Crawford Hydraulic chuck

  1. ukracer Forum Supporter

    I have had this crawford hydraulic chuck for a while but i have not been able mount it on the backplate.

    Just managed to tidy the workshop a bit more as i have a task to complete tomorrow but not sure how it is supposed to grip....has anyone seen or used one.? 20181019_191011.jpg 20181019_190956.jpg 20181019_190936.jpg 20181019_190921.jpg
     
  2. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    They are usually fitted on CNC lathes. The lathe will have a rotary cylinder at the end of the spindle and a draw tube will run through the spindle connecting the cylinder to the chuck. You activate the cylinder and it pulls the collet into to body and thus grips the material.
     
  3. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    Here is a pic of the chucking cylinder on my lathe.

    ScreenHunter_1936 Oct. 19 21.36.jpg

    A poor quality pic of the drawtube I made up.

    ScreenHunter_1938 Oct. 19 21.38.jpg

    A pic of the drawtube screwed into the chuck.

    ScreenHunter_1937 Oct. 19 21.37.jpg
     
  4. ukracer Forum Supporter

    MMMmmm. Are we talking about the same type..
     
  5. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    Ah probably not seeing as how that is a manually operated one :D
     
  6. ukracer Forum Supporter

    It seems at the end he turns the key but i don't think my key does anything. It turns about 5 turns and goes solid but his seems to click and rotate again mine doesn't.
     
  7. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    I presume the key just winds in a plunger that compresses the oil and pushes a cylinder back and hauls in the collet.
     
  8. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    I don't think the clicking/rotating of the key is anything other than a safety feature so that you can't crank the pressure up too much, sort of torque wrench style, when it gets to a certain torque the key wont tighten the screw any more as it just clicks round.
     
    slim_boy_fat likes this.
  9. ukracer Forum Supporter

    I thought that might be the case but the front of the chuck alters the grip on the part. I thought the key might lock the front in place but o can still turn it...lol when i get it mounted to the backplate i will have another look.

    I just looked at that video again. I now see its the key that clicks. Not the chuck.
    As you say so you cant put too much pressure on.
     
  10. Hood

    Hood If it walks like a duck....

    Messages:
    11,810
    Location:
    Carnoustie, Scotland
    It does seem it is meant to be a dead length style chuck so you would think the taper section moves forward to compress the collet and thus push against the front cap. Maybe there is no oil in it or seals leaking. If you take the nose off and then turn the key you should be able to see if there is any movement in the taper seat.
     
    ukracer likes this.
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