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IndustryArena Forum > MetalWorking Machines > Bridgeport Machines > Bridgeport / Hardinge Mills > Bridgeport clone mill quill feed shaft play.
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  1. #1
    Join Date
    Jan 2015
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    27

    Question Bridgeport clone mill quill feed shaft play.

    I have a Bridgeport clone machine ( https://www.machineryhouse.com.au/M607D) and noticed tonight when using the quill power feed the quill was bouncing up/down about 1-2mm when doing light cuts with a boring head. Movement could be seen on the quill handle side with the handle shaft moving up/down 1-2mm. Never seen this before and machine is only 1 year old with probably less than 30 hours of light use( Hobby use).

    Was late so I stopped using it, will look at it tomorrow but just seeing if there were any ideas as to what could have happened. Don't really want to start pulling things apart till I've got an idea of what's wrong. I would say a bearing on the handle side of the quill feed shaft had gone, but looking at the parts drawing there is no bearing or bush on that side.

    Hoping someone can give me an idea. :idea: Thanks

  2. #2
    Join Date
    Dec 2013
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    5717

    Re: Bridgeport clone mill quill feed shaft play.

    As I recall that end of the quill shaft is supported by the fit of the pinion shaft hub sleeve (the part that engages the inside of the return spring and the handle pin) Sounds like it's a bit loose in the bore. There is no bushing in that area. Best guess that it was bored too loose when manufactured. Maybe adding a bushing would be the best fix.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
    Join Date
    Jan 2015
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    27

    Re: Bridgeport clone mill quill feed shaft play.

    Thanks Jim. Been fine for the last year or so of operation, so don't know why it's doing it now. It's a Taiwanese clone, not Chinese, which may or may not be any better. Had another look tonight and with the quill down so the feed wheel will engage , I have around 5 mm of vertical movement if I push the quill up! That doesn't seem good to me. Maybe I've damaged the quill power feed? Rarely use it and disengage when not , so don't know .Looks like I've have to watch a couple of youtube videos on pulling the feed mechanism apart and find out what's going on.

  4. #4
    Join Date
    Dec 2013
    Posts
    5717

    Re: Bridgeport clone mill quill feed shaft play.

    The quill pinion normally has some play, but 5 mm seems a bit much. That could be a loose key. Some pinion gears are machined into the shaft, and some are keyed to the shaft, just depends on the manufacturer. Overall the hand wheel feed goes through a number of gears, so by the time you add up all of the clearances you might get quit a bit of play. I have removed the hand wheel feed system, and all of the gear train, so I can't check that on my machine, but I do have about 1 mm play in the quill pinion when using the lever. I think most of that may be in the key in the hub sleeve. I have converted my machine to CNC, so I have a pneumatic backlash compensation system.
    Jim Dawson
    Sandy, Oregon, USA

  5. #5
    Join Date
    Mar 2013
    Posts
    88

    Bridgeport clone mill quill feed shaft play.

    Does it matter how for the quill is extended? The quill spring and the quill load ( weight of tool and cutting force) may be on the edge of balance? Does it do it if you apply pressure to the quill handle?

    Edit- ie the backlash in the feed gears could be causing the issue?
    Sent from my iPhone using Tapatalk Pro

  6. #6
    Join Date
    Jan 2015
    Posts
    27

    Re: Bridgeport clone mill quill feed shaft play.

    Here's a video showing what's happening.

    https://drive.google.com/open?id=10Y...uIAfsWCMWUp4KV

    I've used this boring head before with not problems. Only going slow taking light cuts on a 0.003" feed. Hole was plasma cut and just cleaning it up. the hole does have a slight taper to it from the plasma, so maybe this is causing the bump?? That would sort of make sense.

    I don't think I've damaged the auto feed as it has a kickout top and bottom, so if I started it with it engaged it should kickout. I'll try the same setup with a straight drilled hole and see if it does the same thing. Still don't think it should do it, but don't really have the experience to know for sure and it just didn't look right!

    thanks for the replies and views.

  7. #7
    Join Date
    Dec 2013
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    5717

    Re: Bridgeport clone mill quill feed shaft play.

    It looks like you need to figure out why the pinion shaft is jumping around. That is not right. It also looks like the auto feed is working fine, I don't see a problem there.

    Having said that, I have seen quills jump a bit when making an interrupted boring cut, but yours is excessive.
    Jim Dawson
    Sandy, Oregon, USA

  8. #8
    Join Date
    Apr 2015
    Posts
    170

    Re: Bridgeport clone mill quill feed shaft play.

    I find that putting a slight pressure on the quill clamp helps with the bouncing during a boring operation, though there is clearly another problem here. When the quill is power fed it drives through an angled tooth dog clutch that is preloaded to slip if the load gets excessive. From memory there is an adjustment grubscrew with a lock nut which alters the spring tension. If this spring was to break or become weak it could introduce it may introduce backlash between the two halves and give you this problem.

  9. #9
    Join Date
    Mar 2013
    Posts
    88

    Re: Bridgeport clone mill quill feed shaft play.

    Looks to me that the quill handle shaft is moving around vertically in its bearing/bushing. I just checked my Acer and there is almost no discernible slop in the vertical direction.
    Some seems amiss there



    Sent from my iPhone using Tapatalk Pro

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