There is a whole range of plastics designed for just this purpose. Many have a lubricating agent built in. I have used both teflon and Delrin which is my preference because it is easier to machine to a precise bore. Holes really need to be bored out on the lathe or mill, drilling is just for the first rough cut. Your boring tool will need to be ultra sharp and set exactly on the centre height or a micro poofteenth below centre otherwise it will dig in. If you have trouble getting the correct bore, bore out as close as possible or just oversize then slit the block half way thru. It may close up, not a problem as you have left room for three screws in line passing thru the slit into the opposite side of the block. One is threaded into the near side to open up the hole, the other two threaded into the far side to pull the hole in. Hope this is clear. |