Many weeks ago I asked for suggestions on hw to cut an 18" radius on my small mill. There were several suggestions and in particular Jason showed pictures for two methods. Some calculations showed that neither would work on my mill because the work required exceeded the size of my mill. I had to revert to my original idea of moving the workpiece with a leadscrew. Since I could use the leadscrew in the final project, a lot of work went into making the pieces. The screw is 316 SS single point threaded for a tight thread in the tapped hole in the steel follower which has to align with the reamed hole in the brass post.
The workpiece was clamped to a piece of 1/2" aluminum plate which was in turn mounted to the table on a pivot spaced above the table for the leadscrew to fit.
The slot was first cut with a ball end 1/4" carbide endmill and then opened up with a reground 3/8" HSS endmill and both edges cut to final size. The whole thing was a hairy-scary operation. No way to hold things solidly and to get the job done in a reasonable time I drove the leadscrew with a battery powered drill.
The rest of the project will go in another thread.
The workpiece was clamped to a piece of 1/2" aluminum plate which was in turn mounted to the table on a pivot spaced above the table for the leadscrew to fit.
The slot was first cut with a ball end 1/4" carbide endmill and then opened up with a reground 3/8" HSS endmill and both edges cut to final size. The whole thing was a hairy-scary operation. No way to hold things solidly and to get the job done in a reasonable time I drove the leadscrew with a battery powered drill.
The rest of the project will go in another thread.
