Table Saw - not 90 degrees after lowering blade

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Semmons23

New User
Steve
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. 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?
 

Semmons23

New User
Steve
I can not feel any movement in the arbor. If its a loose trunnion it won't be any fun to fix it - half the saw would have to come apart from what I can see.
 
M

McRabbet

I know these are some basics, but they are worth checking: 1) With the blade all the way up, is it at 90 degrees to the table top (use a precision square against the plate of the blade and do not touch any teeth; repeat the other side of the blade)? and 2) is your tilt mechanism all the way against the stop and set to zero (if it is not clamped down at Zero, it could have moved a little). I'm suspecting the tilt mechanism is not at Zero degrees.
 

Glennbear

Moderator
Glenn
I had a similar problem with a saw I previously had. The problem turned out to be accumulated sawdust/gunk on the blade lowering mechanical parts. :wsmile:
 

Semmons23

New User
Steve
Its a Jet Xacta Deluxe - 3HP, Left Tilt. I have recently used my Wixey magnetic angle finder to set the 0 and 45 degree stops. I'm at 90 - at least within the tolerances of the wixey but it also checks out with a square but I don't think that really has anything to do with it. I did also check that the tilt lock was completly locked and it is. 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.

I've uploaded a video to youtube to display what is happening. Could be what glennbear suggests. I'll try cleaning everything up and seeing if that helps.

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

McRabbet

Were you certain that the ZCI was firmly down and both parallel and flush to the table when you cut the slot? In your video, it appears that the edge of the ZCI is raised a wee bit and that could cause the subtle error you are seeing (or feeling). IMHO, A little dust on one of the tabs when you cur the slot versus no dust now (or vice versa) would cause what you are seeing.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
It is only the blade tips rubbing right?

I don't think it is anything to worry about and suspect it is nothing more than an uneven, not fully run in ZCI slot. Use it for awhile, making sure you make cuts with the blade at all heights- the rubbing will go away. ALL my ZCI's make a little rubbing noise when new until they are sufficiently run in, just the nature of the beast.
 

cptully

New User
Chris
I'll have to agree with Alan. All of my ZCI's are home made from hardboard and shims to get them level with the table. I made them by fitting the hard board into the table with no blade installed. Then took it out, installed the blade, lowered it as far as it would go, turned the saw on and CAREFULLY put the ZCI back in place,making an initial scoring cut as I did so. Finally I raised the blade to the needed height. If I use a different height the next time, I get some rubbing. The ZCI's I have were made for 37.5 and 45 deg cuts so there may also be an element of angular mis-alignment involved here since I have to reset the saw to the angle the ZCI was cut at...
 

Woodman2k

Greg Bender
Corporate Member
The other thing to look for is if you cut your zci with a new/clean blade and it now has picked up some pitch it will catch the side of the slot and ring the teeth.My grizz rings a little as it spins down with my thin kerf blade but does not do anything with the full ferf blades and they are 12" blades. I don't think you have a problem to be concerned with.
Greg
 

Alan in Little Washington

Alan Schaffter
Corporate Member
I'm a bit confused. What are you trying to measure with the dial indicator? You can't use it on the blade disk because typically it is not flat (and doesn't need to be). The disk should be the same thickness at any given radius, as measured when you rotate the blade, but it will change if you raise and lower the blade and measure at different radii- blades are often thicker near the arbor hole and thinner near the tips. Measuring at a carbide tip is the only way to do it.

But, the distance between the miter slot and a carbide tip will always be the same regardless of blade height or amount of rotation if the blade is perfectly parallel to the miter slot or the gauge is kept in the same spot in the slot, and ONLY if there is no tilt- the blade must be perfectly perpendicular to the table. If it is not, the distance will change- due to the design and operation of the typical TS trunnion assembly, the blade swings an arc as it is tilted, but raises and lowers in the plane of the blade. If it didn't the blade would hit the table when raised and lowered.
 

Semmons23

New User
Steve
What I'm trying to show is that the blade is not raising and lowering in the plane of the blade. It raises fine but when I lower it the plane changes. Since the plane is changing it is rubbing on the zero clearance insert.

I not sure how to explain this or measure it properly. Any suggestions would be great.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
What I'm trying to show is that the blade is not raising and lowering in the plane of the blade. It raises fine but when I lower it the plane changes. Since the plane is changing it is rubbing on the zero clearance insert.

I'm not sure how to explain this or measure it properly. Any suggestions would be great.

You can't measure that against the blade disk with a dial indicator like it looks like you are trying to do- blade disks are rarely flat. The only way I can think of doing that is with a reference master plate available at Rockler and other WW retailers.

24180-01-500.jpg


Also, I can't imagine how this can be problem in only one direction. If it is not following the direction of tilt, it has to be following some other angle- and should always increase as the blade goes one way and the decrease as the blade goes the opposite way. Otherwise, the tilt would continue to change. There could be runout that you are just not noticing when the blade is at one extreme. Again, I think there is no problem and you are just seeing a characteristic of a new ZCI. I don't know, but suspect .001" is probably well within spec for arbor flange runout.
 

Cato

New User
Bob
I have had rubbing when installing a new ZCI and it went away with use.

I have heard of people excessively tightening their arbor nut and creating issues, when it just needs to be lightly snugged and not cranked supertight.

Do your cuts suffer any at the different blade heights?
 

Semmons23

New User
Steve
I would think that if I raise the blade and it moves a certain amount - lets assume it gradually moves from 0 to .005 - .001 per 1/8". When I lower the blade it should follow the exact same path and the indicator should move back to the original location at zero moving .001" per 1/8" down since that's what is did on the way up. This to me would indicate the blade is not flat or its flat but I'm not at 90 degrees to the table. This is not what happens - it jumps out of alignment within the first 1/8" or back into alignment depending on the direction its travelling and stays there throughout the test.

I have tested runout at the tooth on my WoodWorker II. After raising the blade, taking a measurement on the tooth, sliding the indicator to the back and rotating the same tooth back I get less that .001". I repeat the test by lowing the blade first and its .008" The further out to the edge you take the measurement the larger its out. I should say, the further down the miter slot or away from the arbor...Not that I'd trust it but the factory (before shipping) claimed the runout was .0003". I really don't think I have runout in the blade or the arbor (certainly not when I raise the blade first).

I cleaned all the gunk out of all the gears and it didn't change anything.
 
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Howard Acheson

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

That is a rule my grandfather taught me 50 years ago. When raising the blade, gravity takes the little bit of "play" or lash out of the gearing and allows more accurate cuts.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
I would think that if I raise the blade and it moves a certain amount - lets assume it gradually moves from 0 to .005 - .001 per 1/8". When I lower the blade it should follow the exact same path and the indicator should move back to the original location at zero moving .001" per 1/8" down since that's what is did on the way up. This to me would indicate the blade is not flat or its flat but I'm not at 90 degrees to the table.

Concur. That is what I described.

This is not what happens - it jumps out of alignment within the first 1/8" or back into alignment depending on the direction its traveling and stays there throughout the test.
How is your dial indicator? Any backlash or friction? Do you get the same results with a different one?

Have you checked the arbor/flange for flatness and run-out? Are you always measuring using the same tooth? With an ATB blade like a WWII, the teeth are canted, alternating left-right. Did you make sure the blade is not warped in any way and that all the same-side teeth track in the same plane? Run it up all the way and check every other tooth, then do the same thing with the blade almost buried.

I have tested runout at the tooth on my WoodWorker II. After raising the blade, taking a measurement on the tooth, sliding the indicator to the back and rotating the same tooth back I get less that .001". I repeat the test by lowing the blade first and its .008" The further out to the edge you take the measurement the larger its out.
You mean you get less than .001" difference measuring from the miter slot to same tip when the blade is rotated with the tip to the front of the table and then the back of the table with the blade full up, but .008" when you run the blade down then back up again? How do you get it back to the .001"? I am still not following. Something must be moving - the whole trunnion or the arbor is moving axially.

If it always changed by the same amount every time you ran it up and down it would mean there is some sort of twist in the whole mechanism- the plane of the blade actually rotating on its axis as it raises and lowers- it is twisting ever so slightly as it goes up and down- that could theoretically happen at all tilt angles. I can't visualize how that would happen without looking closely at the trunnion assembly.

Have you closely inspected the entire trunnion assembly including pinions and rack? Is there any play anywhere? Is the trunnion firmly attached to the cabinet? Is the cabinet warped? Any loose bolts or cracks anywhere? I can't say but it may be possible for something like that to happen if there is a problem with either the front or rear trunnion/mounts.

Then again it could be just a combination of the blade and miter slot not being parallel, and moving the dial indicator along the slot to line it up with the tooth as less of the blade is exposed. Remember, this a 3 axis situation and a problem in one direction can affect both of the others.

My recommendation- start from scratch:

1. Clean all parts, and make sure they operate smoothly.
2. Visually inspect the trunnion, racks, pinions, keepers, followers, cabinet, arbor, etc. for any obvious backlash or irregularities in shape or movement.
3. Inspect and verify your dial indicator is working properly.
4. Check the arbor for run-out and the arbor flange for flatness/run-out
5. Loosen the CI top attachment bolts and do a careful realignment of the blade - miter slot. Making sure they are perfectly parallel using a gauge plate, not a blade.

Then check to see if you get the same results. If you do, ask for a new saw.
 
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