Bridgeport 2J2 Mill Vari-drive and motor questions

I recently bought what seems to be a fairly clean 2J2 that comes back as a 1985 model. I ordered a VFD for it and temporarily wired it up to just be able to see if it worked before going any further (I still have to move the machine to its final spot, etc.

I was able to get the mill to start, but after just a couple of seconds (like 2 or 3) the motor makes an odd scraping noise, the VFD throws a code and I can stop the motor with my finger. I pulled the motor and tried it with no load...same thing. It turns freely, seems smooth and I can't feel any movement when I push/pull on the shaft, so I'm guessing it's either on the other end of the shaft, or something else....I know very little about electric motors. If anybody has any thoughts I'd appreciate them. Ultimately, I'll probably be looking for a shop in the Detroit area to take a look at it.

When I dropped the pulley cover I found some parts in it...half of the key, the set screw, some of a plastic bushings and the plastic slider the key rides on. As you can imagine, the veridisc and spring assembly were wobbling a bit on the shaft. I did some research and it sounded like some folks simply replace the disc and spring assembly rather than repairing it. Does that make any sense? I have a press and should be able to get the spring off safely, and the replacement parts look affordable. Is this a balance issue if people replace the assembly or am I missing something?

There was definitely some black grit inside the case and in the cover, but the belt looked fine. I'm guessing it's probably smarter to just replace the belt since the motor is out, right?

So, any advice or thoughts on the above would be appreciated. If there's anything else I should have addressed don't feel bad about pointing it out...I'm certainly inexperienced with machinery and trying to learn as I go. Thanks!

Post a picture of the motor tag so we can see what voltage and phases we’re dealing with.

If it’s 220v 3 phase you can spin the motor shaft with some speed, I used a DeWalt drill and then jump it with residential single phase 220v on any two wires (as long as motor is wired correctly for 220v 3 phase!!!!) and it’ll run just fine. Make sure you can remove the drill *BEFORE* you juice the motor or you’ll need braces to fix your teeth when it spins up on its own.

A motor plate we need. And what voltage do you have available to feed the VFD?

I was powering the VFD with 230V single-phase from a 60A circuit...my welder circuit. I also tried to power the motor with a static phase converter that I have used in the past on other motors and it was no better.

Here's the motor plate.

Here's a short video...two seconds in you can hear the scraping.

Hmm, it seems you indeed had some mechanical damage going on but I’m no expert and I have seen worn miss wired motors “rub” And bang when the electromagnetic fields are pulling the rotor in weird directions. The weak motor is a sign of a bad winding or a bad vfd.

If you have a multimeter then you can measure the windings for continuity. I would start at the junction box and double check the LOW VOLTAGE wiring is correct per the data plate. Then test the 3 wires for continuity. If you have similar resistance across the 3 leads then go ahead and manually spin the motor up and jump your 220v across 2 leads, as long as your internal wiring is correct then it don’t matter what wires of the three you pick.

Be aware however, a 2hp 220v SINGLE phase motor will pull 13ish amps full load so you need a 10-15 amp fuse or breaker to be safe in case of short out. I didn’t use any protection when I jumped both my knee mill and southbend lathe to test them.

If wired correctly and you get near equal resistance you should be good, I would THEN jump it on the single phase and watch it run and feel it out. On single phase it’ll have about 2/3 the hp so atleast 1HP amd you won’t be able to gently stop that with your hand

Homebrewblob said:

Hmm, it seems you indeed had some mechanical damage going on but I’m no expert and I have seen worn miss wired motors “rub” And bang when the electromagnetic fields are pulling the rotor in weird directions. The weak motor is a sign of a bad winding or a bad vfd.

If you have a multimeter then you can measure the windings for continuity. I would start at the junction box and double check the LOW VOLTAGE wiring is correct per the data plate. Then test the 3 wires for continuity. If you have similar resistance across the 3 leads then go ahead and manually spin the motor up and jump your 220v across 2 leads, as long as your internal wiring is correct then it don’t matter what wires of the three you pick.

Be aware however, a 2hp 220v SINGLE phase motor will pull 13ish amps full load so you need a 10-15 amp fuse or breaker to be safe in case of short out. I didn’t use any protection when I jumped both my knee mill and southbend lathe to test them.

If wired correctly and you get near equal resistance you should be good, I would THEN jump it on the single phase and watch it run and feel it out. On single phase it’ll have about 2/3 the hp so atleast 1HP amd you won’t be able to gently stop that with your hand

Click to expand...

I probably should have been more specific. When the noise happens, the VFD throws a code and stops supplying power to the motor, so that's why I can stop it with my fingers...it's just coasting down. The motor seems to be spinning up to speed normally for the first two seconds, and it did turn the spindle when still installed in the machine, but as soon as the noise happens it shuts off.

The motor is definitely wired correctly for low voltage. I checked twice and redid the connections to make sure all the wires were making good contact...no change. I'm certainly not an electrician, but I'm pretty good with a multimeter and do quite a bit of electrical troubleshooting at work so I'm confident the supply side is good. I'll definitely check continuity and resistance on the three windings...certainly can't hurt.

Homebrewblob said:

Hmm, it seems you indeed had some mechanical damage going on but I’m no expert and I have seen worn miss wired motors “rub” And bang when the electromagnetic fields are pulling the rotor in weird directions. The weak motor is a sign of a bad winding or a bad vfd.

If you have a multimeter then you can measure the windings for continuity. I would start at the junction box and double check the LOW VOLTAGE wiring is correct per the data plate. Then test the 3 wires for continuity. If you have similar resistance across the 3 leads then go ahead and manually spin the motor up and jump your 220v across 2 leads, as long as your internal wiring is correct then it don’t matter what wires of the three you pick.

Be aware however, a 2hp 220v SINGLE phase motor will pull 13ish amps full load so you need a 10-15 amp fuse or breaker to be safe in case of short out. I didn’t use any protection when I jumped both my knee mill and southbend lathe to test them.

If wired correctly and you get near equal resistance you should be good, I would THEN jump it on the single phase and watch it run and feel it out. On single phase it’ll have about 2/3 the hp so atleast 1HP amd you won’t be able to gently stop that with your hand

Click to expand...

Update: I got the same resistance across the three legs no matter how I combined them....good sign.

At that point I pulled out a good 5hp 3-phase motor I have on the shelf and tried powering it with the VFD. It did the same thing...a couple of seconds, an odd sound, and it would stop.

At that point I grabbed my static phase converter and powered up the Bridgeport motor...worked perfectly. I even put the sole of my shoe on the vari disc to give it some resistance and it didn't even slow the motor a bit. In short, I'm pretty confident the motor is fine, and it's a VFD setting. I spent an hour going through the VFD manual trying all sorts of things, and got it a bit better, but now it throws a code after around 10 seconds.

I bought the VFD from Wolf Automation, and they have a good rep, so I'll give them a call and see who I should talk to in order to sort out what's happening. At least I won't have to replace the motor!

I also found there was almost no glue in the Vari disc where the bushings were...probably why they failed. When I say almost no glue, it was just a couple of tiny spots here and there.

More to follow...

G-ManBart said:

When I dropped the pulley cover I found some parts in it...half of the key, the set screw, some of a plastic bushings and the plastic slider the key rides on. As you can imagine, the veridisc and spring assembly were wobbling a bit on the shaft. I did some research and it sounded like some folks simply replace the disc and spring assembly rather than repairing it. Does that make any sense? I have a press and should be able to get the spring off safely, and the replacement parts look affordable. Is this a balance issue if people replace the assembly or am I missing something?

There was definitely some black grit inside the case and in the cover, but the belt looked fine. I'm guessing it's probably smarter to just replace the belt since the motor is out, right?

Click to expand...

G-ManBart
Yes replace the belt and while things are apart pull the front vari-disc and inspect the bushings and key.
The Goodyear belt runs quiet for a home shop as it has a softer rubber compound than a Gates belt. The Gates belt will have a longer service life and is the one I installed on a regular basis. A drive belt that has a varying width will transmit vibration to the nylon bushings in the vari-sheaves. Result is the bushings release from the epoxy and wear out faster.
The spring for the motor vari-disc can be compressed and held in place by one person while another removes the socket head cap screws.
Since the motor shaft bushings are obliterated inspect the shaft for scoring damage.
Replacing the assembly(disc and spring) or installing new keys and bushings depends on how deep the pockets are and if one has a fear of failure attempting new tasks.
The bushing-key replacement is a simple fix and there are a number of write-ups on how to do it. Search the Bridgeport threads for similar repairs. Some of the threads have step by step instructions for this type of repair.
Do you have a Bridgeport manual for operation and parts? Easy to find one for free as a pdf.
Bridgeport Factory Literature
Bridgeport Milling Machine Parts Diagrams Series IJ and 2J

My brother was a Special Agent-IRS. They have a nick-name for the FBI
John

jhruska said:

G-ManBart
Yes replace the belt and while things are apart pull the front vari-disc and inspect the bushings and key.
The Goodyear belt runs quiet for a home shop as it has a softer rubber compound than a Gates belt. The Gates belt will have a longer service life and is the one I installed on a regular basis. A drive belt that has a varying width will transmit vibration to the nylon bushings in the vari-sheaves. Result is the bushings release from the epoxy and wear out faster.
The spring for the motor vari-disc can be compressed and held in place by one person while another removes the socket head cap screws.
Since the motor shaft bushings are obliterated inspect the shaft for scoring damage.
Replacing the assembly(disc and spring) or installing new keys and bushings depends on how deep the pockets are and if one has a fear of failure attempting new tasks.
The bushing-key replacement is a simple fix and there are a number of write-ups on how to do it. Search the Bridgeport threads for similar repairs. Some of the threads have step by step instructions for this type of repair.
Do you have a Bridgeport manual for operation and parts? Easy to find one for free as a pdf.
Bridgeport Factory Literature
Bridgeport Milling Machine Parts Diagrams Series IJ and 2J

My brother was a Special Agent-IRS. They have a nick-name for the FBI
John

Click to expand...

Thanks! I made a little fixture to remove the spring on the motor vari disc, so that wasn't a challenge. The shaft seems to have survived without any significant scoring, so that's good. The bushing replacement looks pretty simple so that's the plan for now.

I did a bit more disassembly last night and the spindle vari disc bushings are intact, but show some wear so I'll replace those as well. I figure I'll replace the bearings and add a new timing belt while I have it all apart.

Now I just have to get the VFD tech folks on the phone and sort through that pain...ouch.

Hey, Treasury agents got Al Capone, so they can't be all bad

G-ManBart said:

Now I just have to get the VFD tech folks on the phone and sort through that pain...

Click to expand...

Are those even made anywhere except China anymore? Good luck, do you speak Mandarin lol

The timing belt does not need replacement as often as the Vari-disc drive belt. Inspect all the pads for tears or separation. If present replace.
The 1&1/2 hp and 2 hp take different timing belts.
The two bearings in the front disc bearing cartridge will have a very long service life. Rotate the bearing by hand to detect 'dry' bearings or if grease is still on the job. The plastic seals can be popped out and the bearings re-greased. Mobil red synthetic for grease and a fine dental pick for seal removal.
Consider replacing the top bearing #4 for the upper spindle. This radial bearing has a lot of side load from the drive belt. Replace with a quality bearing rather than an 'economy' bearing.

John

Homebrewblob said:

Are those even made anywhere except China anymore? Good luck, do you speak Mandarin lol

Click to expand...

No idea where it's made but I briefly talked with the tech guy at Wolf Automation (where I bought the VFD) and he said to call back if I ran into any problems. He also said that if it was really complex he could put me in touch with a tech person at Taco Westinghouse. I can only assume their design and tech folks are here and the units are made overseas.

jhruska said:

The timing belt does not need replacement as often as the Vari-disc drive belt. Inspect all the pads for tears or separation. If present replace.
The 1&1/2 hp and 2 hp take different timing belts.
The two bearings in the front disc bearing cartridge will have a very long service life. Rotate the bearing by hand to detect 'dry' bearings or if grease is still on the job. The plastic seals can be popped out and the bearings re-greased. Mobil red synthetic for grease and a fine dental pick for seal removal.
Consider replacing the top bearing #4 for the upper spindle. This radial bearing has a lot of side load from the drive belt. Replace with a quality bearing rather than an 'economy' bearing.
View attachment 298316View attachment 298317
John

Click to expand...

Thanks! The top bearing #4 was in good condition, but I still ordered a new one which is supposed to be a quality sealed bearing...seemed like cheap insurance. The timing belt looked decent, but I figured it was worth spending the $20 to have one less thing to worry about. I'm probably being overly cautious, but I'd rather spend a few bucks on something I didn't need than have to pull it all apart in 6 months if something fails that I could have replaced. The good thing is that I've been surprised how affordable these sorts of parts are....fingers crossed I don't run into a problem with an expensive part!