lathe problem

J

JerseyBill

AzB Silver Member
Silver Member
I have a chinese lathe and it fell when I was moving it on a flatbed truck.
The trucker had it repaired, (his fault) and now when I try and cut squares on it (ie. auto feed) The handle pops up and it stops feeding.
What do you think the problem is and is it fixable? I realize from far away it might not be able to be diagnosed. But maybe it can?
13x37 metal lathe by central machinery (harbor freight)
I have other lathes so it's just a third or fourth lathe. I live near Binghamton N.Y. in case anybody is near.

Thanks, JerseyBill
 
Does the hand wheel work for moving the carriage back & forth? If so then it should be an easy fix. If not, you're looking at trouble.

Under the carriage there is a thread chase split nut that when engaged, closes on the feed screw. The spinning feed screw inside the split nut pulls the carriage along with it. That split nut acts kinda like an alligator clip with threaded jaws, and is made of brass. That brass wears out and the problem you are having is the result. It may simply need adjusted, or you may need to replace the split nut. It is intended to wear, so don't worry. Most likely it's just out of adjustment & will be a quick fix, and you'll learn something about how the machine works in the process. If you need parts, you could probably find them at Grizzly. You'll just have to tear apart the carriage & get to it. I'd be surprised if it needs new parts. A slight adjust of the split nut will likely fix it, and that's just tightening a set screw.

If this is not the problem, and your carriage doesn't move smoothly along the bed with the hand wheel, then your machine was tweaked in the fall. That's is VERY unlikely. Even the cheap HF machines are cast steel with hardened ways, not easily twisted or tweaked. If there is damage from the fall, it'll likely be obvious like a huge crack or break.
 
common problem, i also have a terd central. The half nut more than likely broke at the shoulder where the alignment pins are. Grizzly may have a comperable, if not you will have to email HF and wait ten years for a response on a way overpriced pc of brass. Mine did the exact same thing. Atleast you can use the powerfeed in the meantime if your not threading
 
I think he is having powerfeed problems

from what Bill described, not thread feed issues. The half nut is disengaged during powerfeed, unless you have a small lathe that drives both off the lead screw. If the safety interlock is not adjusted correctly both systems can engage partially and cause issues, or the small gear that rides the feed rod may be damaged. I have a Jet 12X38 lathe that popped off, while power feeding, all the time. It required me to buy an involute cutter and make the gear as one was not available. I mention that because my HF lathe, the same size as yours, that I bought new in April 2006, has been discontinued, and replaced with a new model. HF said the parts for mine were not available. How old is your lathe Bill?
BUT there is hope if you are in the same pickle: I found their new model lathe parts were often the same, even same part numbers off the diagrams. I wanted a new tailstock quill and a change gear and both parts were a perfect fit, it just took a lot of crazy crosschecking on my part to ascertain the correct numbers and risk buying the parts. I think the new SKU number for the new model lathe is #65044, my old model number was 33274, was that the same as yours Bill? There is also a grizzly model that is a close match too, not sure of Grizzlies SKU number as I could not find my paperwork from when I did my repair two years ago. But Grizzly has a much better parts supply, and you get them fast. I hope this helps? The moral of the story: all these lathes were made by the same chinaman, or his cousins, at the same factory, yah just have to play detective to find replacement parts, or make them?
 
olsonsview said:
from what Bill described, not thread feed issues. The half nut is disengaged during powerfeed, unless you have a small lathe that drives both off the lead screw. If the safety interlock is not adjusted correctly both systems can engage partially and cause issues, or the small gear that rides the feed rod may be damaged. I have a Jet 12X38 lathe that popped off, while power feeding, all the time. It required me to buy an involute cutter and make the gear as one was not available. I mention that because my HF lathe, the same size as yours, that I bought new in April 2006, has been discontinued, and replaced with a new model. HF said the parts for mine were not available. How old is your lathe Bill?
BUT there is hope if you are in the same pickle: I found their new model lathe parts were often the same, even same part numbers off the diagrams. I wanted a new tailstock quill and a change gear and both parts were a perfect fit, it just took a lot of crazy crosschecking on my part to ascertain the correct numbers and risk buying the parts. I think the new SKU number for the new model lathe is #65044, my old model number was 33274, was that the same as yours Bill? There is also a grizzly model that is a close match too, not sure of Grizzlies SKU number as I could not find my paperwork from when I did my repair two years ago. But Grizzly has a much better parts supply, and you get them fast. I hope this helps? The moral of the story: all these lathes were made by the same chinaman, or his cousins, at the same factory, yah just have to play detective to find replacement parts, or make them?
Click to expand...

Gotcha. I figured if he was using a router he'd be using a slow thread feed.
 
I do have a router and taper bar setup on this lathe. The thing is that if I hold the handle down it will do the whole length of the piece okay. If I let go of the handle, it starts to ride up and eventually completely out and stops feeding.
thanks for all your help, I"ll check the model no. and take a look at the nut.
Bill
 
model no.

olsonsview said:
from what Bill described, not thread feed issues. The half nut is disengaged during powerfeed, unless you have a small lathe that drives both off the lead screw. If the safety interlock is not adjusted correctly both systems can engage partially and cause issues, or the small gear that rides the feed rod may be damaged. I have a Jet 12X38 lathe that popped off, while power feeding, all the time. It required me to buy an involute cutter and make the gear as one was not available. I mention that because my HF lathe, the same size as yours, that I bought new in April 2006, has been discontinued, and replaced with a new model. HF said the parts for mine were not available. How old is your lathe Bill?
BUT there is hope if you are in the same pickle: I found their new model lathe parts were often the same, even same part numbers off the diagrams. I wanted a new tailstock quill and a change gear and both parts were a perfect fit, it just took a lot of crazy crosschecking on my part to ascertain the correct numbers and risk buying the parts. I think the new SKU number for the new model lathe is #65044, my old model number was 33274, was that the same as yours Bill? There is also a grizzly model that is a close match too, not sure of Grizzlies SKU number as I could not find my paperwork from when I did my repair two years ago. But Grizzly has a much better parts supply, and you get them fast. I hope this helps? The moral of the story: all these lathes were made by the same chinaman, or his cousins, at the same factory, yah just have to play detective to find replacement parts, or make them?
Click to expand...

43618 is the sku #, it's a 12x37 gap bed lathe.
I checked the half nut and it's about 3/16 away from the screw when open, I can close it but it doesn't seem to be fitted all the way down in the threads from what I can tell. How would I adjust? It might be that. The lathe isn't real old, I've had it about four years and my friend about two, and he barely used it and I have several so it doesn't get much use here either.
thanks, Bill
 
different model from mine Bill

But the real question is: are you using the power feed to cut with your router, or are you using the thread feed? I always use the power feed which I can control with the quick change gear tumblers to alter speed feed. They both can be used. If you are using the thread feed and that lever will not seat correctly, I would first want to get at it and see if there is some debris stuck in the threads of the nut? That alone is a PITA if I recall, if your lathe is the basically the same as mine. I have a 12X36 gap bed lathe, also the same exact age. How weird that they have so many models of similar lathes.
I have had issues with metal debris getting into my half nut, all I did was blow it out with a long nozzle and compressed air to fix it. I know that there is a safety interlock between the power feed and thread feed controls, though I never had to adjust mine Bill. The manual mentions that it may need adjustment, though says nothing about how to do it.
The half nut is supposed to be a wear item that needs replacement once in awhile, my lathe manual recommends that the owner makes some and keeps them on hand, they provide a print in the manual, but maybe you can buy a new one if your lathe is still supported, it did not look easy to make the nut, I wish now that I had bought at least one spare for mine, best of luck Bill.
 
I've been in and worked at a couple shops where their lathes had this problem. I have seen 2 different ways to deal with it,and both worked.

One of them used a thin,stiff wire (like a coat hanger) with a trailer hitch ball for weight to keep the lever held down when feeding.

The other one had a short piece of bungee cord with the hook on the end to hold it down,and a small scrap of 2x4 on the bottom of the carriage apron to add tension.

As odd as this sounds,neither of them created an additional problem by causing the feed to engage by accident.

Making a new half-nut shouldn't be that big of a deal,but it COULD be.

For those of you that have ever had to make a 1 3/8-5tpi internally threaded (not tapped) Acme,you understand.

For those that haven't,imagine having to hand grind a single-point Acme for internal threading out of a crashed 1/2 HSS end mill.

Then you have to do the math to calculate the bored hole size before you even start on the threads,then add the math for internal Acme thread depth,etc and it might make you sick OR have you calling all over looking for pre-ground cutters. Tommy D.
 
using a weight

Tommy-D said:
I've been in and worked at a couple shops where their lathes had this problem. I have seen 2 different ways to deal with it,and both worked.

One of them used a thin,stiff wire (like a coat hanger) with a trailer hitch ball for weight to keep the lever held down when feeding.

The other one had a short piece of bungee cord with the hook on the end to hold it down,and a small scrap of 2x4 on the bottom of the carriage apron to add tension.

As odd as this sounds,neither of them created an additional problem by causing the feed to engage by accident.

Making a new half-nut shouldn't be that big of a deal,but it COULD be.

For those of you that have ever had to make a 1 3/8-5tpi internally threaded (not tapped) Acme,you understand.

For those that haven't,imagine having to hand grind a single-point Acme for internal threading out of a crashed 1/2 HSS end mill.

Then you have to do the math to calculate the bored hole size before you even start on the threads,then add the math for internal Acme thread depth,etc and it might make you sick OR have you calling all over looking for pre-ground cutters. Tommy D.
Click to expand...

Tommy,
Funny you said this, because when I was cutting wood and having the problem I thought of saving me the trouble of holding down the lever and putting a weight on it, BUT, someone said it won't kick out if it has a problem as it's designed to do?? You think??
thanks, Bill
 
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