Thread: Leadscrew router Planing/Thicknessing jig

Gday all

In this thread a while back I was looking for ideas on how to make a router planing & thicknessing jig with an indexing system to advance the router across the workpiece for each pass.

I have been vegetating on the design of it for ages, have accumulated the bits over this time, and have built it in the last week or so.

I wanted it big enough to handle a workpiece 8 ft long, up to about 450 mm wide, and up to 4 thick.

For the base of the fixture I used half of an 8ft aluminium extension ladder. This gives the base plenty of strength and rigidity, I didn’t want it sagging in the middle with the weight of the router carriage moving across the top and/or the weight of the workpiece. This ladder base sits on the Triton Superjaws and Multistand, the pivoting head on the multistand is useful to ensure that the ladder sits flat without any twist.

To the ladder I screwed a piece of 25mm chipboard, the same width and about 6 inches longer. I would have preferred melamine for this sub-base but didn’t have any thicker than 16mm, and I was concerned rebating the sail track would weaken it too much. When nearly finished building the jig, I found that it didn’t slide very well over the chipboard so I ironed on melamine edging to the edges and the sides of the top face of the sub-base. This was waxed with paraffin wax. 32mm benchtop chipboard with laminate and edging applied would have been great for this sub-base.

A length of Capral sail track cut into 4 pieces was set into the chipboard by routing a trench and screwing it in with c/sunk screws.

I made up some dogs to slide in the sail track which each have a ¼” cup head bolt, washer & nut to secure in place. I used some offcuts of 40x8mm KDHW cover strap for the low profile dogs, and some offcut 65x19 KDHW bevel skirting board for the bigger ones. These have small brads hammered in to the edge and clipped off to make small sharp points.

The router (mine is a Hitachi M12V) sits in a carriage, it is the Triton router table mounting plate and clamping setup bought as a spare part direct from Triton.

The carriage sits in and moves across the carriage base, or gantry as I reckon it looks like. The gantry consists of two angle iron rails (40x40x3mm I think) spaced apart and braced the width of the carriage by a couple of pieces of 19mm ply Each end of the gantry has spacers of more 19mm ply to elevate it off the sub-base, which are easily added or removed to give a planing thickness from 108mm down to 0. On the bottom of the spacers are sliders made of some black (possibly polypropylene) plastic (remember that plastic skip load in Bayswater or Boronia on Cup Day a few years ago, Sturdee? )

The sliders were rebated on the router table so they are an L cross section, which runs on the top and locates the gantry against the edges of the sub-base.

For the indexing function I was so keen on incorporating, I used some 12mm Reidbar and coupling nuts. The Reidbar is steel concrete rebar which has a coarse screw thread (roughly 4tpi) and various proprietary fittings are available which screw onto the bar. Same principle as allthread & hex nuts.

I needed to fix one coupling nut to the traveling router carriage, this was managed by routing a piece of pine into an inverted channel profile and securing the nut by screwing the wooden channel over it onto the router carriage. This secured the nut in place while allowing the reidbar to run through it without fouling.

To the end of the gantry I secured a couple of bits of the 19mm ply with a hole drilled for the reidbar to pass through. I cut a coupling nut into 4 shorter nuts, and locked each pair of these either side of the ply, with a couple of washers cut out of thin polyethylene to cut down friction & wear against the ply.

I made a crank handle by cutting out another piece of the ply with the scrollsaw, and securing a couple of small bearings on the end for a knob with a bolt & dome nut. The middle of the handle was chiseled out about 5mm deep to house one of the short nuts, and the handle was locked between the two nuts on the end of the reidbar.

To set up, the base is sat on the superjaws & multistand. The superjaws are clamped lightly onto the base, after the multistand head is leveled to it if necessary.

The carriage/gantry is then set onto the base, and the router clamped in, with a 38mm tray cutting bit in the collet.. A 8ft long piece of scrap with a notch cut in the end is set above at an angle from which the router power cord is hung to keep it out of the firing line.

The workpiece is secured onto the base with the dogs, with corner/s propped up with plastic wedges if necessary to stop it wobbling.

The router is fired up, depth set, and with one hand on the crank (er, so to speak ) and the other pushing the gantry is moved back & forth over the workpiece. In between each pass the crank is turned the desired amount to achieve the lateral movement. This was 1-2 turns for fast cutting and ½ turn for a finishing cut.

The quality of the cut is amazing, I tried it on 2 pieces of redgum (one with straightish grain & the other with great fiddleback) and another piece of unknown parentage, and they come out dead smooth & flat, and the high angle cut of the router bit really handles the cranky grain well.

I was really pleased with the speed of cut too, the Hitachi router has plenty of grunt which helps, but is very quick to slide back & forth adjusting the crank each time.

This is the beauty of the lead screw idea I reckon, you can stand upright, just swaying back & forth & watching the cut, so it’s not taxing on the back or neck.

Thanks for reading, and sorry about how wordy this post is, I was just stoked with how well the jig worked and wanted to record the detail in case anyone else wanted to build one.

Plenty of pics to follow.

Cheers……………….Sean