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1944 Bridgeport with J head

PeteN

Plastic
Joined
Jan 2, 2024
Bought an old Bridgeport fairly cheap and close by to where I live. It had tight table and quill but I was unable to power it up since the guy didn't have 3 phase. One thing he mentioned was that I'd need 2 more bolts to attach the quill since they were missing. Didn't think that was an issue until I got it home and looked in the 2 bottom locations and the holes in the head don't match the holes in the ram. They are slightly higher and outward, about 1/2 hole off. The top 2 bolts are fine. I know the newer Bridgeports use t-bolts for these locations so I am not aware of the bolt circle patterns for these old mills. Seeing the age of the mill (1944) I doubt it came with the J head. I'm just surprised that no one had fixed this missing bolt issue when they were using it. I haven't pulled the head yet so I haven't made any measurements on how to resolve. I did some searching and I saw the bolt pattern for the M head and it appears to be much smaller than what I have. Any insight?
 

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How about some more pictures of what you are talking about?
Pictures of the open holes for a start. Next, a picture of the serial number and more pics of the mill. What kind of ram does it have? Pictures of the head, too.
 
Bridgeport S/N 4422
J83453
Round Ram
Hard to get pictures deep in the hole pocket but the red circles represent about what I am seeing.
1706277182015.png 1706277240948.png
 

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Bolts aren't the problem, threads are probably gone.
I have taken the head off similar by bolting a stud to the table, holding it in a collet in the spindle, loosen the remaining bolts then dial the y axis away. Table all the way up quill retracted.
 
Something is not adding up. If you got bolts in the upper holes, should be no reason why you can't get bolts in the lower holes. As far as I know this has not changed over the years. Experts, correct me if I am wrong.
 
I agree with all the comments above that something doesn't add up. The lower holes in the head and the threaded holes in the ram are offset like I showed in the pic with the red circles. I need to pull it apart this weekend to see what is going on. Just was trying to get some info if the bolt circle is the same on all round rams. Since it doesn't use T bolts like the newer versions it has to be on the same bolt circle to work. It was hard to believe that someone ran it like this for years. I don't know when the J-head was installed though.
 
Something is not adding up. If you got bolts in the upper holes, should be no reason why you can't get bolts in the lower holes. As far as I know this has not changed over the years. Experts, correct me if I am wrong.
I agree 100% with what you stated above.
The ram should be a t slot groove for the long bolts to rotate around the so you can angle the head.
The OP is suggesting the ram has “fixed” bolt positions which is unlike any standard Bp I’ve ever had or repaired.
 
Maybe the original bolts were broken and replaced with t nuts? So you just need to loosen the top 2 bolts and rotate the head back and forth to get the bottom 2 bolts started?
 
Maybe the original bolts were broken and replaced with t nuts? So you just need to loosen the top 2 bolts and rotate the head back and forth to get the bottom 2 bolts started?
I guess I’m wrong here- it’s been a few years but I used to have a round ram j-head and if I remember correctly the head doesn’t rotate independently from the ram- you rotate the ram to rotate the head.
 
Those are just T bolts that hold it on. There's a circular T slot in the front of the ram that they go into. You need 2 more. And, I wouldn't recommend grabbing something in the collet to lift off the head. Use an engine hoist or some way to lift from above.

 
Those are just T bolts that hold it on. There's a circular T slot in the front of the ram that they go into. You need 2 more. And, I wouldn't recommend grabbing something in the collet to lift off the head. Use an engine hoist or some way to lift from above.

Any specific concern? I’ve done that with success, and H&W sells something that fits into the R8 slot and works similarly.

I will say that I used a 3/4” collet and the thing with the 3/4” shaft had better be very well attached to the table. Don’t do something foolish like clamp a piece of round stock into a vise alone and expect it to hold.
 
Any specific concern? I’ve done that with success, and H&W sells something that fits into the R8 slot and works similarly.

I will say that I used a 3/4” collet and the thing with the 3/4” shaft had better be very well attached to the table. Don’t do something foolish like clamp a piece of round stock into a vise alone and expect it to hold.
Yea, it's a spindle not a lifting lug. Never mind, it's your mill do as you please.
 
Static load rating of the spindle bearings is approximately equivalent to four Bridgeport's stacked on top of each other supported by the spindle. Probably more like six Bridgeport's.
 
Static load rating of the spindle bearings is approximately equivalent to four Bridgeport's stacked on top of each other supported by the spindle. Probably more like six Bridgeport's.
So one would have to really try to mess up a spindle bearing? I’m guessing a fully retracted quill is quite strong as well.

Not that I want to encourage anyone to do something they aren’t comfortable with to their spindle.
 








 
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