Need help w/ fence jig concept

[cgallery]

I'm working on a push block/jig that straddles the fence. The purpose of this jig is to hold a piece of wood on its end so I can put a mortise in the bottom, using my router table (I use my BT3K fence for routing as well).

So I'd like the straddling jig to fit tightly (little to no slop) but not bind.

Niki (Nikki?) once posted a method where he used some wheels and bolts to remove slop from a similar jig. A good idea, but may add more than I'd like to the complexity and bulk.

A complicating factor is that I have some wooden "cheeks" on the router side of the fence (to provide bit clearance). I imagine that when these have to be replaced that the thickness would change a little bit. I'd like my straddling jig to be able to accomodate small changes to overall fence thickness.

Any good alternatives?

[RodKirby]

Any ideas from this...



http://www.woodhaven.com/detail.aspx?ID=1895

[mpc]

My immediate thought is based on the assumption that you want "to fit tightly (little to no slop) but not bind" to keep the jig dead-vertical.

Instead, how about an out-rigger setup like those Polynesian canoes? A vertical piece for the main support of the workpiece, a horizontal one attached to it, this horizontal piece runs over the top of the fence. It has a couple slots in it for bolts to hold a stubby vertical piece that runs along your router face cheek pieces (allowing thickness adjustability) but it also continues horizontally for several more inches... and then has a fixed down-piece (out-rigger) that rides along the router table top. This extra wheelbase will give it a lot more vertical stability.

mpc

[ragswl4]

Here's the link to Niki's rolling mortiser: http://www.bt3central.com/showthread.php?t=31548

[cgallery]

Thanks for all the input. I came up w/ something similar to the roller system, but uses a pressure plate which is really just a piece of plywood.

I've included some pictures here. Basically, the thumbscrews push on a piece of wood which pushes on the fence. I can make the thing slide as loose or tight (or lock it in place) as I like.

I'm going to use this for making the mortises for floating tenons in some face frames I'm making. I just need to make some stops for the top of the fence.

It is held together with furniture-type bolts and cross-dowels, so I can adapt it to other uses as I see fit.