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  1. #1
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    Default Bridgeport Newbie

    Hello all!

    New member here to PM and also to Bridgeport mills as well. I am a student and I just accepted a job as a machine shop manager and machinist at a local company. Unfortunately some of the people here are not used to having someone machine parts for them and they "try" to do it themselves. This leads to my problem; I walk into the shop to mill some parts and when I turn on the motor it spins just fine but no rotation is transferred to the draw bar and the tool doesn't spin.

    Like i said, I am a student and i have experience machining but I have little to none in fixing/working/troubleshooting these machines. Any sujestions you could throw my way would be awesome!!

  2. #2
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    No offense, but I think it will be not to your liking...

    You are not qualified for the position. Instead of just doing a 8 hour day which will lead to a bad situation, on your own time you will have to read manuals and lookup information. Build a library from downloaded manuals and become the expert.

    Otherwise hiring somebody who knows the stuff. Then you can learn from the "somebody". But I take away from your "Hello all" that the local company is small and will depend on you knowing the stuff. Get ready for it.

    In the meantime you can ask questions here and probably get enough answers for the following day.

    Your problem with the tool rotation:
    1. Is the belt on the motor at correct tension?
    2. Variable speed pulley or step pulley drive system?

  3. #3
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    Default

    I agree with Ron but in order to help you.

    If you have never used a BP mill download a manual they are free & all over the net.

    Perhaps your staff are yanking your chain & leaving the machine in neutral

    http://https://www.google.co.uk/search?q=bridgeport+head&client=safari&hl=en-gb&prmd=ismvn&source=lnms&tbm=isch&sa=X&ved=0ahUKE wiRgpuPn-zWAhWKJhoKHRqUDB8Q_AUIEigB&biw=1024&bih=672#imgrc= EFlU6qaXM7rQnM:

    Look at lever 15 it has 3 positions the mid one is neutral and disconnects the drive from the spindle, forward & back give high & low speed - that may be the wrong way around.

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  5. #4
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    Default

    Hey Ron and Trey,

    Thanks for replying! Luckily it was my skill as a CNC operator and machinist that got me the job not my skill fixing really old mills! Also since I am a student half the job is meant as a learning opportunity anyway (company is owned by the school). That's what brings me to the forum; my love to learn about how to do these tasks.

    As to Ron's questions:
    1) yes the tension is correct, same as last time I ran the machine
    2) It is a step pulley drive system

    As to Trey
    1) It could be possible someone used the machine since last I used it and left it in neutral I didn't check that

    I only wok this job Tuesdays and Thursdays so I will see if that is my problem on Tuesday. If it is not "someone yanking my chain" and its not in neutral any other thoughts on what it could be?

    Thanks Guys

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    Let's say that you inserted a collet up into the spindle and tightened the drawbar so that a tool in the collet is held tight.

    Does both the rear and front pulleys rotate?
    Did you try running in back gear mode?

    It is not uncommon for a CNC guy to not know much about manual machines, and vice versa.
    Last edited by rons; 10-13-2017 at 10:07 AM.

  7. #6
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    This is great...what school is it.

  8. #7
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    Default

    The back gear lever is not in the correct position.

    Good luck, don't stress you'll make it.

    Make Chips Boys !

    Ron

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    I don't know your circumstances nor the machining tasks you'll need to accomplish but I have to say, with all due respect, that your questions are so very basic that you shouldn't even approach the mill until you've done some reading. The engagement of the drive system in the step-pulley mills is so very basic that your questions (while good that you did ask) means your inexperience could lead to damage and/or injury to yourself and/or the machine. I'm not knocking you, we all were born without knowing, I'm more than a little surprised that a university would be so casual as to allow someone to operate machinery without proven and demonstrated experience. The very fact that you've been appointed as "manager" is another matter I won't go into. The point of my reply is not to point up your inexperience or to question the "wisdom" of a higher learning center. My point is that I've seen many bad things happen by people that were supposed to be skilled tradesmen. Damaged machinery and ruined parts/tooling was the least of the incidents. There were times I had to take people to the ER, and worse due to inexperience. All it takes is one moment to occur and you may not see it coming. Your experience with CNC will likely not be comprehensive nor relevant enough to transfer to manual machinery, they are different animals with different pitfalls. There's only a couple of reasons for the mill to have been left in neutral (if it was) so it may very well be that somebody is yanking your chain. The reason is not important, what is important is that if you don't know how to change the spindle speed on a high/low step pulley drive then there's a real good chance that you'll commit the error too many of us have heard before. If you don't know how to change the belt to a different pulley you'll likely pinch or break a finger. If you don't know how to positively engage the high/low drive then sooner or later you'll turn on the machine and a gawd-awful noise will loudly announce to all within earshot that the FNG should have done more reading. Rather than discourage your ambition I would encourage you to be better prepared by seeking out advice either by reading or asking someone in the shop that DOES know. There's no shame in not knowing but there is in not asking. To address your original post, I always double check for positive engagement before I even think of putting my hand near the ON/OFF switch. If I haven't heard the characteristic engagement noise I'll even take it out of gear and put it back in just to ensure that it is. Be careful, machines are dangerous and you're just another material to be cut. This is a good site and some very knowledgeable people here (except me...) that can provide a wealth of information/experience for you AFTER you've done your own searching for information. Good luck.

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  11. #9
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    Default

    To the OP -- in general, I agree with others that you have some study ahead of you, or finding some in-person mentor to help. Specifically to your question about spindle rotation, though: Go look at the labels attached to the machine head that describe high speed and low speed (back gear) operational setup. Read them and understand how the mechanics operate without turning on the spindle, just rotate the spindle by hand (easiest to do with a drill chuck in the spindle) so you understand how the setup works. Having a manual is a grand idea as well.


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