I tried the SMT again

[sailor55330]

Black Walnut,

Good question, and yes, the base is still parallel after adjusting the SMT top correctly. I have even removed and reset the top while adjusting rails. It holds it's alignment even after being removed and re-measured with the dial gauge, so I don't think that's the issue.

I guess the eccentrics could be slipping while tightening, but if they are, wouldn't the alignment of the miter fence be "out" of alignment immediately if things were moving? After getting everything tightened down, the fence is still square until the SMT is moved. Depending on how far forward you slide the SMT, the variance out of square increases, as you bring the table back to the original position, the fence becomes square to the blade again.

I'm not the smartest or best woodworker, but I can follow these steps and by now, I think I thoroughly understand the steps, but I am at a loss. I'm sorry for continuing to clog the forums with the same issue.

I'm beginning to wonder if there is something with the SMT top (warped, milled incorrectly, etc)

[JR]

Ok, I see what's happening now. I definitely use a technique that is different from the one shown in the manual.

As I wrote above, I get the base and table set up to travel parallel to the blade. Then I set the fence to be perpendicular to the blade.

I've been wrong for a very long time now. It works for me.

JR

[sailor55330]

JR,

Right or wrong, it's an approach I hadn't thought of. The Ryobi method sure isn't panning out at this point.

[LCHIEN]

well clearly to me you want to at least set the miter fence perpendicular to the blade as the last step.
theoretically its all the same but practically its hard to argue with.

"in theory, there's no difference between theory and practice, but in practice, there is."

[chopnhack]

I have not toyed with mine nor have I used it, but is it possible that the eccentric is damaged and perhaps the lobe is rolling away as you slide the table past it?

[sailor55330]

Chopnhack,

A good thought, but I ordered and replaced all 4 eccentrics and replaced the nylon slides with new when I bought the saw. There was some slop when I got it. The new parts took care of that.

[crybdr]

I may have an answer for you - but I may be totally wrong! I'll defer to the verteran users of this saw for final opinions.

I've been following your troubles and went downstairs to photograph my setup. Depending upon what you are measuring - my saw might give you the same results. But mine cuts square and true.

You mention measuring the 'sled base' against the blade. I'm assuming that you mean the cast aluminum top with the ribs and angle markings? If this is so.....this could be the problem. The aluminum top is cast aluminum, with subsequent machining. None of the edges of the aluminum top have been squared to the drilled holes during manufacturing. As you can see from my photo below, the top of my SMT doesn't line up with the top of the saw - yet it yields square cuts. As a test, set your SMT fence to it's factory '0' setting (swing the little leg up as a stop) and put a big square against it - you will notice that the right side of the SMT aluminum casting is likely not square to the SMT fence - but this is not a problem. It's adjustments relative to a square sled rail that yield a square cut with this saw.

Here is a picture of the aluminum top of my square cutting SMT - butted up against the top casting of the saw. The front part of the aluminum casting is in touch with the top casting of the saw - the back part of the aluminum casting of the SMT is 1/8" away from the top casting of the saw.


Any measurements to determine SMT alignment to the saw blade need to be made from the extruded sled rail(black anodized on my saw). Once that is done, fence squareness relative to the SMT travel is adjusted. The SMT cast base will vary from saw to saw, mine is extreme.

If this isn't the case, I'm sorry that you've had so much trouble with the SMT. But, I'm glad to see you back here and continuing to do woodwork.

[PhilofKayDu]

SMT not parrallel.

I am by no means a master with my bt3k. But after I got my saw; I had a similar difficulty with my SMT. The last owner said to me he replaced the eccentric screws. That did not fix the problem. I to dismantled and reassembled mine many times. Here is my solution: I made new plastic glides that the eccentric part of that screw goes thru. Square shaped plastic washers (4), and (4) eccentric screws did the trick for me. And now I am building my own version of the SMT. To work in unison with theOEM SMT. Good luck. I hope this situation does not frustrate you into getting rid of your saw. I really like mine. Phil

[crybdr]

I've never had to use the recommended alignment exercise referred to here. I'll probably need to refer to it someday - it's a great resource.

There are two completely separate systems here that need to be aligned in order. Here is how I think about the alignment process....

First, you need to make sure the rail upon which the SMT slides is parallel to the blade. Here's an illustration of what I am talking about. Forget the SMT table for now, just focus on getting the rail parallel.

Once you are satisfied that the rail is parallel to the blade - it's time to align the SMT sled/fence to be perpendicular to the blade.

This adjustment needs to be measured from the fence face - not the aluminum casting to which it attaches. Use a BIG square and make sure that it's on fence face and the blade face and not resting on a tooth. That's a good starting point.....you may want to make small adjustments depending upon your results.

[crybdr]

Just to reiterate...the borders of the sled may make it look like it is out of alignment, but it's not - the most important thing is to use the eccentric screws to align the fence to be perpendicular to the blade. The fence alignment is key. The alignment of the sled borders don't matter at all.

This is of course after aligning the rail to the blade....

[sailor55330]

Cry,

First, thank you, your images are very helpful in defining what part is what.

For clarification, the black part of your diagram, which you are calling rail, is what I have have been referring to as the base of the SMT and it is aligned to within .0015" of parallel to the blade. While that may not be perfect, I do believe that that small of a tolerance is probably closer to parallel than many of the saws in use and it seem very unlikely that it would cause a variance of 1/16" over 12 inches.

With the fence fixed in place and clamped solid, I have been using the eccentrics as described in the manual (and discussed here) to bring the fence face into square with the blade. To your point, I have never used the edges of the SMT top as a reference for measurement or alignment, as I understand they are independent to the alignment of the miter fence face. Once the fence face is in alignment, I have made certain that everything is tightened accordingly, with no side-to-side slop in the SMT top that could affect alignment. At this point, I am able to verify that the miter fence face is square to the blade, BUT once the SMT is pushed forward (in the direction of the red arrow in your diagram), I can watch the miter fence face alignment change as I hold a sqaure to the blade and fence.

It seems to me that if the SMT rail is aligned, and the SMT top does not have any side-to-side movement, then it wouldn't matter if the SMT is on a 45, 28, or 86 degree angle, assuming the miter fence face is square to the blade. I'm confident that the SMT rail is aligned very close to perfect and the slides/eccentrics are all new and adjusted to eliminate side to side play, so where is the movement coming from. The only thing I have left to think of is if the part of the SMT rail or SMT top is warped or milled incorrectly.

Not trying to be a complainer, but I am truly stumped. The alignment process just shouldn't be this difficult.

[pecker]

I have read through this, but don't remember seeing any mention of the locking clamps, which hold the SMT to the rails, being adjusted. This is how you get the smt to slide on a parallel path to the blade.

The fence adjustments are all done afterward.

[Stytooner]

It does matter. The SMT top needs to run parallel to the blade.

This I think is where you are having the trouble.

It's a three step alignment. The base or black track first. Then the SMT itself.
Lastly then the SM fence.

Your track is probably good enough. I didn't use a dial indicator on mine. Just a large quilting block square. The SMT top actually needs to be trued up to the blade as well because it holds the fence in relation to the blade. This is why it has eccentric screws to bring it in alignment with the blade. It may still appear crooked as in the image above, but that is because the blade isn't aligned to the table top, but everything else is aligned to the blade.

You get the SMT running parallel to the blade and you will have no issues aligning the fence part to 90 degrees.
Remember also that the markings on the SMT are pretty thick, so they are more of a guide for the fence rather than an absolute. They will get you close, but the stop should be tuned last. Should give you a perfect unvarying 90 degrees to the blade through the full travel.

[sailor55330]

Pecker,

I'm not following what you are saying. Based on what i think understand, the locking clamps are used to hold the SMT assembly in place. There are adjustment screws on the SMT base that are used for aligning the entire SMT assembly. I have never seen or heard or read of any steps or method to use the actual locking clamps as part of the adjustment for the SMT.

Can you please elaborate?

[LarryG]

One elementary step that I didn't see mentioned, although I may well have missed it:

Did you check your drafting triangle for squareness? Most people assume these things are dead-nuts accurate, and broadly speaking they do tend to be much better than the average carpenter's square -- but the problem with "broadly speaking" is that it may not apply to your particular triangle. I spent 20-odd years on the drafting boards before CAD came along, and I've seen more than a few drafting triangles that weren't even close to being square.

So: have you checked yours?