Second apron gear failure in a few hours.

[GreggC]

Hey guys,
I have a Shop Fox M1049 lathe, same as the Grizzly 4000,
After a couple hours of use the gear that engages the lead screw worm gear in the apron failed.
I called for a replacement gear and once it arrived I installed it, everything nice and clean, lots of grease.
I start making parts again and a couple of hours later the gear fails again.
I was not pushing the machine, Im turning aluminum at 400 rpm with .003 / .004 cuts.
See pic of the piece I was working on, if I was doing anything wrong or pushing this thing
I think it would show in the work.
Has anyone heard of a problem with these aprons ??
Is there possibly a manufacture defect ??
Im still under warranty, maybe I can get them to send an entire apron assembly.
Im at a loss and quite frustrated, I am now down again for weeks waiting for parts from China.

 

[woodchucker]

Any chance your half nuts are engaged at the same time as the travel is on? Is there anything on the rack that might be getting into the gear? And you are not crashing the carriage on a stop right?
Is there so much wear on your carriage that it is not sitting tight to the rack with the right amount of backlash. If too tight, or if worn and too loose you could cause premature failure.

 

[GreggC]

Any chance your half nuts are engaged at the same time as the travel is on? Is there anything on the rack that might be getting into the gear? And you are not crashing the carriage on a stop right?
Is there so much wear on your carriage that it is not sitting tight to the rack with the right amount of backlash. If too tight, or if worn and too loose you could cause premature failure.

No,
Half nut lever is full up and half nuts are in the expanded position and completely off the lead screw.
No carriage crashes, the lathe is new, only has a few hours on it.

 

[dlane]

there possibly a manufacture defect ??“

 

[markba633csi]

I think we have another member who is seeing this same problem- what is this gear made of? I'm thinking a weakness in the design
Can you post some pictures of the damage and related internal parts?
Mark
ps you may have to choose between returning the machine or keeping it and trying to re-design the failing part(s)

 

[GreggC]

I think we have another member who is seeing this same problem- what is this gear made of? I'm thinking a weakness in the design
Can you post some pictures of the damage and related internal parts?
Mark
ps you may have to choose between returning the machine or keeping it and trying to re-design the failing part(s)

Hey Mark,
Thanks for the reply,
I was just discussing with my wife I thought it might be a defective gear, maybe cheap or sub par material,
or a simple design flaw.
This thing comes from China so who knows the quality of this failed gear.
This morning Ill disassemble the apron and post a pic.
I still have a year left on the warranty however I think Ill explore the possibility of a return and then do
some serious research and get something good.
Right now Im so frustrated Ill spent three or more times the cost
just so I have a reliable lathe.

 

[markba633csi]

Hi Gregg, there are many other better choices out there if you do decide to return it- Precision Mathews has a good reputation
Apparently this particular 9x20 model has some issues
Mark

 

[Bill Gruby]

I had this trouble when I rebuilt my Jet 9X20. I replaced one part and not the other. They were mismatched and the worm ate the gear in a matter of minutes. Next I replaced both and insured the mesh was correct. They have been installed for over 15 years now with no trouble.

"Billy G"

 

[GreggC]

I had this trouble when I rebuilt my Jet 9X20. I replaced one part and not the other. They were mismatched and the worm ate the gear in a matter of minutes. Next I replaced both and insured the mesh was correct. They have been installed for over 15 years now with no trouble.

"Billy G"

When I called for warranty I asked for the gear and worm gear, they sent both, I replaced both.
The second gear failed in approx 1.5 hrs.

 

[Bill Gruby]

That worn slides up and down the lead screw guided by a key. Did you try to slide it before reassembly. If it binds it will put undue stress on the gear.

"Billy G"