A while ago I read Chems thread
https://www.ukworkshop.co.uk/forums...w-and-router-t28797.html?highlight=guide rail detailing a circular saw and router guide track he made. I'd been thinking about how to make a guide rail and the design I'd come up with was pretty similar so I thought it was worth a go.
My aims were: to reduce the thickness of the track so that I could maintain a good cut depth as I want to use it on material up to 40mm thick, not modify the base of the saw if I could get away with it and to build it without needing to build a router table first.
The solution I came up with was this (sorry for the terrible picture quality I got carried away building it and forgot to take photos - if anyone is interested in this design I'll try and take some better photos of it):
The track is a piece of 9mm thick MDF laminate flooring (pic 3). I ran the long tongue edge over the planer to make it dead flat and then routed three parallel grooves down the length of the board (10mm wide by 4 mm deep IIRC).
I decided to make a shoe design rather than the more common mounted plate for the circular saw for two reasons. Firstly it would allow me to keep the part that attaches to the saw very thin since it wouldn't need to accept counter sunk bolts and secondly there were no obvious points to drill though the base of the saw.
To make the shoe (see pictures 4 and 5) I cut a piece of 6mm ply a little larger than the base of the circular saw. I retracted the blade guide and sat the saw on the ply then carefully glued blocks around three edges of the saw. This gave me a nice tight fit around the saw with no play.
I then cut and carefully planned up some scrap pine so that it exactly fitted into the grooves in the track with no play (see picture 1), this took a little while but it wasn't too hard. I made the runners such that when they were in the groves they stood about 1mm proud of the track. I spread a thin coat of glue on the runners and pressed the shoe down on to them. Once the glue had dried I put some 80 grit on the bench and carefully sanded off the additional 1mm on the runners. This sounds like a lot of messing about but it's imperative that the runners line up exactly with the grooves or the shoe it will bind up and you want the shoe to run on the track not the runners which are there just for guidance.
To finished the shoe I drilled two holes and expoyied in some bolts (see picture 5 again). I made some hooks out of an old shower cubical (I couldn't find any that fitted that didn't cost the earth) and I use wingnuts to hold the shoe onto the saw.
Finally, I had to deal with the track moving while cutting. I first tried clamping the track to the piece, that worked but it was a lot of messing about so I decided to try non-slip netting. A trip to the shops and £1 later and I had the problem fixed. I've just used carpet tape to attach the non-slip netting to the track (pic 2).
Pic 3 is just after cutting though a 30mm piece of oak. Over all the track assembly is about 16mm so I'm pretty happy and it cuts a surprisingly good straight line. Total build cost as <£5 - I had to buy the wingnuts.
The main downside of this design are that because the track isn't clamped down you have to be a bit careful when you first start off. The weight of the saw is beyond the end of the work piece which can cause the track to pivot up slightly and drift away from the line at the far end. I know this from experience as I got complacent and rushed a cut which ended up a 2mm from the line.
Hope you like it.
