A friend has a Sawsmith radial arm saw in good working condition, but getting blades is a problem. A special mount holds the blade on the shaft and uses a 1 1/4 inch hole rather than the standard 5/8 inch hole. The establishment that once sharpened his original blades is no longer in business. I suggested enlarging the 5/8 inch hole in a carbide tipped blade to a 1 1/4 inch hole. The challenge is to be precise and keep the hole centered so the blade does not wobble when finished.
In the photo you see an original blade with 1 1/4 inch hole (satin finish). It is resting on top of a new 9 inch 40 tooth carbide tipped blade with a 5/8 inch arbor hole (chrome finish). You can also see the special mount that requires a 1 1/4 inch arbor hole. The blade fits onto the shoulder on the left piece. The nut on the right screws onto the fitting at the left to lock the blade between the two pieces.
I used a marking pen to outline the size of the new hole on the carbide tipped blade.
Step 1: Mount the blade for enlarging the hole
I do not have machine tools and decided I could do the job with a faceplate on a wood lathe and a Dremel tool. I have a plywood disc mounted on my faceplate.
I glued a scrap piece of fiberboard at the center of the plywood disc and marked the center while the lathe was running. I scribed a 5/8 inch circle on the scrap of fiberboard.
Step 2: Turn the scrap to make a center for mounting the saw blade
I turned the scrap of fiberboard to make a round center 5/8 inch in diameter. The hole in the saw blade will fit snugly over this round center and will center the saw blade on the plywood disc with precision. It is important to stop regularly and check so the fit of the blade on the fiberboard is as exact as possible.