# PM 1228 left hand threading



## Aukai (Aug 23, 2020)

I have not done, or needed to do this, but watching Tubalcain do a left hand thread with CCW chuck rotation, and the power feed going away, toward the tail stock. Does the 1228 do that? I can't seem to remember that being possible. I hope this isn't a  moment


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## ttabbal (Aug 23, 2020)

The 1127 does, so I can't see why the 1228 wouldn't. I do it with an upside down tool to thread away from the chuck.


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## darkzero (Aug 23, 2020)




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## Z2V (Aug 23, 2020)

The 1236 does also.


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## Aukai (Aug 23, 2020)

Thanks will, I have to look at it a bit to figure it out. I was pretty sure it wasn't push a button, or twist a lever....


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## Z2V (Aug 23, 2020)

Oh, I see you have to shift the idler cluster to reverse the lead screw. Yeah, on the 1236 it’s just move the lever. 
Thanks Will


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## Aukai (Aug 23, 2020)

Your lucky....


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## Z2V (Aug 23, 2020)

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.


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## Aukai (Aug 23, 2020)

Never, but it may come in handy figuring it out.


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## Z2V (Aug 23, 2020)

Quick funny story. I’m working side by side with my apprentice taping dozens of 3/8” holes with hand taps. I went to the tool crib at the start of the shift to get fresh taps and found a left hand 3/8 tap so I grabbed it. I gave the LH to my 
apprentice and kept the right hand for myself. We start drilling and tapping holes and he couldn’t get his tap to start for some reason. I went to his holes and tapped a hole. He would go to a hole I drilled and couldn’t tap it. I would come behind him on the same hole and tap it. He got so frustrated, HE QUIT AND WALKED OFF THE JOB. I didn’t like him anyway, mission accomplished. Fun times


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## Aukai (Aug 23, 2020)




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## darkzero (Aug 23, 2020)

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.



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.


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## mikey (Aug 23, 2020)

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!


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## mmcmdl (Aug 23, 2020)

It's easier to buy a right hand nut !


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## darkzero (Aug 23, 2020)

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.


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## Aukai (Aug 23, 2020)

Not sure if doing anything wrong, I put my selector knobs between gears to stop the threading shaft from turning.


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## darkzero (Aug 23, 2020)

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.


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## pstemari (Aug 23, 2020)

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.

Sent from my Pixel XL using Tapatalk


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## Aukai (Aug 23, 2020)

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.


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## darkzero (Aug 23, 2020)

If it had a neutral, it would most likely be on the tumbler or whatever used to switch leadscrew directions.


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## mikey (Aug 23, 2020)

Can't you loosen the screw that holds the thread dial indicator against the leadscrew and move it away? It only needs to be in contact with the lead screw when you're cutting threads.


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## Aukai (Aug 23, 2020)

I can look at that.


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## darkzero (Aug 23, 2020)

Looking at that diagram it looks like maybe there is enough range between the 2 idler gears for a neutral position? You could mod that shift plate to have a secure neutral position. I'm assuming you have to open the cover to access that lever but I'm sure you could make some kind of lever so that it sticks out of the cover. But you'd have to cut the cover.


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## darkzero (Aug 23, 2020)

Then make a kit & start selling them!


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## Aukai (Aug 23, 2020)

Whatever works  
Pau hana, going home


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## mikey (Aug 23, 2020)

Aukai said:


> Pau hana, going home



Translation for non-Hawaiians: My work shift has ended and I'm going home now.


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## darkzero (Aug 23, 2020)

Is it weird that I'm a mainlander & I understood it?


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## mikey (Aug 23, 2020)

Yeah, but you've been adopted by us and you have a deeper connection, too, so I'm not surprised you caught it.


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## darkzero (Aug 23, 2020)

Pau is was like one of the first words I learned cause it was easy to remember. Second was "all buss up", when I heard that I was like wth are you saying!   

But the street names over there, I still have no idea how to pronounce them!


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## Aukai (Aug 23, 2020)

All buss up  too much Okolehau


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## markba633csi (Aug 23, 2020)

Spam and eggs for me please!


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## darkzero (Aug 23, 2020)

Aukai said:


> All buss up  too much Okolehau



I had to look that one up.


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## Aukai (Aug 23, 2020)

then....


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## Winegrower (Aug 23, 2020)

But seriously, folks...my first task at the railroad museum was to help repair the old Ford tractor.   It had a water pump shaft that had been worn in two where it passes through the front grill, or something like that, can’t recall exactly.
There was a left hand thread on one end, and while I had never cut one, my old Logan has a lever to spin the lead screw the other way, so I did that and cut the thread left to right, otherwise exactly as normal.  

There is no need to use an upside down tool as was mentioned previously.


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## darkzero (Aug 23, 2020)

Winegrower said:


> There is no need to use an upside down tool as was mentioned previously.



I believe the upside down LH tool mentioned previously is to still cut a RH thread but away from the chuck (left to right). Threading away from the chuck with a "conventional" tool is normally how a LH thread is cut.

I only run my internal threading bar upside down, but it's a normal RH tool & I cut on the backside of the bore, right to left, normal spindle rotation, RH thread.


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## Winegrower (Aug 23, 2020)

I no longer see the post that discussed upside down tools.   We are in complete agreement in any event.


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## darkzero (Aug 23, 2020)

Post #2. I had to do a double take too.


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## darkzero (Aug 23, 2020)

markba633csi said:


> Spam and eggs for me please!



They have it at MickeyDs too!


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