Hi all,
I have a Whitney no. 6 horizontal milling machine I need help with. I can not remove the shaft that holds the cutters. I thought it was just a taper type fit that was wedged into the spindle. I've tried everything to get it loose, including heat, a rod and hammer (taping on the back side through the spindle), soaking in Croil and even a slide hammer. Is there some secret to getting this shaft off the machine? Is it maybe threaded on? Help!
Removing a stuck arbor from a horizontal mill.
1) We are assuming the arbor has a self locking taper that has been in place for a while.
Even a NMTB can lock up with a bit of dry oil and some rust.
2) You have tried heat, penetrating oil, and brute force.
Assess what is holding the spindle in place.
Do you have other spindle tooling laying around for the machine to examine? That would be a good place to start.
Most mills use a drawbar that passes through the spindle to the arbor, assuming yours has one, remove it and examine the condition. If it’s badly rusted, then there is a good chance everything on the front end is as well and rust is probably your problem. If you think rust is the issue, phosphoric acid will attack it. Phosphoric acid is the active ingrediant in navel jelly. Its also found in the metal conditioners sold for automotive paint jobs. In this case I would want something thinner than navel jelly. Heat is another good choice.
No draw bar or hollow spindle means some other means of retaining the arbor. Does the arbor have wrench flats? Does the spindle have a locking system? If so, apply a bit of a twist and see, but don’t break anything. I would not expect to see a thread in type arbor on a mill, because most are expected to run clockwise or counterclockwise.
Is there a large spanner nut on the spindle, like an L series lathe nose?
Look at the back end of the spindle. Is there a set of left hand external threads on the spindle? If so, there was probably a capture nut of some kind that allowed the draw bar to function as a jack screw and push the arbors out.
You can tap an R8 or NMTB taper loose. Morse and B&S tapers require a bit more help. Beating them out is poor form and can damage spindle bearings.
Other options beyond those tried.
Assuming you have a hollow spindle, you could run a NPT tap into the back end and mount a grease gun to the machine and use it to push the spindle loose. The grease will push out radially on the spindle and loosen the fit in addition to pushing axially on the spindle. Grease gun hoses and pipes usually have 1/8” NPT fittings, so you can mount up directly, without a zerk. Placing a broom handle or dowel in the spindle prior to pumping in grease will reduce the amount of grease needed. Use a good thread sealer and steel fittings. Grease guns put out a surprising amount of force.
Dry ice and gasoline, or liquid nitrogen can be used to cool parts and shift them around. This technique is popular with the antique gas engine crowd for freeing pistons. They work with larger diameter parts, but you might try it. Cool the shaft, heat the spindle and see if it frees up.
You have already tried hammer and bar and slide hammer, so the bearings are probably in sad shape now.
Place a heavy T bar on the arbor and use jack screws or a pair of bottle jacks between it and the frame to push it free. You need to be carefull you dont jack the spindle out of the casting or dammage something you dont want to.
Pull the entire spindle and arbor assembly and find someone with a hydraulic press to push it apart.