Pm1236 1-3 speed selection froze

[FTlatheworks]

I have a pm1236 lathe. It leaks oil, the leadscrew locknut was loose, so it wouldn’t cut threads in the same spot even when engaging half nut according to proper thread dial/lead screw location. Precision Matthews was no help and blamed these issues on me being too picky and operator error, even when sent videos of the proper half nut engagement. Main reason I got upset with them was because they didn’t say check the leadscrew lock nut ever. I spend more time fixing this 6000 dollar junk than running it.

Now I have a new issue. The 1-3 speed selection won’t budge. There is so much slop in the 1-3 gear set, the locking key, the arm that pushes the gear set, and the gears on the speed selection knob itself.

I don’t even know where to begin with what should or shouldn’t be replaced, but it’s out of warranty. I’m not so sure that they would have honored it anyways. They would probably tell me I’m not pushing hard enough, or the gears aren’t lined up, or it’s a Chinese machine. I’m hesitant to even call and ask for parts because I was a jerk, and I don’t want give anymore money to them, but then I can’t even get this running. The reason I complained on the beginning about the quality is because I worried that the machine would fall apart much sooner than a lathe should. Now it’s 3-4 years old and that’s clearly going to be the case.


I can get the gear set to move, but only with gear head lid off lining up the gears perfectly and enough force that it will eventually create more slop and potentially shear the rod on the knob and wear the sides of the gears down. It has always been very picky and had to be lined up perfectly, but now it is flat out seized up, and the gears are rubbing and making new noise when running on b-2. When looking at the 1-3 gear on the spindle they are crooked and have alot of side to side play. Also I believe there is a missing pin, but it wasn’t there when I got the machine either.

Someone that knows these machines please let me know what I should do to fix first. My thought was to replace the entire 1-3 speed assembly, including the knobs, arms, spindles, gears, and bearings?

 

[markba633csi]

Probably either the gearset or the shaft it rides on were sloppy from the factory, unfortunately it's hard to find this kind of stuff
within the warranty period. I feel your pain.
The good news is it's most likely fixable but will most likely involve disassembly and maybe even some reverse-engineering on the
shifter fork mechanism or other parts
Get a price on the gearset and the shaft, for starters

 

[FTlatheworks]

Probably either the gearset or the shaft it rides on were sloppy from the factory, unfortunately it's hard to find this kind of stuff
within the warranty period. I feel your pain.
The good news is it's most likely fixable but will most likely involve disassembly and maybe even some reverse-engineering on the
shifter fork mechanism or other parts

I’m pretty posive it’s the gears on the right for 1-3 speed. One gear in the pair is sitting sideways against the other. The whole set wobbles too, but the key seat also sits higher on the right side and wobbles around as well. The a-c selection works fine. I’m just really curious as to how pm is going to handle it and how much this is going to cost me.

There are shiny spots all over this shaft and key seat where it is sticking, but how much damage is it going to do to my other gears if one wobbles on the shaft while it runs?

 

[markba633csi]

To me, the fit of the gearset on the shaft should be snug as possible, no wobbling at all. It could do damage if it crashes into other gears.
The thing is, this may be a high-wear mechanism and may not stay fixed for very long- not much you can do about that
unless you want to re-design the whole freaking thing- I know all about that; I have an Italian car
It might be possible to braze up the inside bore of the gearset and re-bore it to size
You'll want to mic the shaft for wear- maybe replace

 

[hotrats]

I own a 1236. In trying to thread, I have issues locking the half nut at the proper time. I'm still pitiful at threading, but figured out better timing for engaging the lock nut. I know I need to practice more (lot's more).
Sometimes I'll have to rotate the chuck when changing speeds. Doesn't seem to be as serious a problem as you have though.
The 'wobbly gear' and ill fiting key may need to be addressed. Probably just remove all connected parts of this gear train and inspect, adjust/modify, and reinstall. It may be that the loose fitting gear caused premature wear on other parts, leading to today's condition.
I also own a PM940 mill. It's leaked oil from around the spindle for years now. I don't use it much (or the lathe) so have lived with it. It got the best of me and I finally took the mill apart. Probably a good thing as there was casting sand and other 'gunk' in the case. Having it apart also revealed the oiler for the fine downfeed was not dropping oil on any gears. All bearings arrived yesterday, so hoping to get back together soon.
It is kind od disheartening to have a newer machine need such work, but seems to be what we have to live with and learn about our machines at the price point we deal with.
I seem to remember someone else having issues and it turned out to be a ill-fitting key/oversized keyway.
Good Luck!

 

[FTlatheworks]

I own a 1236. In trying to thread, I have issues locking the half nut at the proper time. I'm still pitiful at threading, but figured out better timing for engaging the lock nut. I know I need to practice more (lot's more).
Sometimes I'll have to rotate the chuck when changing speeds. Doesn't seem to be as serious a problem as you have though.
The 'wobbly gear' and ill fiting key may need to be addressed. Probably just remove all connected parts of this gear train and inspect, adjust/modify, and reinstall. It may be that the loose fitting gear caused premature wear on other parts, leading to today's condition.
I also own a PM940 mill. It's leaked oil from around the spindle for years now. I don't use it much (or the lathe) so have lived with it. It got the best of me and I finally took the mill apart. Probably a good thing as there was casting sand and other 'gunk' in the case. Having it apart also revealed the oiler for the fine downfeed was not dropping oil on any gears. All bearings arrived yesterday, so hoping to get back together soon.
It is kind od disheartening to have a newer machine need such work, but seems to be what we have to live with and learn about our machines at the price point we deal with.
I seem to remember someone else having issues and it turned out to be a ill-fitting key/oversized keyway.
Good Luck!

It should have been addressed when I told them it was an issue upon arrival of the machine, but instead they waited. Now, inevitably, what I was worried about, has happened and they will get my money for the parts.

I disagree, it’s not what we deal with. I could have bought any lathe that wasn’t this import junk for 1-3 k and probably never had any of these issues.

I don’t have issues locking the half nut at the proper time. It was the leadscrew spanner lock nut was backed out enough to let the leadscrew move back and forth cutting two different threads on the same piece of stock.

 

[FTlatheworks]

To me, the fit of the gearset on the shaft should be snug as possible, no wobbling at all. It could do damage if it crashes into other gears.
The thing is, this may be a high-wear mechanism and may not stay fixed for very long- not much you can do about that
unless you want to re-design the whole freaking thing- I know all about that; I have an Italian car
It might be possible to braze up the inside bore of the gearset and re-bore it to size
You might need to replace the shaft itself

Idk about changing anything. I’ll probably just pay to replace all that crap and sell it for Pennie’s on the dollar and get a real machine.

Gear sets shouldn’t be wear parts like brake pads unless something was wrong from the start. My issue, I don’t have a mill to make new key seats and all the other things I would need to do to braze and bore that gear cause I wouldn’t want to use the same spindle.

 

[markba633csi]

The gear bores probably are not hardened as much as the teeth, hence they wear faster than the shaft they ride on.
Easier and cheaper for the factory

 

[woodchucker]

sounds like you may need to put bronze sleeves in the gears.
Have you maintained the oil in the head? Changed the oil soon after break in?

 

[Firstram]

Pull the bolt holding the shift fork to the shaft. That could isolate the binding to either the gears or the shaft. You should also remove the shifter detent, usually under the knob, they can cause all kind of problems when out of adjustment.

If needed, you can repair the gear bore in the lathe. Pull the gears, reassemble the machine and use 2nd gear to bore and bush. Polish the shaft and move on!

Any new lathe will probably have issues as well.