If the pipe on your projector is the same as mine you'll need to get a 7/8ths piece of square tubing. This is the first thing you need Do this before you do anything else or you realy are going nowehere fast.
there are a few companies that make the stuff. but i didnt get any response to my inquiries for a single piece of pipe.
3/4" angle iron joined with another piece facing it to form a tube is 7/8ths so i had planed on trying to weld two pieces together. a 7/8ths piece of pine is two soft and frnkly a bit flimsy any way to take wieght of the head and to hold up to the roollers inside. Also it needs to cut pretty truly to not have the rollers loose there grip.
what I ended up using is this. A piece of aluminum edging 4foot long. Its a channel ment to be put over the edge of a 3/4" piece of plywood. I had intended on uning two of them.sourounding a piece of wood. cut 3/4" - 5/8" 4 feet long. and to the length of the edging. I was going to use two piece cut of the excess and fit them together over the wood. I ended up using one instead. I had some scrap wood cut from a differnt project that fit perfectly so didnt feel like cutting off the exess metal. if I end up haveing problems I'Il go back and do that later
just put the edgin on your cut wood and test the fit on your projector head. Its a little tricky getting it in theres a sliding wedge that likes to fall out and mis algin itslef. you have to push in place and up to have enough room to ge the arm. (yours and the original) If the fits to tight to roll up and down easily plane the wood thiner or sand to fit (only use a planer if your planer will take of paper thin shavings) be careful if you make low spots it wont grab and you'll have to start all over again. Smooth the wood with some fine sand paper. dont take of much wood your just making a smoother surface here.
once i got the fit righ and snading done i rubed a little parfin wax on the back of the wood to act as a lubricant
add a screww to at least two points throught the metal into the wood. if you couneter sink the holes for a scwerhead to fit in you"ll have eonugh clearance to get all the way to the top of the. the second spot will have parto the bracket on it so you dont have to worry about the second screw right now. If you want to glue it in i have no problem with other than that i dont know how long the aluminum will hold up against the steel roller and if the glue changes the thicknes you have more work to do thining it out. again.