was the reveal, wasn't it? viewtopic.php?p=290810#p290810 Roughly 0.140" and roughly a circle.

- David

[dusty]

I think this was the reveal, wasn't it? viewtopic.php?p=290810#p290810 Roughly 0.140" and roughly a circle.

- David

If it was...I have questions. Aah...unless the pen that he used introduces some offset making his dot smaller than I envisioned. That would make his dot larger by the radius of his pen.


You are right. I am WRONG< WRONG< WRONG. The pen is not moving about the hole. The table is moving.

Now I have the brain teaser.

Ed strikes again.

I woke up in the middle of the night realizing I was wrong.

[dusty]

I am having trouble with pictures taken with my new Smartphone. Thet are rejected because they are too large.

Until I figure this out it will have to suffice to say "Ed's Image has been confirmed"; my dot is approximately 1/8".

The Dotv.jpg (345.03 KiB) Viewed 653 times

Please ignore the unwanted hole at the tip of the calipers.

It now occurs to me that the diameter of the dot is equal to the distance between the bolt (3/8") and the trunnion hole (1/2"). This had me puzzled big time.