PM-1236T review

[xr650rRider]

One thing worth experimenting with on your 3 jaw (any chuck other than 4 jaw) is try it in all the D1-4 positions. Test runout and then rotate 120 degrees to next position on pins and test again. Every chuck I've tried, there is 1 sweet spot. My 3 jaw that came with PM-1340GT is right at .0015" runout for 1 position. Mark the spindle and mark the chuck and always install in same spot.

 

[Ischgl99]

One thing worth experimenting with on your 3 jaw (any chuck other than 4 jaw) is try it in all the D1-4 positions. Test runout and then rotate 120 degrees to next position on pins and test again. Every chuck I've tried, there is 1 sweet spot. My 3 jaw that came with PM-1340GT is right at .0015" runout for 1 position. Mark the spindle and mark the chuck and always install in same spot.

I tried that, there was no significant difference in runout. The position of the high point is different as well between the two sets of jaws, so I even if I move the chuck body on the backplate to try and reduce the runout, it would most likely make it worse.

 

[Ischgl99]

While cleaning out the metal particles in the gearbox settling wells for the bearings, I decided to take a closer look at the gears to see if I could find something that could be causing the issue. One of the gears on the input shaft is showing wear the others do not. The gear on the right is the one, you can see a wear pattern only 2/3 across the tooth. This is the gear cluster for the 1-2-3 lever.

There is a lot of play in the lever in each position, enough that the gears might not be fully in mesh, see video.

I knew it was a bit loose since I got the lathe, but not really knowing how it should operate, didn’t know if that was normal or not and didn’t pay too much attention to it other than making sure it was in the right spot. Seeing how much the gears move with the cover off, that looks much more than should be normal, but someone can correct me if I am wrong about that. I took the handle off to check and see what might be causing it to not lock into the proper position and it looks like everything is there, but there were two steel balls under the spring and not one as is shown in the manual. I did tighten the set screw quite a bit to add more force onto the spring before removing the handle, but that did not help.

The steel balls ride in a series of dimples for each of the three lever positions. The dimples are 4.3mm deep for a 6mm ball. That seems a lot deeper than necessary and I am wondering if the second ball was added to compensate for that. Anyways, my investigation so far hasn’t come across a way to lock the handle in position better.

 

[Ischgl99]

A change I made to the lathe is the lubrication of the Norton gearbox. The gauze that comes from the factory is not much more than a screen that lets the oil flow through quickly and not really doing much. The first few holes got almost all of the oil. I decided to try some felt as wicks to slow the oil flow. McMaster-Carr had some round felt cord, of course not the 5mm I needed, so I bought 1/4” and 3/16” to see which would work. I made a test fixture with the wicks in the same size hole as the gearbox and let the oil flow through. It dripped through over the course of hours and I think it will work better than the fast flow rate with the gauze.

The 1/4” felt wouldn’t fit in the holes, and the 3/16” is a bit loose, so I split one end into quarters and spread it out to act as a stop so it would not fall through. I did not put a wick in the two bearing locations in the back since oil does not flow through there and needs to be drawn down as the shafts spin. I pumped a bit of oil in there, enough to cover the bottom of the chamber and let it soak. The flow rate is low enough that most of the oil stays on the gears and does not drip off as much. I will be watching this to make sure I am not starving the gears of oil, but so far it looks like it is going to work and all the gears are now getting oil instead of just the first few before.

 

[Navy Chief]

A change I made to the lathe is the lubrication of the Norton gearbox. The gauze that comes from the factory is not much more than a screen that lets the oil flow through quickly and not really doing much. The first few holes got almost all of the oil. I decided to try some felt as wicks to slow the oil flow. McMaster-Carr had some round felt cord, of course not the 5mm I needed, so I bought 1/4” and 3/16” to see which would work. I made a test fixture with the wicks in the same size hole as the gearbox and let the oil flow through. It dripped through over the course of hours and I think it will work better than the fast flow rate with the gauze.

The 1/4” felt wouldn’t fit in the holes, and the 3/16” is a bit loose, so I split one end into quarters and spread it out to act as a stop so it would not fall through. I did not put a wick in the two bearing locations in the back since oil does not flow through there and needs to be drawn down as the shafts spin. I pumped a bit of oil in there, enough to cover the bottom of the chamber and let it soak. The flow rate is low enough that most of the oil stays on the gears and does not drip off as much. I will be watching this to make sure I am not starving the gears of oil, but so far it looks like it is going to work and all the gears are now getting oil instead of just the first few before.

View attachment 395988

Good solution to the problem, I have been considering something similar for a different lathe with the same problem. Had not considered round felt, I was thinking about replacing the gauze with a felt pad to slow it down ..

Sent from my Pixel 5 using Tapatalk

 

[Ischgl99]

Good solution to the problem, I have been considering something similar for a different lathe with the same problem. Had not considered round felt, I was thinking about replacing the gauze with a felt pad to slow it down ..

Sent from my Pixel 5 using Tapatalk

Thanks, I was thinking flat felt as well at first, but was making an order for mcmaster Carr and saw they had the round, so I went with that. I think I had to buy in increments of 5 feet, so now I have several lifetimes supply left lol. If you want any, send me a pm with your address and I can cut some for you.

 

[davidpbest]

Several of use have implemented one shot oiler systems for our lathes with Norton gearboxes. In case you haven't seen these, here are some threads that illustrate what a few of us have done.

One shot lubricator PM1340GT quick change gears (photo heavy)

I installed a “one-shot” lubricator for the quick change gears on my PM1340GT lathe. Others have done this upgrade as well and mine is just another example of how it can be done. A couple of my buddies that have plowed this ground before were extremely helpful in sharing their insights with...

www.hobby-machinist.com

Pm1340gt Gearbox Pump Oiler System

The PM1340GT is very nicely built, works very well, and I have very few bones to pick with its features and overall quality. One area that did concern me when I was revising the front control switches, was the oiler system for the open Norton style gearbox. The current system (which is probably...

www.hobby-machinist.com

Single-Shot Oiler for PM1340 Lathe

I decided to replace the factory supplied oil distribution drip tray. Click on photo for descriptions.

www.flickr.com

 

[Ischgl99]

Several of use have implemented one shot oiler systems for our lathes with Norton gearboxes. In case you haven't seen these, here are some threads that illustrate what a few of us have done.

One shot lubricator PM1340GT quick change gears (photo heavy)

I installed a “one-shot” lubricator for the quick change gears on my PM1340GT lathe. Others have done this upgrade as well and mine is just another example of how it can be done. A couple of my buddies that have plowed this ground before were extremely helpful in sharing their insights with...

www.hobby-machinist.com

Pm1340gt Gearbox Pump Oiler System

The PM1340GT is very nicely built, works very well, and I have very few bones to pick with its features and overall quality. One area that did concern me when I was revising the front control switches, was the oiler system for the open Norton style gearbox. The current system (which is probably...

www.hobby-machinist.com

Single-Shot Oiler for PM1340 Lathe

I decided to replace the factory supplied oil distribution drip tray. Click on photo for descriptions.

www.flickr.com

Thanks for the links, I did see those and was about to make one, then decided to keep it simple and see how this works. I have an endoscope that attaches to my smart phone, so I am going to see if I can tell how well the gears are getting lubricated with the felt and if I need to make something like you did. One thing I want to do is a drip tray like yours to help reduce the mess under the gearbox.

 

[davidpbest]

I will say from experience that it's really important get oil to the end of that drip pan at the end closest to the chuck - that last weep hole drips oil down into an area that feeds oil to the bronze bushing that the feed shaft rotates in. On my 1340, there was some over-spray at the factory that got into that hole and then down into the bushing, and it caused the feed rod to lock up solid, which in turn caused the change gears to strip and break teeth. That experience is what lead me to the single-shot oiler implementation.

This is the weep hole I'm referring to - make sure it's clear and you get oil into that end of the drip tray:

That hole feeds oil down into a copper tube that delivers oil to the bronze bushing at the end of the feed shaft.

 

[Ischgl99]

Yes, I recall you mentioning that before, but it’s always good to get a reminder. I left wicks out of that hole and the other one that feeds a bushing so that there should always be some oil in those holes to lubricate the bushings. When I put oil in the tray, I do 3-4 pumps and that leaves enough to cover then entire bottom and refill those holes and enough for the gear drips. Time will tell if my solution works, but it appears so far that everything is getting sufficient lubrication.

Based on your experience, I’m tempted to remove the shaft for those bushings to make sure they are clear and not blocked like your were.