TS Blade Alignment

[Jeff Cord]

I just finished a jig that allows me to use my dial caliper to measure blade and fence alignment.
I found that my the back of my blade is about .008" closer to the mitre slot (left hand slot) than the front of the blade.
I did use the same tooth when measuring.
Is this too far out of alignment? Or is this OK?
If not what should I try to get?
thanks,
Jeff

[Mark Rios]

I think that tolerance is about right for the fence, according to what the good folks around here recommend, but the blade-to-miter slot should be exact for accurate mitering and sledding. There was a recent thread dealing with this and the folks who really know were helping someone with set-up.

[Jim Becker]

The blade should be as close to parallel to the miter slot as possible--dead on is best. In the case of the fence, many folks prefer it to be slightly farther from the back of the blade from the front to avoid pinching, but that deviation doesn't need to be very much at all. I generally try for under .004 on the blade...I think the last time I got it to .002, but it was some time ago and I don't measure and/or adjust my cabinet saw all that often.

[Jeff Cord]

This particular measurement is the blade.
I also measured my fence and, although it isn't perfectly straight (It's a General fence and as I run the caliper the length of the fence the measurement moves +- a couple of thou) but the back end of the fence is about .003 further away from the blade than the front of the fence. This sounds OK.
It's really the blade to mitre slot that I'm curious about.
Jeff

[Michael Ballent]

I try to get the blade dead on to .001 at most. The difference between the front of the fence and the back should be .000-.005 with the back of the fence toed out. Also remember that the blade is 10" diameter (so the .001 is more twist ) verses the fence which is probably in the 24+ in range... HTH

[Jeff Cord]

I just started trying to adjust this.
My saw (GI 50-220) has 6 bolts (it appears, the manual is really no help) but there seems to be little wiggle room with the trunions. I was expecting that they sould move some small distance and, once I was happy, I could then tighten.
There doesn't appear to be any wiggle room and it is more like I need to give it a whack (indirect whack that is, I have a board that I put against them) in order to get them to move.
Is this typical?
btw: I now have it to about .002 out and it seems like even if I had it at 0 when I tighten it moves a bit.

[Michael Ballent]

I just started trying to adjust this.
My saw (GI 50-220) has 6 bolts (it appears, the manual is really no help) but there seems to be little wiggle room with the trunions. I was expecting that they sould move some small distance and, once I was happy, I could then tighten.
There doesn't appear to be any wiggle room and it is more like I need to give it a whack (indirect whack that is, I have a board that I put against them) in order to get them to move.
Is this typical?
btw: I now have it to about .002 out and it seems like even if I had it at 0 when I tighten it moves a bit.

I think that your TS is a cabinet saw... if so your loosen the bolts of the table and align the table to the blade... never touch the bolts on the trunion. You only touch the trunion bolts on contractor saws since they hang off the table.

[Frank Chaffee]

I just finished ripping some 2 1/2" strips off of some wide 8' long 3/4" thick cedar. By the time the rip neared the end of the board, the gap at the other end between the narrow ripped board and the wider remainder ranged from 4" to 6", so I am assuming that there was a lot of stress in that board that was released when I did the rip cut. Jay
This sounds like 5° give or take to me.
If we assume that the strip Jay cut was curled, then the angular opening in the twelve inches beyond the blade to the end a tablesaw fence may have been only 1/10th of that, or 1/5th°. 1/5th°over 12” is about .040”, or slightly more than the 1/32nd inch that Mark Singer recommends opening the table saw fence.

Come to think of it, Mr. Singer recommended that opening along the full length of the mitre slots, so the relief he suggests is actually less than required for Jay Knoll’s rips. Well for wood, we are in the ballpark here.

So my next question is, if ripping wood sometimes?, ofttimes?, relieves stress’ that cause it to spread open, then why are table saw fences not split to accept this?

I keep asking this question because I got hurt once and don’t ever want to go there again. Research, research, research.

Frank

[Stu Ablett in Tokyo Japan]

From what you said, it is not clear, but you are checking the same tooth on the blade front and back, correct?

You are marking a tooth and then checking at the front of the blade and the back of the blade using the same tooth as a reference, yes?

Just checking.

Sure sounds like you have that pretty much dead on, my De Walt BT 744 saw would be on a good day if I could get it that close!

Good luck!

[Michael Ballent]

So my next question is, if ripping wood sometimes?, ofttimes?, relieves stress’ that cause it to spread open, then why are table saw fences not split to accept this?

I keep asking this question because I got hurt once and don’t ever want to go there again. Research, research, research.

Frank

Quesions are good, and keep'em coming. :D It can probably clear up some things for the folks (lurkers) that do not post.

Ripping wood can relieve stress in the wood. I have ripped wood and the kerf behind the wood started to close up, and I have seen it open up as well. To best answer your question... as you rip something ply, MDF, wood, plastic etc. you should be applying pressure as you cut against the fence, so as you rip the wood, presumably the edge that is against the fence should remain in line throughout the cut, but that will not prevent anything else from moving as potential stress is relieved. My tablesaw (a SawStop) happens to have a riving knife that hugs the blade, regardless of what the height of the blade. The euro machines have them as well. The reason I bring this up is because if you are using neither a riving knife, nor a splitter you are really increasing the chances of getting kickback. If there is a really long rip then you can see the wood start to move toward the back of the blade and if you are not applying pressure toward the fence and there is no splitter/riving knife, the wood can catch the back of the blade and launch the wood back at you.

By moving the back of the fence a little (.002 or so and that's my story and I am sticking to it) toed out, it gives you a little bit of wiggle room. The last thing you will want to do is have the fence toed inward, which WILL pinch the wood as it's exiting the back of the blade. :eek:

Now my order of preference as far as safety to minimize kickback...

(Blade should be as close to parallel as possible IMO)

1. Blade guard
2. Riving knive
3. Some flavor of splitter
4. Fence towed out

If you have any more questions I or other will be happy to share :D

[scott spencer]

I think that your TS is a cabinet saw... if so your loosen the bolts of the table and align the table to the blade... never touch the bolts on the trunion. You only touch the trunion bolts on contractor saws since they hang off the table. Michael - The 50-220 is GI's fairly new hybrid that uses the table mounted trunnions...similar to the old Emerson, Ridgid, and DW setups that have the cast dust shroud connecting the front to rear...thus the 6 bolts vs. 4. The technique to loosen the trunnions and nudge them into position is correct, although often not that easy. Not sure if they make a set of PALS to fit this, but it might be a good application for them.

The trick to getting the setup to stay while tightening the bolts is to not tighten each bolt all the way in one try...snug one, snug the next, and work your way around....then tighten them after they've all been snugged after checking that the alignment is still on. Sometimes better quality bolts and washers can help this process. 0.002" should be fine, especially if it's not a causing any pinching at the fence.

Good luck.

[lou sansone]

call me wood butcher, but 0.002 toe out is too close for comfort IMHO. What is the big deal with puting it more like 0.010"?

lou

[Jeff Cord]

Scott, your description is exactly correct.
The "attachment" between the bolts and the table are pretty tight and as I tighten individual bolts I re-measure (yes, I am measuring the same tooth front and back) and I can see that as I tighen the bolts it starts to move away from 0.
It's at about .002 so it sounds like that's close enough.

[Roger Everett]

Jeff:
What works best for me is to develop a step by step aproach to tuneing up the TS. I also use a dial indicator.
1- w/ d-i check for run-out at blade shaft flange, should be right on. any variation is multiplied by 1/2 dia. of blade.
2- install blade and check for run out as close to outter edge as possible, if off by much, mark and rotate blade 180* on shaft.
3- mark 1 tooth and check w/di at front, then rotate blade to check at rear, as you did w/ di on jig running in miter slot. Generaly if a contactors saw the trunion is bolted to top, loosen bolts( generally 4 ) adjust, if cabinet saw, trunion is bolted to cabinet, so you loosen and move top. Develop a torque sequence ,as in tighten bolts 1-3-4-2 a little at a time to keep adjustment from moving as much as pos.. At this time blade should be as close to 0 as pos. to slot.
4- Then adjust fence to either blade or slot. If you got everthing right on so far,adjusting to slot is easier to get fence either to 0* or 2-3000ths toe out, depending on which line of thought you follow.

P.S. don't forget that if even if your fence was right on, after adjusting blade to slot, it changed and needs to be adjusted. It's also a good idea, to do any lubing of trunion and rack and pinion adjusters first as part of tuning up TS.
Roger