Mortiser Fence-Setting Jig

[OPJ]

Hi guys,

As some of you may recall from almost a year ago, I bought an old cast iron benchtop mortiser (labelled "Smiths Woodworker"; very similar to Multico in appearance) off eBay (barely visible in the shot below... ).

Overall, I'm still impressed and very pleased with it - it remains a vast improvement over my former Fox mortiser! :wink: It has a cast iron bed that moves left and right but, not forward and back. This means I have to manually adjust the fence by slackening off the two mounting bolts and sliding it (near-impossible to keep it parallel and square to the chisel).

That's the only thing I really don't like. One suggestion I was given previously was to set it once and cut a load of spacers to reduce the distance from the fence to the chisel. However, I'm now thinking of building a pair of setting jigs, like this:

Yes, it's heavily inspired by something I've seen Steve Maskery do (on his router table, I think?). :roll:

I can't think of a way to join them together - at least, not without removing the clamp in the centre - so, I think it'll have to be a pair - unless anyone can see another way? There's not enough room behind the fence, either.

Basically, I'll use a length of M6 studding to set it to the current fence position and then wind in back or forward by a certain amount, depending on where the fence needs to be, and offer the fence up to the new setting before retightening. M6 has a 1mm pitch, apparently and, as Steve always says, a Bristol lever on the end [not illustrated] makes it simpler to count the number of rotations. :wink: I may try and add another lever on top (hence the two holes) to lock the setting. Or, I may not bother.

Each jig can be G-cramped to the bed of the machine. I may even add a couple of rare earth magnets as well.

So, what do you think?

Thanks for looking.

 

[Steve Maskery]

Hi Olly

Hmm. Personally I think you are making it all too complicated. Don't get me wrong, I'm delighted to be an inspiration to the younger generation of whipper-snappers, but what is wrong with using a combination square to set the fence? Just set it to the distance required from the front edge and bring the fence up to it. If both ends are the same, job done.

If you do make a jig like this, I would not have your invisible Bristol levers clamping directly onto your lead screws, the thread will get damaged in no time. Make it so that the wood itself clamps to the lead screw.

 

[SketchUp Guru]

Is the front of the table where your jigs will hook, a valid reference for squaring the fence to the chisel? Do you know that the front edge is machined so it is parallel/square to the chisel? If it is, I think Steve's suggestion of using a combination square is a good one. If it isn't, then I think your two jigs make some sense. Then, assuming you start with the fence squared to the chisel and can always use wind the same number of turns on both screws you'll be fine.

I would add some sort of disks with index marks to the screws so you can count fractions of a turn.

I'll throw out another Steve Maskery-inspired idea. He's full of them, you know.

Use his opposing wedges between a reference edge and the fence. Make the wedges with a 1:10 slope so that if you move one 1mm along the other, the width of the pair will change by 0.2mm. The reference edge would need to be made to straddle the clamp. Install it with the fence parallel/square to the chisel and attach the hooks over the front edge. Then you should be all set. Quickie, low quality sketch follows.

If the wedges are made long enough, the notch in the reference could be placed on the fence side so the reference can slide in. Let the wedges straddle the gap.

 

[OPJ]

Steve, thank you - the idea of using a combination square is so simple and yet, at the same time, so effective. I'm disappointed I didn't think of this myself, as I regularly use my square for all sorts of tasks just like this. :roll: I will double check that the front edge of the table (both sides of the mount for the clamp) are straight and true to each other though.

(I'd guess they might have used a combination square back in the olden days, when this machine was first built.... :wink

Dave, thank you - I do like the idea of using 1:10 wedges, as per Steve's bandsaw fence. Sadly, it looks like I may not need it, though...

Thanks again to both of you for saving me a lot of work!