Harrison m300 lathe disconnecting lead screw with bad carriage

[Bill D]

I have a Harrison M300 lathe with what I think is a sheared woodruff key on the apron handwheel. I have disconnected the leadscrew and drive shaft(wrong term)before to drop the apron to clean the inside. They have tapered ends that friction fit into the threading gearbox. Just turn the apron handwheel and they pop out. I think I locked the half nut before forcing it apart. Of course I removed the bearing at the right hand end of he bed first.
The problem is the apron handwheel just spins and nothing moves. So I will have to lever the joint apart somehow. I am open to suggestions. It is not the handwheel being set in the free wheel position. When threading the wheel will turn like it should but touch it and rotation stops. It feels like it is spinning on the shaft.
Bill
ignore red circle on attached image. I do not understand the free wheel aspect maybe the sheared key is outside the apron. Just remembered the DPO broke the handwheel and brazed the spokes back on. years ago.

 

[APD]

why dont you remove the handwheel and check if the woodruff key is broken?

 

[boslab]

+1, undo the screw, pull the hand wheel,

Mark

 

[Bill D]

The shaft into the apron turns with the handwheel so the problem is inside the apron. Looking at the diagram I think it may be a shear pin not a key. I am hoping I can drop the bottom cover plate and use a mirror to look up at the pins. I need to make a new gasket for the bottom cover anyway because it leaks.
Bill D

 

[Joe Henderson]

Might as well drop the apron or pull the carriage off. You're going to have to do it anyway if the trouble is inside.

 

[Bill D]

Might as well drop the apron or pull the carriage off. You're going to have to do it anyway if the trouble is inside.

Yes, but how to disconnect the leadscrew with no geared traverse? I worry to much pounding or lever force may break the carriage before the taper joints pop loose.

 

[gustafson]

I would think if using the leverage of the handwheel and rack was all it takes to remove the tapered shafts, tapping the carriage with a dead blow would do the job. It is a lathe after all, many many pounds of thrust in normal use. I guess I would make sure I released whatever is retaining the tailstock ends of the shafts.
Since a key or pin is broken on the handwheel, I am wondering if that is really the way to do this job after all.

 

[APD]

A block of wood against the gearbox/apron and machinist's jack (or similar screw jack, bar/pipe clamp spreader) pushing them apart would provide similar force to hand wheel without the risk of hammering

 

[Joe Henderson]

I don't remember the leade screw or feed screw having any sort of taper. I think they're keyed into the gearbox and held with a little jackass 4mm set screw. I didn't have my apron apart, but I had to disconnect all that mess to get the gearbox off. Had to change out those little engineering marvels of delrin cams that swell in the oil bath and make it nay impossible to rotate the numbered gear lever on the apron.
There is a Harrison forum. I believe it used to be the Yahoo groups but is independent now. I'll see if I can find it.
now you'll have to take the switch box off the end and get those two blind locating pins out to remove the lead screw and feed rod. You might get by leaving all that intact and just lifting the carriage off. At least you might be able to figure out what went wrong.

 

[winger]

There should be a slip clutch joining the screw and feed rod to the gearbox. there are some very small screws retaining the tension adjuster nut.
going by my memory of a DoAll, which was made by Harrison.

Dave

 

[Bill D]

OP Here: Embarrassing to admit but there was no problem. I am in the process of moving and somehow the shifter was moved so the longitudinal feed was not engaged. It looked to be in the correct position and I had not shifted it into the power cross feed position for over one year so I had not bothered to check it. The knob is kinda hidden under the cross slide and behind the half nut lever.
So just a reminder to check the basics before pulling things apart.
Bill D