Grinder plans

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Kevin McGovern, Mar 20, 2017.

  1. mike-E

    mike-E

    400
    Mar 2, 2013
    you could have over center cam with two pieces of steel a bolt and a handle. mount an upright piece with a through hole on the front two main plate/ tooling slot bolts. a second piece would be the pivoting gas spring mount. picture mine with one side of the pivot block removed and mounted to the side instead of the top. super easy to do, and if you dont like it there wouldnt be any extra holes.

    http://www.bladeforums.com/forums/showthread.php/1289109-My-new-kitchen-appliance
     
  2. mike-E

    mike-E

    400
    Mar 2, 2013
    you would have the very first available plans/grinder kit with over center cam. something to think about.
     
  3. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    So then I would be able to gotten the horizontal arm correct?
     
  4. mike-E

    mike-E

    400
    Mar 2, 2013
    no matter what, to get the arm horizontal, the tool arm is going to have to be in the right distance into the pocket. i have a scribed lines on my attachments.
     
  5. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    but once the gas spring is installed, won't that limit it's travel too far from horizontal? Then I see where the distance the tool arm is inserted makes up the difference for belt circumference.
     
  6. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    I think I could just incorporate that into the outside (left as you face it) plate. (the one with all the holes in it). Then I would still have plenty of upper arm area to play with to get the angle right with any given gas strut length. Make sense?
     
  7. mike-E

    mike-E

    400
    Mar 2, 2013
    ''I think I could just incorporate that into the outside (left as you face it) plate. (the one with all the holes in it). Then I would still have plenty of upper arm area to play with to get the angle right with any given gas strut length. Make sense?''. EXACTLY!!!. that's what i mean/was trying to convey. it will be so simple to make two extra pieces and you have plenty of steel left on the 12x24 plates. once you use a quick release you will never want to do without it again. are your bolt centers equally spaced on the plates hole package? if not, then change that so the extra piece can be slid back and forth along the top to 3 different locations. you can either have it so you push or pull the handle to tension the arm by simply reversing the pivoting/gas spring mounting piece. if you want help drawing the spring mount piece i'll try to explain it the best i can.
     
  8. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    Bolts are equal centers, I would have to move the tapped holes to the main plate though. Not huge.
     
  9. mike-E

    mike-E

    400
    Mar 2, 2013
    no you dont. that piece will only need to be about 2 and 1/2 inches high and only have to extend below the bolt holes by a quarter inch.
     
  10. mike-E

    mike-E

    400
    Mar 2, 2013
    draw an upside down block letter capitol ''T". the bottom needs to be 1/2'' thick and long enough to span your bolt centers. the center section will need to be 1 3/4'' wide and 1 1/2'' tall. do not shape the center section like a tombstone. leave the corners so you can tap a 1/4'' hole. that hole will be for a stop bolt for the cam action. for the other piece draw a 1/2'' circle inside of a 1 and 1/4'' circle. draw a 2 1/4'' long straight line up one side of the larger circle from the horizontal center line. now extend the circles vertical center line straight up to meet the top of the first vertical line. that 5/8 wide "finger" will get a 5/16 - 18 tapped hole at the end and the length will determine the "camming" stroke. you can drill another hole below it to change the stroke length if you want. you will need to drill and tap a hole for a set screw to hold that piece onto a 1/2'' bolt that has about an inch of unthreaded body. back to the "T" piece. it will need a 1/2'' hole for the bolt also. put it centered left/right. you want it just high enough so the radius of the 1 and 1/4 circle clears the top of the grinder.(about 11/16 up the 1 1/2'' height). the finger will lay flat on top of the grinder when the belt is not tensioned. the 5/8'' width of the finger will put the bottom of the gas spring as low as possible while at rest.
     
  11. mike-E

    mike-E

    400
    Mar 2, 2013
    the hole at the end of the tracking wheel arm will need to be 1/4''. that will be tapped 5/16-18 for the other end of the gas spring. you can also drill a series of holes to allow for angle/height changes in the spring to suit your needs. this will give you flexibility when it comes to spring strength and belt tension. i recommend a 30 pound spring, but 40 is ok too. you wont need more than that though. (edit to add) go to mcmaster carrs site and search gas springs. click on the top left category of springs with ball-end studs. the second one down the list is what you want.
     
    Last edited: Mar 21, 2017
  12. MBurks

    MBurks

    269
    Mar 21, 2016
    I gotcha,

    That looks like a great machine!
     
  13. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    revised drawings to correct base plate mounting hole and motor mounting hole interference.
     
    Last edited: Mar 21, 2017
  14. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    Sorry about the video of a screen. But this shows the cam over function. it will be included in the plans shortly. This means that the user can use a spring, gas shock and handle or gas shock and cam over. let me know what you think. Once the plans are revised, you will see the semi circle and pivot hole in the upright that allows the cam over. The cam on the back and the handle you see in the video will be on the cutout plate.


    [youtube]3lTziCfftPA[/youtube]
     
    Last edited: Mar 22, 2017
  15. kuraki

    kuraki Fimbulvetr Knifeworks

    Jun 17, 2016
    Oh hey I like that. Nice.
     
  16. mike-E

    mike-E

    400
    Mar 2, 2013
    positioning the spring at that angle will require a much heavier spring. 80 - 100 lbs would be my guess. which in turn will require a longer handle. it does look nice.
     
  17. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    I'm intending to use a 50# gas strut. So is the problem the angle? It seemed to me that 50# is 50#? My current grinder has a #50 strut at about this angle, but slanted the other way.
     
  18. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    Oh, and the handle is to be tapped to accept a rotating handle coming out the left side.
     
  19. mike-E

    mike-E

    400
    Mar 2, 2013
    the closer to the arm pivot point you get the less spring force the belt will feel. also the farther from a 90 degree straight up push you get the less pressure the belt will feel. in your plans how much space would you say is between the bottom of the tracking arm and top of the grinder if the arm is horizontal?
     
  20. Kevin McGovern

    Kevin McGovern

    Jul 31, 2015
    I don't have all the design tools at home, but about six inches. I went with the vertical arm mount point, as I'm trying to make it as easy to assume as possible for the end user. Basically get the cut parts back from the cutter, rl, tap some holes and bolt together. I had trouble working the cam over feature in without encroaching on the belt, tracking adjustment, while keeping the shock as close as possible to the centerline of the arm.
     

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