Table Tilt Lock

[dusty]

Dusty
Could the problem be with the table piviots? If there is wear there they could allow the table/trunnion to lift up instead of holding everything in place to allow the locks to put sufficient pressure on the trunion to lock it.


After all the talk about this I am now pondering the wisdom of the dollar bill. If the trunion is pushed against the ledge seen in the pictures adding the dollar just adds more movement room. And I would guess causing the table to flex. Seems unlikely. I suspect there is things yet undiscovered about the SS and the table lock.

PLEASE keep us informed on what you learn! THANKS

I am not sure what you mean when you a problem with the table pivots but let me add a couple more details before we go there.

Whether or not you can put a feeler between the trunnion and the table bar is a "crap shot" based on where the trunnions were located when they were tightened down during table alignment.

By pushing the trunnions as far apart as they will go, there is a significant (1/8"+) gap between the trunnion and the table bar when the table is locked.

If the trunnions are pushed inward (toward one another) when the trunnions are secured to the table during table alignment, that gap diminishes and may become none existent when the table tilt is locked.

Pictures would help here but I could not take any. The camera is on the charger.

[BuckeyeDennis]

I am not sure what you mean when you a problem with the table pivots but let me add a couple more details before we go there.

Whether or not you can put a feeler between the trunnion and the table bar is a "crap shot" based on where the trunnions were located when they were tightened down during table alignment.

By pushing the trunnions as far apart as they will go, there is a significant (1/8"+) gap between the trunnion and the table bar when the table is locked.

If the trunnions are pushed inward (toward one another) when the trunnions are secured to the table during table alignment, that gap diminishes and may become none existent when the table tilt is locked.

Pictures would help here but I could not take any. The camera is on the charger.

Dusty, if I understood Nick correctly in this post, and in the video that JPG referred to, he is saying to use the dollar bill to get exactly 0.005" of total clearance between the table bar and the trunnions, when unlocked, so that the table will tilt freely. This is done by first locking the trunnions down with the table loose, using the dollar bill as a 0.005" spacer, to position the trunnions properly while tightening down the table down to the trunnions. The resulting 0.005" gap would then result in a slight, but presumably negligible bending of the table when the lock is tightened.

As as engineer, I've learned that the most useful way to model any solid object is as a spring. Some objects are very springy (like a spring), and others are very stiff (like a chunk of granite). But they all have a finite "spring constant", and will deflect to some extent when a force is applied to them.

If the trunnion-to-table-bar gap is too large, then tightening the lock would surely flex the table, and the clamp shoe may not travel far enough to clamp the trunnion securely against the table bar. In this circumstance, positive locking would not be achieved.

[algale]

I am not sure what you mean when you a problem with the table pivots but let me add a couple more details before we go there.

Whether or not you can put a feeler between the trunnion and the table bar is a "crap shot" based on where the trunnions were located when they were tightened down during table alignment.

By pushing the trunnions as far apart as they will go, there is a significant (1/8"+) gap between the trunnion and the table bar when the table is locked.

If the trunnions are pushed inward (toward one another) when the trunnions are secured to the table during table alignment, that gap diminishes and may become none existent when the table tilt is locked.

Pictures would help here but I could not take any. The camera is on the charger.

I'm at a disadvantage because I don't have access to my 520 at the moment but I'm having a hard time with the bolded language.


When you do a table alignment you must loosen at least three of the four table bolts and engage the lock. Don't the lock wedges push the trunnions (which are unrestrained by the table bolts) against the table bar?


If I am correct, it is not possible during alignment to lock the tilt lock without driving the trunnions flush against the table bar. That is why the dollar bill trick is used, to give a slight gap (on one side only) when the lock is released and the bill removed.

I still believe that small gap (if you used the dollar bill trick) will be bridged when the lock wedges are driven against the trunnions during normal operations.

Disclaimer: I'm not an engineer.

[dusty]

I'm at a disadvantage because I don't have access to my 520 at the moment but I'm having a hard time with the bolded language.


When you do a table alignment you must loosen at least three of the four table bolts and engage the lock. Don't the lock wedges push the trunnions (which are unrestrained by the table bolts) against the table bar?


If I am correct, it is not possible during alignment to lock the tilt lock without driving the trunnions flush against the table bar. That is why the dollar bill trick is used, to give a slight gap (on one side only) when the lock is released and the bill removed.

I still believe that small gap (if you used the dollar bill trick) will be bridged when the lock wedges are driven against the trunnions during normal operations.

Disclaimer: I'm not an engineer.

Yes they do! and Yes it will! At least one of them will. The other gap size is dependent on where the trunnions are. As stated, we typically tighten one trunnion bolt which tends to secure that trunnion where ever it is located at that time.

Does this effect the overall function of the tilt lock? I don't know.

[dusty]

Dusty, if I understood Nick correctly in this post, and in the video that JPG referred to, he is saying to use the dollar bill to get exactly 0.005" of total clearance between the table bar and the trunnions, when unlocked, so that the table will tilt freely. This is done by first locking the trunnions down with the table loose, using the dollar bill as a 0.005" spacer, to position the trunnions properly while tightening down the table down to the trunnions. The resulting 0.005" gap would then result in a slight, but presumably negligible bending of the table when the lock is tightened.

As as engineer, I've learned that the most useful way to model any solid object is as a spring. Some objects are very springy (like a spring), and others are very stiff (like a chunk of granite). But they all have a finite "spring constant", and will deflect to some extent when a force is applied to them.

If the trunnion-to-table-bar gap is too large, then tightening the lock would surely flex the table, and the clamp shoe may not travel far enough to clamp the trunnion securely against the table bar. In this circumstance, positive locking would not be achieved.

I don't disagree with any of what you are saying and I have been securing the table and aligning the table in accordance all these many years.

I still have a table tilt lock that is not always reliable.

I think it should be and am trying to determine what I am doing wrong or different from others who don't seem to have the same experience..

[algale]

Yes they do! and Yes it will! At least one of them will. The other gap size is dependent on where the trunnions are. As stated, we typically tighten one trunnion bolt which tends to secure that trunnion where ever it is located at that time.

Does this effect the overall function of the tilt lock? I don't know.

If I were you, I'd would loosen all four table bolts loosey-goosey then lock the tilt lock (which will register both trunnions flush against the table bar --don't use the dollar bill). Then finger tighten one of the headstock-side bolt as a pivot point. Then align. Then firmly tighten both headstock side bolts before loosening the tilt lock and tilting the table to get at and tighten the other 2 bolts. And don't wax the trunnion. Let's see if that solves your locking problem.

[forrestb]

It had been so many years since using Nick's method in the advised Sawdust Session that I forgot the $20 bill trick.

I just re-adjusted my 520 table following Nick and it has made setting the table angle a lot less sticky. So thanks! for that.

I found that the PowerPro magnets make it very hard to exactly position a tooth for the dial indicator so I made a spot on the face beside a tooth and got 0.000 degree off-axis before tightening and wound up with 0.003 after tightening.

Time will tell whether or not I am still getting droop but I will report that later.

Forrest

[dusty]

This is sorta comical. Forrest has not been using the dollar bill trick and now decides to try it again and seems to have achieved reliable ilt lock. I, on the other hand, have been using the dollar bill trick and just decided to try a test without it. I did this on a table that I just won on eBay. Yeah, you guessed it. It appears to be locked solid.

Now I gotta do it on the goto machine where alignment counts and so does tilt lock.

Yes, I will clean the wax off the trunnions before I do this and give it a go exactly like algale recommends. No wax and no dollar bill.

Incidently, the dollar bill was used to eliminate the squeal that sometimes occurs when tilting the table. After playing with this yesterday and today I am going to suggest that further unlocking the tilt lock will do the same thing.:):rolleyes::)

[forrestb]

My only comment was the $20 bill use eliminated the stickiness when trying to set a specific angle - like 90 degree.

I have set the table to 90.1 degree, put the 520 fence at the extreme right hand side of the table and will check where the table is in the morning. (hopefully, where I left it:p )

I really can't believe the table droop is solved, but if so I'll be a happy man!

Forrest

[dusty]

My only comment was the $20 bill use eliminated the stickiness when trying to set a specific angle - like 90 degree.

I would conclude that the stickiness was caused by the table bar making contact with the trunnion when unlocked. The dollar bill trick was advertised to be the solution.

I have set the table to 90.1 degree, put the 520 fence at the extreme right hand side of the table and will check where the table is in the morning. (hopefully, where I left it:p )

I really hope that there is no droop when you go to check this morning.

I really can't believe the table droop is solved, but if so I'll be a happy man!

Forrest

I also hope that I get similar results. After playing with two table assemblies for nearly three days now, I can find nothing that looks as though it would/should cause my slippage problem. Droop as Forrest says.

PS: I have initiated a "droop test" on the eBay main work table. If this works out satisfactorily, I will realign and retest both my Shorty and my GoTo machines.

Note: The table is not supported by the table leg with the adjustable stop collar. It was used to achieve the 0° tilt (90° to the blade) and then the tilt lock was secured. With the tilt lock secured, I backed off the adjustable stop collar. It was left in place so that if the tilt lock slips the bottle jack will not be dumped on the floor. I have three digital gauges in place to collaborate the resulting readings.

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