Boxford tight

Check things in stages. Is the motor and countershaft loose and oiled. disengage the changewheels. Normally one expects the main bearings to get warm and loosen up if anything. Si anything getting warm in this short period of use?
Check the two ring nuts at the back end of the spindle. Do you have two even? If there is only one so they can't be locked against each other or they are loose then they could have moved and tightened things up.
If using back gear don't forget it needs oiling both the layshaft and the pulley on the main spindle - both have oil holes maybe with screws in them.

Sounds like a backlach adjuster is tightening up, or possibly some threads from a shop rag, or a shredding v belt have got pulled into a bearing? only thing to do is go in and have a look! If the chuck is hard to turn, and you cannot detect any gear backlash before it becomes hard to turn it looks like it is the mainshaft spindle bearings. What did you do on the lathe the last time you used it? any clues there?

Phil.

A Boxford should have no trouble coping with temperature variations. The amount of expansion and contraction might affect the ultimate accuracy but none of the bearings should tighten up to the extent you describe.

As Bazyle says, check progressively through the whole power transmission system. Possible overpacking of grease, or wrong type, of grease might be a cause but also 'belt slipping' depends on how tight the belt is in the first place.

It is normal for the headstock bearings to get very slightly warm with prolonged running at high speed but the method of checking preload is well documented so may be worth checking yours.

Ian P

If you over grease the headstock bearings, you slow the spindle speed down, and if the spindle turns, then you will notice the headstock temperature to rise until the excess has squeezed out.
Suppose the original grease is in there, 20 or so years old, it will have become a bit stiff as most of its oils will have drained away. Perhaps the last time you used the late, you turned the grease caps a turn or two - hey presto, the lathe will turn slowly until that old grease has squeezed out of the bearings a little.
If that is the case, just run the lathe at a slow speed until the bearings warm up and squeeze out some of that old gunk. It took my Boxford AUD about 20 mins at 50 F to squeeze out new grease after a re-build.
BobH

10 thou of spindle up and down movement? Plus basically seizing up after a few minutes' use? Something is seriously amiss with your headstock bearings. I would be consulting the manual and parts diagrams and getting ready to do as you say and pull the spindle and bearings and do a thorough clean and inspect and re-install, with new bearings if needed. I don't think the type, quality or quantity of grease has sufficiently strong magic to cause or cure this. Plenty of Boxford parts diagrams online to consult and I'm sure there's someone here who has been there before who can help.

But also, it might just be the endfloat/preload adjustment come loose. That could conceivably allow the up and down movement in the tapered roller bearings and possibly, possibly be allowing the spindle to move enough to be causing something to rub on something it should not, and thus start to bind up under use. Something in around the pulley and spacers, back gear etc etc. Might be worth fiddling with before tearing the whole lot down.

Hi Kevin, which model headstock do you have? Does the spindle turn easy if the back gear lever is in the neutral position?

Regards Nick.

Hi Kevin, click on Headstock MK1 in this **LINK**. You may be able to find what you think is missing from the drawing.

Regards Nick.

That does not explain why you have ten thou up and down movement in the spindle though. Still check your bearing adjustment.

If you have both the bull wheel locked to the pulley and the back gear engaged, yes the lathe will be locked. Don't do it under power!

No not a cap head screw. There is a steel pin on the lever and you can make a brass shoe to roughly fit the groove and drill a hole to fit the pin. It is a wear out item if you don't oil the groove in the bull wheel regularly. It doesn't need to be made curved to fit the curvature of the wheel, straight will do. It is about 3/4 long (high) and half inch deep.

I had this problem repeatedly a few years ago with my Boxford when it was situated in a cold unheated workshop. Worked normal for a few minutes then a gradual slowing of the spindle to zero speed and a squeal from the v belt and the motor dropping below the centrifugal switch speed, kicking in the start winding and then cutting it out again a second or so later. The pulley was effectively locked solid to the spindle.

It was eventually traced to a lack of end clearance / lubrication on the multistep pulley (item 250) that fits over the spindle. Remove the two grub screws in the bottom of the v groove, lubricate with lathe oil, replace the grub screws and run under no load for 10 mins or so, with both the sliding gear and back gear disengaged such that you are only driving the v pulley and nothing else (the spindle may drag slightly)

If no improvement and the pulley stops again then back off the nut 119 by a smidgen. A blow or two from a nylon or hide faced mallet on the non chuck end of the headstock might be useful.

The method of setting the bearing preload is detailed in the Boxford spare parts leaflet which should be floating around online, my experience says it is very temperature / bearing grease dependent, and the setting is in my view maybe on the high side. What preload works now could easily be useless come mid-summer.

http://www.boxford-software.com/spares/3656HeadMk1.html