Removing Bridgeport 2J head.

[rszimm]

The bolt that flips the head upside down spins free and now it's stuck at a cockeyed posistion. I'm guessing that the bolt has come disconnected from the worm gear inside. With the worm gear there, I can't backdrive it vertical, and cant turn it with the bolt. So I guess I'm taking the head off. I already know it's just the 4 bolts on the front, but there's a lot of weight there. Is there a best practice for slinging the thing and jacking it up so it doesn't come crashing down when I release the bolts?

Here's a photo. It's tilted down because I was transporting it and figured that if I couldn't rotate it upside down, tilting the head down might lower the center of gravity a little. The tilt still works, so I can fix that.

 

[4GSR]

I suspect you broke a tooth off on the worm gear that lets you tilt the head side to side. Bring the nod back up to its original position. It's been a many years since I've messed with a 2J head. Your best bet, if the worm gear is damaged, is to get ahold of the head with a overhead crane or engine lift and remove the four bolts holding the head onto the ram and remove.
You generally have to assist the head when tilting sideways to the 90° position or totally upside down.
There is no easy way to grab the head per say. Just have to rig up something to help you out.

 

[rszimm]

Thanks. Yeah, I'm worried that the thing is so top heavy that if I sling it below the housing where the belt is that it'll just flip over when I get that last bolt off. We'll see.

 

[4GSR]

Most of your weight is in the motor. Get it supported, the rest is hanging below the COG.

 

[lucky7]

Depending on your physical strength, what I’ve done in a place with no crane, is remove the motor, then upper housing, then head in front of knuckle… you get the picture. All in bits that one person can lift off. Takes awhile.

 

[jccaclimber]

There's an easy way to do this, assuming you can manhandle it back to vertical (I'd do this with one person on each side, but it should be doable). Chuck some 3/4" round REALLY well in the vise (or turn a 3/4" circle into square stock, put a dowel into a hole in a bar, etc). Clamp that up in a collet, unbolt the head, and with the ram back slide the saddle forward. H&W also sells something more secure to do this for $50, which you could also make yourself if desired. https://machinerypartsdepot.com/product/mhrp/. If you do go for the stock chucked in a vise, make it snug. You don't want it to tip sideways as that's a lot of torque on a small spot.

As mentioned above, removing the motor and back reeves drive cones will make it a fair bit lighter. You're probably aware, but you're missing a cover that goes over the fan on the motor. Note, the worm gear alone isn't up to the task of bringing an inverted head vertical without supporting a lot of the weight.

 

[M.B. Naegle]

^^^ I've done the same approach with one of our old BP's that had the same issue. New gear from H&W wasn't too expensive or hard to install either. If I remember right, the J and 2J both use the same parts in the knuckle and swivel assembly's.

To put ours back upright, I think I just had someone support and push on it while I spun the adjusting gear, since it was only a few broken teeth and would jam otherwise.

 

[rszimm]

Got it off with a beam clamp, a chain hoist and a ratchet strap. Not a whole lot of clearance there. The worm gear looks fine. The gear it meshes to looks fine. Indeed, the worm gear just spins free and doesn't seem connected to the bolt. That explains why I couldn't manhandle it back to vertical (can't backdrive a worm gear), and why it won't come off. Now I just have to figure out how to get the worm and adjusting bolt out of there. There was a little set screw that I took out, but that didn't seem to release anything. I guess I'll have to look for some drawings somewhere...

 

[rszimm]

I was able to get the bolt out by putting some vice grips on it and prying it out of there. I now see the problem. The bolt has sheared off. It should look like this link. Instead, mine looks like the photo below. What's worse is the end that broke off is jammed up inside the worm gear, so I can't get that out of there. Ugh. I'm guessing the only option is to drill it out? (and I'll probably totally screw up the worm gear in the process).

 

[Clive603]

Glad you got it off safely.

Totally agree with the suggestion about the head removing / re-installing post. Mine is a touch more sophisticated with an R8 taper rather than the simple round post to grab in in a collet. Looked to be a more secure way of going about things as it puts the load directly into the spindle. I also made a simple support from Speedframe, a knock together 1" square tube and joint system common in the UK, to hold the overhanging motor and drive stuff. Seemed a good idea to limit off centre loads.

When I'm wanting to work on the head I just swivel the motor round sideways so its over the table, engage both supports to use the Y and table feeds to move the unbolted head.

Having the head upright and firmly fixed to a moveable table makes working on thing so much easier. Beats the heck out chasing it around a bench with it lying on its side.

Clive

 

[rszimm]

Success! I got it out after a lot of struggling trying to drill it. (it's hard to drill a part that wants to spin). In retrospect I probably should have put a small hole in the back and then try and tap it and then pull the broken part of the shaft out. I don't have a 3" long tap though so I just drilled the whole shooting match out. I did end up messing up the inside hole of the worm gear, so I guess I'll have to replace that now. Off to google bridgeport parts!!!


I also found a tubalcain video on removing the head that seems to be similar to what you guys were all saying.

It didn't particularly apply to my situation because I couldn't get the head vertical, but it looks much easier if you start with a vertical head.

 

[M.B. Naegle]

One thing that helps (once yours is fixed) is to try to avoid letting the gear do all the work. Push/pull it into place as you work the screw so that that 3/8" piece of mild steel isn't the only thing supporting the head. It can rest on the gear when stationary as you tighten the front bolts, but I don't like using the gear alone to lift the head into place or to support it as it rotates downward.

 

[rszimm]

Thanks. I think I found the core problem. The gear that the worm gear meshes into had its two mounting bolts sheared and the roll pin was bent/offset. When I tried to re-install I found the gear wouldn't sit all the way into the pocket in the ram. I think that maybe it got installed such that it wasn't flush against the back which put a huge stress on the mounting bolts, eventually causing the bolts to shear, the gear to shift, and then the worm didn't mesh well and it broke the worm gear bolt.

Anyway, thanks everyone for your help! Any suggestions for where to buy a few Bridgeport parts?

 

[4GSR]

T..................

Anyway, thanks everyone for your help! Any suggestions for where to buy a few Bridgeport parts?

Go look at post #6 for the source for BP parts.

 

[jccaclimber]

Thanks. I think I found the core problem. The gear that the worm gear meshes into had its two mounting bolts sheared and the roll pin was bent/offset. When I tried to re-install I found the gear wouldn't sit all the way into the pocket in the ram. I think that maybe it got installed such that it wasn't flush against the back which put a huge stress on the mounting bolts, eventually causing the bolts to shear, the gear to shift, and then the worm didn't mesh well and it broke the worm gear bolt.

Anyway, thanks everyone for your help! Any suggestions for where to buy a few Bridgeport parts?

I get all of my Bridgeport parts from H&W. I started because they were well priced and had good availability. I kept doing it because they have amazing support even when I'm not buying something from them. On occasion they've even talked me out of buying something from them because it turned out I didn't need a new part, but rather an adjustment. Call them up when placing your order and they'll let you know what, if anything, to watch out for, or what else to check on while you're in there. No affiliation, just a very happy customer.

 

[rszimm]

Thanks. Ordered from them a few hours ago. If I had seen your message first I would have called......I'm sure there will be a next time

 

[Clive603]

It didn't particularly apply to my situation because I couldn't get the head vertical, but it looks much easier if you start with a vertical head.

The "grab a post in the spindle" method can still be made to work if you fix the post to some sort of angle bracket and support the heavy, seriously overhung, motor end with a suitable jack, wood cribbing or other arrangement. I'd probably have just taken the end of some square bar down to round so it could be held in a collet and grabbed the other end in my biggest machine vice. No issues with getting the angle right that way.

Most of the weight is taken by the support at the other end anyway.

I have some stout car scissors jacks, ex scrapped SAAB 900-9000, that are very useful for such odd-ball support of relatively large things. Bolt the base down and fix a suitable adapter to the to plate using the two holes thoughtfully provided by Mr SAAB and stuff isn't going anywhere until you tell it.

Lacking the workshop height to right a direct lift or an engine crane with sufficient reach I would have to have done the job that way. Once the head was off and on the table getting it down to where engine crane could reach would have been easy peasy.

Clive