I tried the SMT again

[sailor55330]

Hello,

I was building a bench and found a need to "trim some 12.5x12.5 in panels by about 1/8th of an inch, so I decided to try the SMT again, which has plagued me in the past. I found that again, my cuts were off by about 1/16-1/8" over the 12" panel.

I decided to try again to align the SMT, but this time, I had my neighbor join me just to verify I wasn't losing my mind--he's a smart guy and has done some carpentry and basement finishing, so he's not a stranger to tools by any means.

I check the SMT sled base against the blade and we both agree that according to my dial gauge, there is .0015" variance. That's 1/2 the thickness of a piece of paper for reference--should be well within normal tolerances. Then, we set the fence at 90 degrees to the SMT top. Next, we checked the fence and found it was out every so slightly, so we aligned the SMT using the eccentrics and a plastic drafting square. All good and tightened things up and re-checked.

We both made test cuts. Neither of us could get a square cut after about 1.5 hours of trying, adjusting, and using different hold techniques.

I am now officially delerious and completely over the whole saw.

[JR]

Sailor, I commend you for diving in again!

After aligning the SMT have tried adjusting the fence to the blade rather than the SMT top? That's the way I do it.

JR

[Bill in Buena Park]

...After aligning the SMT have tried adjusting the fence to the blade rather than the SMT top? That's the way I do it.
JR

Same for me. Probably not the prescribed method, but I:

1) Mount and lock the SMT on the rails
2) Using framing square, set the fence square to the blade (against the teeth, not the plate)
3) Move the SMT forward, and watch for any gap that opens, or if the square starts to bind against the teeth; if so, I loosen the locks on the front OR back rail, move that part of the base in or out to compensate for the alignment issue, then re-lock to the rail; follow this with step 2) above, and repeat until there's no gapping or binding.

This usually takes no more than a couple minutes to dial in and start cutting.

[Uncle Cracker]

That's why I retired my SMT (that, and I got tired of it jabbing me in the hip... ). Put on miter slots and got an Incra miter gauge, and the old BT was reborn. I'll have it forever, even after I bring in a new Uni someday when business picks up again...

[Dutchman46]

Have You checked the blade to see if it is aligned correctly? It might be that the table is off a small bit. Mine is rite on the money. I couldn't be happier with the sliding miter table. Mine is 10 years old, and needed to make an adjustment, and that is it. I will agree that the miter hanging off the table is hard on the body, but it is just a small price to pay.

[RAFlorida]

I, like the others, retired the smt.

By squaring the fence to the blade, I always come out with good cuts.

[Stytooner]

I am glad that I never had any trouble with mine. Either of them. 3000 and then a 3100.

First, I would align the lower track so that it was parallel to the blade. If that is out, no amount of fiddling will get the rest right.

Then I aligned the top with the eccentrics.

Lastly align and calibrate the fence and stop on the SMT.

I often install and remove my SMT and it always goes back aligned perfectly.

I will say that chances are if you ever get it right, you won't ever have to mess with it again.

[sailor55330]

Again, thanks for the encouragement.

I double checked again this morning with a dial indicator and plans for a jig to check the SMT base that I found on here. It is less than 2/1000's from being perfectly aligned, which I think is pretty close.

When I check the fence against the blade, I put the fence in what I would call the "starting postition", or pulled back as if you were preparing to make a cut. The miter fence is square at that point. I then slowly moved the SMT top forward, with the drafting triangle held firmly against the blade between the teeth. By the time I get the SMT about 1/3-1/2 of the way towards the back, as if I was making a cut, I can actually see a gap of roughly 1/16th of an inch develop between the square and the SMT fence.

The gap develops on the side of the SMT fence closest to the blade. If I start with the SMT in the middle of the sled base, and adjust the SMT to 90, when I move the SMT to the front of the saw, the gap develops again, but this time on the outboard side of the saw. I don't knwo what I could be missing. I have done the alignment procedure so many times that I can nearly quote it.

It really seems that the issue is in the alignment of the SMT top and not the sled base since I get repeatable results when I measure the sled base, but I can't get it to align--it almost seems like the eccentrics don't allow enough travel to bring the top back into alignment, yet I replaced them when I got the saw.

I really don't understand. At least I guess I can take some comfort in the fact that others have stuggled with this particular saw.

[Uncle Cracker]

At least I guess I can take some comfort in the fact that others have stuggled with this particular saw.

More the SMT, rather than the rest of the saw... I believe that every SMT has its own personality...

[yamato72]

Ditto regarding aligning to the blade. On my BT, the saw table isn't square to anything, there is an 1/8" difference front-to-back when the BT table is butted against my new saw table (which is square).

Align the rip fence and SMT to the blade and ignore any temptation to line anything up with any edge of the saw table....

[sailor55330]

To date, I have only aligned to the blade, never to any other part of the saw.

[JR]

To date, I have only aligned to the blade, never to any other part of the saw.

Well then maybe I've misunderstood more than one thing you wrote.

You wrote that you checked "the SMT sled base against the blade..." I took this to mean that you had a dial guage afixed to the sliding miter TABLE (not the base, but the TABLE). The tip of the dial guage is on the side of the blade and when you move the table to the rear, the dial guage indicated "there is .0015" variance". Is this correct?

You wrote "Then, we set the fence at 90 degrees to the SMT top", but based on your latest post I should read this as your having set the fence to 90 degrees to the blade. Is this correct?

You then wrote "Next, we checked the fence and found it was out every so slightly, so we aligned the SMT using the eccentrics and a plastic drafting square." This seems out of sequence to me. You should adjust the eccentrics in order to get the table to have no variance when doing the measurement with the dial guage (your .0015" is an excellent result for this test). After that is done is when you need to set the fence at 90 degrees to the blade.

JR

[sailor55330]

JR, my apologies for not being clear, it was late and I was frustrated.

1. I checked the alignement of the base of the SMT assemby with respect to a marked spot on the blade (blade was rotated front and back to check 2 points). A dial gauge was used, with the metal tip of the dial gauge pushing against the blade and a fixed jig to hold steady against the SMT base sled (the pan underneat the SMT table top). The variance between the 2 measured points was .0015 and it was repeatable.

2. The SMT fence was set to 90 degrees as per the indicated marks on the top of the SMT table and clamped in place and reconfirmed.

3. The SMT fence was then checked against the blade with a triangle drafting square and found to be approximately 1/16 of an inch out of alignment when the SMT top is pushed to the front of the saw.

4. Using the eccentrics as described in the manual, the rear two nuts were loosed slightly and the eccentrics were adjusted to allow maximum play in the table top, which was then pushed towards the blade and held in place with sufficient pressure.

5. The miter fence was then brought into "square" with the blade by adjusting the eccentric as described in the manual. Once alignment was acheived, the top locking nut was tightened on the appropriate side and the opposite eccentric was used to remove any side-to side play. Once accomplished, the remaining top locking nut was tightened.

6. Alignment of the miter fence in relation to the blade was again checked and found to be at 90 degrees.

Upon moving the table as if excuting a cut, the miter fence would again become out of square with the blade. If the miter fence was moved back into the original position, the alignment would return.

All fasteners have been checked and found tight and secure, rails cleaned, no sawdust or foreign debris. The SMT is not moving square to the blade despite having verified all of the measurements with repeatable results.

JR, in my manual, it clearly states that the miter fence is set at "zero" using the red tab with relation to the markings on the table top and then securing it in place and the next step is to use the eccentrics to bring the whole SMT top into alignment. At no time does it ever mention actually adjusting the miter fence to the blade independently of the SMT top. It clearly states,

1. Adjust the miter fence to "0" on the SMT top

2. Ajust the right rear eccetnric screw from the lower side fo the miter table so that max paly exists between the slide and miter base

3. Use a square against the blade and use the left rear eccentric to to adjust until the miter fence and blade are square, and then tighten.



Is that not correct? It sounds like you are saying to:

set the smt base to parallel ( I am at .0015)

Set the table top to parallel using the same type of measurement/method

Square the fence to the blade.

That process is not in my manual. My manual references adjusting the SMT base pan and then adjusting the entire top to align the miter fence to the blade.



If I have been following the wrong sequence because of a misprint in the manual, I am going to scream

[jking]

It sounds to me like for whatever reason, after you've adjusted the SMT to square to the blade, it is slipping back out of square. I do know the eccentrics can be a bit tricky to tighten without moving. It sounds like you've done this enough times you'd have noticed if that was happening.

I feel bad for you. I only had to make minor adjustments to my SMT & it's been fine. When I've had out of square cuts, it's been because of material not being held in place tightly during cuts.

[Black wallnut]

Sailor, you have the correct order. After adjusting the top is you base still parallel per the checks in the manual? The next step may be to ensure your base has straight and parallel edges by removing the top.