Thread: whats involved in boring a larger spindle and bigger key in a pulley

Very simple job to enlarge the bore on any lathe large enough to swing the pulley. The keyway can also be cut by moving the carriage manually with a suitable tool in the toolpost and the lathe stopped, though this is a bit time consuming if a cast iron pulley - aluminium is easy. The quick way to cut the keyway is to use a broach, but they are not common in home shops because of the cost. Either way not a major job though.

Frank.

[QUOTE Mostly importantly, is it a 1 or 2 slab job? [/QUOTE]

A slab of what? A slab of beef? or a slab of lamb? I'd do it for a slab of lamb!

Well to answer your question, it has to be done in a workshop/machine shop. It shouldn't take more than 1 1/2 hours for an apprentice to do it or 1 hour for a tradie. There is one small problem to be checked. How big is the hole in the pulley and how big is the shaft (diameter). The keyway is probably 1/4 inch so the depth of the keyway will be 1/8 inch also. Check how much thickness of aluminium will be left being the thickness of the hub after the pulley is bored out. Then check how much metal will be left for the thread for the screw that holds the key in place. Sometimes there is not enough metal and the screw strips the thread. If this happens and the pulley is loose on the shaft (bad workmanship in boring) you can always loctite the pulley on. I'll take the Lamb slab, that's what you are talking about isn't it?

Kody

Kody,

You beat me to it! I just logged back on to add to my post that the pulley boss size should be checked to make sure there would be enough thread left for the set screw after the pulley was bored, and found you had already done it.

Frank.

If you havent allready purchased the pulley and if you buying from an engineers suppliers ask them to have the pulley keyed and bored to your requirements.All of the suppliers that I use in Sydney will provide this service for not much more than the cost of the pulley.