Jointech miter sled fence pivot

[al ladd]

I've been working on a new table saw sled, trying to incorporate the best ideas I can find along with some new ones I've developed.

The defunct Jointech Smart Miter table saw sled had the remarkable ability to pivot it's fence without changing the distance from fence end to blade. Very cool! Anyone know how this is accomplished? Did the mechanism hold up for those of you who have or had one?
Thanks!

[Bob Potter]

Yes I have one and the pivot point is at the end at the blade end and the indexing is back toward the other end. You can cut a board say 10 inches or any given length and miter it and what ever the length was it will be that from point to point. You do not have to reset your tape from 90 to 45 . Once it is set it is good for what ever you have it set at. In other words you do not have to change it for the next cut.

The indexing is on the bottom. There is little notches that do have a little play but does not bother with positive setting of your angle.
Jointech had a lot of good idea's. Hope I didn't confuse you to much, Bob

[al ladd]

Thanks Bob.
That makes sense from a geometry stand point, but I don't understand how the pivot point can actually be there. The pivot would literally have to be half in the path of the blade, and the fence wouldn't stay on the pivot. Even if the center of the pivot was only about 1/16" from the outer top corner of the fence, which I think is structurally impossible, it would still produce about a .025" error when tilted 45 degrees. I think there has to be something going on that shifts the pivot as its rotated. I had been focusing on a pivoting mechanism that would pull the fence laterally as it pivots, whcih seems possible, but quite tricky to pull off (the pivot could be a triangle).

Maybe it's the quadrant for the angle that pulls the fence in a slotted pivot to compensate for the change in x axis position? Hmmmm.....I'm thinking that the quadrant , if it tightly holds the bolt that fastens the fence there, can be altered from the typical perfect arc to pull the fence in the required x axis direction. The pivot would be round, but would fit in a slot that allowed that travel.

Have you (Bob, or anyone else)actually taken the fence off the sled to see how it's mounted near the blade?

[Bob Potter]

No I have not taken the fence off although if something would ever happen to the sled I have thought about using the fence. The fence is a channel inside of a channel, which makes it very strong when it telescopes. It goes out to 48". There is a knob to loosen, no need for tools. I don't know if you have ever seen one in person or a video showing how it works but that would maybe help you see how it works. You may be able to find some video's on line of the sled. I do have a video that came with the sled it is a tape.
Bob

[Bob Potter]

I looked up on line and found the video that I have. Now this is in parts so I don't know it it will copy all of them

https://www.youtube.com/watch?v=pP-ghKnOpSc if this doesn't work out than disregard. There are more that I haven't checked out.
Bob

[Bob Potter]

Well it didn't copy the second part but when it is over there should be more listed to click on that will show you more .Also if you just type in Jointech Smart Miter there is 4 parts to the video that I have. You will have to watch them separately but should give you a better idea of how it works. Any way I'm trying.
Bob

[Ed Aumiller]

smartmiter.jpg
This is an educated guess....
Look at the sled and watch the videos...

I believe the "pivot point" is actually an enlongated slot in the bottom of the fence. The slot to set the angle is different for the top and bottom halves of the board. It is made so that the tip of the fence is at the edge of the sled at 90 degrees. when you adjust the fence to 45 degrees upward the fence actually moves slightly closer to the edge of the sled because the top 1/2 of the groove moves closer.. That is why you use the upper portion for the long edge of what you are cutting.

When you swing the fence down to cut the short edge of what you are cutting, the fence goes a lot closer to the edge of the sled because the bottom portion of the gauge is closer to the edge..

That is why there are 2 scales on the fence, one for the long edge and a different one for the short edge.

Hope I explained it ok..

It would be very difficult to make one without knowing how to make the grooves for the adjustment accurately...

Good luck

The secret is that it is not a true pivot as normally thought of...

[al ladd]

Thanks for these replies. I did see those videos, and they show how nice the mysterious zero clearance at any angle is. Anyone who has used a conventional miter gauge or angle adjustable sled using a quadrant can see how useful and magic-seeming it is.

I think Ed is correct that the "secret" is that the quadrant is not the usual arc of a circle-- it's manipulated to move the pivot end closer or further than you'd expect from a point pivot. I woke up after posting this question with the answer in my head, but it was necessary for me to draw it to be sure, and then I noticed the irregularity of the quadrants in the Jointech sled, a dead giveaway. The geometry is pretty cool! Not that hard to figure with a CAD program really, but I'll have to see if I can make the mechanics actually work smoothly enough to make the sled work in real life.

[Ed Aumiller]

Al, I made a mockup from 1/8" hardboard.... made a piece 1 5/8" wide by 20" long with a 45degree on the end as the fence... put a groove in the center of it about 2.5" long starting about 1 1/2" from the end with the miter in the center of it... the groove was the width of a 6penny nail.... put a 6penny nail about 2.1" from the edge of a piece of hardboard.. put a pencil hole about 12" from the 45 end...
put the fake fence on the nail and held everything against a straight edge (I used my table saw fence), then keeping the fake fence tight against the straight edge, put a pencil in hole and turned it in arc...
see photos...
SmartMiter3.jpg SmartMiter31.jpg SmartMiter32.jpg

Thinking about making one using a router on the end of a board with a groove so the arc will be correct..just for the challenge of doing it...

[Joel Rosenberg]

I know this thread is a couple years old, but does anyone have a digital copy of the Jointech Smart Miter Sled instructional video? The link to YouTube that Bob Potter posted says that video was taken down.

Digital copy would be best/easiest, but if someone has a VHS I'd be open to coordinating to digitize it, or if someone has a CD/DVD but no drive anymore, I'd also be happy to make a copy.

Thanks!