SMT Problems

[Bo]

I have been making a few table legs for a desk and I noticed that the cuts using the SMT have been off very slightly (maybe 1/64) top to bottom. The legs are just over 2" square. I made sure the miter fence is dead on to the saw blade using a engineering square. The front to back cut is good. I squared the blade to 90 degrees with the same square, I mean really took time to make sure it was at 90 and I still get the 1/64 top top bottom difference. I put a straight edge on the blade table to the SMT and noticed that the SMT was lower and uneven. I have tried to locate anything that would raise the SMT to parallel with blade table (or even higher would work if parallel) I don't see anything that makes this adjustment on the saw. I ended up putting shims under the miter base above the guide bar. The guide bar is simply a piece of aluminum with a groove cut in the middle. the screws that attach the miter base to it actually self tap into this groove.

I haven't noticed this problem on thinner stock, like 3/4 wide. I guess that 3/4 isn't enough to to show a top to bottom difference. I ended up putting a framing square on the SMT fence and against the saw blade to "dial in" a cut 90 degrees to the SMT. This has worked OK but it's a pain to reset the blade to the "true" 90 degrees to rip cuts.

Hopefully, one of you guys has seen this before and has an answer.

Thanks,

Bo

[Bo]

I forgot to mention that this saw is a BT3100-1. Also all the normal adjustments have been done to the SMT.

[LCHIEN]

not sure what you mean when you say a leg is off 1/64th "top to bottom".
I just don't have a picture of what you mean.
Are you saying the legs are 2" square all the way down but the top is not crosscut square to the leg? is that 1/64th in 2" or 1/64th in 30+ inches?

There's been some issues with the height of the SMT... usually its a bit proud of the main table we think for not dragging teh workpiece on the main table. - some people like to even it up. in your case it sounds like the SMT is low.

Perhaps my FAQ addresses your issue?

[pecker]

I I put a straight edge on the blade table to the SMT and noticed that the SMT was lower and uneven.

Bo

Well, that sounds like a problem right there. The SMT is supposed to be higher, by about 1/32", than the main table.

With the smt being lower, when you crosscut your 2x2, it will be at an angle, as part of the 2x2 is on the main table and part is on the (lower) smt.

[Bo]

The legs are 35 1/2" when crosscut looking side of leg looking top to bottom at cut it's roughly 1/64 off as like the blade is at 89 degrees. Not length wise, the 2" crooscut

Any way other than shims to raise the SMT? I thought about washers but the SMT is uneven so bringing it up would bring it up uneven. Too bad it's not designed to fine tune this issue with the saw

[Black wallnut]

The legs are 35 1/2" when crosscut looking side of leg looking top to bottom at cut it's roughly 1/64 off as like the blade is at 89 degrees. Not length wise, the 2" crooscut

Any way other than shims to raise the SMT? I thought about washers but the SMT is uneven so bringing it up would bring it up uneven. Too bad it's not designed to fine tune this issue with the saw

Bo, I think your problems are deeper than they appear on the surface of the saw. On the uderside of the SMT base where it clamps to the front and rear rails there should be some shim tape installed by the factory. Did you buy the saw new or have you just lately acquired it? If you purchased it used it is possible that whomever owned it before removed these shims. It seems to me that your biggest issue is that the rails are not larallel to the table surface. If it were me I'd take the saw off the stand and start over. Make sure that the stand is square, true and the saw mounting surface is level with the floor. If you have to adjust one of the feet to make it so, do. If your shop floor surface is not level or has high spots and low spots set up the saw stand in your normal working location. Mark the floor so you can return it to the same place after storage. It is entirely possible for the stand being tweaked to cause the saw body to distort throwing every thing off. Once you have ensured that your stand is square and level remount the saw. Then realign SMT base, SMT table, SMT fence, and the rip fence. If the plastic shims have been removed you can replace them with some aluminum tape available from a hardware store.

As others have mentioned the SMT by design is slightly higher than the main table. It should also be level with the table as you've guessed. If you find that after squaring the base that your rails are not level address that condition. Until your rails are level your results will be less than ideal.

[Tom Slick]

are you sure your framing square is "square". it could be out 1/64" easily.

[Bo]

Thanks for all the ideas that might correct this problem. The saw does get moved around alot on an uneven garage floor. I will level the saw as Mark suggested and see if this helps. The aluminum tape seems better than the cedar shims I used.
Thanks for the help.
Bo

[gimpy]

There might be some good info in this link, don't know, though:

http://benchmark.20m.com/tools/BT3100/bt3100index.html

[Black wallnut]

There might be some good info in this link, don't know, though:

http://benchmark.20m.com/tools/BT3100/bt3100index.html

It's time for me to take a stand! This link is not good. Although some of his methods will work they are not completely right. His use of a block and screw is perhaps IMHO his only good idea. He is flat wrong about the rails and he is flat wrong about the SMT base alignment, although with his method of the later you can get there. His tolerance of .004" seems to me as rather course and I think you should be able to do better than this. For the rip fence you should be able to get .004" from the front of the blade to the back end of the fence. For the SMT you should be able to get within .001"! I questing his ability to either understand the SMT or articulae his thoughts about it. One glide is static and three are eccentric. The front right is static, the rear right is used for adjustment for parallel, and both left ones are for backlash. The adjustment is a rather fine feel type of thing; you want contact but not pressure between the glides and the SMT base. If you have pressure it will not slide or will with effort, if you have a gap it will not remain square.

His idea that the rails should not be moved once set is simply wrong. He is right that it is a good idea to check once moved, although after doing so several times I can assure you that their relationship in regards to the blade is unchanging in the whole range of adjustment. This is not to say that there could be lemons or mistakenly manufatured saws out there. It would be much more valuable to check your front rail to prove that it is straight and if it is not replace it. If they are not mounted level at any point then the error will be the same anywhere along their length, unless they are bent or the locating bosses are out of tolerance.

[gimpy]

Black wallnut, sorry about the link. I've had it bookmarked for quite awhile, don't remember for how long or where/who I got it from. Just in the last couple weeks or so, I've been looking at tuning my saw up a little. In fact, I just received a dial caliper last week from Grizzly for thast purpose and went through all my old bookmarks and found this site. I haven't read it real close, but did print it out to read it later. I will now throw that away and delete the link to that site.

Didn't mean to give out bad info.

[Bo]

Thanks Mark and the others who replied. I got some aluminum tape and leveled the saw. I used a straight edge and got the SMT perfectly level with the main table. The crosscuts came out perfect. Thanks again for the help.

Bo