I am going to attempt to make a prop hub for this Mculloch weedeater engine. I am not sure of the cc's but this engine is smaller than a 25cc so I am guessing that it is around 18 to 21 cc. I know that the shaft is 5/16 but I am not sure if the threads are 24 or 28. Does anyone know offhand? Thanks. I know I could just order a prop hub from Dave Carr or Ralph C. , but I have a neighbor that has a huge lathe and I would like to give it a try. He has tons of bar stock laying around.

I have a mess of McCollochs and they are all 32's. One was a 28 but I converted it to a 32 also. I have never seen one smaller than a 28. They are all 3/8". All the other brands of converted weed whacker I have are 5/16-24. Why don't you get some nuts from the Hardware and see which one fits?

Jim

Why not just measure off a known distance on the threads and count the threads in that distance? Measure off 1/4 inch, count. If you count 7 threads, then you have 7 X 4 = 28 threads to the inch. If you count 6, you have 24.