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New 2 X 72" Grinder Build

Discussion in 'Grinders' started by dancom, Jun 4, 2017.

  1. dancom

    dancom Dust Maker

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    Did some late-night assembly...

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    These 1.5" spacers I cut on the bandsaw with a fence to keep them the same length.
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    Test fitting the tool arms in the receivers.
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    The joints interlock the pieces and strengthen the unit.
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    So far so good. Waiting for some wheels to arrive.
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    The base will be done on Tuesday. The flat platen will be next.

    Thanks for looking!

    Dan
     
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  2. ConnorBC

    ConnorBC Active Member

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    Looking sharp!!! :)
     
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  3. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Dude, that is one friggin' sweet looking grinder. And it tilts? Fuhget about it!! Love the nameplate, (you should add one that says "Caution: if you need a caution plate, don't use this or any machine") and even the hammered finish. Too cool. I can't wait for the final tests. If this thing tracks have as good as it looks like it will, I'm going to get one cut methinks. I've got a line on a new (well, old) treadmill motor with an mc-60 so I'm ready to go. Well, i have to finish about 4 major deadlines at work, pack my entire house and shop, move to a new town, get all setup and then I'm ready to go. Very nice grinder Dan. I can see a lot of people using this bad boy.
     
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  4. dancom

    dancom Dust Maker

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    Thanks Todd.

    I hope to have my wheels in soon and will be moving on to the VFD enclosure. Everyone is so busy this time of year. I want want Winter to come back. Oh wait, I didn't just say that did I?

    The grinder design is intended for a 56C (face mounted) motor. I would highly recommend getting something that is TEFC. For just around $215 Canadian I landed this motor.

    I've been trying to help a number of people with treadmill motors. Ugh, so frustrating. Some caveats about treadmill motors.

    1: They are not sealed and contain powerful permanent magnets. Imagine how steel dust is going to love it inside there?
    2: Without feedback, these motors are poor at recovering after being loaded. If there is no signal from the motor (muscle) to the controller (brain) the controller doesn't know how much to compensate for changes in loading. So they bog down and slowly wind up again after the load is lightened. Treadmills operate as a closed loop system and use a tachometer to monitor the motor speed and the controller can be used to compensate for changing loads. That means you should use the whole console and tachometer input, which is a massive chunk of real estate.
    3: It is difficult to install any kind of useful wheel or pulley on them. I ground the flywheel down on mine. Some guys made wooden drive wheels. But the time spent making something and hoping it is balanced can be hours.

    I did use my treadmill motor on my mini lathe and it seems to work okay with large gear reduction and relatively constant loading.

    Dan
     
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  5. parker

    parker Active Member

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    Nice chose! That's the same stuff and coulor I painted mine. It looks awesome and doesn't show the dust as bad as a bright coulor. Altho for the first time outta all the times I've used the hammer paint (as it's my fav) it did not hammer on very well. I'm glad to see you'rs did. Looking good Dan!
     
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  6. dancom

    dancom Dust Maker

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    Parker,

    I love this paint too. It's perfect for shop machines. I think the trick is that the first coat needs to still be still a little bit tacky when the second coat goes on. On the grinder frame I applied the second coat at 30 minutes. However, I painted some spacers and did their second coat after waiting overnight and the hammered effect just wasn't there. It was like first coat was too dry to react with the second coat. (?)

    I wish they had more colours, like greens and blues. By the way, one can is perfect to paint all the parts of the grinder with two solid coats.

    This is the product link:
    http://www.rustoleum.com/product-ca...iversal/univeral-forged-hammered-spray-paint/

    Regards,

    Dan
     
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  7. parker

    parker Active Member

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    That makes sense. I did wait over knight or long enough that it was dry to touch.
     
  8. ConnorBC

    ConnorBC Active Member

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    I too really like the hammer finish. For me also it's hit and miss and wonder if the wait time between coats is crucial?... I made some strong mounts for my Dillon reloading presses and the hammer finish looked flawless. With the same can I painted the upright on an engine stand and the hammer effect was barely there... I'll keep using it though and try to fine tune the effect.

    Dan, what VFD did you decide to go with? The grinder is looking great!

    Connor
     
  9. Kevin Cox

    Kevin Cox KC knives

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    That is one sweet looking little grinder you have there. Can't wait see see it all done.
     
  10. Kwesi

    Kwesi New Member

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    Can't wait to see the first video you are going to post of the grinder. What are the size of bolts and the supplier?
     
  11. Kevin MacPherson

    Kevin MacPherson Member

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    Dan, my two cents. Call it "The Danamite OSG Project". LOL
    Thanks for all your support Dan. You truly are a generous soul and as always everyone on this forum appreciates all you do to help us improve not only as knifemakers but also as people willing to assist others as generously as you do.
    KM
     
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  12. dancom

    dancom Dust Maker

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    I finally got the base and used the rest of the paint. The joints are tight fit with the paint. It could use a few extra thousandths on the base or one can scrape the paint.

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    Underside of the base needs to be flush, so I am using flathead 10-32 x 3/4" screws. The flatheads are countersunk with a 1/2" 82° countersink bit.
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    It's really important to lock the threads with Loc-tite.
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    Vertical position
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    I think the base is a good mass, but not an overly large footprint.
    So far the prototype is coming along well.

    More later.

    Dan
     
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  13. dancom

    dancom Dust Maker

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    And the workings of the tension and tracking arm.
    The stack of flat washers was the cheapest and easiest way to make a spacer, but they looked so primitive. So I cut some schedule 40 pipe, cleaned it up and made a cover for the washers. Looks like a massive thing, but it's really a "washer cover." LOL I used some 2-3 oz leather to make lubricated washers. The arm is nice and firm but still moves.

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    The belt tension is based on two 38 pound springs with a 1:2 mechanical (dis)advantage. This will leave the belt tension really close to 38 pounds. Hopefully my math is right, but it feels good and the added length of the handle makes it easy to depress the arm. I steered away from using a gas spring as my personal experience is that they suck in the cold. These springs were standard 3" springs which cost a whooping $1 and change each.

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    So far only one little thing to correct. I am going to need some 0.02" shimstock to open up the pockets just a smidge. Maybe run a single shim down the middle.
    More to come.

    Dan
     
  14. dancom

    dancom Dust Maker

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    The bolts between the frame members are 1/4"-20 x 2-1/2" SS. The tracking arm bolt is 1/2"-13 x 3" SS, all the stainless steel hardware I brought up from McMaster-Carr. It's killer to buy that at the hardware store, about 3 times the cost.

    Dan
     
  15. dancom

    dancom Dust Maker

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    I quite like Danomite!
     
  16. John Noon

    John Noon Well-Known Member

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    Are the CAD files available online yet? was thinking of having them on my blog and going to start saving up some pennies to build my own. really starting to notice the limitations of the grinder I have and need a upgrade sometime this year
     
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  17. dancom

    dancom Dust Maker

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    Sorry, not yet John. This weekend I should have everything up and running. I'd hate to give out a file and find that one hole is off and causes people to have to go back and get something re-cut. Water jet or laser is not cheap.
    I am currently working on the flat platen and should have the motor and VFD going this weekend. Then I can check everything for alignment, balance and document.

    Do you have a small list of some of these limitations? I am curious as to whether they are going to be addressed in this build.

    Dan
     
  18. John Noon

    John Noon Well-Known Member

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    biggest is the lack of attachments, I have to make them myself and seeing other grinders that rotate and can be used with a longer tool rest for squaring edges is much better than simply eyeing things up. Figure by the time I build holders and modify my grinder I could start with something better and keep the one I have for shaping handles.
     
  19. dancom

    dancom Dust Maker

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    I had a suggestion to use a thrust bearing on either side of the tensioning/tracking arm. Currently I am using two pieces of oiled leather and there is very little side play in the arm. Would the bearings be worth the extra cost in anyone's estimation?
    Thanks,

    Dan
     
  20. John Noon

    John Noon Well-Known Member

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    I would keep it simple and skip the bearings. For something with little movement and low cycle frequency I would go plastic bushing or shims on either side of the arm, probably take several years to wear out if they ever did.
     
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