Table Saw Fence

[BigSky]

Having been through some issues with my 520 rails which did not all mount parallel to each other (because the fence mounting pads were not all the identical distance apart), I will say that it is certainly possible that the front or rear rail or both may not be perpendicular to the miter slot (which should be parallel to the blade).

When you move and then lock the fence on (a) the main table, (b) a floating table and (c) an extension table do you observe the same issue in terms of the fence skewing?

Oh boy, this could get complicated!

Axiom One: Two items both perpendicular to a third item are parallel to one another. Or is that a Postulate?

[mrhart]

After all your input and some experiments, here is what I had.
I have losened the 4 screws and squared the fence to the miter slot-retightened.
I have cleaned the rails and scuffed up the black wear pads just slightly for a better grip.
I have adjusted the nut/spring on the lower front lock. If I adjust it to flip all the way down, it won't grab the rail tight enough and the fence moves. If I adjust it so it flips down to about the 4 o'clock position and won't go further, it holds the fence.
Almost everytime I slide the fence back and forth like I was setting up for a cut, and then clamp the lower lock, the back of the fence swings a little left. Now when it does swing left, it pulls is square where before it did not.

Its better than it was, but I feel like the lower lock should flip all the way down and feel more like the top lock. I wish I had another 520 I could just mess with for a minute to compare it to another.

This all started with the replacement of the upper lock handle which I got in the mail from SS as the PO must have dropped the fence at one point and broke the handle. After that I was paying more attention to the adjustments on the fence and how it swings left. As I was using the table saw on a project is when I noticed a cut slightly out of square and that the fence was clamping crooked.

[SDSSmith]

After all your input and some experiments, here is what I had.
I have losened the 4 screws and squared the fence to the miter slot-retightened.
I have cleaned the rails and scuffed up the black wear pads just slightly for a better grip.
I have adjusted the nut/spring on the lower front lock. If I adjust it to flip all the way down, it won't grab the rail tight enough and the fence moves. If I adjust it so it flips down to about the 4 o'clock position and won't go further, it holds the fence.
Almost everytime I slide the fence back and forth like I was setting up for a cut, and then clamp the lower lock, the back of the fence swings a little left. Now when it does swing left, it pulls is square where before it did not.

Its better than it was, but I feel like the lower lock should flip all the way down and feel more like the top lock. I wish I had another 520 I could just mess with for a minute to compare it to another.

This all started with the replacement of the upper lock handle which I got in the mail from SS as the PO must have dropped the fence at one point and broke the handle. After that I was paying more attention to the adjustments on the fence and how it swings left. As I was using the table saw on a project is when I noticed a cut slightly out of square and that the fence was clamping crooked.

Sounds like your lock position of about 4 o'clock is about where it should be. For reference on my machines, both the upper and lower levers are approximately parallel to each other. Also there is a flat on the bottom of the cam end of the lever. The flat is approximately parallel to the ground.

The key is the fence locks hold the fence and when the front one is locked down it pulls the fence square.

[dusty]

After all your input and some experiments, here is what I had.
I have losened the 4 screws and squared the fence to the miter slot-retightened.
I have cleaned the rails and scuffed up the black wear pads just slightly for a better grip.
I have adjusted the nut/spring on the lower front lock. If I adjust it to flip all the way down, it won't grab the rail tight enough and the fence moves. If I adjust it so it flips down to about the 4 o'clock position and won't go further, it holds the fence.
Almost everytime I slide the fence back and forth like I was setting up for a cut, and then clamp the lower lock, the back of the fence swings a little left. Now when it does swing left, it pulls is square where before it did not.

Its better than it was, but I feel like the lower lock should flip all the way down and feel more like the top lock. I wish I had another 520 I could just mess with for a minute to compare it to another.

This all started with the replacement of the upper lock handle which I got in the mail from SS as the PO must have dropped the fence at one point and broke the handle. After that I was paying more attention to the adjustments on the fence and how it swings left. As I was using the table saw on a project is when I noticed a cut slightly out of square and that the fence was clamping crooked.

I have the convenience of two fences both adjusted independently by myself. Evaluated now together, they are not identical. They both lock securely and they are both reasonably square to the table BUT when the separation between the two is measured (infeed vs outfeed) they are not exactly parallel (as I would have hoped).

However, I consider them both to be parallel to the blade.

The lock handles do not secure in exactly the same position (close but not exact).

See for yourselves.


[ATTACH]19205[/ATTACH]

[ATTACH]19206[/ATTACH]

[ATTACH]19207[/ATTACH]

[ATTACH]19208[/ATTACH]

[ATTACH]19209[/ATTACH]

[keakap]

Having been through some issues with my 520 rails which did not all mount parallel to each other (because the fence mounting pads were not all the identical distance apart), I will say that it is certainly possible that the front or rear rail or both may not be perpendicular to the miter slot (which should be parallel to the blade)....

"may not be perpendicular to the miter slot"

Ab-so-lute-a-mondo!

[in my case I went for the quick fix-- all new tables]

Btw, has anyone ever successfully, and without a trip to the hospital, fully clamped the upper fence clamp before fully clamping the lower?

[keakap]

...ut I feel like the lower lock should flip all the way down and feel more like the top lock. I wish I had another 520 I could just mess with for a minute to compare it to another.

This all started with the replacement of the upper lock handle which I got in the mail from...

And there is the problem. Not all those cams are identical.
I can't remember right now what it was titled, but there is another thread from this past year on this subject, essplaning what is wrong with those cams and what to do about it. If I can find the thread I'll post it.

Problem is the hump on the cam is misshapen. Must be from Notre Dame. The screwy ones provide max clampage (remember him from the Beverly Hillbillies? Jed Clampage) at the point where they are about 3/4 of the way to completely closed-down. Trouble is when you pass that max point, clamping gets weaker to and til the end.

IS fixable. Remove it, file it (removing the hump) and re-adjust pressure.

l a t e r :
checked mine and pretty much as I remembered, bottom (square) lock is standard, top cam was the one altered, so when I clamp, it's to that sorta 4 o'clock position on bottom lever then a quick full close on the top one. I kinda like the extra effort it takes to get the bottom clamp 'just right'. It forces me to pay attention to getting the fence locked good and square each time.
And I just now remembered why I de-humped the top cam in the first place: that one was WAY harder to get locked than the bottom, to the (ridiculous) point that I was actually damaging my hands locking and unlocking it, and I mean bruises, sprains, pain, the works. No fun.

[keakap]

...Or is that a Postulate?

Let's not bring religion into this...