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2 X 72 Grinder Design Wip

Discussion in 'Grinders' started by derickm, Mar 31, 2014.

  1. derickm

    derickm New Member

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    With everyone posting their designs of grinders I thought I would add what I have been working on into the mix.[​IMG]
     
  2. dancom

    dancom Dust Maker Best Shop Tool

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    Cool, that vertical will drop into a keyed base? I am guess we're going to see some tracking adjustment and a tensioner fitted on there.

    I feel somewhat antique doing mine in AutoCAD 2D!

    D
     
  3. Icho-

    Icho- Staff Member

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    Lookin cool so far.

    Dan. Sometimes the older stuff is simpler. There are times I want to go back to the 2d cad because you don't have to worry about a simple change deforming the whole design. Lol
     
  4. derickm

    derickm New Member

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    I definitely prefer the good ol' autocad 2d but this is more visually appealing and yes it will go into a keyed base and I am still working on how and where I want to put the tracking adjustment. Material wise I'm thinking 3/8 steel or alum. of some sort.
     
  5. dancom

    dancom Dust Maker Best Shop Tool

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    Before considering a direct drive system, I made this table in Excel to show the the SFM as a function of RPM and drive wheel diameter. A bad choice of motor or drive wheel here could really slow you down.

    [​IMG]

    I opted for a 2 pole motor with a 4" drive wheel, so about 3600 to 3800 SFM, but with the VFD I can go faster than 60 Hz. I am hoping for 80Hz, but yet to be tested.

    Fixed speed units would want a 2 pole motor with a bigger, say 6", drive wheel to get in that 'sparks be flyin' (5000 SFM) zone.

    My $0.02. Sorry no more pennies... make that my $0.05.

    Dan
     
  6. derickm

    derickm New Member

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    Thanks fro this Dan, I was thinking 2 pole motor but I haven't decided on drive wheel I was thinking 4" drive wheel but I may opt for the 5". I scored a GE 2hp 3 phase motor 1800 rpm but I may use it for something else.
     
  7. dancom

    dancom Dust Maker Best Shop Tool

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    I've heard stories and read posts in the CNC forums of people running 4 pole motors at 120Hz with VFDs, that would be 3600 RPM give or take. The logic is that for economic reasons the manufacturer will use the same bearings and similar construction techniques in both types of motors. Lots of assumptions there and surely not all motors are created equal. My advice is to use the faster 2 pole motor to start with.

    A 2 pole motor, fixed speed, with a 5" wheel would scream pretty well.
     
  8. Icho-

    Icho- Staff Member

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  9. dancom

    dancom Dust Maker Best Shop Tool

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    Icho,

    The links work. Awesome! How fast have you ran your drive/motor?
     
  10. Icho-

    Icho- Staff Member

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    I usually go to about 1850 rpm max. I don't remember what sfm that works out to. If I go much higher than that the VFD gets an error when I shut down or slow it down. I think I read that at the motor acts a generator and creates voltage when it is spinning at the high speed while not under power causing the VFD to fault out. Something like that I think.
     
  11. dancom

    dancom Dust Maker Best Shop Tool

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    Must be that 6" "flywheel" you got there! LOL
     
  12. Tony Manifold

    Tony Manifold New Member

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    I was looking at those. Glad to hear they work for you.
     
  13. derickm

    derickm New Member

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    Here is a little bit of a update on the design.[​IMG]
     
  14. dancom

    dancom Dust Maker Best Shop Tool

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    That's coming together. I see you beefed up the drive wheel. Looking cool.
     
  15. Icho-

    Icho- Staff Member

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    I was considering bigger if they had it at Beaumont. Lol. I wasn't sure if the 6" would move the belt fast enough because it is rated for 1800rpm. I glad it worked out.

    Ya I'm very happy with it so far. There are a couple options you can get with the VFD. One is a resistor that acts like a brake for the wheel. The VFD has many settings in it and one of them is how fast you want the belt to stop. I have it set up to stop pretty quick but it is not maxed out. I don't think the resistor is necessary for me any way. The other option which I wouldn't mind getting in the future is a cord that connects to the removable control panel on the front of the VFD. This way I can get the VFD out of the way of the dust and have the little panel somewhere convenient.


    Your design is looking pretty cool Derik.
     
  16. dancom

    dancom Dust Maker Best Shop Tool

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    The braking resistor probably wouldn't be used much as the inertia of the motor/load on a belt grinder isn't that great. At my work we have applications where loads are driven through gearboxes (e.g. large turn tables) or conveyors are moving a ton of stuff need to stop quickly. This is where the braking resistor comes into play. A fast decel should work just fine for the light inertia of a motor and a few wheels.


    I am making a remote control panel for grinder. It's a few switches and the potentiometer wired into the VFDs control terminals via an small umbilical cord. I'd be happy to share the design with you and help you get the wiring right on your GS2.

    This is also important for the life expectancy of the fan. Most VFDs are NEMA 1 or IP 20 meaning dust (and water) can get in them. Dust will eventually cause a fan failure. Metallic dust is well...bad. When the fan seizes up the heat sink temperature goes up and the drive shuts off. Replacing the fan is a piece of cake, but a hassle and unwanted expense.

    Did you get your Beaumont wheel(s) in Canada?

    Dan
     
  17. Icho-

    Icho- Staff Member

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    That would be awesome Dan. For now I will mount it somewhere high and to the left of the grinder but in a convenient spot. I can't start any new projects cause I want to make some knives. LOL


    No I got the wheels shipped to Detroit using the kinek address that I've mentioned.
     

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