G4003G VS PM1236 VS ?

[coolidge]

After ripping Grizzy a new one on quality issues maybe I should toss them a bone. You know what impressed me, dang the spindle runout. I put my Mitutoyo dial indicator on the spindle, the needle wouldn't move. I thought something was wrong with the indicator. Irritated I purchased a 10ths Mitutoyo test indicator...dang the spindle runout was about 1-2 tenths wow! I was super happy with that for a China lathe. There are a number of other things I really like about the lathe. And more sloppy stuff and defects. A real mixed bag. But you got to like that they got the spindle runout that good.

 

[verbotenwhisky]

Looking to buy my first lathe. My intended purpose is to thread rifle barrels (specifically barreled actions with 18-24" barrels) and that is it for the time being. I run a small gunshop on the weekends and have sent out more than 100 barrels this year to get threaded and want to start doing it myself. I have some machining experience and a family member who is willing to help me out who has done it his whole life. I have a $10k budget, this includes tooling and everything ill need to get going. I looked for older american lathes on facebook and craigslist for the last few months and im tired of waiting. So now im stuck between these two Chinese lathes.
what would be your pick and why? im leaning towards the g4003g because i need the shortest spindle length i can get. id love to get into the PM-1340GT but I will blow my budget after tooling. I am open to other ideas and machines!

Pre purchase worksheet answers that werent touched on:
I have zero limitations on size, our shop has 3 phase and have equipment to pick up 15tons
looking for turn key machine, not a project
Barrel sizes range from 4"-26"


G4003G :
$5300 Shipped
1 year warranty
15 5/8" spindle length from spider
comes with a spider
very popular lathe with lots of information on upgrades and troubleshooting


PM1236 :
$5800 shipped
3 year warranty
comes with coolant system and footbrake
17" spindle length without spider

My PM1236 came with a spider. I have been very pleased with the machine and if you are cutting imperial threads it does have an imperial lead screw. Machine is a gear head with plenty of range. It does have change gears. PM is a very good company to deal with and they do provide good tech support and if the need arises they will honor the warranty. I have purchased a number of items from them.

 

[verbotenwhisky]

Here's the Baldor motor mount with some notes.

Three plates. A front plate with 3 slots to mount on the last casting, a middle spacer block to achieve the correct overall spacing of the motor out from the lathe to clear the motor electrical box, and a rear plate for the rubber motor isolation mounts and motor.

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Why some of these mounts are yellow chromate and some just zinc is a McMaster-Carr mystery.

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Isolation mounts installed.

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The three plates assembled. Note the offsets (X, Y and Z) to position the motor pulley in line with the spindle pulley and to clear the lathe end cover, chip pan and the electric box cord grips and cords. I took a lot of measurements to create a 3D model of the lathe in CAD to get all this sorted.

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Here's the mount fitted to the lathe.

QUALITY NOTE: Grizzly China idiots mis-drilled the factory cast iron mount such that there was no upward (loosening) belt adjustment in the motor mount. Two of the bolts had another 3/4 inch of adjustment, the third was bottomed out in the slot. China idiots new this since the belt had to be pried on and off due to lack of adjustment, they shipped their sloppy don't care defect anyway, typical.

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Here's the Baldor, I have about 1/4 inch of clearance between the lower electrical box and the rear edge of the lathe chip pan.

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This was the dimension to worry about. I had calculated 3/16 inch of clearance between the motor face and the edge of the lathe end cover. This is not an issue on the factory motor because the motor face is cone shaped with plenty of clearance. The Baldor motor face is flat and flush. I ended up with precisely the calculated 3/16 inch phew!

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I ended up with ample space for the wiring that fits behind the motor mount. The lathe casting is recessed in this area. Also plenty of room between the motor and electrical box, cord grips and cables.

Not the obsessively LARGE motor cable lol, that's because this motor wiring requires 5 or 6 wires to accommodate forward and reverse. That's a whole story. I will likely address this issue one day as that cable is just ridiculous.

QUALITY NOTE: China idiots strike again, one of the electrical box cord grips was so oversized for the cord it had zero grip on it. I had to buy and install the proper size cord grip. As I recall I also found some loose wires in the electrical box, including one of the ground wires I'd have to check my notes. Ditto for the old G4003G so checking the electrical connections is a must on these lathes before startup.

View attachment 510367

See that link cable, it's in the trash now. In 2016 those link belts were manufactured in eastern Europe and pretty decent. It's obvious manufacturing has moved to China now and the quality has gone to pot. Lots of complaints in reviews, I tried them anyway and yeah they are trash. I ended up going with a rubber cogged belt made in the USA, possibly the finest belt I ever purchased it's crazy good.

QUALITY NOTE: Note the large chips along the side of the top cover. These Grizzly China lathes have rather pitiful paint jobs. It arrived already chipped up. I made the mistake of later sticking a piece of blue painters tape to this side of the headstock, yeah a whole slab of paint came off clean. (face palm)

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PM offers a Baldor upgrade for the PM1236. I would suggest downloading the lathe manual from PM, it is available on their sight and will provide some insight into the particulars of the machines operations. I cracked the casting on my tail stock shifting it back and forth for turning a taper and PM replaced the tail stock, the only other issue I had was I had the machine the aluminum DRO scale mount on the cross slide to gain access to the cross slide lock. If I had a complaint it would be the tail stock quill really needs to travel an inch or two further and I plan a modification to solve the issue in the future..

 

[mksj]

If you replace a single phase motor with a 3 phase motor they are typically much smaller in dimensions for the same HP/RPM specifications. The Baldor single phase farm duty motor is much larger then comparable 3 phase motors with the same HP/RPM ratings, and there are both metric and US frame 3 phase motors with the electrical box on the top of the motor. Some examples are below, that should all fit this lathe. Three phase motors will run smoother and under tighter speed control when using a VFD in sensorless vector mode, you do not have limitations as to start/stop cycles per hour and durability that are seen with single phase motors.

 

[verbotenwhisky]

If you replace a single phase motor with a 3 phase motor they are typically much smaller in dimensions for the same HP/RPM specifications. The Baldor single phase farm duty motor is much larger then comparable 3 phase motors with the same HP/RPM ratings, and there are both metric and US frame 3 phase motors with the electrical box on the top of the motor. Some examples are below, that should all fit this lathe. Three phase motors will run smoother and under tighter speed control when using a VFD in sensorless vector mode, you do not have limitations as to start/stop cycles per hour and durability that are seen with single phase motors.

PM offers a Baldor upgrade for the PM1236. It is a gear head lathe, this motor installs as a direct replacement, I will likely do the conversion eventually but I see no reason to complicate my life by adding 3 phase and VFD to a machine that works perfectly for what I use it for.