Longworth Chuck for the Stomper

Discussion in 'Jigs' started by cnsranch, Mar 26, 2017.

  1. cnsranch

    cnsranch Jerry Prinds

    I'd like to make my own chuck......I've got a cnc machine that would cut the arcs with no problem. I've also got a lot of 1/2" corian that would work well with the chuck.

    What escapes me is how the bolts ride in the lower piece of the chuck. Are the arcs cut into the lower piece wider than the top so as to accomodate the bolt head?

    Are the two pieces attached to one another somehow?

    Couple pics would sure be nice.
     
  2. stuart johnson

    stuart johnson Super Moderator Staff Member

    The bottom plate has the same grove on the top of the plate with a shallow dado on the bottom for the bolt head to slide along. Sorry, I don't have any pictures but if you look at the SegEasy construction video it shows an example. Title: Segmentology
     
  3. Roy Esslinger

    Roy Esslinger PRO Member

    I made on on my cnc and used carriage head bolts and they slide very nice, Corian really works well.
     
  4. William Prickett

    William Prickett PRO Member

    I currently have the stomper

    Can anyone make a larger discs like 21"
     
  5. cnsranch

    cnsranch Jerry Prinds

    If you haven't made or gotten a stomper you gotta.
    After destroying a bowl I figured it was time.
    Mine's 2 pieces of 1/2 mdf covered with formica. The sprinkler I ordered has a screw adjuster on top - using that to center...as a result I have only a tiny indent at the center of the base.
    My weight is 20#, melted lead in a cast iron pan son uses to cast bullets. Added a handle, and since I'm currently using my shopsmith to turn, and had an extra shaft, added a couple inches of it to the lead before it set.
    Although not dry enough to turn, I did spin these two glue ups on the lathe, and they're as true as they can be.
    This thing rocks!
     

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  6. stuart johnson

    stuart johnson Super Moderator Staff Member

    Be careful when you have a tall vessel. Sometimes the stomper will bend a bit causing your ring to be misaligned a small amount.
     
  7. mfisher

    mfisher Super Moderator Staff Member

    Good point Stuart. I had that happen once on a vase I made.

    I also found a 10lb bar bell weight has a hole that fits over my faceplate. Works well.

    The stomper at the woodclub is mounted on a lazy Susan. It is nice to be able to turn the bowl around to ensure one is happy with the alignment of the rings.
     
  8. William Prickett

    William Prickett PRO Member

    how do you mean?
     
  9. stuart johnson

    stuart johnson Super Moderator Staff Member

    When the stomper is extended fully or at least halfway there will be some lateral movement. It isn't much but it is enough for some misalignment. I might have mislead you when I said it will bend. The actual sprinkler rod doesn't bend but it can move off line.
     
  10. Pete M

    Pete M PRO Member

    I did away with the flexing issue by doing away with the sprinkler head years ago. I use an air cylinder instead with no side to side movement.
     

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  11. cnsranch

    cnsranch Jerry Prinds

    Pete.....can you expound on your air cylinder concept some? Thanks.
     
  12. Pete M

    Pete M PRO Member

    Jerry,
    This is a post from 2013 which explains the function.
    I have used the segment stomper on my last project "All American Trio". I found that the plastic shaft on the stomper could easily be deflected in one direction or the other causing inconsistent ring centering. This was especially true the taller the bowl got. I decided to modify the process by using an old air cylinder instead of a pop up sprinkler head. The cylinder has a stroke of 16". Since the air cylinder has a steel shaft there is no deflection at all. Operation is very simple. Open the ball valve to extend the cylinder shaft then close the valve. The air is only connected to the bottom of the cylinder, the top port is left open to exhaust as the cylinder extends. The bottom port has the air supply (maybe 3-5 psi). It also has a check/exhaust valve that will allow air to escape when weight is applied to the top of the shaft thus lowering the piece to the ring in the centering chuck. When the segments make contact with each other the weight is no longer pushing down the shaft and it stays where it is keeping the piece centered on the bottom ring. The bottom ring is held in place by a version of the Longsworth chuck. I also turn all my rings round before stacking.
     
  13. cnsranch

    cnsranch Jerry Prinds

    Thanks Pete - pretty slick.
     

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