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Pulling Series 2 Bridgeport Head -- what else while I'm in there?

DMoneyAllstar

Plastic
Joined
Feb 27, 2018
Last year I hit the "home machine shop lottery" when my work decided to give me a couple machines from the former shop. I snagged a 50x14 Clausing engine lathe as well as a very well equipped Bridgeport Series 2 mill. Trailered it all home and had the neighbor pluck them off with his Bobcat T300.

The mill has Accurite CNC (gen1), power drawbar, vice, a Hardinge rotary axis, lube pump, and some tooling. Came from a clean machine shop with very light use and maintained well. CNC servos were just serviced / replaced before they let the last machinist go. I've seen it run and perform some amazing feats.

Onto the problem. When I was moving the Bridgeport home, I loosened the 4 main head bolts and successfully rotated the mill head 180-deg for transport. Then the mill sat in my shop with a heat shrink poly boat wrap for 14months. Finally got my rotary phase converter and decided to uncover the machine and get it setup. First thing I did was a mistake: I forgot to loosen 1 of the 4 head bolts and ended up snapping the worm gear shaft fairly easily. I was excited, what can I say. Made me so angry because the head moves so freely/effortlessly when the bolts are loosened. I just got carried away with the impact gun. New worm gear / bolt on order.

So now I'm pulling the mill's head. ANYTHING ELSE I SHOULD MAINTAIN OR REPLACE WHILE I'M IN THERE WITH THE HEAD OFF?

Thanks for your help!
 
Don’t use an impact wrench on the rotation bolt


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That's excellent advice. The rotation bolt should only be used gently and then only with assistance in positioning the head.

Hind-sight is 20/20. I was using my little Makita 18v cordless impact, but without the the 4th nut loosened, I hit a wall. The nut was a pain to get to (behind z-axis cnc box) and it "looked" loose. I knew better.

I'm not planning on touching much of anything else. Just hope the worm gear and what's left of the shaft will come out without too much surgery.

The mill head is basically upside-down in transport position (motor-side down). The motor and the power draw-bar are closest proximity to the table, so I'll really only be able to lift the head off with my 2-ton hoist and load balancer. And then reinstall it in same position, and then crank her over.

Also hoping the Accurite Z-axis removal / reinstall is simple (uses same 4 head bolts with threaded couplers connected to mill's bolts).
 
Ah so this is a Series II Special? Just a normal 2HP head?

It is a simple process, but time consuming to get the Z axis casting off. Take the motor off, scale off (if it is scale driven, yours could be rotary encoder driven), take the belt and pulley off, remove the thrust nut, then you gotta remove the 4 bolts holding the casting to the head. This part is kinda by feel, but at this point you gotta lower the ballscrew so that you can finagle the casting off of the head. At this point, you should be able to remove the head.

Jon
 
Here's the machine (before I moved it). Picture it now with the 4th axis removed and the entire head rotated 180-deg...

Bridgeport_01.jpg
 
Ya thats just a regular Bridgeport, JR would argue whether its called a Series I or not.

So taking the Z axis casting off can be a pain, but its more just a little time consuming. I know my description above was quite vague, but if you wanna call I can give you a more detailed walk through of how to get it off. 800-285-5271

Jon
H&W Machine Repair
 
To be honest, I didn't realize I called it a series 2 in the title, lol. Not like it says Series 1 right on the machine or anything. ****IT IS A SERIES 1, 2HP MILL****

I've peered into the Z-axis casting. Doesn't look like much in there except I'm not familiar with how the cnc attaches to the quill. I've got some books and schematics to reference. And then afterwards I need to make sure the Z-assembly is re-aligned so that Acu-rite Millpwr works worth a crap.

Good news is that I've got my replacement head bolt.

Here's my actual setup as she sits today at lunch-time...

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Last edited:
Special spanner socket

Finally getting the Z-axis Acu-rite pulled off so I can get to pulling this head.

Where on earth do I get me one of these?

"Z-axis Locknut Torque Tool ID 2003-7447"

special_tool_BP1.JPG

Thanks you!

Dan
 
Finally getting the Z-axis Acu-rite pulled off so I can get to pulling this head.

Where on earth do I get me one of these?

"Z-axis Locknut Torque Tool ID 2003-7447"

View attachment 265621

Thanks you!

Dan

If you can’t find it, make it. Does your lathe run? If not find a piece of pipe, a cheap socket , whatever. You would be amazed what a couple hours with a hacksaw and a file can accomplish. I have made many weird tools like that over the years


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To my knowledge, Acu-Rite will only sell those to the distributors. I will find out though. It is just a locknut socket, the only part of it is special is that it seems to be thinner than the set we have here. Thats cause of the tight squeeze on the Z axis.

Jon
H&W Machine Repair
 
If you can’t find it, make it. Does your lathe run? If not find a piece of pipe, a cheap socket , whatever. You would be amazed what a couple hours with a hacksaw and a file can accomplish. I have made many weird tools like that over the years


Sent from my iPhone using Tapatalk Pro

Thanks. I've sized up a socket that would work with a little help from the die grinder.

Lathe is next on the priority list to get back online.

You'd think with that special part # being in a few manuals, someone would be making something for like $40. This is America, right? =)
 
To my knowledge, Acu-Rite will only sell those to the distributors. I will find out though. It is just a locknut socket, the only part of it is special is that it seems to be thinner than the set we have here. Thats cause of the tight squeeze on the Z axis.

Jon
H&W Machine Repair

Ahh, makes sense. I imagine either my work's shop once had "the tool" or made their own since our electrician setup my mill and another with the Acu-Rite cnc setup. Our tool room and it's supporting staff are long gone. Thanks for the info!
 
Vice grips did the trick. Wasn't on there as firm as I imagined. Head is free. Just need to get my hoist a load balancer and get this job done (safely). Thanks for the help!
 
Head pulled, bolt & gear replaced, and head re-assembled. Just need to get rest of Acu-Rite z-axis put back together.

As you can see in the pic, it actually worked out for me in the long run to have to deal with the head in "travel position". The weight of the motor on the bottom made the lift simple & stable.

As most have experienced, I had to cut out the old gear and remnants of the head-position shaft with the Dremel cut-off wheel. I made (3) cuts along the axis of the shaft/gear and used a chisel to pop the gear into a few pieces. Cleaned up all the debris, re-greased and installed new shaft and gear. Using the engine hoist made it pretty quick & simple.

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