Bridgeport problem

I moved my Bridgeport to my new shop a couple months back. The new shop had
to be completely re-wired and I didn't get the machine back under power
until a few days ago. This morning, I tried to tram it in and use it and
hit a problem:
The quill is stuck.
Actually, that is an over-simplification. It moves just fine the first inch
of its travel, then it stops. It doesn't jam, per se, it is just like it
hits a stop. The power downfeed works properly in that first inch, but,
when it hits the stop, it won't go any further (this is turning it by hand;
obviously I'm not going to do it under power...).
When I moved the mill, I inverted the head to lower the center of gravity
and moved it back to its normal position a day or two after the move.
I tried listening to the head in various places with a mechanic's
stethescope, but I couldn't here any sharp, metallic sounds when it hit
whatever is stopping it.
Anyone else been through this or has anyone overhauled a BP 2J head and can
suggest what happened?
Thanks.
Jerry
Reply to
Jerry Foster
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A SWAG: the quill skirt (the sheet metal shield visible thru the quill stop slot when the quill is extended) shifted and is hanging up on something.
Reply to
Ned Simmons
Forgot to ask...
Does anyone know where I can download a copy of the manual?
Thanks.
Jerry
Reply to
Jerry Foster
Real dumb, but it must be asked - is there any chance the quill stop on the front (the circular nut you thread up & down) is about 1" from the top?
GWE
Reply to
Grant Erwin
try my website.
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If you like it, place a link to it from yours.
i
Reply to
Ignoramus24273
Ahh, 2J is a little different, but most of what I know should still apply. The one area that is different is the motor pulley has spring-loaded sheaves for the vari-speed belt. I think you can wedge the sheaves apart to release tension on the belt when you remove the motor. Once the motor is off, you can remove three nuts on the vertical bolts at the top of the main head casting and then lift the belt housing straight up and off the spindle. (I think on the 2J you have to disconnect a high-low clutch link.)
This will expose the entire inner working of the quill. There is a steel sleeve screwed to the top of the quill that can be easily removed. My guess is that this has somehow gotten mashed and is hitting the top of the quill bore, instead of sliding into it. (I have never gotten an explanation of what this sheet metal part is for. It attaches to the top of the quill and wraps around it. When the quill descends, it slides into a slightly larger ID part of the bore at the top. It is called out on the parts drawings as the "quill skirt".) If it was bent and hitting the top of the main casting, I think it would bind right about where you are getting that. Another possible thing could be the drawbar has gotten off center and is hitting the id of the top bearing cap. That is at the top of the belt housing.
There are plenty of other things it COULD be, such as a chip that has fallen into the quill's rack. If that is it, then you can carefully remove the quill return spring, disassemble the overload clutch on the power feed, and remove the pinion out the right side. This will allow you to get in there and clean the rack teeth. (Without the pinion and spring, the quill will be able to drop all the way out of the housing, so support it with a wood block.) Something could have gotten into the stop ring slot in the front, you can remove the stop ring with an allen wrench after removing the stop rod. That is actually pretty intricate to reinstall, however, so I don't want to recommend that over the net!
Jon
Reply to
Jon Elson
The pulley is tapped for a puller to compress the spring on the rear pulley. I haven't done one in a while but I seem to remember using two pieces of threaded rod a drilled plate and some nuts to compress the spring. The biggest problem is the plastic bushings on the pulley sheaves. They wear out and cause vibration. The other big problem is the second belt in the lower part of the housing. It is a timing belt and when it gets worn it sounds like a bearing is going bad but it is the teeth of the belt not quite meshing with the drive sprockets.
you will also have to remove the drilling stop and auto feed release in the front to get at the allen screw that holds the block that the knurled drill stops hit against.
The first thing I would do is check on that sheet metal liner as you said. I would bet it moved around and the slot is not in line with the block that I refered to above with the allen head cap screw holding it to the spindle cartridge.
John
Reply to
John
The quill can be dropped without messing with the drive.
Reply to
Steve Austin
I'm not sure I understand why there are so many suggestions for the bent quill skirt. Certainly that can be a problem, and cause what you observe, but why would that occur under the stated conditions? If it was OK before the move, it should still be OK.
If you inverted the head, I suspect that there is something that got dislodged and jammed the rack/pinion for the quill, especially noting your comment about not hearing any impact noises. I did some work and cleanup on my J-head some months ago, and was amazed at the amount of crap and chips floating around in the belt housing.
Reply to
matt
--Just for grins squirt some LPS-2 on the exposed bit of quill, behind the depth stop screw, then work the quill up and down a bit. If that seems to improve things you're probably dealing with a tiny bit of corrosion from the long hiatus.
Reply to
steamer
Yes, but if the quill skirt is binding up, then it is definitely NOT going to come out the bottom. His skirt may not be totally trashed yet, but much pushing on it will wreck it. It won't be really hard to fabricate if it is mangled, though. But, the consensus of us bystanders (who have not actually seen the problem close up), tends to be in favor of the skirt catching on the main housing. If this is indeed the problem, you HAVE to pull the belt housing to reach the area at the top of the quill and get to the skirt.
Jon
Reply to
Jon Elson
Agreed, I see no reason why the quill skirt would get damaged by inverting the head. Possibly some chips had found their way inside the main casting, and rolled into the wider groove at the top of the quill bore, jamming the skirt. That's about the only thing that I can think of. There should be no way chips can get in the main cating, but.....
Yes, this is just as good a possibility as the skirt.
Jon
Reply to
Jon Elson
ayup...very common.
Gunner
Reply to
Gunner Asch
I had the head laid over 90 degrees and was playing with it. It seemed to me that the jam-up was occuring in the vicinity of the downfeed lever. So, "stuff" in the rack-and-pinion area seems like a good possibility. And, of course, that is "somewhat" easier to take apart than it is to take the whole top off... I'll start there, when I have some time to work on it. Meanwhile, the mill is usable. It's just that I get a lot of exercise with the z-axis crank...
Jerry
Reply to
Jerry Foster
It is some help. Your manual is for a 1966 J head and mine is a 1980 2J, but the problem area is similar enough that the manual is of some help. Thanks for sharing.
Jerry
Reply to
Jerry Foster
The group keeps speaking of the skirt. Item #128 is that item.
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HTH,
Wes
Reply to
Wes

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