Blade alingment on a Table saw.

Ron Roase

Member
Messages
268
Location
Bloomington MN USA
Have a question that dose not seem to have an aswer,or at least none that makes any sence. OK I use my ajustable square from the mitter slot to a peticular tooth on the blade...wich I mark with a magic marker then slide it to the rear of the saw and ajust it till both front and back are the same (with in 1 or 2 thousands. As long as I leave the blade at a 90% setting I am OK.
But the moment I tilt the blade to 45% and make a few cuts and the return to 90% ...... now the front and back are not the same from the miter slot. I also have those Pal ajusters on it. It is a Delta Contractors Saw Also it is pretty old mabe 25 years or so. Other then that It is great. I just know that I must always re-check it and re-ajust it after cutting 45% miters. I am using a thin kurf blade and it appears to cut just fine in a rip or cross cut opperation but I feel resistance when cutting at 45% Any suggestions would be appreciated. Maybe I different blade should be used when cutting 45%
 
I have read about this, it's something peculiar to the contractors saw and the way everything hangs off the table. I can't remember the details but I bet if you align it, tilt you blade 45 and check it, it is no longer lined up. When you make a cut you out of line and probably forcing the top to move.

I don't remember the cure, but your not crazy.
 
I have an older contractors saw that is presently in "retirement" but I remember it going out of alignment and when I checked underneath I had found that the mounting bolts had worked themselves loose. Check to ensure that the table is mounted securely to the base and the same for the trunion to the table. When I finally figured it out some of the bolts had backed out considerably.

Also, I used to find that munge would build up at the positive stops and I would have to get in there and constantly clean them up so I could get it back to 90 degrees or to the full 45 degrees. Different problem I know but one I constantly battled with the saw mainly because I was using it to trim houses and it was all pine so resin build up was a nightmare.
 
It's a common problem with contractors saws, and the 80's ~ 90's Sears saws were probably the worst.

The problem is caused by the weight of the motor hangin out the back, off a (relatively speaking) flimsy bracket that's attached to the rear trunnion.

I doubt it can be eliminated, but it can be minimized by replacing the trunnion bolts with better quality (Grade 8) hardware, and perhaps using blue (NOT RED!) Loctite on them.

Better yet - make a sled for your angled cuts, and leave the blade at 90°.
 
If the problem had been that the alignment made with the blade square went out when the blade tilted, but came back when square, the problem would have been that the axis around which the carriage rotates to tilt the blade was not parallel with the top. That can be readjusted.

But if you tilt the blade and the alignment is changed when you square it up again, that means something is wrong with the mechanism. If you have an older Delta contractors saw like a 34-444, yours does not have a flimsy construction like some of the Craftsman saws. It should be very solid, and with proper setup it should be able to stay in adjustment.

What could go wrong? The carriage that holds the blade fits between two trunnions, riding in semicircular grooves. If these fit snugly, the carriage should tilt without shifting. But during the alignment process the trunnions can move apart from one another, leaving room for the carriage to shift. That could allow the movement you note.

The solution is to clamp the trunnion to the carriage during the alignment, to keep the carriage tightly in the trunnion grooves. If you can reach, clamps on both front and rear trunnions are helpful.

Usually the clamps are removed after the alignment, when the trunnions are securely bolted to the table. But if you find you can't get it to stay aligned after tilting, leaving a C clamp on a trunnion will keep you from accidentally tilting the blade, and might keep the saw more stably aligned.
 
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