SMT woes

[gjat]

Okay. I decided to re-install my new DSMT with shims to get the elevation right. But first, I thought it was best to double check the SMT alignment and scoot it over a bit to ensure good clearance but ran into a brick wall.

Using a square, dial guage, and a block of wood, i can get the SMT base dead square. However, I can't get the SMT table to cooperate. I find it's either too loose, or not square. I spent 3 hours on it today and no joy. What the heck am I doing wrong. I'm following the book step by step exactly, but I either can't get it square, or the rear right eccentric screw stays too loose.

help me. I feel almost as frustrated as Sailor, or worse, because I used to be very happy with the alignment before I decided to readjust everything to add the DSMT.

There'res got to be an easy way to get the table right, especially since I can get the base right pretty quickly. I'm using a dial gauge. Maybe I'm looking for too close of a tolerance, but I can get my SMT Base dead nuts on repeatedly.

[cwsmith]

Wish I could help, but (and I realize this is probably a dumb question, considering I have a BT3100-1) what is a "DSMT"?

I saw mention of it on a previous thread.

TIA,

CWS

[gjat]

Dual Slot Miter Table. The accessory that allows you to have the traditional miter slot in addition to, or in lieu of, the Sliding Miter Table.

[LCHIEN]

it keeps coming to my mind, if it ain't broke, don't fix it.

I guess that doesn't help much now.

[pelligrini]

I find it's either too loose, or not square. I spent 3 hours on it today and no joy. What the heck am I doing wrong. I'm following the book step by step exactly, but I either can't get it square, or the rear right eccentric screw stays too loose.

When you say too loose or not square do you mean that you can get it square, but it's too tight to move? If so, try rubbing some wax paper on the edges of the base. You might try flipping the back right plastic runner if it's not getting tight.

[Black wallnut]

The one tip I'd like to offer all is just snug up the eccentrics and turn them during adjustment with a nut driver from above. To try to turn them with a slotted drover from below and then tightening the nuts without moving the screw is crazy and dang near impossible. In use the screws do not need to be tight anyway, just snug. The nylock nuts will keep enough tension on the screws so that they will not vibrate loose.

[gjat]

The one tip I'd like to offer all is just snug up the eccentrics and turn them during adjustment with a nut driver from above. To try to turn them with a slotted drover from below and then tightening the nuts without moving the screw is crazy and dang near impossible. In use the screws do not need to be tight anyway, just snug. The nylock nuts will keep enough tension on the screws so that they will not vibrate loose.

I figured that out. It kinda seems that I can't get the two rear eccentrics correct.

This is what I'm going to try. I've got the base dead square. I've got the front two eccentrics adjusted so there's no slop. (I did wax the rails on the SMT base and have good movement with little effort and no slop.)

I'm going to bring the rear-right eccentric all the way in using B-wallnut's method. Then all I need to do is bring in the left rear eccentric to snug and make sure it's tight enough, using B-wallnut's method. That should make the travel of the table square to the blade, correct? Even if the table is skewed, if it's traveling on the squared base, a point on the table should be always parralless with the blade. I always square the miterfence to the blade anyway.

Does that all seem correct?

[Black wallnut]

Yes that is correct. The SMT top may be skewed but as long as the base is parallel to the blade the SMT will track parallel. The left eccentrics are for slop removal and the right rear is for adjustment; the top pivots on the front right fixed screw. Keeping this in mind it is actually a simple matter of setting the fence and adjusting the right rear until the fence is square to the blade and then remove the slop. The hardest part is to make the base parallel.

After the base and the top are both aligned to the blade the only other possible issues that I can think of are the attachment points of the SMT fence.

[gjat]

Thanks, B-w. I'm at 7/1000 within paralell now. That's well within my skill level of accuracy. I think I was over-thinking the sliding table squareness. Now that I'm thinking about it. It's probably easiest to make sure the table is sliding smoothly with no slop and just check squarenss of the table base runners to the blade. They're just much easier to adjust and control.

[sailor55330]

Thanks, B-w. I'm at 7/1000 within paralell now. That's well within my skill level of accuracy. I think I was over-thinking the sliding table squareness. Now that I'm thinking about it. It's probably easiest to make sure the table is sliding smoothly with no slop and just check squarenss of the table base runners to the blade. They're just much easier to adjust and control.

7/1000th......and to think I've been beating myself up over 2/1000th.......*sigh

[gjat]

I think the level of accuracy came up a year or two ago. We all used to just use squares, rulers, and pencil marks to square things up. It is 'wood' after all. It's physical dimensions are relatively dynamic, unlike blocks of steel.

We all started using dial indicators and digital calipers where we could easily see differences of 1,000's of an inch and forgot what a 1,000th of a inch is in reality.

In actuality, we literally started splitting hairs when aligning our tools.
"Flaxen hair is the finest, from 1/1500 to 1/500 of an inch in diameter … and black hair is the coarsest, from 1/450 to 1/140 of an inch."

Take into consideration that you may have a grain of sawdust, a loose wood fiber, a gnat's ass, etc. between your wood and the miter fence, square, caliper, or tape measure. Then consider how stable you can hold the piece of wood as you move it through a blade spinning at 3,500+ rpm with associated vibration...