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  1. #1
    Join Date
    Apr 2013
    Location
    Toowoomba Qld
    Posts
    401

    Default grinding noise in my head... of the knee mill

    So I think I need to pull down the head in my Bridgeport clone milling machine. Was cleaning up some large stock and had used a face mill in high speed. Worked fine, finished that and for the hell of it figured I would run my shop made fly cutter over the top to clean it up. The fly cutter has to have the spindle run in reverse, was getting some chatter so was running it in low speed / back gears. Wasn't taking a heavy cut, only 0.2mm depth. Seemed to run fine but then flipped the material over, chucked the face mill back in and went to run it.

    I think the mill is now angry at me as it sounds like it's chewing rocks when running it on high speed


    Before I go stripping it down does anyone know what could be the cause of the sound ?

    Extra info
    When spinning the spindle by hand in high it seems to bind like it's winding up and grabbing the brake or something, turn it a bit more and it lets go again.
    When engaging the low speed I have to put shims under the top collar so it lifts high enough that the gears don't rub together, has been like this since I got the mill so never thought much of it and don't use low speed much.
    To me it looks like there is a burr on the teeth of the dog gears so not sure if that is possibly stopping the gears coming together more ?

    Any help appreciated, now I'm off to look up how to disassemble the top part and probably to make some special tools to do the job...

    Thanks
    Wayne

  2. #2
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    That sounds a bit like a loose fastener bouncing around. Perhaps check everything accessible is tight.

    Michael

  3. #3
    Join Date
    Apr 2013
    Location
    Toowoomba Qld
    Posts
    401

    Default

    Good news and bad news

    Found the problem, Michael was sort of right, it was a loose fastener of sorts

    a-parts.jpg

    The nut labelled 74 in this picture had come loose, will need to replace parts numbered 73 : Lockwasher & 74 earing locknut as they are both are damaged.

    Will need to touch up the thread on the bottom of 57 : Splined Gear Hub but should be able to salvage it.

    Some extra info incase anyone lands at this thread trying to diagnose their own. When turning the spindle by hand it would appear to wind up in one direction, bind a bit then let go and spin freely again. Wasn't able to engage the quill power feed and by pulling out the shift lever for it could see that it had come loose and was floating around the bottom of the shaft. Only wish I had of found this before pulling down the rest of the head...

    Now to find some spare parts. It's a bridgeport clone but appears to be all metric, having a quick check on the thread looks like it might be M40x1.5 but will need to do another check as was half asleep last night when checking.

    Cheers
    Wayne

  4. #4
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,942

    Default

    Glad to hear it wasn't too drastic a problem, should be a reasonably cheap fix?
    Kryn
    To grow old is mandatory, growing up is optional.

  5. #5
    Join Date
    Apr 2013
    Location
    Toowoomba Qld
    Posts
    401

    Default

    Final update, mill is back in action

    Nut was sorta a N08, except that the shaft was not made to spec and the nut is meant to be thinner then the M08.
    Ended up having to re machine it in the lathe. Put a piece of stock in the lathe, machined a pocket and used Loctite 641 to hold the nut in the fixture, turned it thinner then recut the threads oversize as the shaft was not not quite 1 9/16" - 18tpi, Thread pitch was about 5 tho oversize.

    Washer was a W08 but once again not quite to spec, the tang that holds the shaft was to wide as the keyway cut in the shaft was to narrow. Didn't take long with a hand file to make it fit tho.

    Was happy that didn't even have to make any special tools, a ER40 hook type spanner was just the right thing to tighten the nut. Not sure if there is a torque spec or anything but gave the spanner a few whacks with the mallet until the washer lined up and bent the tab to hold it in place

    Happy camper again, think the problem may have actually been in the mill all along as always had a bit of a rattle but is now quite. Got to be happy with that.

    Cheers
    Wayne

  6. #6
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,942

    Default

    Glad to hear that all is well with your head (of the mill) now
    Kryn
    To grow old is mandatory, growing up is optional.

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