Introduction: Homemade Table Saw - Part 3 - Lead Screw, Sledge Fence Stop & Finger / Comb Joints Jig

In this video I made an attachment to a simple sledge, of a fence stop and lead screw.  The pitch on the threaded rod is 1.25mm and the thickness of the blade is 2.5mm.  With every two full rotation of the wing knobs the stop moved the same distance along the fence as the thickness of the blade.  With intervals of four rotations, the cuts should align to create finger or comb joints.  It is a bit fiddly but worked.  I will have to do a bit of sanding to get it right because at the moment the last join felt really tight.  I am also probably using the wrong kind of blade because the cut leaves a bevelled groove.

0:12 I mark a guard to slightly cover the exit area of the saw blade.  I should have really left more space behind for a piece as long as 2/3rds of the blade but this will have to do for now.  I cut these out very quickly on the sledge.
0:52 I square off an offcut and mark the two outside corners to be cut.
1:53 The plan is to use a piece of threaded rod as a lead screw.
2:04 I square off another offcut to make the fence stop.
3:24 I glue down the blade guard.  I kept the gap between because the contract between the shadow and ply would remind me there is a blade in there, and also it is another a space for saw dust to shoot out at me.
3:36 Marking the centre of an t-nut onto a square ply which I will add to the fence stop later.
3:50 Gluing the stop down over the fence.  In retrospect I should have made this with insert nuts so I could take the stop off when cutting longer pieces.
4:12 I drill the holes using a size 4 drill bit and hold the pieces over each other drilling through to make them.  This feels quicker and providing you have a good grip while holding the pieces at an identical corner, they should be pretty accurate.  I then drilled them to the larger sized.
4:41 Gluing and clamping edge pieces.
5:08 I use a forstner bit to sink the head of the t nut into the wood.  I glue this to another identically sized piece of wood and then the lot to the fence stop.
5:59 After the glue has set, begin to screw everything down.
7:00 I feed the threaded rod through.  It is not a real lead screw so it will always have a bit of play to it.  I had to increase the size of the holes on the outside blocks to compensate for this.
7:23 I try to collect easel wing knobs when I find them broken and thrown out.  They are really nice, large aluminium things which I am locking in place with a nut on either side.
7:42 It takes a while to go across but it seems to work.
7:48 I am squaring off some scrap wood I found and doing to have a go at making the joints.
8:05 Raising the bed so the bald protruded just a little higher than the thickness of the material I am going to cut.  It’s definitely a little awkward to use this design and I have began to think of a new design for a table saw.
8:20 Clamp two pieces together offset by the thickness of the blade.  The pitch on the threaded rod is 1.25mm and the thickness of the blade is 2.5mm.  With every two full rotation of the wing knobs the stop moved the same distance along the fence as the thickness of the blade.
9:01 It was so tight I didn’t need any glue.  As you can see I am hammering it quite a bit because it was too accurate leaving identical spaces between the cut as the saw blade made.  In future I am going to have to work out a way of, either with different rotations or gearing, to allow slightly smaller teeth between each cut.

Comments

author
andrea biffi (author)2013-05-27

Very interesting, thanks for sharing!!