Parallel setting jig for SMT?

[gwyneth]

I've been taking off and putting on my SMT a lot in the last couple of weeks. (The mobile stand I am making is taking longer than expected, partially because of the time to measure and adjust things every time they go back on, which is every time the folding cart unfolds...)

Has anybody here come up with something that could be placed between blade and SMT so that, if appropriate screws and back clamps are loosened for adjustment, would involve just tapping the SMT into the 'parallel setting jig', then tightening the screws, clamps, and front screws?

The real time involved in adjusting the SMT so it tracks parallel to the blade is not the loosening process, but the tighten-measure-test-process. With something like this, it would stay in the parallel position when tightening the screws, clamps, and screw (more than once I've gotten it parallel while loose and slightly moved it while tightening).

Is there any reason this approach would not work? I kind of visualize something with this profile, though something like a block for the middle--that the SMT could be moved against, maybe.

[LarryG]

Backing up a bit from what you actually asked ... are you saying you're doing a realignment every time you remove/replace the SMT? That should not be necessary. You should be able to set it on the rails, lock down the front levers, then lock down the rear levers, and be good to go.

Before I retired my BT3100, I had the SMT on and off the saw endless times, and never once realigned it strictly because I'd had it off the saw. (I did have to periodically fine-tune the adjustment after many hours of use, during which things would get knocked out of adjustment over time.)

[LCHIEN]

I never bother to check parallelism of the SMT anymore when I move it; it's always right on. But, I have BT3000 that sits there and you have a 21829?

Not sure why they would be different.
Do you use the always lock both at front (simultaneously), then lock both at back (simultaneously) technique on your SMT? This is reputed to make it align more repeatably.

[gwyneth]

Backing up a bit from what you actually asked ... are you saying you're doing a realignment every time you remove/replace the SMT? That should not be necessary. You should be able to set it on the rails, lock down the front levers, then lock down the rear levers, and be good to go.

Yes, I'm saying that. Loren, yes, I'm locking the front two then locking the back two.

Who knows what small misadjustment might result from the folding, unfolding, put tables back on process? I won't know for sure until it can stay horizontal long enough to make thorough checkup worthwhile.

[LarryG]

Who knows what small misadjustment might result from the folding, unfolding, put tables back on process? I won't know for sure until it can stay horizontal long enough to make thorough checkup worthwhile.

Even so, given reasonable care, and assuming you're not taking the rails off too, a realignment should still not be necessary.

Instead of going through the whole laborious process -- which, granted, is a job calculated to make you mean -- why not just make a couple test cuts and check the results to find out if there's actually a problem?

[cgallery]

I agree with the suggestions made.

You may also want to make some reference marks w/ a permanent marker (your rails are black but a fine-tipped black marker will probably still show up). I would make a mark on the back of each rail where it meets the table. I would also make a mark on the front and rear rails where the SMT attaches.

If you're careful, and observe your marks immediately after making them, you can pretty easily figure out later-on if something is moving enough to require adjustment.

The eye is an amazing instrument and can perceive minute changes (a few thousandths) where reference lines are present. The trick is to use the edge of the reference line and the point it references.

[gwyneth]

Instead of going through the whole laborious process -- which, granted, is a job calculated to make you mean -- why not just make a couple test cuts and check the results to find out if there's actually a problem?

It would be kind of silly to do the adjustments without first noticing problem cuts, wouldn't it? The whole point of this excercise is to avoid to doing adjustments...

cgallery, I'm not clear about what you're suggesting concerning the first set of marks--no black rails. Back of each rail where it meets the SMT?

I do appreciate all the help, even if I inadvertently sound cross, or 'mean', as Larry puts it.

[leehljp]

It would be kind of silly to do the adjustments without first noticing problem cuts, wouldn't it? The whole point of this excercise is to avoid to doing adjustments...

I do appreciate all the help, even if I inadvertently sound cross, or 'mean', as Larry puts it.

Larry didn't use the word "mean" as being "mean spirited" but as: you mean . . . that . . . (meaning)

Also, you said: With something like this, it would stay in the parallel position when tightening the screws, clamps, and screw (more than once I've gotten it parallel while loose and slightly moved it while tightening).

Is there any reason this approach would not work? I kind of visualize something with this profile, though something like a block for the middle--that the SMT could be moved against, maybe.


The vast majority of people have not had the need to do what you are asking. I think it a jig would work fine, but the way I envision it, it would take some kind of very precision jig to make the SMT be parallel to the blade . . . in the way that I perceive you describing it. But I would like to see the jig you are describing. I have been amazed at the different jigs people make and simple ones at that.

AS to why it hasn't been done - so far it hasn't been necessary for most people. As others have said - once the SMT is set to parallel, it stays parallel even when removed and replaced dozens of times on the rail. I check mine about every 6 months and only have to re-align about every 2 years when I notice a cut is not parallel.

There are a few SMTs that come out that are not parallel and do not hold to parallel. I had one and fixed it myself but I still had to adjust it every few months. I also bought a second SMT from someone parting out their BT and it works fine and holds its position well.

Having said that above, I have run into a couple of woodworkers that grew up with the mindset that the parallelism of the fence HAD to be checked EVERYTIME it were removed and replaced. They just couldn't envision that it could be removed and replaced and be parallel as a matter of fact.

ON the BT, it has been exactly that - staying parallel (when removed and replaced) as a matter of fact. I think everyone is basically saying that the jig is not needed by them or for most BT owners because the SMT replaces itself (using the proper prceedure) in parallel with the blade more than 99.5% of the times.

[cgallery]

cgallery, I'm not clear about what you're suggesting concerning the first set of marks--no black rails. Back of each rail where it meets the SMT?

Basically, the first set of marks is used to make sure the rails don't move relative to the table. The other set of marks is used to make sure the SMT is always in the same position on the rails.

[Lonnie in Orlando]

Uh Oh, he's posting that infernal "No-Measure" method again ...

I'm sure that members of this forum are tired of me posting my "No-Measure Alignment Method" of aligning the BT3K, but here it is again!

This is an easy / fast method of adjusting or checking alignment. Here is the link to the post on the Ryobi forum ...
http://www.ryobitools.com/dc/dcboard...id=2917&page=2

Note this update:
Phil Bumbalough's 5-cut method for squaring the miter fence from his "BenchMark" site is better than the method that I originally wrote in the "No Measure" post. Perform this "5-cut" step after you have insured that the table moves parallel to the blade.
http://benchmark.20m.com/tools/BT310...XcutFence.html

For what it's worth, I have seldom needed to realign my BT3000. I move and remove the SMT a lot, and it stays in good alignment. However, I do check alignment of the rip fence, SMT, and the miter fence when I start a new major project. The check takes only seconds with the "No Measure" tool.

- Lonnie

[LarryG]

I do appreciate all the help, even if I inadvertently sound cross, or 'mean', as Larry puts it.

For the record, I meant that aligning the SMT is a job that can try one's patience. "A job that'll make you mean" is a figure of speech with which you may not be familiar. That is all I meant; nothing else should be read into my words.

It would be kind of silly to do the adjustments without first noticing problem cuts, wouldn't it?

The wording of the first paragraph in your OP strongly suggests that you were realigning the SMT as a routine part of the re-assembly process, i.e. assuming the alignment would be off, before making any test cuts. Your first reply to me reinforced that: "Who knows what small misadjustment might result from the folding, unfolding, put tables back on process?" I did not mean to insult your intelligence. I was merely trying to respond to the question as it was written.

All that aside, the central point that everyone (not just me) has been making remains: if you're having to re-align the SMT solely because you removed it from the saw, something is wrong.

[leehljp]

Larry: "A job that'll make you mean"

LOL! I missed that the first time reading it. Old timer's talk - I've forgot most of that!

[gwyneth]

For the record, I meant that aligning the SMT is a job that can try one's patience. "A job that'll make you mean" is a figure of speech with which you may not be familiar. That is all I meant; nothing else should be read into my words.

The wording of the first paragraph in your OP strongly suggests that you were realigning the SMT as a routine part of the re-assembly process, i.e. assuming the alignment would be off, before making any test cuts. Your first reply to me reinforced that: "Who knows what small misadjustment might result from the folding, unfolding, put tables back on process?" I did not mean to insult your intelligence. I was merely trying to respond to the question as it was written.

All that aside, the central point that everyone (not just me) has been making remains: if you're having to re-align the SMT solely because you removed it from the saw, something is wrong.

I really was testy, not about your post, which was, as always, thoughtful and helpful. It's actually been hot up here, and the back porch/'shop area' is like a greenhouse.

What I meant about the "who knows" part was that with all the takedown, putup, bumping, etc., the problem might be something besides the SMT itself--there are plenty of possibilities in these sub-optimal working conditions, and I was being frustrated by the idea of chasing what might be an intermittent problem.

It's excellent to be able to learn the way it should be (i.e., parallel when put back), and I really appreciate it.

Over the weekend, I unfolded it in a different position--no rips over 12" but good cross-cuts, which suggests the possibility of a levelling problem or something 'environmental'. Once it comes off the mobile cart, it can be tuned thoroughly.

[jon_ramp]

Gwyneth, I don’t mean to hijack your post but have a question and comment related to this topic.

I have only had my 21829 (BTCraftsman with folding base) a short time and have only used it twice. I know it was aligned when I initially set it up. During my last project I noticed that my cross cuts were not square. I thought the SMT was out of alignment, went through the process of alignment frustrated to no end why I couldn’t get it there, then found one of the rails was not locked down. I’m sure that was user error and not the SMT.

While removing the SMT should not require an alignment check every time it is replaced, how would moving the rails play into this situation? Since the 21829 is designed to be portable, it is more likely that users would be moving the rails more often than a typical BTx user. Theoretically it should not make a difference, but I’m not sure and would be interested in anyone’s comments.

[gwyneth]

jon_ramp, you're not hijacking it at all--in fact, you've helped clarify things. I'd previously thought that any SMT issues of mine arose from taking the table off and putting it back on.

But now that I know that it's not supposed to change things, I've begun to look at other possibilities specific to 21829 movement.

I have the same vague suspicion as you--that there's some factor, probably related to the rails, that changes things somewhere in the process of folding it all up and unfolding it.

It's clear the designers failed to take at least one thing into account when developing the cart system: the blade guard bounces all over when the cart is moving the vertical saw. Thus, I am not totally confident that they took everything into account affecting or affected by the rails going vertical.