Lagun 310 Stuck Spindle

[mcsf]

I have a Lagun 310 with what seems like a stuck quill. This machine is was an original Lagun 310 CNC ride with a Delta control. Eight or so years a go we upgraded to a Heidenhain Control and all has been fine - until now. A month or so ago we got a malfunction code from the Z Axis. We have had one of these in the past albeit on the X. Thaqt time it was a bad scale. We had our machine tool tech take a look and he decreed that it was almost certainly the scale.

Off it went to Heidenhain.

It came back - indicated it on the machine fired up the control and blamo - same problem.

Then the tech tried to turn the Z axis ballscrew. No motion of the spindle.

At this point I somewhat take over - well after the first rounded bolt on the ballscrew to quill interface. I figured I could round off bolts on MY TIME.

Anyway I got the ballscrew undone and the quill , much to my surprise, did not fall free. I had wood underneath it but I could not even get it to move by raising the knee against the block against the spindle (GENTLY of course!)

I am looking over the blueprints to the head and do not see what could be holding the quill in place - binding to be more precise.

The ballscrew WAS tight - difficult to turn by hand but not impossible.

How does the quill brake work? I see braking blocks in the diagram (right side of the head as you face it) Four of them in fact - but I do not see what actuates them.

What am I missing? Should a ballscrew be really easy to turn? Should the quill be able to be moved by hand?

Anybody? Bueller?

[RdHawg]

Is the ball screw still attached to the step motor? As the stepper's braking action would hold it in place? (Just random mussing)

[mcsf]

Nothing is connected anymore. The ballscrew is out and the 4 bronze "brakes" have been released as well. This thing is stuck for good!

[HuFlungDung]

Did the machine show any excessive running temperature at the quill or the head casting? A very hot spindle temp could have initiated a seizing scoring problem within the head casting. Was that area around the quill ever getting any oil applied?

What about the drive spline for the spindle? Any chance it is fouled with dirt or rust and is seizing in the drive pulley?

[mcsf]

It was a heat problem. I was running at 4K RPM with a 5 to 1 speeder head. I ran three cycles that took a few hours to run each. The last cycle ran unattended and the machine did a Z axis retract. The next morning I came in and the alarm went off when I tried to move the Z.

[HuFlungDung]

Ouch!
I used to install a fan to blow over the housing whenever I'd have a few hours running.

So I suppose the quill has started to raise a score mark in the housing. I don't know if there is much you can do except to take the top off the head so that you can get in there with a good penetrating lubricant and spray the housing but good and let it soak. This will not loosen it, but hopefully, it will get some lube in where the scoring/galling may have begun.

I'd be expecting to use force. Some kind of a connection between the quill and the table could perhaps be made with a length of threaded rod, and a coupling nut to attach to the drawbar bolt. Start with the table up high, and wind the knee down to try to pull the quill.

It may be of benefit to try to heat the head casting. Of course, you don't want to burn all the paint off with a torch, so maybe a battery of heat guns or something. You'd have to strive for a diffential in temp between the quill and the housing, so you need a lot of heat applied rapidly to have much effect. Perhaps some method of packing the spindle with dry ice or something could be tried. If it were possible to drop the spindle out of the quill, that might be thought, depending how it is constructed. Then you would have only the quill tube to keep cool and probably could do that while the head casting is heated.

At the time you get the head heated and the quill cooled, then its time to try the pull out. If a galling process has begun, you can expect it to get worse as you pull, until the 'gob' pulls out past the top of the quill.

As a preemptive measure, I took my die grinder to the inside of the head housing, and ground a spiral track from the lube fitting to assure that any applied oil would forever after surround the quill completely.