Please could you clarify what you mean by the Y-axis. You talk of moving it “up and down”.

In conventional milling machine terminology, X goes left-right, Y goes in-out and Z goes up-down.

It is important that we all use the same terms or you may receive incorrect advice.

I suggest you check the slide way lock (little lever LHS of the knee) to make sure it’s released.  I think there is a short brass push stub down the threaded hole – has this jammed up?  If so you’re into keyhole surgery to invent a means to pull on the stub.

On a machine that isn’t exercised much the old rancid oil turns to varnish and acts as glue rather than lubricant.  Having abrasive in the mix makes this worse.  Loosen the gibs and flush out the goo with brake cleaner and new oil.  Don’t use motor oil, it will have detergents in it which love water (condensation) and make a nasty sticky emulsion.  Hydraulic oil thinned with paraffin or white spirit is a good maintenance cheat.  Automatic transmission fluid thinned with acetone is ideal.

Heat is your friend.  I suggest an electric fan heater blowing on the knee for a day or so the get the casting good and warm to release the sticky varnish.

The Z axis hand wheel runs in a casting below the knee, and turns pair of bevel gears and a threaded leadscrew in a bronze nut captive in the bottom drip pan of the machine.  If the hand wheel is stuck completely as you describe the stuck components are in the handwheel and spindle, not the slideways.  Which would be pretty odd as the relevant parts are sheltered below the knee.   If you’ve got a bit of backlash of the leadscrew turning against its captive nut then the jam is in the lead screw or the slideways – much more likely as the dovetail slide of the Z axis on the front of the column is exposed to the elements.

But the first thing to try would be to dribble some thin (thinned) oil down the vertical dovetails for a few days and see if things free up.  Don’t use WD40 – though it is good at getting into cracks and freeing things up it dries eventually to a hard varnish and then you have the same problem again but worse.

Do keep us posted.

Simon

Im a chemist and know ethanolamine will attack copper ,brass and probably bronze ,so possibly youve destroyed the leadscrew nut.

On 11 November 2024 at 19:28 mark smith 20 Said:

Im a chemist and know ethanolamine will attack copper ,brass and probably bronze ,so possibly youve destroyed the leadscrew nut.

Sounds horribly likely.   I see Hexol is an industrial grade surfactant, so we have a powerful oil/grease remover that corrodes Copper alloys, mixed with powered glass.  Potentially nasty if it gets inside the gibs, leadscrew and nut.  I agree with Michael – strip and inspect.  With luck, the mill is just caked solid with glass powder, but there may be corrosion and erosion damage to fix as well.

The usual treatments for freeing up gummed up oil and dirt won’t work on glass.  It will have to be cleaned physically.

By the way, never force stuck hand-wheels!  Easy to damage the machine more seriously.

Dave

I have had second thoughts on how the knee gibs are adjusted.

Slacken off the front facing bolts one at a time and tighten finger tight.

Slacken fully the locking lever screw.

Hold the adjuster screws while slackening the lock nuts and then slacken the screws 1/2 turn.

The knee should be free to move up and down.

Screw in the adjuster screws until they just touch, starting from the central ones and working outwards and check for the gib just starting to hold the knee from moving easily. Tighten each locknut in turn while holding its adjuster screw.

Finally tighten the bolts and check that the knee can be moved reasonally easily with the wheel.

If I were going to do this, I would first remove the bed and Y axis, the knee, their leadscrews and nuts plus the bevel gearing for the knee and throughly wash and relubricate every part. And make sure the rubber guard at the back of the bed was in good order. The gib on the X is a taper gib.