Making a rip fence system.

[dave pant]

My uncle owns a machine shop and I usually end up there when coming up with some sort of plan.

My new plan is a super smooth and accurate fence for my table saw.

I am doing this because I already have the stuff and I am guessing it will cost me about 75$ to do.

Anyways I am using Thomson linear ball bearings and case hardened 1" diameter shaft on the front and back of the saw.

One thing I been thinking about was the length of the fence itself. I think the Biesemeyer fence is like 42" long and overhangs over the back of the table.

Why is this? I was planning on making mine only 34" long because my saw is 27" deep.

Since this system I am making is going to be pretty sweet I wanna make sure I do it right and am able to use it on any saw for the rest of my life heh.

Should I make my fence 42" and if so why?

Thanks =)

Dave

[david brum]

Longer fences are especially helpful when cutting large sheet goods. As the bulk of the wood gets past the end of the fence, it gets harder to keep the wood from tilting away and ruining the cut. The longer the fence, the easier it is to make those straight cuts. I personally wouldn't mind if my Shop Fox fence were even longer.

[Mark Rakestraw]

+1 on what David said for sheet goods. Then ripping solid wood however sometimes tension is released and the board starts to move beyond the cut. In this case it's helpful if the fence stops immediately after the blade, other wise it pushes off the fence and ruins the cut. European fences and the old Unifece were adjustable so you could move the fence fore and aft. I have a version of that on my saw and really like that feature.

[dave pant]

Thanks guys I think I will just keep my fence at 34" then. I dont usually cut big sheets and this seems like it would be ok for both types of work.

[Mike Schuch]

+2 except I really like having a fence that extends in front of the table too when I am cutting 8 foot sheet goods. It makes for a MUCH straighter cut.

If it were me I would make a fence with a 34" face that can be easily removed and replaced with a 60" face for those occasions that long work pieces present themselves.

What are you going to use for locking the fence in place for a cut? Are you going to have a lock on the front and back rails? How do you plan to adjust the fence for square? I assume you will have two linear bearings spaced some distance (maybe a foot or so) apart on both front and rear rails to maintain square? If so what would be the pro's and cons of just having the whole fence be a foot wide?

With linear bearings on the front and back it seems like the difficulty will be making the rails perfectly parallel once mounted on the saw so the fence doesn't bind.

What kind of saw is the fence going on?

How long do you plan to make the fence? Are you going to use open carriage bearings so you can mount and support the 1" rod at various points along its span? The rods might also make a nice mounting point for movable front and rear support tables?

[dave pant]

Ill post this picture. They say a picture is worth a thousand words right =)

linearbearingfence.jpg

1.I would have to buy 2 more bearings if I made 2 fences.
2. To lock it there is a clamp like thing that when I turn a knob it locks down on the rail.
3. I am just locking the front bearing on the rail.
4. I will adjust the fence square to the table and then to the front and back of the blade.
5. I am only using 1 bearing on each end of the fence.
6. The fence is only going to be 2.5" thick and 3" tall with extruded almuminum on the top for accessories.
7. I am using round shaft for the rails these are pretty tolerant of misalignment. As long as I am really close they should glide smoother than any fence made.
8. The fence is going on a 12" old Craftsman floor saw.
9. I plan on making the fence 34" to take it off I will just slide it off the end of the table.

[Chris Parks]

I think the fence needs to be modular to set up the alignment. My idea would be to make the carriages each end and then attach the fence to these with an adjustment of some kind between the fence and the carriages. One end has the adjustment the other end must have a pivot, not to do this would defeat the use of the bearings, it would make a really sweet system. The fence face could be made either extendable like on some compound sliding saws or a quick release attach system for different lengths.

[dave pant]

Im not following you totally but I think I kind of do. The picture that I made doesnt actually have everything on it. I only put 1 bracket on each end but actually it will have 3 that are adjustable for hieght.

[Chip Lindley]

Einstein said: "Everything should be made as simple as possible, but not simpler." If you are adding two linear bearings to the front rail, you are on the right track.

As with the Biesemeyer T-square fence, the wide stance of the front angle provides lots of stability, registering the "Tee" squarely against the guide tube. Also, the outboard ends of the "Tee" have adjustable pads for squaring the fence exactly; not just almost!

Another BIG concern (for me) is that there seems to be no ready way to add a self-adhesive rule and pointer on your Thomson fence to measure rip width quickly and accurately.

The fun is in the experimenting. Make your linear bearing Fence as you see fit. The obstacles you run into will have to be overcome, OR the project will have to be scuttled as close, but no cigar! Just food for thought.

[dave pant]

Another BIG concern (for me) is that there seems to be no ready way to add a self-adhesive rule and pointer on your Thomson fence to measure rip width quickly and accurately.

I have a Digital Wixey scale for measurements.

[Chris Parks]

Second time around, hope I don't lose it this time. The bearings have to be concentric to the rails to move freely but the fence needs calibration to align it to the blade an mitre slot. The chances of doing this while building it and then bolting the assembly are somewhere between nil and damned all so it needs to be allowed for. As a ruke you need a bit of toe out on the outfeed side so the timber does not become trapped between the fence and the blade.

Make the bearing carriages with adjustment on the out feed one that can move the fence sideways an appropriate amount and the other end will have to have a pivot because you don't want to pull the bearing carriages out of line with the rails. The pivot will have to be lockable after adjustment or it will move all over the place, DUH. It only needs to be locked at one end. The bearing carriages may need wiping seals to keep the crap out, suck and see I guess but I would put some in, they only need to be felt seals not neoprene as the felt ones will have less stiction.

[bob hertle]

One comment Dave,

You need "wheelbase" at the front, IOW, 2 bearings spread apart by a reasonable, say 10-12" distance. It will do 2 things: Make it a whole lot easier to square it up, and provide moment resistance, or the ability to stay in square after you smack the far end with a sheet of plywood. Don't rely on a single Thompson bearing to do this!

Regards
Bob

[David Keller NC]

Dave - Can't answer the question (rip fence length) for Biesmeyer's design, but there's a feature to a uni-fence that you might consider copying since you're making your own. A uni-fence allows sliding the fence perpendicularly to the front edge of the table. By doing this, you can have the back end of the fence terminate just before the blade, which means that you can use the fence without extra clamps/jigs as a stop when cutting the shoulders of tenons (or making a number of small cut-offs of exact length). This feature also allows one to use an auxillary infeed table, with the extra fence length on the infeed side, which makes aligning glued-up panels and sheet goods for the intended cut very accurate indeed.

[Jamie Buxton]

One additional feature that is really useful is the ability to easily remove the fence. I use my table saw for cross cuts (with a cut-off box), and the fence needs to come off for longer pieces. With your choice of linear bearings, I think they'd have to stay in place, and the fence would need to separate from the subassembly that holds them. But when it goes back on, it would need to return to be exactly parallel to the blade. Ideally, the removal and replacement would be done without tools, in just a couple seconds. The Beisemeyer and Unifence designs do.

[dave pant]

I think Im with ya this time Chris =).

Well this is what my plan was.

currently I know the blade and miter slot are parallel.
I was just going to sit the fence in the spot where it belongs which is butted up against the fence.
Then slide the bearings under and bolt then to the fence in that spot.

@Jamie -> My fence will be a little more annoying because I will have to slide the fence off the end of the rails instead of just lifting it off.