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  1. #13
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    Quote Originally Posted by bill south View Post
    This is just sooo coooool!
    Bill
    Your strong sarcasm is agreed with...

  2. #14
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    Jun 2005
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    3443
    Thanks Guys!
    Wow, and I haven't even starting cutting metal yet

    For those who are interested, the prints are now finished and available!
    Just send me a PM!
    Eric

  3. #15
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    Jun 2005
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    The remainder of the material arrived today, along with all the carbide tooling needed to drill holes through the balls!

    It looks like I will be starting this project on Monday 10/05/09, not a day too soon either

    Eric
    Attached Thumbnails Attached Thumbnails 100_4686.JPG  

  4. #16
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    Jun 2005
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    I started working on this project at 10:00 AM, and everything is going just fine!

    First I mounted a flat 12" round steel plate on top of my little 8" rotary table, milled the top nice and true using a 3" face mill.

    Then I cleaned up one of the large aluminum plates, filing off any burrs & hi-spots. Then I washed it with Acetone, and put three strips of double sided tape on the aluminum plate. Then I marked the center of the plate with an sharpie, and centered it on the round steel plate.

    Next I used a large fly-cutter with a sharp carbide bit, and set the tool so the point was in the center of the plate. With the spindle running at 350 RPM, I slowly raised the knee until the cutter made contact. Now I slowly rotated the plate under the cutter, until I had as flat and smooth a surface as possible! The aluminum plate was .03" oversize, and I removed .015" from the 1st side.

    Then I used 4x screw jacks to lift the plate off the tape, and repeated the process on the 2nd side! The plate now measures 1.000" on all four corners, and has a slight hollow in the center. The only straight edge I have thats long enough is my 18" vernier caliper!

    A DIY Blanchard Grinder!

    So I now proceeded to repeat the process on the 2nd plate! They will look really nice after anodizing!
    Attached Thumbnails Attached Thumbnails 100_4694.JPG   100_4695.JPG   100_4696.JPG   100_4697.JPG   100_4698.JPG  

    100_4699.JPG   100_4700.JPG   100_4701.JPG   100_4702.JPG  

  5. #17
    Gold Member
    Join Date
    Feb 2007
    Posts
    4550

    Eric,

    How much did all of the aluminum plate for this cost?

    Cant wait to see it finished.

    Jeff...
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  6. #18
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    Jun 2005
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    3443

    Project Cost

    Hopefully when its finished, I can get all the aluminum anodized, Burgundy would look nice!
    Attached Thumbnails Attached Thumbnails Project Cost.jpg  

  7. #19
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    Dec 2005
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    1408
    Quote Originally Posted by CalG View Post
    Anyone know a source for cannon balls?

    This man is on a mission.

    "Go big, or go home!" ;-)

    CalG
    Dear CalG,

    That had me falling about! Thank-you.

    Best wishes,

    Martin

  8. #20
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    Dec 2005
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    Dear widgitmaster,

    What a fun project, and thank-you for posting.

    I worry about the bearings. Friction could be your undoing Could you perhaps try a mockup to get an idea of how the bearings perform, maybe just one swinging ball in the chosen geometry, and see how long it swings for?

    MVVHO,

    Best wishes,

    Martin

  9. #21
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    Jun 2005
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    Quote Originally Posted by martinw View Post
    Dear widgitmaster,

    What a fun project, and thank-you for posting.

    I worry about the bearings. Friction could be your undoing Could you perhaps try a mockup to get an idea of how the bearings perform, maybe just one swinging ball in the chosen geometry, and see how long it swings for?

    MVVHO,

    Best wishes,

    Martin

    Thanks Martin!
    Your concerns are noted, but I can't think of any substitute for a ball bearing that will support a 1040G (2lb 4.8oz) steel ball! A string or wire tether is not easy to work with, and makes it impossible to align the balls.

    I believe the force of impact resonating throughout the entire frame will be better controlled by a solid pendulum supported by precision pre-lubricated steel bearings. Also, the ability for the big balls to spin reduces the wear by offering a full 360 deg. of possible surface area for contact!

    If you have a valid alternative, I will consider it!
    Eric

  10. #22
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    Feb 2007
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    4550
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  11. #23
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    Jun 2005
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    3443
    Quote Originally Posted by jalessi View Post

    I rest my case!

    Although they have bigger balls, the cables are too flexible and ALL the energy is lost due to poor alignment! The first one only worked 5-times, and all the balls separated upon impact, causing the returning ball to make multiple impacts. It even looked like the one in the middle bounced up upon impact! I do not think plastic would be a good choice either!

    When working properly, the balls in the middle should be totally motionless, and all the energy should be transferred through each ball to the outer ball! Thus causing it to react with equal and opposite force! Thus Newton's Law!

    In my honest opinion, my design will gain tremendous efficiency due to perfect alignment, and any friction caused by using ball bearings at the pivot point will be negligible! Gravity causes the friction, but Gravity also perpetuates the motion!

    Eric

  12. #24
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    Dec 2005
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    1408
    Dear Eric,

    I think you are absolutely right to go for a rigid pendulum instead of "string", but maybe CalG's suggestion of a line pivot might be worth considering instead of ball bearings.

    Good luck, and please keep posting.

    Best wishes,

    Martin

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