Table Saw Setup Issue

[Steve Emmons]

I have a 4 month old Jet Xacta Deluxe 3HP, Left Tilt cabinet saw. I had noticed some vibrations (by sound more than anything) after I installed my zero clearance insert. It sounded like the blade was rubbing on the insert but it only happened some of the time. I've realized today that when I raise the blade and spin it by hand (unplugged of course) the blade moves freely and doesn't touch the insert. However, if I lower the blade even a slight amount and try to spin the blade it will rub on the insert. I then raise it just a bit and the rubbing stops. Doesn't seem to matter what height or if I lock the mechanism down or not. This is happening with all my blades (FWWII, Oshlun 80 tooth and Delta Dado) - all rub on the left side. I tried checking it with my Wixey angle finder but its not sensitive enough. It only moving like .001 or so (no feeler gauges so thats a guess) but its enough for the rubbing to occur. Seems to be 100% repeatable.

Is this normal or is there something I need to adjust? Should I just always plan on setting my final blade height via raising the blade and never lowering?

Thanks

Steve

[michael case]

The blade should sty on the same plane when raised or lowered. On the assumption the insert is not moving, then I would say that you saw is changing alignment when you raise or lower it. You may want to use a more controlled method to test the alignment and see whats trully going on and how much. What does you owners manual say?

[Tom Hintz]

If I remember right that saw has a separate top that you move to get the blade parallel with the miter slots. (I am getting another saw similar to that next week for my shop) If that is the case you can just nudge the top over a tad to give the blade a little clearance. Maybe the top got bumped or jolted somehow to move it just a little. If that top is movable (a bolt under all four corners) you can fix this easily and make sure that the blade is perfect with the miter slot all in one operation.

[Howard Acheson]

It is not unusual for that to happen. When the blade is fully raised the mechanism is against a stop. This will ever so slightly move the plane of the blade. When you lower the blade is no longer has this pressure.

As your ZCI wears, you will find that it will not longer happen. But, many newly made ZCI will make a noise due to the close proximity of the blade teeth and air movement.

[Steve Emmons]

Tom you are correct that this saw does have 4 bolts to rotate the top but that really isn't the problem - at least I can't see how it would be. As long as I raise the blade and lock it down everything is square. If I lower the blade and lock it down, its no longer square. I can't really tell if its not square to the miter slot or the blade is tilting because I can't measure it accurately enough. I have some measuring devices on order so maybe they'll help. This youtube video should demostrate the issue.

http://www.youtube.com/watch?v=WYvjqe4qRmk

[Steve Emmons]

I was able to get my dial indicator attached securely to perform a bit more scientific test and its indicating that its moving .007" in the front and .002" in the back. I've uploaded 2 more videos to show this. I'll call Jet and see what they say but I may just have to train myself to always set the depth of cut while raising the blade, never lowering it.

Tom - if you have time to look at this when you get your new saw that would be great.

http://www.youtube.com/watch?v=_EHKU1DTSKk

http://www.youtube.com/watch?v=f5liGjKMINs

[glenn bradley]

I would contact Jet to see if that issue is within their tolerances. If not, they will probably assist you through correcting what seems like a backlash control issue. The saw probably has an adjustment for the worm gear to take out slop if (and that's an "if") that is causing the behavior; my zipcode saw does. A workaround certainly seems to be always raising the blade to final height but, on a new saw in that price range I would pursue it as a warranty design or workmanship issue if possible.

[Steve Emmons]

I contacted jet today and they told me how to take the slop out but they didn't think that was the problem they think it's either a loose trunnion bolt or a cracked trunnion. Hours of work ahead just hope it's not a waste if time and if it's a cracked trunnion it's going to probably be a huge effort to fix. Let's hope it's the slop!

[Steve Emmons]

Well I haven't taken the top off because I've been able to get to a bunch of bolts, and a lot were loose including at least 3 of the trunnion bolts and 1 of the motor mounts so I've tightened them all up but nothings has changed. I also ran these tests without the belt attched in case it was too tight but it didn't change the results.

I did get my magnetic dial indicator mount so I mounted to the bottom of the cabinet and put the dial indicator under the shaft (part number 144 - http://www.ereplacementparts.com/jet...759_33056.html). I mounted it on both ends and it really doesn't move - .001 - .002 at the most. but when I mount it just in front of part 146, the worm gear, and lower the blade, the shaft raises .007 which is the amount that I see the blade moving. Its not out of round it just raises .007 and stays there no matter how much I lower the blade. If I then raise the blade, it goes back to zero and stays there no matter how high I raise the blade.

Any thoughts ???

Thanks!

Steve

[Tony Bilello]

Is is possible that the blade is not 90* to the table or more likely the insert?

[Jay Allen]

I may just have to train myself to always set the depth of cut while raising the blade, never lowering it.

That is generally good practice anyway. I was taught that in a machine shop class many years ago and I still apply it to any kind of mechanism where rotary motion is converted to linear. It "pushes" any "slop" out of the moving parts.

[glenn bradley]

Since you see the actual shaft part moving, I again would want Jet's comments on it. You have more than done your due diligence. Their tech guys would be able to tell you if you have an issue or if that is just the way it is. That way you are not trying to "fix" something that is within design paramenters (I hope that amount of slop is not). If it is the result of wear or a poor fit, they will (should) be better equipped to point you to the problem cause.

[Steve Emmons]

Well the new saw showed up today along with a twin. For some reason they sent me two. They'd probably never know but I'll send it back. Anyway, its put together, tuned up and NOT exhibiting the same problem as the other one so I'm happy. Everything rides up and down with very little deviance - I'd call it .0015". Thats certainly better than .010"!

Old one is boxed up and ready to go - along with its twin!

Steve

[David Nelson1]

Steve,
So I take it you never did find the problem?

[Myk Rian]

Maybe the top got bumped or jolted somehow to move it just a little.

It is not unusual for that to happen. When the blade is fully raised the mechanism is against a stop.

Neither of these are valid reasons. The blade should not move to the side, for any reason.
I'm thinking the arbor bearings are the cause.