Help! > Mistakes, muckups, and dangerous behaviour

An anxious afternoon

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Charles Lamont:
It is mid afternoon today and I reversed my usual sequence. While fitting the chuck and an end mill, I reminded myself, twice, not to forget to tighten the vice before switching on. So the job grabbed as soon as I touched it with the cutter, badly enough to stop the heavy old milling machine dead.

The job, a jig, is not pretty but probably salvageable. The 9/16" HSS cutter needs a couple of tiny patches of welded-on mild steel removing, otherwise it appears to be fine. The Autolock chuck is fine. The vice is a little Myford one and not enormously robust, but at a cursory inspection I think it is undamaged.

Unfortunately however, over about 5 or 10 degrees of rotation of the mill spindle, there is a tight spot and the sound of some kind of metal-to-metal contact. Bugger. Get a large mug of tea.

The machine is a venerable Beaver Model A http://www.lathes.co.uk/beaver/page2.html, nearly as old as me. There is a drawing on that page of the spindle assembly, which will help with what follows.

Having remembered how to get the quill out, and put back the bits I didn't need to take off, it was clear there was something wrong inside. I have had the machine for about ten years now, and I have never inspected the spindle bearings, so now is the time. It is a simple but very well made assembly, and it came apart without much difficulty, other than the top inner race being a well-nigh perfect fit on the spindle, certainly no looser than I would wish.

Well, after some grease removal and head scratching (with a wiped hand) the only thing I can find is right at the bottom, outside the labyrinth seal, the largest diameter of the spindle has picked up in its non-functional bore, or something foreign has got in there. I had to use a slip stone and fine wet-or-dry to polish out the tiny lumps - too hard to have much effect with a fine file. I have not put the spindle back together yet, as I want to give the bearings a thorough clean and greasing, which I did not have time to do this afternoon, but I am 97.5% sure that is the extent of the problem. Phew!     

Brian Rupnow:
Charles--I hope that your mill hasn't received any damage that you can't fix. At least you didn't get hurt. It gets scary very quickly when something like that happens. By the time you've hit the emergence stop button, whatever was happening has happened!!!----Brian

Kim:
Owch... doesn't sound like any fun :(

Glad you're OK and that it looks like the machine is OK too!  That's a good outcome :)

Kim

Jo:
Keeping my fingers crossed that was all it was.  :)

Those Beavers are very robust old machines. I wonder how many of these modern machines will still be going strong after 80 years  :old:

Jo

Chipswitheverything:
Hoping you can sort this out and be back in action...   Remember, years ago, hearing a great bang from a workshop in my place of work as I approached the door. A colleague using a massive and old Richmond mill, a real slogger, had had a job shift on the table, and had split in half! a 1 1/2" diameter milling cutter, on a 1"shank, and completely kippered a new Autolock chuck in the incident.  The mill had main bearings in a quill of about 8" dia., hadn't done much to that..
I kept the cutter in two halves for years on a toolbox near the mill, the perpetrator was very lucky to be uninjured.  Dave

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