spindle question

[hall6ppc]

Ok this question is not for a Bridgeport exactly. However it is for a Prototrak bed mill that has a head (varible speed) just about like a Bridgeport series 1 mill. So I thought I might get some advice here.
With the machine off , when you turn the spindle by hand back and forth you fell some lost motion or "slop". I have measured it and come out to about .090. I have noticed this in other older Bridgeport's but not as bad .
However I have not noticed any finish problems in my work and the machine holds good tolerance. The only time is shows up is when you are running a fly cutter or doing interrupted cuts, it will be a little noisy.
Now my question , what is wore in the head and is it worth trying to fix ( cost wise). I talked with my local Prototrak distributer and all they said was they would have to send it off for repairer.

Thanks for any help !!

[HimyKabibble]

If it's like a Bridgeport, it's the splines between the spindle and the dog clutch. Hopefully, the wear will be mostly on the dog clutch, making for a fairly inexpensive and simple repair. Otherwise, the spindle will also need replacement.

Regards,
Ray L.

[hall6ppc]

Originally Posted by HimyKabibble If it's like a Bridgeport, it's the splines between the spindle and the dog clutch. Hopefully, the wear will be mostly on the dog clutch, making for a fairly inexpensive and simple repair. Otherwise, the spindle will also need replacement. Regards, Ray L.

Thanks Ray!
I thought it was something in the splines of the spindle. Well I am pretty mechanical inclined but seeing how I have never opened up a mill head for repair I might send it somewhere for that. I just didn't want to sink a bunch of money in it because it's only used in my home shop .

[HimyKabibble]

Originally Posted by hall6ppc Thanks Ray! I thought it was something in the splines of the spindle. Well I am pretty mechanical inclined but seeing how I have never opened up a mill head for repair I might send it somewhere for that. I just didn't want to sink a bunch of money in it because it's only used in my home shop .

First thing you should do is liberally grease the splines, and carefully center the top of the head over the bottom. Do this by running the spindle at top RPM, with the bolts holding the top of the head loose, and move the top of the head around. You'll likely find a position where things are considerable quieter. Tighten everything up there. A certain amount of noise is normal, as those splines can't be very tight. Centering will minimize the noise, and the grease will help damp out what's left. It'll still make noise with a fly cutter, or other tools making intermittent contact.

BTW - If it is like a BP, it's a very simple assembly, no reason to be afraid of disassembling it.

Regards,
Ray L.