- Joined
- Sep 3, 2011
- Messages
- 478
I would probably open it up to at least 5/8", depending on how close that puts you to the rim of the hand-wheel. Plunging in with an endmill is a good way to straighten the hole. Ideally it should then be drilled and reamed to bring it to the nominal size of your sleeve. If you don't have the right size reamer, you can make a "D-bit" reamer (link).
You may not be able to use your boring head with an unmodified 3/8" boring bar to bore a 1/2" hole, because the end of the boring bar likely doesn't have enough clearance to work. You may have to grind more clearance on the bar or make up a custom tool from a round HSS tool blank (or an old endmill).
Make the sleeve 0.0001 to 0.0005" larger than the finished hole. You can also drill and ream the existing hole to get a nice round hole, without trying to straighten it, and press in a solid plug. Then you just drill a new, straight hole in the plug. Another option is to make the sleeve/plug 0.002" smaller than the hole and use Locktite 609 to bond the bushing to the handwheel.
Is the existing crank handle held on with a nut? I think that the handwheel is usually tapped and the handle is screwed directly into the handwheel.
You may not be able to use your boring head with an unmodified 3/8" boring bar to bore a 1/2" hole, because the end of the boring bar likely doesn't have enough clearance to work. You may have to grind more clearance on the bar or make up a custom tool from a round HSS tool blank (or an old endmill).
Make the sleeve 0.0001 to 0.0005" larger than the finished hole. You can also drill and ream the existing hole to get a nice round hole, without trying to straighten it, and press in a solid plug. Then you just drill a new, straight hole in the plug. Another option is to make the sleeve/plug 0.002" smaller than the hole and use Locktite 609 to bond the bushing to the handwheel.
Is the existing crank handle held on with a nut? I think that the handwheel is usually tapped and the handle is screwed directly into the handwheel.