Bought a used 3100

[dt_busse]

Hi all

First post. I've been a long time lurker

I have had a Sears version of the 3x00 for four or five years years now and like it, except for the shims problem which I haven't fixed yet but have been dealing with by reaching under the saw and pushing up on the motor when raising the blade. It drops down fine.

Anyway I just bought a very low priced and apparently little used 3100 from craigslist. It was worth the price to me for parts if I dont get it into usable shape. I took apart the stand and tables and front and rear rails to carry it home in my Honda hatchback. Put it back together and started to try aligning parts. I'm stuck at step one, trying to get the rails parallel when they're attached to the main table. The SMT base is fine if I mount it on the rails to the right of the blade. (At least it will slide toward and away from the blade.) But, if I try to mount it on the rails to the left of the blade, the rails pinch on the "guide bars" on the bottom of the SMT base, and it's very stiff to slide the base toward or away from the blade. I turns out that the front and rear rails are about a sixteenth closer together at the ends to the left of the blade than they are at the ends to the right of the blade. On the left side, that's enough to pinch the guide bars. (Guide bars is what the manual calls them. See item # 15 on page 46 of the 3100-1 owners manual.)

As far as I can tell, the rails themselves are straight arrows, but then I just have a 4-foot level to check with, not any kind of engineers straightedge. I haven't found anything in the Owners Manual (or here yet) that tells me how to make the two rails parallel. Is there a manufacturer approved way to make the rails parallel to each other and perpendicular to the blade? Is there a thread on this? If not, any good ideas on how to jury rig it?

I haven't ever had to do much with the sears version - model 228110 - other than readjust the table every once in a while so that the SMT gives me a 90 degree cut, so this is pretty new to me.

[bigstick509]

Sorry I can't help with the rail problem, but I'm sure one of the more knowledgeable members will come up with a suggestion.

[gsmittle]

Do you have the rails clamped down? IIRC (it's been a LONG time since I put my 3100 together) there are some little plastic levers under the rail mounting points that snug the rails to the saw body. If your rails are a bit loose that might be enough to bind the SMT on the right side.

Or maybe a thin shim behind one of the rails might help.

Other that that, I got nuthin'.

Oh, and welcome to the board! This is a fine bunch of folks, always ready to help and sometimes they even have some good suggestions.

g.

[Uncle Cracker]

...and sometimes they even have some good suggestions.

Liar!

[LCHIEN]

my thoughts on the matter:
Take the rails off your 22811 (I'm assuming they're fine) and put them on the BT3100. If the rails are parallel then the rails are off on your BT3100. If there's still non-parallelism, then its the saw base that's bad.

If the new rails are bad, then just use the old 22811 rails on the BT3100

If the saw base is bad, then I'd consider a small shim or two to make them parallel - easiest way of you want to use that BT3100. Simple math ratios can tell you what the shim thickness required is. Assuming there's nothing else wrong. Usually the bosses where the Rails mount are machined into the top casting so its hard to imagine it being off.

[dt_busse]

Do you have the rails clamped down? IIRC (it's been a LONG time since I put my 3100 together) there are some little plastic levers under the rail mounting points that snug the rails to the saw body. If your rails are a bit loose that might be enough to bind the SMT on the right side.

Or maybe a thin shim behind one of the rails might help.

Other that that, I got nuthin'.

g.

Wow, that was fast.

Thanks for the welcome.

Since I wrote that first post, I played with the saw a little more and backed off the tiny allen-head set screws that hold back the guide bars (at least that's what it looks like they do) that are under the SMT base. I can slide the base and the sliding table closer to and farther from the blade with little resistance now, but that still leaves the front and back rails out of parallel.

On the levers that hold the rails clamped down, yup, I pushed them to the clamp down position. Actually, with those levers left loose, the SMT and its base slide left to right just fine. It's when I clamped the rails tight that the SMT base/guide rails got jammed between the rails.

I tried the shim idea, but there isn't an obvious way to shim them. There are only two very small spots at the top and bottom of the clamps where the rail actually touches the table. I'm still working on that possibility.

Dave B

[dt_busse]

Bought a used 3100

my thoughts on the matter:
Take the rails off your 22811 (I'm assuming they're fine) and put them on the BT3100. If the rails are parallel then the rails are off on your BT3100. If there's still non-parallelism, then its the saw base that's bad.

If the new rails are bad, then just use the old 22811 rails on the BT3100

If the saw base is bad, then I'd consider a small shim or two to make them parallel - easiest way of you want to use that BT3100. Simple math ratios can tell you what the shim thickness required is. Assuming there's nothing else wrong. Usually the bosses where the Rails mount are machined into the top casting so its hard to imagine it being off.

I tried swapping the SMT and the accessory table, and got the same bad results. I never thought of swapping the actual rails. Grr. First thing tomorrow. Thanks a lot for the idea.

Dave B

[dt_busse]

Thanks for the ideas.

my thoughts on the matter:
Take the rails off your 22811 (I'm assuming they're fine) and put them on the BT3100. If the rails are parallel then the rails are off on your BT3100. If there's still non-parallelism, then its the saw base that's bad.

Same Difference.

If the saw base is bad, then I'd consider a small shim or two to make them parallel - easiest way of you want to use that BT3100. Simple math ratios can tell you what the shim thickness required is. Assuming there's nothing else wrong. Usually the bosses where the Rails mount are machined into the top casting so its hard to imagine it being off.

I'm going to see if I can figure out where to fit shims.

Dave B

[pelligrini]

Small narrow ones can be put in between the rails and the attachment point on the rails. I used the narrow tangs off of some starter shims I had in the garage. I did that with my 21829 when I was attemting to align my rails perpendicular to my blade. I didn't know that it didn't really matter. It was before I found BT3central, or read the users manual.

They can (and usually do) fall out when moving the rails. I found it to be a big hassle.

You might consider swapping saw tables. I don't know how involved that is though. I'd check the fit of your SMT on the other saw before swapping first.

[mpc]

Take the rails and hold them against each other - instead of your level - to see if either/both are bananas. Hold the rails so that the edges normally clamped to the saw body are touching and look for gaps between the rails... then rotate ONE of them 180 degrees (so the clamping face of one rail is touching a non-clamp face of the other) and try again - in case both have similar bends. Also, compare them to rails from the other saw. One of my spares turned out to be slightly bowed; it took a little work to straighten it. I just slipped some wood scraps on the garage floor to raise the "bent inwards" end and applied pressure to the center of the rail. Worked fine.

As you noted, the machined surfaces the rails butt against (part of the tabletop) are not easy to shim. Resist the temptation to file one down too... until you've proven nothing else is bent. Hopefully a previous owner didn't file one either - eyeball them carefully, looking at the machining marks - if one looks considerably different, it was probably filed. I'd instead apply metal foil tape to raise one machined surface rather than filing down it's companion. At least this is easily un-done.

mpc