Bridgeport Y axis nut
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  1. #1
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    Default Bridgeport Y axis nut

    The Y axis nut had about .050 lash as read on the dial. Suddenly it has .200 lash. So I figure the adjuster screw backed out. So I remove the Servo power feed and the bearing block to make a quick adjustment. Much to my surprise there is no adjusting screw. I removed the lead screw for a better look and discover the nuts are one nut with no apparent adjustability. The slop is the whole nut moving in the trunnion. Can I tighten it up without a major tear down? I have quite a bit of work right now and need it up and running. It is no garage queen, it works for a living every day.

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    I'm no expert, I've had 3 bridgeports, 1 old round ram, middle aged step pulley, and a youth vari speed. All had an adjuster bolt, I think it was above the leadscrew. Is there a place for an adjuster screw and it's just missing. Worse case you could drill/tap a bolt into the trunion to at least hold the nut still

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    Quote Originally Posted by sam_stlouis View Post
    I'm no expert, I've had 3 bridgeports, 1 old round ram, middle aged step pulley, and a youth vari speed. All had an adjuster bolt, I think it was above the leadscrew. Is there a place for an adjuster screw and it's just missing. Worse case you could drill/tap a bolt into the trunion to at least hold the nut still
    I know the screw you are referring to, that is the one I was going to adjust. It's not there, and the nut is one piece, not two so it can't be adjusted anyway. The nut seems to be able to move in the trunnion. What holds it in place? I need to repair this without a tear down, is it possible?

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    bump bump bump

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    So your yoke is not drilled and tapped for an adjusting screws and a locking screw? Typically a single nut has a cut on one side. So you should be able to have the adjusting screw on the same side as the cut, so that you can actually tighten and loosen the tension on that part of the nut that will give you the adjustment.

    Obviously you could take your nut out and cut it in half. Then make sure when you put the nuts on the screw, make sure that your nuts are nut flush against each other with the keyway lined up.

    Jon

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    Quote Originally Posted by HWElecRepair View Post
    So your yoke is not drilled and tapped for an adjusting screws and a locking screw? Typically a single nut has a cut on one side. So you should be able to have the adjusting screw on the same side as the cut, so that you can actually tighten and loosen the tension on that part of the nut that will give you the adjustment.

    Obviously you could take your nut out and cut it in half. Then make sure when you put the nuts on the screw, make sure that your nuts are nut flush against each other with the keyway lined up.

    Jon
    What is holding the single nut in place? It has end float in the trunnion, that is where the problem is. I am working through the hole in the knee casting that the Y lead screw goes through so it is hard to see what is going on.

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    I know this is not the answer you are looking for, but in the time this post has been up, you could have already gotten a new yoke and y axis nut from [email protected] in the mail

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    It is so simple to do it the right way. If you 1.2 ass it you will be wasting double the time next time you have to fix it the right way. Overnight the parts from Barry,

    YouTube

    YouTube

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    Quote Originally Posted by moonlight machine View Post
    What is holding the single nut in place? It has end float in the trunnion, that is where the problem is. I am working through the hole in the knee casting that the Y lead screw goes through so it is hard to see what is going on.
    That was my question. Does your yoke not have two drilled and tapped holes in the right hand side of the yoke? That is how the nut is captured in the yoke. I am not sure exactly what you are trying to say. Is your key sheared?

    Pictures time, I think.

    Jon
    H&W Machine Repair

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    LISTEN ALL YOU DICKS THAT THINK I AM A HALF ASSER. I have a very complicated setup that includes a 500lb 18" tilting rotary table on that mill right now. If all I had to do is slide the table off and there it is, knock it out I would have done so without a post. I know full well how to order parts from H&W, my new oiler tank showed up today. Now the question I would like the answer to, What is supposed to hold the non adjustable 1 piece nut in place? It has .100 approximately of END FLOAT, with the lead screw in place you can push the nut in and pull it out and see as plain as day the NUT moving in and out of the trunnion. It has no other movement. The trunnion has a set screw along side of the nut and the old style large head adjusting screw is not there. The set screw is tight and it makes no difference to the end float if it is loose or tight. It appears to have a plug of some kind in the hole where the adjusting screw should go. Is it possible that there is a set screw from the side or top that should be holding the nut in place? Unless I tear down my setup I have to work through the lead screw hole in the front of the knee.

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    [QUOTE=moonlight machine;3377720]LISTEN ALL YOU DICKS THAT THINK I AM A HALF ASSER.
    It appears to have a plug of some kind in the hole where the adjusting screw should go.]

    Hey chill out there moonlight!

    If you look at the video, the smaller screw is just to keep the larger one from loosening, it’s been a little while since I was in there on my bp but I think the larger screw is both the backlash adjustment and also the retaining screw. Sounds like the head may have popped off of yours, leaving the “plug” that is appearing to be in the hole.

    We’re you putting a large load on the Y feed when it got a lot worse?

    It’s going to be hard to get it out if it has busted, I think it would have to come apart to fix it.

    Don’t shoot the messenger!

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    Quote Originally Posted by moonlight machine View Post
    LISTEN ALL YOU DICKS THAT THINK I AM A HALF ASSER. I have a very complicated setup that includes a 500lb 18" tilting rotary table on that mill right now. If all I had to do is slide the table off and there it is, knock it out I would have done so without a post. I know full well how to order parts from H&W, my new oiler tank showed up today. Now the question I would like the answer to, What is supposed to hold the non adjustable 1 piece nut in place? It has .100 approximately of END FLOAT, with the lead screw in place you can push the nut in and pull it out and see as plain as day the NUT moving in and out of the trunnion. It has no other movement. The trunnion has a set screw along side of the nut and the old style large head adjusting screw is not there. The set screw is tight and it makes no difference to the end float if it is loose or tight. It appears to have a plug of some kind in the hole where the adjusting screw should go. Is it possible that there is a set screw from the side or top that should be holding the nut in place? Unless I tear down my setup I have to work through the lead screw hole in the front of the knee.
    The adjusting screw is what holds it in place, the one you said is not there. I had mine apart about a year ago and when I took out the adjusting screw it was bent really bad, so I replaced it with a new one. As cyanidekid stated, yours may be broken off. You stated there was .050 lash, then there was .200, could be that it broke off at that time.

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    I think the head of the adjuster screw is broken off. I have seen that happen a couple of times ,usually from a forklift running into the table. Try a left hand drill bit on that "plug".I personally have removed 2 broken off remains that way.Bring the table out as far as you can.Pain in the ass working through that small opening to do anything.

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    After stating in post 10 exactly what I have and need the next 3 replies tell me about the 2 piece nut set up!!! Unbelievable!! I know about the 2 piece adjustable back lash system. That is what is on the X axis of this machine.

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    Ok on post #10....

    Having only the Y-Axis window is tight quarters.
    I have made repairs where the adjuster screw and keeper were snapped off. The casting is a solid stop for the nut in one direction only. Any other force is directed at the head of the adjuster screw and it may snap. Overtighten the adjuster beyond what the nut will compress leaves a latent force when added to a force from milling will cause failure.

    Suggest:
    Loosen or remove the Y-Axis gib and move the table as close to the operators front position as possible.
    Remove the Y-Axis and nut together (sounds like there is nothing holding it in place) and get a better look at the casting.
    There should be a counterbored hole where the adjuster lives and there should be a break-out in the wall so the head of the adjuster
    will overlap the nut.

    The set screws:
    There should be no set screws at all.
    Unless.....a previous owner did some type of repair.
    There is a possibility the adjuster was over torqued till the casting was cracked creating a break-out between the threads and the bore for the nut. If so, cleaning to expose the "set screw(s)" and readjusting the p.o. brilliant repair just to finish the current job. Watch the cutter force when milling so that the pressure is directed towards the back of the casting.
    Replacing the X-Y bracket is the repair option unless you can c/b d&t a new location for the adjuster.

    The nut:
    Purchased new from HQT, (I usually ordered $1,800 a year and was on direct purchase) the nut will have slots cut so the the "one piece" nut
    can be progressively collapsed. Same as stock Bridgeport parts.

    The adjuster tapped hole is either 3/8 or 5/16" with a smaller tapped hole just to the right for a keeper.
    This should be the same as the table, viewed from the left side.
    crossfeed.jpg1of2-.jpgturret-mill-h-83-chip-shield.jpg2of2-.jpg
    Good Luck, John

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    Ya, there shouldnt be a set screw. And a picture really could have helped, ya know.

    There is no difference on how the nut is captured whether it is a one or 2 piece nut. The adjusting screw and the locking screw capture the nut into the yoke.

    So I am going to assume that I am one of the dicks you spoke of, since it was right after my comment, I am gonna explain why I said what I said. While I did not expressly say that before, it is my bad that I assumed you would have understood that being asked about it would have been a reason to look at it. I also discussed the 2 nuts because you mentioned that there was no adjusting a single nut, so I wanted to give you another option.

    Jon

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    Quote Originally Posted by HWElecRepair View Post
    Ya, there shouldnt be a set screw. And a picture really could have helped, ya know.

    There is no difference on how the nut is captured whether it is a one or 2 piece nut. The adjusting screw and the locking screw capture the nut into the yoke.

    So I am going to assume that I am one of the dicks you spoke of, since it was right after my comment, I am gonna explain why I said what I said. While I did not expressly say that before, it is my bad that I assumed you would have understood that being asked about it would have been a reason to look at it. I also discussed the 2 nuts because you mentioned that there was no adjusting a single nut, so I wanted to give you another option.

    Jon
    That's just it the nut has very little wear, it is loose in the trunnion. I am the second owner of this machine, I bought it in 1980

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    and the adjusting screw is bottomed out? I am wondering if someone possibly put in a not normal nut... or perhaps the yoke is actually damaged. Have you removed the nut to measure the OAL? If you move the table all the way forward and the knee up, can you look under the knee through the hole and see in the back of the yoke to see if its cracked or damaged?

    Jon
    H&W Machine Repair

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    Quote Originally Posted by HWElecRepair View Post
    and the adjusting screw is bottomed out? I am wondering if someone possibly put in a not normal nut... or perhaps the yoke is actually damaged. Have you removed the nut to measure the OAL? If you move the table all the way forward and the knee up, can you look under the knee through the hole and see in the back of the yoke to see if its cracked or damaged?

    Jon
    H&W Machine Repair
    Got it apart. Easy to see what happened. The big Walter tilting rotary table was clamped in the front "T" slot with 4" hanging off the back of the table. I was using the power feed, I must have hit the column. The lead screw jacked the nut out of the trunion. This sheared the nut away under the big headed adjuster screw. that is where the end float came from. The lead screw and nut are in great condition. To repair it I turned a groove in the nut at the point the adjuster screw should hit the little shoulder. Then I turned a little Piston ring and popped it in the groove with the gap at the key. I compressed the ring with a tie rap and slipped the nut in place. The adjuster screw sets down in the pocket in the trunnion as it should and hits on the piston ring to hold the nut securely in place. All re assembled again with only .005 lash on the dial. Thanks for the input from all, sorry I got a little bumpy.

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