Tablesaw rebate fence

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Steve Maskery

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Several years ago, when I was filming my DVD series, I made a secondary fence for my tablesaw which was designed to help when using the tablesaw to cut rebates or grooves, such as as you might have for a cabinet back.

It worked very well, but it went into storage in a barn for a couple of years and didn't come out again. I now have a particular use for it, so it is a good opportunity to make a new version which also happens to improve on the original.

The important thing about a groove or a rebate is that is is the same depth all along its length. I don't want it to be shallow in one or two places because the workpiece has risen up above the blade. It also has to be straight, not slightly wonky because the workpiece has wandered away from the fence. This fence addresses both these issues.

It consists of an MDF fence which clamps to the main saw fence. There are two featherboards, one just in front of the blade and one just after, as well as an adjustable guard, which keeps my fingers and the saw blade apart, even when there is no workpiece between us.

The original featherboards were cut straight at 90 degrees, but I figured that if I angled them in the right direction, I could get them to pull the workpiece in towards the fence as well as down onto the table. This turned out to be easier said than done!

My first attempt was to cut the shape, rout the slots and then make a series of stopped cuts on the tablesaw to give me a set of fingers, all cut from one solid piece of wood. Unfortunately I had got the geometry wrong in my head, so I ended up with a fine-looking featherboard that pushed the workpiece AWAY from my fence, the exact opposite of what I was trying to achieve.

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This happened because my tablesaw tilts to the right, towards the fence. If I had a modern design where the blade tilts left away from the fence, all would have been well, but that is not the situation in which I found myself.

The idea remained a good one, however, so I simply had another go. I cut a load of individual fingers and spacers and glued them together, but whilst it worked properly at the end, it was a nightmare to glue up, because the fingers slid sideways over one another as I applied pressure across. Keeping it all flat was very difficult.

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There had to be a better way and I went back to the original idea of cutting a series of kerfs in a solid piece. And if tilting my blade to the left isn't an option, the workpiece must be tilted to the right.

The Jig.

I made a jig. Well that is a rather grand term for three pieces of scrap, but it'll do. I took a piece of OSB, about 400mm x 180mm, attached a runner underneath the left-hand edge and a lip along the right-hand edge. These were glued and screwed, but the screws come out once the glue has cured.

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With the screws out, I ran the jig over the surface planer to give me two flat areas, and trimmed the lip so that it had a vertical side.

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The featherboards.

I started with a board long enough to make both featherboards. This gives me plenty to get hold of instead of trying to make stopped cuts on a very short workpiece. I marked out where the slots were going to go, as well as the limits of the fingers.

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The featherboards need to be adjustable in height to accommodate different thicknesses of workpiece, so the first task was to rout the slots in the edges of the featherboards.

This is done by “dropping on”, which means lowering the workpiece onto the cutter while it is already spinning. It's not the easiest of operations tp perform, but it can be made a lot easier and safer by clamping a couple of stops to the router table.

If the stop needs to be off the end of the table, I can clamp an OSB hook to the fence instead of a block of wood to the table. It does the same job.

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Starting with the workpiece hard against the rearmost stop, it is lowered onto the cutter and pushed forward until it hits the end stop.

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I cut the slot in several passes. The first pass, in particular, needs to be very shallow indeed, because there is nowhere for the sawdust to go. Thereafter there is at least some space in the existing groove to take the sawdust. I continued, taking not more than 3mm per cut (it is all too easy to snap a 6mm cutter), until I had broken through the top surface.

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The second pair of slots requires me to alter the stops, but the fence stays where it is.
 

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With the slots routed, it was time to cut the angles. The featherboards are angled at 30 degrees to the bed of the saw, so the ends of the board are cut on the SCMS. It's easier to do this now than after the fingers are cut.

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On the tablesaw, the jig is put with the lip against the fence, in a position where the blade will cut the kerf furthest from the fence.

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I pushed the workpiece, complete with the supporting jig, into the blade until I reached the limit line, then stopped the saw.

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A kick-stop is a boon here, as I don't have to take my hands off the workpiece in order to stop the saw.

I turned the workpiece round and did the other end in the same way.

Now the job has to be moved over for the next cut. I inserted a 6mm piece of MDF between the workpiece and the fence, I held the workpiece down hard on the table, removed the MDF and slid the fence up to the workpiece. This moved the whole thing over by 6mm.

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I made the second cut, then repeated the whole operation until I had made a series of fingers, at both ends, right across the face of the board.

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I separated the two featherboards, trimmed back the sides where the slots are by a few millimetres

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and cleaned the whole thing up. Corners were rounded, edges smoothed and all the stray whiskers sanded off.

I had two splendid featherboards.

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The fence itself is a piece of MDF skirting board. I marked directly through the slots of the featherboards to mark the positions of the clamping levers.

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However, when drilling for this kind of fixing I have to start from the back, because the larger hole which will accommodate the embedded nut needs to be drilled before the clearance hole for the Bristol lever. The easiest way of transferring these positions from the front face to the back is to drill a tiny hole, just 1.5mm, from the face, all the way through. I can then turn the board over and see exactly where I need to drill.

The first hole is 10mm diameter, and just deep enough to accommodate the nut, about 7mm. Then a 6.5mm hole is drilled right though.

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Using a bolt, a large washer (to spread the pressure), and a 10mm spanner, I pulled an M6 nut into each hole

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Next, we consider the guard. I routed a V-groove across the face of the fence at 30 degrees. This was done by removing the fence of my router table, inserting my tablesaw mitre fence and clamping the workpiece to it.

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A corresponding V-groove was routed in the guard support.

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This guard support also needs a slot making in it, but as this piece is thicker (I wanted a bit more surface to attach the plastic guard itself), it would have meant making many shallow cuts with the router table. Instead I took the easy option and set to with my Domino...

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The guard support is aligned with the fence by a key, a length of square-section wood, which mates the two V-grooves. It has to be very precisely machined – too big and the support will not sit well on the fence, too small and it will allow the two parts to move about. It needs to be a Goldilocks fit.

I made another embedded nut in the same way as before. If I had thought ahead I would have done them all at the same time and saved myself the double set-up time.

I then cut 4 Bristol levers to 55mm long, just right to clamp the featherboards to the fence. A washer between the featherboards and the fence keeps the feathers from binding.

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At the moment, the featherboard fence is just clamped to my existing fence, but I'm going to see if I can improve on that, as the clamps are a little bit intrusive. If you have any bright ideas, I'm all ears.

In use, the featherboards are adjusted so that they just press lightly on the workpiece. Not so hard that it becomes difficult to push, but enough to hold down. The guard is adjusted to be just clear of the board. At the end of the cut, I need to be using a push-stick that is thin enough to use flat on the table, to get underneath the guard.

The result is one very clean, straight and even groove or rebate.

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Very impressive, especially the way the geometry of it pulls the workpiece into the fence.

Aigner used to do something similar, I can't remember the price but knowing Aigner it was probably about £800!
 
Genius, Steve.
These are the sort of details I would not think of in a million years.
As for clamping Axminster sell universal fence clamps.
 
custard":18xu7xt3 said:
Very impressive, especially the way the geometry of it pulls the workpiece into the fence.

Thanks for clarifying that - I was trying to work out why the fingers themselves were being cut diagonally front to back.
 

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