PM 1228 left hand threading

Z2V said:
At least you don’t have to change any gears, just shift the idler from left to right. Shouldn’t take a minute or two, how often do you need to cut left hand threads? I have done it to mess with coworkers heads with taps when I was working but really only done it on the lathe just to do it. :laughing:
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Yup, on my old lathe I had to install a seperate idler gear to reverse leadscrew direction. I hated doing that.

I've only needed to cut a LH thread maybe 3 or 4 times but I do change the direction of feed quite often. Switching the lever on the PM1236 to the middle position disengages the leadscrew or power feed rod, I do that quite often too.
 
My Emco Super 11 switches direction or goes into neutral with one knob. It takes a second to switch feed directions. Them Austrians sure can build a lathe!
 
It's easier to buy a right hand nut ! :big grin:
 
It became a force of habit for me. On my old lathe it had no quick change gearbox. The change gears were noisy. So whenever I didn't need to use the lead screw (had no power feed rod) I would loosen one screw & swing the the entire gear train out of engagement. Had to open the side cover to do that but the cover was on hinges & there was no safety interlock.

On my current lathe while the noise doesn't bother me, it's a gear head anyway, I flip the lever to disengage the gear train anytime I don't need to use it. It's right on the face of the headstock, quick to do so might as well. Figure less wear on the gear train. For the same reasoning I also swing my thread dial out of engagement when I don't need it.
 
Not sure if doing anything wrong, I put my selector knobs between gears to stop the threading shaft from turning.
 
Not necessarily wrong per se but it depends. I'm guessing it wasn't designed for that reason, if it was there would be a detent & you would feel it. Downside to doing this is there potential for it to engage the next position unwantingly while machining, like vibration could cause the selector to switch. Also depends on how long or short the throw is to engage the next position. If it has a somewhat short throw there's a higher chance of what I mentioned. But only you will know your lathe better than anyone else even if someone has the same model lathe. If it works for you without issues than I suppose it should be ok, for the change gearbox anyway.
 
The main risk I can think of is that you might bump a lever and drop it into gear while it's running. Depending on what sort of spring detent your lathe has, that might be pretty easy to do. A really strong spring detent could potentially be a hair trigger. One that's mushy, or that has a wide neutral section with no force pushing it to the nearest detent, would be fine.

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If the half nut is not engaged the shaft will just spin. When the shaft spins the threading dial is going, and the end bearings as well. If the half nut is in any contact, that would be wear also. Just concerned with those things, as there does not appear to be a neutral.
The instructions say not to shift above 600 RPM, over that would be a consern.
 
If it had a neutral, it would most likely be on the tumbler or whatever used to switch leadscrew directions.
 
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