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Speed Controller

Discussion in 'Grinders' started by John Noon, Sep 18, 2016.

  1. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I thought i'd post this link. I know many of you have likely already considered and/or are using a treadmill motor for their potential for infinite speed adjustment. I've attached a video and a schematic that summarizes a bunch of reading I've been doing on treadmill motors. Many of them typically use a PWM (pulse width modulation ?) speed controller. In particular, the MC60 speed controller board is very easy to use on DC motors. These controller boards can be bought seperately on ebay (search for "mc60 speed controller") and treadmill motors can sometimes be found at the curb. Just kidding, but many people sell them cheaply. Some treadmills will have a usable mc60 already. It seems to be a fairly easy wiring job to get a powerful DC motor working with nearly infinite speed control on the cheap if you can find an old treadmill.

    Here's a wiring diagram that I found and there's a great youtube video at . I've got dibs on a treadmill sitting at the inlaws house and plan to use it this year on my grinder version 2.0. I'll let you know how it goes but, I'm super slow with things so it may be this time next year.

    In the meantime, thought you guys may find this interesting and useful.

    [​IMG]
     
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  2. John Noon

    John Noon Well-Known Member

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    never touched internal wiring just put on a 6.125" pulley instead of the 4" one the previous motor used. I think the SFPM is around 2800 instead of 1700 and doubling that speed right now might be a little much although it may happen down the line
     
  3. Grayzer86

    Grayzer86 Active Member

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    Variable speed is the single best upgrade i have made to any part of my shop in the last 7 years after going to a 2x72. Mine will allow me to run from 0-180hz but i have the limiter set at 120hz right now so i dont get crazy. While the extra speeed is nice, where i really benefit is being able to slow that belt speed way down for very fine grits or working handle materials that burn easily. Not only does it keep heat way down, it also dramatically increases belt life on both ends. Fine belts last longer run slow usually, and some course ceramics need to be run super fast to fracture properly and stay sharp.
     
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  4. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I hear you. I was never really interested in electronics before i made a knife grinder. The more I read about speed control and the various ways to accomplish it, I sort of got into it a bit. I'm no expert, by any stretch. I barely understand the lingo. But, there's something really cool to me about taking an old tread mill apart and getting a powerful motor and speed control from it. An option that would otherwise cost me big bucks and just using my head and the internet, I can do it for nothing. To be honest, I think it may be one of the biggest draws for me to this whole craft. Making something useful from nothing at all.
     
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  5. John Noon

    John Noon Well-Known Member

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    The daughter had a old tread mill that was basically junk or didn't run well. It came up for sale a few months back and was with the son-in-law, he saw it and never stopped. So waiting for another to show up at the dump. Still have the single speed 2hp that I was using and may build a grinder just for handle shaping and drop the speed with a slightly smaller pulley or V-belt drive

    I just learned what it sounds like when a belt disassembles itself at full speed:eek:. Just a little to much pressure when off the platen I guess or a sharp edge
     
  6. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    this is the kind of thing where i learn something interesting and then i go overboard. I see a small collection of old treadmills piled up in my store room in the near future. I'll get another grinder done and a pic for Dan's gallery. : )
     
  7. dancom

    dancom Dust Maker Best Shop Tool

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    I am currently working on a DC PM treadmill motor with MC-60 board.
    http://www.canadianknifemaker.ca/index.php?threads/treadmill-motor-hacking.2442/

    There are a few problems to overcome for a typical grinder application.

    1 - Once the power is turned on, the motor will not start unless you turn the speed control pot all the way to 0 V then bring it up to your desired speed.
    2 - The 17 mm motor shaft is not a common size to couple to and it's only an inch long.
    3 - The motor is open frame, and it needs to be shielded from dust and debris typical of a grinding environment.

    I hope to have solutions for each of these shortly. I'll post here with the results.

    Dan
     
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  8. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Awesome Dan. You've beaten me to the punch. That's cool, I needed a brain to pick on this one too. I did find something about one of your problems in my readings. Apparently some cars in the US use .67 inch pulleys for automobile alternators. The forum i found (I think it was an instructible actually) said he used one on his and it worked great. He did have to drill and tap for a set screw. I don't know what you'd do if you wanted a bigger step pulley though. Maybe have to have an adapter made or something.
    Anyway, thought it might help. Let me know how it goes. I'm still trying to procure my treadmill.
     
  9. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I also had a note about copper tubing as a spacer. Type L Tempered copper (5/8) has an ID of almost exactly 17mm (smaller by about .03mm for a nice tight fit. The OD is is within .001 of 3/4". It's supposed to work really well as a spacer. Here's the table i copied. I hope this helps too...

    [​IMG]
     
  10. dancom

    dancom Dust Maker Best Shop Tool

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    Good find. Looks like that 3/4" copper pipe is what you'd need to stick a 3/4" bore sheave on the motor. Not sure what to do with the keyway.
     
  11. John Noon

    John Noon Well-Known Member

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    Well interesting 10 minutes of putting the jumper on my VFD to 2X and rough shaping a 6" blade in a couple minutes. A totally new experience to say the least going from 1700 SFPM on original motor to 2800+ SFPM with the 3 phase and larger pulley then 2X and according to the link now a whopping BELT SPEED: 5484 SFM (Surface Feet per Minute).

    Okay this is the first time I felt the need for the belt guard and not sure touching the belt with a finger will only be rough skin, from this point on I am thinking finger removal. Actually had sparks coming off the 240 grit belt for the first time without a hard push.
    Part of me is wondering how long a 2x4 would last being stuffed into the belt. Now I just have to replace the large pulley as it is a little out of round or something as the belt vibrates at full speed.
     
  12. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    So John, this might try your patience a bit but can you explain a bit about when faster speeds are a good idea and when slower is etc.? In general, i know that the harder the material the slower you want things to go. At least for the drill press and even many saws. But i know that this is too simplistic and general for grinding/knife making.

    Can you clarify for me (us) when faster/slower speeds are a better idea?

    Thanks John. I sort of know this stuff but I don't really understand the why of it all. Plus, I figure that since i have this huge pool of knowledge and experience available, i'd rather hear the information right from the horses mouth.
     
  13. John Noon

    John Noon Well-Known Member

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    considering missing bit of my finger nail, faster may not be better {} close to big hole in hand.

    The biggest advantage to the speed and say 36 to 60 grit belts id I just put the course bevel on three knives in 1/4" A2 steel, 1/8" CPM154 and sanded the outline of two others in about a half hour maybe hour. Should have kept better track of time but first sign something was up was back spasm and got distracted trying to find a comfortable work position.
    Really at have to reconsider the work surface height now since I spend more than ten minutes at a time there.

    from this point on I will be running 100-400 grit at half the speed and finesse the final shape to the bevel along with plunge lines.
    With lots of water cooling you can bevel a large stack of knives pretty fast and if they do not turn color you are ready for heat treating. I have done about twenty over the last year and it would take hours to put on a bevel if not over a couple of days since I would get tired of staring at the blade going back and forth. Now I could easily make a half dozen blades a day if I put my mind to it maybe more? Polishing and gluing really slow things down so no risk of going into mass production just yet.

    oh and for wood and composites I will be running 1/4 speed max to keep the material from burning up and in the grand scheme of things it is actually real helpful to be able to slow a course belt down and shape the Ricasso in seconds or simply blow it up.
     
  14. Kevin Blenkhorn

    Kevin Blenkhorn New Member

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    Has anyone had any trouble with the KB VFD"s? I have a new KBAC27D wired to a 2hp 3ph 1750 rpm motor. I have the 240v input and the green and yellow lights come on but when I hit the on switch nothing at all happens. NO voltage to the output lines. I am cheating a bit running it off 2 plugs on separate phases but that shouldn't matter, input reads 245V.
     
  15. dancom

    dancom Dust Maker Best Shop Tool

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    Was it running before or are you just powering it up for the first time?

    You may have to condition the capacitors before running it.

    Dan
     
  16. Kevin Blenkhorn

    Kevin Blenkhorn New Member

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    No it has never been running and there is no where in the manual and I have not seen anything on line about conditioning capaicitors.
     
  17. dancom

    dancom Dust Maker Best Shop Tool

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    The caps are not the issue, but there is a note in the manual on page 4 about reconditioning them. If the unit has be unpowered for over a year. That's not your issue. Steady yellow means STOP. Is the start switch wired to the board?
     
  18. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I'm sorry I can't help with your issue Kevin. I only know a little about wiring etc. and the only thing I know about treadmill motors and speed control is a wiring diagram i found online. I'm sure you're well beyond that already. Wish i could offer more. Besides, if anybody can help, it'd be Dan.

    Have you tried resyncing the tri-lithium matrix flux inhibitor with the warp coil hyperdrive fratamistat? <sorry, i couldn't resist...nerd who uses humor sometime at the wrong times here, and sometimes forgets the humour too >
     
  19. dancom

    dancom Dust Maker Best Shop Tool

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    He got it sorted. Faulty switch.

    No need to re-sync the TLMFI.

    Dan
     
  20. dancom

    dancom Dust Maker Best Shop Tool

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    Reminds me of a brilliant German guy I used to work with in electronics R&D. He used the word "dumafratz" for lack of a better word to describe "terminal #17". We needed to bring it out on a micro-controller to the motherboard. I was doing the test fixtures for manufacturing and one day, much to his surprise, he spotted "T17 DUMATRATZ" printed on the front panel of the test unit. As far as I know it is still there today. Ah great memories of the shenanigans we'd get up to.
     
    Last edited: Feb 27, 2017

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