Pm1236 1-3 speed selection froze

[FTlatheworks]

That's more info than I had from you on the ticket. I'll add that in.

Ya, I didnt figure that out for sure until 11 o clock last night. I had a hunch, but now I’m almost positive that’s what’s going on.

 

[woodchucker]

It’s a gear head lathe. Look at the picture at the beginning of the thread.

lol have you just been guessing at what I need to do to fix it? It’s a pm1236 gear head lathe. The speed selection is seized up. The key and the gear both have play in them. There are two different gears on the same shaft with the same key. The one on the left side works fine, the one on the right seizes up. If I manage to force the right side gear to mesh and I turn the chuck by hand the gear lash changes and it becomes hard to turn the lathe by hand in certain spots (gears are binding). So the gear shift fork can’t change the gear position because there is enough slop between the shaft/keyway and the keyed gear bore for the gear to turn sideways. The shift fork pushes closer to the OD of the gear, rather than pushing closer to the ID where it would create less tilt in the gear which would result in less wear and friction.

yes I knew that. but some gears are not shaft connected, they are like idler gears, just retransmitting from one place to the other, others are keyed. Some gears are two gears together. I was not sure which gear you were having problems with.. you mentioned it's not sitting perpendicular, but none of the gears appear to be at an angle.. so I was not sure which one.

 

[verbotenwhisky]

I do the same also on my 940 some. Not all the time though.

I suspect it is much the same with all the gear heads. I wanted a PM940M but when I ordered it wasn't available so I settled for a PM932M and ordered it. It had not shipped from China when I placed the order and I periodically checked its progress and the date kept slipping. One afternoon 3 months down the road I called PM and it had moved to an additional 3 months out and I said "do you have anything else I could get faster that I might be interested in?" to which the response was "We have a PM940V-PDF with everything you want on it and hardened ways but it'll cost more." So I have a PM940V-PDF and I am excessively happy with it so far and I do not have the issues with the gear box.....

I like my lathe also but it is chunky, leaks just ever so slightly and does everything I ask of it.

Sorry for getting long winded....

 

[verbotenwhisky]

It’s a gear head lathe. Look at the picture at the beginning of the thread.

lol have you just been guessing at what I need to do to fix it? It’s a pm1236 gear head lathe. The speed selection is seized up. The key and the gear both have play in them. There are two different gears on the same shaft with the same key. The one on the left side works fine, the one on the right seizes up. If I manage to force the right side gear to mesh and I turn the chuck by hand the gear lash changes and it becomes hard to turn the lathe by hand in certain spots (gears are binding). So the gear shift fork can’t change the gear position because there is enough slop between the shaft/keyway and the keyed gear bore for the gear to turn sideways. The shift fork pushes closer to the OD of the gear, rather than pushing closer to the ID where it would create less tilt in the gear which would result in less wear and friction.

Man, I hate that you are having issues, every machine is a lil' different; but, if you talk to Mike and are patient he'll help you. PM really doesn't like having customers with issues and Mike is good people.....

 

[Rich Berg]

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!

Hi I also own that mill, nothing but trouble, first thing it did was popped the start capacitor, then burned up the contacts in the reversing switch. other motor problem again. now its leaking oil. put some auto transmission sealer in it, seems to have helped.
We do this to ourselves by buying Chinese stuff.
Good luck Rich

 

[FTlatheworks]

yes I knew that. but some gears are not shaft connected, they are like idler gears, just retransmitting from one place to the other, others are keyed. Some gears are two gears together. I was not sure which gear you were having problems with.. you mentioned it's not sitting perpendicular, but none of the gears appear to be at an angle.. so I was not sure which one.

You pose a good point, I hope it’s those gears. I can’t imagine it’s not because they don’t mesh well with any other gears in the case well (other gears as in the gears that turn the chuck).

I’m talking about the three gear set at the top of the case. They are on a shaft that isn’t connected to motor, or chuck. They are the speed selection gears (they transmit the power and change the ratio). I wouldn’t imagine that it would take enough slop that you could physically see it in a picture before problems arise.

I don’t know who I’m emailing at pm and who I’m talking to on here btw. I’m going to throw the indicator on the gears and get some number on lunch.

 

[FTlatheworks]

Hi I also own that mill, nothing but trouble, first thing it did was popped the start capacitor, then burned up the contacts in the reversing switch. other motor problem again. now its leaking oil. put some auto transmission sealer in it, seems to have helped.
We do this to ourselves by buying Chinese stuff.
Good luck Rich

That sucks and I feel your pain. It’s a lathe not a mill.

 

[MikeWi]

My name is in the email signature. it's me.

 

[FTlatheworks]

My name is in the email signature. it's me.

Ok, I see it. Sorry, I’m used to all the extra text on the email listing the business information. I got used to just reading the response, because I thought it was always from multiple people in tech.

Have you guys ever had this issue of these gears seizing? What’s normally done if so? My only reason for asking to buy the whole assembly was due to the fear of taking out other gears in the head due to improper lash. Maybe that’s not an issue with a transmission gear like this one? I don’t know. I know on gears that transmit torque 180 all the way down to 1 degree at a time it trashes them pretty quick when they don’t have the proper lash, but those are on machines with rollers pulling material through them.

 

[MikeWi]

There's two of us, and you've worked with both. I've never seen an issue like this one where the gears don't want to slide. Unless I hear a good diagnosis, we'll just replace that whole shaft and gear assembly to be safe.