Some of the jigs I make are jigs I wished I had made a long time ago, and this is one of those jigs. Yes, I did make another jig similar to this a few years ago, but this one seems easier to use and adjust, and the bonus is that with the clear plastic base, even with sawdust flying, I cans still see farily well what I am doing.
For the construction of this jig I decided on using a better grade of 3/4 inch plywood. I didn't have enough longer pieces around so time to go out and purchase a full 4 x 8 sheet.
Watch it on Youtube: https://youtu.be/bm9SDuWIAk0
I starte off by using my circular saw to cut strips off the 8 foot side of the sheet. I cut 2 of each of the following 3 inch, 2 inch and 1.5 inch, these would form the rails that the carriage would slide on, I also cut one more 3 inch that would serve as the sides of the carriage. I also found I did not have any clear plastic chunks bit enough so off to the plastic store to snoop through their cut-off bin to see what I could find ...
The only piece that I could find that was close to the measurements I wanted which was about 10 or 12 inches wide by up to 40 inches long, was a sheet of Lexan. I have never worked with Lexan and all I really know is that it's a bit more expensive and it has a high shatter proof ratio which is why it is used and sold as bullet proof glass. The guy at the plastic shop told me it cuts and drills almost identical to the more common clear Plexiglass plastic I would normally use. He said I would be fine with it ... and he was correct.
I started off assebling the rails and glued the 1.5 and the 2 inch size strips to the bottoms of the 3 inch strips. I used yellow glue and my air nailer to pin the strips on rather than trying to clamp them. I cut my rails at 5.5 feet. This would accommodate wood that is 5 feet long, such that I might use for desk or small table tops.
After the glue was dry, I ran the bottom side of each rail through my jointer to get a nice flat, even surface. I then ran the upper side through my table saw to make sure the tops were also flat, even and parallel and after that treatment, both rails were identical and even.
The first thing I needed to do for the carriage was to ensure my plastic sheet was slighly sider than my router base as it sat between the plywood sides. In my case I only had to trim the end of Lexan sheet, which I did on my sliding mitre saw, slowly and carefully by easing in from the to and it cut off perfectly. Next I needed to take of my plastic router base so I could emmulate the holes into the Lexan as that ould need to be my new router base for this jig. I used a large punch to find the holes, then drilled pilot holes through each punch mark and flipped the Lexan over and used those pilot holes as guides for my forstner bit to make recesses that would allow the router base plate screws to attach. The sequence of doing these holes is important. DRILL THE HOLES FOR THE TREADED part of the bolts LAST, otherwise you have no reference for the forstner bits when drilling those recesses.
I also happened to have a hole saw that was slightly larger than the diameter of my planing bit so I used that drill out the center hole in the Lexan.
The last thing was to decide on what size screws that I would use to attach the Lexan to the sides of the carriage. I opted for 2 ich #6 screws, only beasue my experience int he past with countersinking holes and driving screws in has been that sometimes this cracks the plastic, so in this case I opted for smaller screws, but more of them.
The last step is assembly, I attached the plastic base to the sides of the carriage and hand tightened each screw.
I found some 2" fir that would would make a good cross piece for the insides of the carriage, so I measured that carefully and attached those pieces with some 3 inch flat head screws, and finally, I attached my router and inserted the planing bit into it.
I found a piece of board to use as a test piece and secured the rails to my workbench and the wood, and when everything was secure, I set the depth of the planing bit to take of just a skim of the board I was planing after finding the high point of the board. I knew this process could take a few passes depending on how warped the board was, but in my case the board was quite flat so I was able to plane most of the board in the first pass.
I was very impressed witht he Planing bit and the Jig ... both worked exdeedingly well and what I really like was the fact that I could see (through the sawdust and chips flying) where I was in the board being planed and where I needed to go. the clear base worked better than I expected.
All in all, this as a fairly easy jig to make and gave me great results on my test board ... looking forward now to planing a live edge desk I am planing to make ..
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Copyrigth Colin Knecht