Tight Miter Fence Clamp Allows Fence Movement

[partialresponse]

I just went out and checked mine, just because, and lo-and-behold, noticed the same thing.

I recently purchased a second BT3100 from CL, and figured I would test it on this second SMT. Same fence, no play!

My guess at this point is that the right pivot hold on the SMT may be a bit outta whack. Now...how to fix.

Since I have the second SMT, will likely align this one to use as my primary

So, if I understand correctly, the one fence can be tightened down with absolutely no play on one SMT but with some play on another SMT? I really don't detect anything suspicious with the fit of the fence's black plastic pivot pin into the (right) mating hole in the SMT. I suppose I can try wrapping some tape around it to make the fit even more snug? My feeling, though, is that the problem is really the fence clamp. Regardless of where I position the fence on the SMT (yes, by not using the pivot pin and hole in the SMT for this test) it can always be rotated slightly with the application of moderate force on one end. And I can always turn the fence clamp knob until it's very, very tight - but the fence still moves.

- Kofi

[partialresponse]

Ok, I getcha now. Truth be told I've never used that thingy.

It's clearly got to be the clamp or the pivot. The clamp can be a little awkward to set up. The head of the bolt needs to be inside a pair of aluminum rails formed on the underside of the table. If it's straddling one or both of the rails it might not be a firm setup.

That's all I got, pal. Good luck.

JR

So how do you prevent your miter fence from rotating slightly when making a cross cut? Anyway, the zero-degree stop tab on the SMT does not prevent the fence from rotating clockwise while making a cross cut (the miter fence will naturally tend to rotate clockwise while making a cross cut.) I suppose the use of small C-clamps to secure the fence to the SMT (at both ends of the fence) is as good a suggestion as has been mentioned.

-Kofi

[pelligrini]

I really don't detect anything suspicious with the fit of the fence's black plastic pivot pin into the (right) mating hole in the SMT. I suppose I can try wrapping some tape around it to make the fit even more snug?

In my case, it wasn't play in the hole, but play at the pivot/fence connection.

Last night, I swapped out the really loose pivot I had with a very tight fitting one from my long miter fence. It's so tight it is not easy to slide the fence on it. (probably ought to rub it with waxpaper). The tighter fitting pivot stopped the previously described movement that was occurring.

It would probably be best to make sure the solid portion of the miter fence pivot is directed towards the front of the saw. The slotted portion may move a little.

[JR]

So how do you prevent your miter fence from rotating slightly when making a cross cut?

I've never noticed it to be a problem. Maybe I have a problem I didn't know about!

JR

[poolhound]

Poolhound - neither of my two extrusions have a tab on them both are flat. One is from my 21829 and the other is off a BT.

OK well that blows that theory

[poolhound]

The head of the bolt needs to be inside a pair of aluminum rails formed on the underside of the table. If it's straddling one or both of the rails it might not be a firm setup.

This may not be helping me. I have the situation that Loring mentioned where the head of the bolt has worn the slot under the SMT. Now it rotates before I can get it tight.

Any reason I shouldnt put a washer or 2 under there?

[pelligrini]

There was a fairly recent thread where someone used a T-bolt for that connection.

http://www.bt3central.com/showthread.php?t=38224

[Black wallnut]

Kofi,
Check that your pivot is installed correctly in the bottom of the SMT fence. The spring tab goes towards the user or the front of the saw.

[poolhound]

There was a fairly recent thread where someone used a T-bolt for that connection.

http://www.bt3central.com/showthread.php?t=38224

Thanks I will give that a try.

[poolhound]

Solid As A Rock!!!

I found a T-Bolt, inserted that and its now as solid as a rock. There is still a minute amount of movment (can hardly see it but I can feel it). I guess the SMT needs some slight tightening but this was masked by the larger, although still slight, movement in the fence.

A re-cal. on the SMT and I will be set to rock-n-roll!!

[LCHIEN]

So how do you prevent your miter fence from rotating slightly when making a cross cut? Anyway, the zero-degree stop tab on the SMT does not prevent the fence from rotating clockwise while making a cross cut (the miter fence will naturally tend to rotate clockwise while making a cross cut.) I suppose the use of small C-clamps to secure the fence to the SMT (at both ends of the fence) is as good a suggestion as has been mentioned.

-Kofi

the zero stop should only be for setting the miter fence to zero, not for holding it there. its a delicate piece, many have broken theirs from either banging the miter fence into it, or perhaps when the miter fence was not clamped and the force of a workpiece broke it. Its a small, thin-wlled piece of brittle metal and breaks easily.

[eddy merckx]

Hi Kafi

I'm jumping in kind of late, but what the heck. I had the same problem with my 3100. In my case it happened because the SMT was crowned, with the apex just under the miter guide bolt. Since there was hardly any surface area to hold the guide in place, it would often shift during a cut unless I was careful to only push behind the bolt. I solved it by clamping the other end of the guide to the table. It was a hassle but worked OK.

You might want to put a good straight edge across your table to see if it's flat. I actually had Ryobi warranty my SMT and the new table was crowned too. I was going to sand the bottom of my miter guide concave to match but never got around to it.

Eddy

[poolhound]

Hi Kafi

I'm jumping in kind of late, but what the heck. I had the same problem with my 3100. In my case it happened because the SMT was crowned, with the apex just under the miter guide bolt. Since there was hardly any surface area to hold the guide in place, it would often shift during a cut unless I was careful to only push behind the bolt. I solved it by clamping the other end of the guide to the table. It was a hassle but worked OK.

You might want to put a good straight edge across your table to see if it's flat. I actually had Ryobi warranty my SMT and the new table was crowned too. I was going to sand the bottom of my miter guide concave to match but never got around to it.

Eddy

Mine is also slightly crowned reducing the surface of the fence that contacts the table and hence the slight movement that I continue to experience. My solution was to stop putzing with it and build dedicated X-Cut and Miter sleds for when I need something dead on.

One solution that I have yet to try would be to fix some small strips of PSA sandpaper to the underside of the fench at each end. They would act as both shims and grip.

[eddy merckx]

Hi Jon

Yeah, the crowned table caused me a lot of frustration. I did try sandpaper on the bottom of the fence. It still didn't work for me. I eventually just clamped the fence down with an F clamp. That is reliable but a pain.

I have often wondered if the crown was some sort of design feature or a manufacturing error.

Eddy

[poolhound]

Hi Jon

Yeah, the crowned table caused me a lot of frustration. I did try sandpaper on the bottom of the fence. It still didn't work for me. I eventually just clamped the fence down with an F clamp. That is reliable but a pain.

I have often wondered if the crown was some sort of design feature or a manufacturing error.

Eddy

I tried the sandpaper thing this WE and as you found it did nothing. Over the past couple of weeks I have built X-cut and Miter sleds which cut dead on the money. So other than for those occasional odd angles I might retire the SMT and build a fixed table.