How To Make A Straightedge Guide Homemade Machines & Jigs
A project on my to-do list for a long time has been a self-clamping straightedge guide made from wood. Years ago I had a retail version, made from aluminum, but found its performance lacking. In particular it would not grip tightly enough, slip and throw off an important cut.
I worked through several designs for this before settling on this one, and I think it hits all the right targets:
- it grips extremely well
- low profile to get the max depth of cut from your saw
- the laminated structure keeps it very straight
- easy to make with commonly available parts
I started cutting out the rails and it’s important that clear, straight grained stock is used for this. I made a series of cuts on my table saw to end up with parts that were straight and true, a method I used in past when I didn’t have a jointer:
I used solid maple for mine, but you can also use any good quality plywood. Baltic birch in particular would make perfectly suitable rails.
The cam handle is probably the most complex part of this project, which says a lot about how easy it is to build. The cam is detailed in the plans and I also show how to lay it out in the build video at the bottom of this page:
Cut out and fine tuned on my belt / disk sander, note the offset of the pivot hole in relation to the outer circular cam surface:
It only takes 1/16″ to get this offset for the right amount of clamping action. I made mine from Baltic birch plywood, but any hardwood will work as well.
Also part of the rabbet has to be cut away for the cam handle to fit between the rails:
The rub plate is made from layers of flexible slippery plastic. I used the lid from an ice cream container and cut four pieces to size:
The first two layers are screwed to the front clamping block with a #6 flat head screw. These physically hold the clamping block in place on the guide.
The cam handle swivels on a steel pivot pin held in place by the pivot blocks:
The pin is 3/8″ and fits snugly in the pivot blocks, but the hole in the cam handle needs to be slightly larger for it to rotate freely. I used a 25/64″ bit to ream it out after drilling the hole with a 3/8″ brad point bit.
The first assembly step is to glue the rails to the top. I used a pin nailer to drive in short pins to keep the parts in alignment:
After the glue dries, the front clamp block / rub plate in put into the slot:
The cam handle is glued on next. Take note of the way the cam handle is oriented, pointing down like this with the guide upside down:
That positions the cam correctly so that it will push on the rub plate as it rotates. You can see this in action in the build video below.
I made convenient marks on the end for common sheet stock sizes:
And to improve the grip of the end clamping block, I glued on a piece of sanding belt:
I used polyurethane construction adhesive for this, but epoxy would work as well:
Set up to trim the edge of this 24″ wide piece of plywood using the router:
And this 48″ wide sheet with the circular saw:
It also works great to improve the cut quality from a jigsaw, when that’s the only tool you have. Out in the field it can be used as a fence for a jerry-rigged table saw using a circular saw.
Here’s the build video covering more details:
If you’d like to make one for yourself, easy to follow step-by-step plans are available:
Straightedge Guide Plans