SMT Alignment: Clarification needed

[mdutch]

And I quote from the Book of Kirby:

Leave all four plastic rail grips locked down. Slide the table to the rear of the saw. At the front of the base, locate two screws. Do not loosen the screws on the rail grips.

Of the two screws located at the front of the base, loosen the left one only.

Note: When loosening the screws, only loosen them a little or the sliding table will rub on them or not be able to pass at all. The base will eventually pivot on the rightmost screw.

If I leave the rear plastic grips locked down the SMT won't move even with 3 out of 4 screws loosened. Seems the front and rear table-mounting brackets are sandwiched tightly between the two rail clamp brackets, so there's not any significant lateral play. I have to release the rear clamps to make the adjustment. Is this considered okay? Or am I not understanding the method properly?

[scoly]

Would guess you are missunderstanding. The locking mech at the front and rear only lock the smt side to side movement along the rails. Smt is then able to move forward and back and should be adjusted to run parallel with the blade. This is the adj you are trying to make. It is possible to have the adjusting screws so tight that it will not let the smt slide. Loosening should correct this. Go here and follow step by step.
http://www.bt3central.com/articles/files/smtalign.pdf
If you have more trouble look at this
http://www.bt3central.com/articles/f...32_r_sheet.pdf
The second illustration is the smt. It shows the screws you need to be adjusting. They are part nos. 25-28.
Be sure to make all adj in order. Each adj has an effect on other adj.
GMack5 gives a very good tutorial here
http://www.bt3central.com/showthread...ght=adjustment
hth. If not come back with specific questions.
Steve

[mdutch]

Okay Steve, I appreciate the feedback... but.

I believe I was QUOTING and working step-by-step from the Rod Kirby document you refered me to. To be more specific, I'll refer to part numbers listed in the manual's Figure B. Sliding Miter Table Assembly:

First, I'm trying to make the miter base (14) parallel to the blade, not the sliding miter table top (1). I do understand that the miter locking clamps (30) are to prohibit side-to-side movement. But I think they are part of my problem...

If you're adjusting the miter base (14) to be parallel with the blade by loosening three of the four screws (17), the base HAS to move left or right at the top to make an adjustment, and pivot on the lower right screw. My base is wedged very firmly between the two holder plates (16) of the miter locking clamp assemblies, there's no way for the base to move laterally left or right, toward or away from the blade, to make it parallel. Only when I release the top two miter locking clamps (30) can I get the base to move toward or away from the blade.

I'm concerned, because it says NOT to release the top clamps. SHOULD my miter base (14) have L/R play between the two miter locking clamp holder plates (16) when the screws (17) are released? Because it doesn't.

FYI, I even tried loosening the last (lower right) screw a tiny bit to see if the base was prevented from pivoting moving. It had no effect.

Bottom line, when I loosened the top two clamps and moved the base over toward the blade and re-tightened the clamps and screws, I was able to get the base within 1/64 parallel over the length of the top table's travel. It's "aligned". So should I shut up because it's aligned?

[bigsteel15]

Why do you want the base parallel?
Shouldn't it be the top that is parallel because your fence will always be square to the top (I'm assuming this becasue this isn't adjustable that I can see)?
Remember that the studs (sorry, I like this terminology better) holding the top to the base are eccentric, so you loosen the lock nut on them, turn the stud, then you need to hold the screw solid while tightening the nut again. Otherwise the stud will turn and throw alignment off again.
You won't get play in the clamping parts because they aren't designed to be an adjustment point.

[mdutch]

Why do you want the base parallel?
Shouldn't it be the top that is parallel because your fence will always be square to the top (I'm assuming this becasue this isn't adjustable that I can see)?
Remember that the studs (sorry, I like this terminology better) holding the top to the base are eccentric, so you loosen the lock nut on them, turn the stud, then you need to hold the screw solid while tightening the nut again. Otherwise the stud will turn and throw alignment off again.
You won't get play in the clamping parts because they aren't designed to be an adjustment point.

For two reasons:

One, because if the base isn't parallel, as you slide the Miter Table Top front and back, it will get closer to, or farther away from the blade, all the while keeping a parallel orientation to the blade.

And two, because Rod Kirby says so.

[scoly]

Sorry Mdutch. I did think that you were referring to the smt and not the base and am very late getting back to you.
To answer, you have it right. Release the rear clamps(m), the two rear screws(L), and the left front screw(n). Refer to page 38 of the manual.
Hope it all goes smooth. Takes a little fiddling but the reward is a very accurate saw.
Steve

[mdutch]

Sorry Mdutch. I did think that you were referring to the smt and not the base and am very late getting back to you.
To answer, you have it right. Release the rear clamps(m), the two rear screws(L), and the left front screw(n). Refer to page 38 of the manual.
Hope it all goes smooth. Takes a little fiddling but the reward is a very accurate saw.
Steve

Thanks Steve, for the clarification. It's good to know I wasn't COMPLETELY off my rocker!

I wonder though, how many of us guys are mis-reading the instructions and trying to square the SMT top using its eccentric screws BEFORE squaring the SMT base. Adjusting the sliding top is useless unless the bottom is square, first. Heck, it doesn't even matter if the SMT top is perfectly aligned unless you're planning on using the (rather crude) degree markings.

In my experience, once the base was aligned square to the blade, the top tracked well enough that I can get perfect 90 crosscuts -- I just use a precision 6" square to set my miter fence before and after tightening the adjusting knob. It's faster and more accurate than guessing at table-markings. I've never even touched the eccentrics!

[gmack5]

mdutch, you may find this helpful.


EVERYTHING, both fences, the Dual Slot Miter Table (DSMT), and the SMT all reference off of the SAW BLADE.

The first thing to do is make sure you're locking down the SMT to the RAIL correctly. Lock down the FRONT two tabs, leaving the BACK two tabs unlocked. Once you have the Base of the SMT locked down, you can then check to insure that it's square to the Front Rail and parall to the Saw Blade, using a 30-60 right Triangle or the Jig listed below and a 1 1/2" Cube of Aluminum or Hardwood.

To check the SMT Base, using a 30-60 Triangle, put the short leg up against the rear face of the Front Rail Such that the Long leg is Horizontal to the Saw Table Top and alongside the SMT Base. You should be able to determine whether or not the Side of the SMT Base is parallel to the long leg of the triangle (and perpendicular to the Front Rail).

Any difference in the distance would indicate that the SMT Base is NOT parallel to the Blade. Adjust the Base in small increments until it's parallel to the blade, using the adjusting screws that hold it to the rails.

Once this is done, you can proceed to adjusting the Sliding Table parallel to the Saw Blade.

OK, lets check to see if the SMT is parallel to the SAW BLADE. (This is what you've been waiting for!)

Move the SMT base a little closer than you had it in the last check for the SMT Base, such that the Probe on the Jig is about an inch or so over the edge of the Sliding Table, towards the front of the Saw.

Place the Block on the Sliding Table, such that one corner of it is just barely brushed when you move the Sliding Table towards the rear. Now reverse the Jig so the Probe is towards the Rear of the Saw, without touching the Block and move the Sliding Table farther back so that the Probe just barely touches the Block (the Block shouldn't move at all). If this condition exsists, then your Sliding Table is Parallel to the Saw Blade and no adjustment is necessary.

If this is NOT the case, then follow the adjustment proceedure below to bring the Sliding Table parallel to the Saw Blade.

There are four screws envolved, a "normal" shoulder screw and three eccentric shoulder screws.

The normal screw is the pivot point and should never require adjustment, since the others use it as a reference point to adjust for parallel and to take the slop out of the SMT, with respect to the base.
The RIGHT FRONT screw is the "normal" screw.

CAUTION: the eccentric screws are a little delicate, so be careful that you don't torque them too hard, as they WILL break off.

To make the SMT Sliding Table run parallel to the saw blade, be sure the LEFT front eccentric screw is "snug", but not tight, to the base, loosen the LEFT REAR eccentric screw and make sure the SMT is good and sloppy (Don't want it to interfere with the effort to bring the SMT parallel)

The Right REAR eccentric screw is used to bring the SMT parallel to the saw blade, adjust it by applying a slight pressure to the RIGHT side of the SMT as you adjust for parallel by rotating the RIGHT REAR screw.
Once you're sure you're parallel to the saw blade, lock down the eccentric screw by keeping it in it's rotational position with a screw driver (I find that an offset screw driver works very well for this) from the bottom as you snug up the nut on the top side of the screw.

NOW take the slop out of the REAR end of the SMT by rotating the LEFT REAR eccentric screw, until the SMT is snug, but not tight, you should be able to push the SMT towards the back with very little effort, in other words, it should "glide" smoothly, with very little or no side to side play. Now snug up the Left Front Eccentric Screw, if needed.

NOTE:Be sure you hold the screw in position with a screw driver to keep the screw from rotating as you tighten the nut on the top of the screw.

Your SMT should now glide parallel to the saw blade!

Your Miter Fence, while not directly envolved in the adjustment, needs to be adjusted also. This is accomplished by adjusting the "Quick Stop", located on the Left side of the SMT, about mid-way down the side. Adjust your "Quick Stop" (the little tab that swings up on the left edge of the SMT) so that it brings your MITER FENCE square to the blade (it's also an eccentric screw) when you gently swing the miter fence up against it.

You can also check your Rip Fence with the same Jig by mounting the Jig with the Probe towards the Rip fence, just barely touching it.

Now reverse the Jig with the Probe at the back of the Saw, if the Rip Fence is the same distance from the Probe as it was with the Probe near the front of the Saw, then it's parallel, if not, there are two Screws near the front of the Saw on top of the Rip Fence that are used to adjust the Rip Fence Parallel to the Saw Blade. I would only loosen ONE of them at a time, using the other one as a pivot when aligning the Rip Fence.

One other thing to be considered.... The Clamp for the Miter Fence consists of a 5/16-18 bolt that passes thru a plastic bracket that provides the clamping pressure to hold the Miter Fence in whatever position you put it. The hex head on the clamping bolt rides IN a grove on the bottom of the SMT. The groove is sized in such a way that it prevents the bolt's turning as you tighten the knob on top of the bracket.

If the Clamping Bolt is properly installed (head in the groove) there is no way that it could deform the Sliding Miter Table, since it merely clamps a piece of Aluminum (the SMT Sliding Table) between the Miter Fence and the Hex Head of the bolt. If you put a washer under the clamping bolt (on the bottom) in an effort to straddle the sides of the groove that it was designed to ride IN, it might deform the SMT when pressure is applied by clamping the Miter Fence with the Clamping Bolt improperly installed.

NOTE: The washer that's supplied as a part of the Miter Fence Clamping Assembly goes on TOP of the plastic Clamping Bracket under the Clamping Knob (it's there to keep the Knob from binding on the Plastic Clamping Bracket when tightened).

That should do it!

You should be good to go!

[DaveStL]

SMT Base and Top Parallelism

To check the SMT Base, using a 30-60 Triangle, put the short leg up against the rear face of the Front Rail Such that the Long leg is Horizontal to the Saw Table Top and alongside the SMT Base. You should be able to determine whether or not the Side of the SMT Base is parallel to the long leg of the triangle (and perpendicular to the Front Rail).

Any difference in the distance would indicate that the SMT Base is NOT parallel to the Blade. Adjust the Base in small increments until it's parallel to the blade, using the adjusting screws that hold it to the rails.

Once this is done, you can proceed to adjusting the Sliding Table parallel to the Saw Blade.

Wouldn't this just make it perpendicular to the rail?

It doesn't seem like the rail is guaranteed perpendicular to the blade. If you're out of room to adjust the eccentric screws that change the angle between the top and the base (with the ultimate goal of setting the top parallel to the blade) then adjusting the base should reduce the adjustment needed on the eccentric screws.

I think of this as a coarse vs. fine adjustment. Set the eccentric screws to their middle ranges, get the top as close to parallel with the blade as possible by adjusting the _base_, and then fine-tune with the eccentric screws.

Dave

[gmack5]

Wouldn't this just make it perpendicular to the rail?
Dave

Yes this is true, the Front Rail MUST be perpendicular to the Saw Blade's path, otherwise the SMT will drift from it's set position and your workpiece will not be square as you intend.

If the Sliding Table is Parallel to the Saw Blade, but the Base is NOT parallel to the Saw Blade, then the Sliding Table will drift from it's set position and ruin your cut, ie, the distance between the Saw Blade and the path of the Sliding Table will change as a function of how much the Base is out of Square.

[DaveStL]

SMT Base vs Rail

Yes this is true, the Front Rail MUST be perpendicular to the Saw Blade's path, otherwise the SMT will drift from it's set position and your workpiece will not be square as you intend.

If the Sliding Table is Parallel to the Saw Blade, but the Base is NOT parallel to the Saw Blade, then the Sliding Table will drift from it's set position and ruin your cut, ie, the distance between the Saw Blade and the path of the Sliding Table will change as a function of how much the Base is out of Square.

So there are two separate adjustments. I understood this the last time I adjusted the SMT...

The table top must indeed travel parallel with the blade, which means the base must be parallel to the blade. If the rail is perpendicular to the blade and the base is parallel to the blade, then the base is also perpendicular to the rail-- but the perpendiculars aren't required. Neither the base nor the rail moves during the cut, so if the rail is not (quite) perpendicular to the blade, the base has to be off perpendicular to the rail by the compensating angle. Seems like adjusting the rail to the blade would entail shimming or grinding the saw body, and it doesn't look like that should normally be needed.

The eccentric screws, then, merely adjust the fence so the degree markings and especially the 90-deg stop are fairly accurate.

Dave

[gmack5]

So there are two separate adjustments. I understood this the last time I adjusted the SMT...
The table top must indeed travel parallel with the blade, which means the base must be parallel to the blade. If the rail is perpendicular to the blade and the base is parallel to the blade, then the base is also perpendicular to the rail-- but the perpendiculars aren't required.

The eccentric screws, then, merely adjust the fence so the degree markings and especially the 90-deg stop are fairly accurate.
Dave

There is only ONE eccentric Screw that has anything to do with the FENCE, directly, and that is the one on the "Flip" stop. The other three have to do with bringing the Sliding Table parallel to the Saw Blade.

However, if the SMT Base is NOT parallel to the Saw Blade, then the distance from the Saw Blade to the Sliding Table WILL change as the Table moves back and forth, eventho it's still parallel to the Saw Blade.

[mdutch]

There is only ONE eccentric Screw that has anything to do with the FENCE, directly, and that is the one on the "Flip" stop. The other three have to do with bringing the Sliding Table parallel to the Saw Blade.

However, if the SMT Base is NOT parallel to the Saw Blade, then the distance from the Saw Blade to the Sliding Table WILL change as the Table moves back and forth, eventho it's still parallel to the Saw Blade.

Absolutly correct on both counts, though I must admit, my head is starting to hurt.

On another note, I'm VERY disappointed in the channel-aluminum bars the base-screws attach to. I've drilled and tapped mine by flipping the bar over 90 deg. With full-thread contact, they don't strip out after the sixth SMT-base alignment!

I believe I understand the process now, and am going to give this thread a rest.