Making a rip fence system.

[keith micinski]

Also I am to fired up about your fence because its 1:30 in the morning and I came home to check and see if there were any updates on the thread. The micro adjuster would be basically like this one. http://www.rockler.com/product.cfm?page=16755

[dave pant]

I followed the link to that micro adjuster. I see it might be something I do after I get the main parts done and see what I have to work with a little better. The way that one works is it sticks to the rail but my rail is round and I dont think it would work. I maybe could make some sort of thing that surrounds the round rail that has magnets on it too.
I decided not to do any more work until the bearings come in and thats not till tuesday or wednesday =(. I am afraid of wasting materials by trying doing work before I even get the stuff.

[Chris Parks]

I keep losing replies to this thread, it must be cursed. Dave, you are using a hardened ground bar but I would start with something cheaper. A round form is fairly stiff but a hollow round form is stiffer again. So to make things simple and cheap I would use a 40mm rear axle out of a race kart, very stiff and would only need to be fixed at the ends. The roller carriers to ride on this I would make in a half round form so the fence could be lifted on and off. You can buy single rollers that can be put into the half round, six each would do it, two top, two front and back. This would also enable intermediate fixing if it were necessary to join sections to make the fence longer. The carriages would be quite long maybe four inches or even longer.

The flip stop would be shaped to the bar and a few rare earth magnets put in it, you would only need a couple as the friction would be so low it will move very easily. As you pointed out, get the basic fence built and see what needs to be fixed then add the tricky bits. I would build this but I refuse to start any more jobs until I finish the one I have on the go now. As an afterthought try and use a cam clamp as a fence lock, a screw lock will drive you nuts.

[Brian White]

Isnt it going to be impossible to remove the the fence even from the end without removing the rails attachment to the saw ?

[dave pant]

Isnt it going to be impossible to remove the the fence even from the end without removing the rails attachment to the saw ?

I dont see how I cant just slide it off. Only issue would be the bolt that runs through the lock and that would just unscrew.

[keith micinski]

I see what Brian is saying. It looks to me like each end is going to have a bracket on it mounting the round bar to the saw itself. How is the Bearing going to slide past this bracket. Doesn't the bearing encompass the entire round bar? I guess I'll have to do a google search for a Thompson bearing when I get home to get a better idea of how it is going to work. So, I just looked and I see they do make open bearings. http://www.thomsonlinear.com/website...l_bushings.php

[dave pant]

linearbearingfenceb.jpg
yeah it has a gap

[Chris Parks]

It can slide off but much easier if it will lift off. To slide it off you need to lower the blade below the table, not a big issue just another inconvenience and I like things to happen easily. Dave, please let us know how it goes and what issues you strike in building and use as the theory usually gets modified when the machining starts.

[dave pant]

I know I wish I could just lift it off but I am not sure about what I have to work with on the bearings until I get them. However I dont need to lower the blade because I can slide the fence off either side.

[keith micinski]

I still say you should do something like the Unifence does except from the top of the bearings. That way you can just unscrew two handles on top and lift the fence faces and the 1x2 tube off.

[Steve Campbell]

Dave I would think if you have two bearings that the best way to use them would be to put them both on same end of the fence. Space them out ten or twelve inches apart. That way you really wouldn't need anything on the other end of the fence. Most all the T-fences out there don't have any rear support other than the table. Mine has small plastic rub strips and slides as smooth as silk. You can also get away from having to get the front rail aliened with a back rail.
There is always a way to build a better mouse trap, but I have to agree that it is hard to reinvent the wheel.

Hope this helps. Steve

[johnny means]

How stiff is 5' of unsupported 1" bar? My slider has a similar fence setup with a 2" bar and the folks at SCMI seem to think that a 5' x 2" solid steel bar requires more than 2 attachment points to avoid flexing. I would think that pushing on the fence in your design would probably bend the bolts that you have at either end of the fence. If you look at and round bar type fence you will see that they were designed to aloow for multiple mounting bolts. could you do a cam style clamp, which would leave the bottom of your clamp open to allow for multiple mounting points?

Also, one of your attachment points seems to be your extension table, not the sturdiest portion of your saw. Maybe you should use a 3x3 angle across the front of the saw to attach the bar to.

Wait a minute. Cam style clamp with an open bottom, 3x3 angle for bar mounting. I think I just turned your fence into another Biessy clone

[Chris Parks]

How stiff is 5' of unsupported 1" bar? My slider has a similar fence setup with a 2" bar and the folks at SCMI seem to think that a 5' x 2" solid steel bar requires more than 2 attachment points to avoid flexing. I would think that pushing on the fence in your design would probably bend the bolts that you have at either end of the fence. If you look at and round bar type fence you will see that they were designed to aloow for multiple mounting bolts. could you do a cam style clamp, which would leave the bottom of your clamp open to allow for multiple mounting points?

Also, one of your attachment points seems to be your extension table, not the sturdiest portion of your saw. Maybe you should use a 3x3 angle across the front of the saw to attach the bar to.

Wait a minute. Cam style clamp with an open bottom, 3x3 angle for bar mounting. I think I just turned your fence into another Biessy clone

I don't see why it should need intermediate fixing points, that might be necessary if the bar was a soft grade of material, maybe. Why do manufacturers use solid sections when a hollow one is not only stiffer but lighter is beyond me. Do you push down on your fence and if so why? other than that there is no load on it to cause deflection, slide and lock. A cam clamp would work given the right shape of the clamp so I don't see any reason to copy a Biessy.

[dave pant]

3 reasons I use the bar I use.
1.Its the proper bar recommended by thomson.
2. It was free
3. I need to tap holes in it and solid bar wont allow the bar to rock because the threads are deeper.

I dont believe just becuase the Beis is so successful that its the only way to do things. Lets not forget their design is in part because of cost too. For someone to make a fence with high precision linear bearings and shaft would cost 4-5X as much and not offer a whole lot of advantage over the beis design.

[ian maybury]

Not sure what the reality is, but I'd be a little wary of the possibility of there being some slop in a linear ball bearing that could add up to some inconsistency in fence alignment - depending on the the locking mechanism. Some Biesemeyer fence designs while using very basic materials avoids this sort of issue by clamping the sliding fence mount to the front face of a box section guide bar.

A linear bearing will probably have seals, what about friction in use?