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DIY 2x72 belt grinder build.

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  • DIY 2x72 belt grinder build.

    So as many of you know I am nearing the end of my plate roller. Time to start thinking of the next tool because I have to keep those pokers in the fire.

    I really like the grinder on Alec Steeles youtube channel. It looks simple enough to build. Main frame looks like 2" square tube stacked 2-3 high which the motor mounts to, upper tension wheel gets mounted to, and then the front open ends of the tube is where the different "attachments" get slid in.

    Similar to this one made by IJustLikeMakingThings




    This should take no time at all!
    Last edited by vpt; 01-23-2019, 01:48 PM.
    Andy

  • #2
    Good looking design. I bet the guy wishes he had a welder.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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    • #3
      I think it's great he was able to build it without a welder. Now that it works, I guess he could go back and weld it together and claim all the bolt holes are there to keep the weight down.
      _____________________________________________

      I would rather have tools that I never use, than not have a tool I need.
      Oregon Coast

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      • #4
        Looking at 1hp dc motors for this thing. I see 90volt and 180volt, does this have to do with rpm as well?
        Andy

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        • #5
          Typically not. 90vdc from 120vac, and 180 from 240. Jim

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          • #6
            Originally posted by jmm03 View Post
            Typically not. 90vdc from 120vac, and 180 from 240. Jim

            Ah ok, thank you!
            Andy

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            • #7
              Normally if you over-voltage dc motors the rpm goes up. I dont know the specifics or really anything about commercial dc motors but all the small motors I have ever dealt with (drills, rc cars, small electronics) more voltage = more rpm. If a dewalt drill motor is rated for (hypothetical) 3000 rpm at 14V but you apply 18V to it, at a constant load the rpm will go proportionally higher. But like I said, if this is a commercial plate designation there may be something I do not know. Just mentioning the fundamentals of dc motors.
              Last edited by ref-mj; 01-19-2019, 04:05 AM.

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              • #8
                Originally posted by jmm03 View Post
                Typically not. 90vdc from 120vac, and 180 from 240. Jim
                Are you sure about that?
                Location: The Black Forest in Germany

                How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                • #9
                  Originally posted by ref-mj View Post
                  Normally if you over-voltage dc motors the rpm goes up. I dont know the specifics or really anything about commercial dc motors but all the small motors I have ever dealt with (drills, rc cars, small electronics) more voltage = more rpm. If a dewalt drill motor is rated for (hypothetical) 3000 rpm at 14V but you apply 18V to it, at a constant load the rpm will go proportionally higher. But like I said, if this is a commercial plate designation there may be something I do not know. Just mentioning the fundamentals of dc motors.
                  I do understand that part of it from much of the same experiences. However shopping for a 1-1.5hp DC motor for the grinder there are two distinct models, a 90v one and a 180v one.

                  Originally posted by Black Forest View Post
                  Are you sure about that?
                  A lot of what I am reading seems to point to 90v from 110-120 and 180v from 220-240.

                  I was hoping to get by with 1hp. Reading it seems 1hp will get the job done, but if a guy wants to lean on the grinder some 1.5hp seems to be the way to go. 1.5hp also seems to lean towards the 180v option. Not a bad option for me to run 220ac as I have the extension cord for the welders I drag all around the shop anyhow.
                  Andy

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                  • #10
                    [QUOTE=vpt;1217667]
                    A lot of what I am reading seems to point to 90v from 110-120 and 180v from 220-240.

                    I was referring to how many volts you get when rectifying the AC voltage. Just make sure what type of rectifier you use if you want to lower the volt out. A straight bridge rectifier will be 1.4 times the input ac voltage I think.
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #11
                      [QUOTE=Black Forest;1217673]
                      Originally posted by vpt View Post
                      A lot of what I am reading seems to point to 90v from 110-120 and 180v from 220-240.

                      I was referring to how many volts you get when rectifying the AC voltage. Just make sure what type of rectifier you use if you want to lower the volt out. A straight bridge rectifier will be 1.4 times the input ac voltage I think.

                      I was looking at getting one of those converters with speed control and all built in the box much like the one pictured. I see many listed to work with both 90v and 180v. I have a bunch of reading to do yet. I have a couple ac motors that would probably work but I think I would like the speed control of dc, plus it seems to be the power source of choice for belt grinders.
                      Andy

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                      • #12
                        Tread mill motors are very popular for this sort of build. If you actually scrap a treadmill they usually have a speed controller that works. Usually there is a fancy control head unit, but you can just use a POT for speed control on the input control leads to the speed controller. 5K pots seem to be the choice for these. I've got one with a 5K pot on it, but it seems to not have a fine enough speed control. I'm going to try a 10K POT on it. Basically its the same as a 0-5 or 0-10 input signal except the speed controller provides its own signal power source and you use the POT as a voltage divider.

                        You can find treadmill motors and speed controllers on Ebay all the time.

                        I'm pretty sure they are square wave pulse output. The idea of pulse is you have full power, but at short intervals. I was told its more energy efficient and the motor runs cooler. The first time I ran across this sort of thing personally was a Minn Kota Maximizer speed control for a 12 volt trolling motor when I was a kid. I know the battery life was a lot longer at medium and low speeds. I think most modern high end trolling motors use this sort of technology built in today.
                        Last edited by Bob La Londe; 01-19-2019, 11:20 AM.
                        *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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                        • #13
                          [QUOTE=vpt;1217679]
                          Originally posted by Black Forest View Post


                          I was looking at getting one of those converters with speed control and all built in the box much like the one pictured. I see many listed to work with both 90v and 180v. I have a bunch of reading to do yet. I have a couple ac motors that would probably work but I think I would like the speed control of dc, plus it seems to be the power source of choice for belt grinders.
                          A three phase motor with a VFD is also an option. That is what I use on one of my grinders. 3hp. If you do much fabrication type grinding 1.5 hp might be a bit on the light side.
                          Location: The Black Forest in Germany

                          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                          • #14
                            [QUOTE=Black Forest;1217700]
                            Originally posted by vpt View Post

                            A three phase motor with a VFD is also an option. That is what I use on one of my grinders. 3hp. If you do much fabrication type grinding 1.5 hp might be a bit on the light side.

                            From what I have been reading and watching in videos it seems most grinders can be cranked up to way to much speed. I am wondering if I could just use a smaller pulley on the drive to get more power into the belt and just sacrifice some top end speed.
                            Andy

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                            • #15
                              [QUOTE=vpt;1217704]
                              Originally posted by Black Forest View Post


                              From what I have been reading and watching in videos it seems most grinders can be cranked up to way to much speed. I am wondering if I could just use a smaller pulley on the drive to get more power into the belt and just sacrifice some top end speed.
                              That's an option. More low end torque that way, but lower speed also means lower material removal rate. If you go that way I'd suggest using a pair of pulley sheaves so you can have multiple speeds. Not as convenient as variable speed control, but atleast then when you need to seriously grind you will be able to.
                              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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