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junkyard belt grinder build (2" x 72")

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  • junkyard belt grinder build (2" x 72")

    we dont have any of those fancy kits over here, so i decided to build one myself. the purpose of this thread is to get advise but also to make me actually do it. i intend to put one hour into it every day and will document how long it took me.

    it will be "junkyard" in the sence, that i will try and use only the stuff i already have or can find around the shop. any purchase will be a failure. it will also be a very crude build, i will not derust the metal, break any edges, ream anything for fit nor will i paint it. its suppsed to be a grinder with the least effort and investment possible. will it be ugly? for sure. will it work? we will see.

    this is the pile of stuff the grinder is supposed to emerge from:



    these are the requirements the grinder has to satisfy:

    - fit into the space on the bench (600 mm)
    - the wheels or platten are not to portrude more than 50 - 100 mm beyond the edge
    - be semi portabe, so two guys can carry it (motor is around 40 pounds)

    for the "grinding point" not to portrude into the walk through space, the tracking wheel has to compensate for all conceivable cofigurations, so it has to move up and down by around 150 mm (300 total). therefore it will get a rotating tracking contraption, to make the adjustment be always rectangular to belt tension.



    what i have in mind looks like this.



    i have never worked on a grinder with a soft wheel. (we dont have these type of machines, i have never seen one, they would probably be considered as unsafe.) if i find out that i still need a slack belt, i might do it in the way shown in the lower drawing.

    the platten will go between the soft wheel and the idler at 45° or so and be at least 400 mm or longer. it might be strange in the beginning, but im sure i will get used to it. i might make a vertical platten with small radius attachments in the future, but dont see any need for it at this point.

    the motor is a 2.2 kw 2900 rpm 3 phase and has been living in this box for ages connected to its vfd:



    i invite any comments or critique about details or the whole concept, as mentioned i have never worked on this type of grinder.

    this must be the larges compilation of belt grinders, btw. i have never seen it mentioned on here:

    http://gonza-rytec.rajce.idnes.cz/belt_grinders2/
    Last edited by dian; 01-13-2016, 01:53 PM.

  • #2
    Don't know much about the subject but your junkyard sure looks better than mine! Your plan looks to be sound & well thought-out....but that's to be expected coming from you.
    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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    • #3
      this'll be neat, looking forward to the build! I have plans for a belt/disk sander rattling around my head, so I'm really interested to see what you come up with.

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      • #4
        -------------No chore for a 'stepper', go for it------------------

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        • #5
          Seems overpowered to me, compared to my classic Rockwell or Taiwanese Delta 1x42's. My 6" belt has 2 hp. But whatever, seems like fun. Will you be making crowned pulleys? And which type of center adjuster will you use? I hate the one on the Delta.

          If I were doing it I would just scale up the 1" Rockwell.

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          • #6


            It's a KMG clone.

            I use to stall my 2 HP 2X72, now running a 3 HP with a VFD as does yours. 3 HP is definitely not overkill. The motor is an under drive to save space. I'm adding a water mist system for heavy hogging next spring.

            I don't have the figures, but I'm going to guess my contact wheel is around 40 Durometer. Never had an issue with the 'soft' contact wheel, which is now 7 years old. The contact wheel is flat and both the idler and drive wheel are crowned. The actual tracking wheel deflection is quite small. +/- maybe 3° or so.

            I use to have a pdf of the plans in my dropbox folder, but I may have deleted them. I can make them available if you would like to see them.

            The KMG uses accessory bars to hold the various wheels. In the photo you can see the adapter for the small contact wheels. The small contact wheels is a 1" but they range from 5/8" to 1-3/4" diameter.

            The slack belt is an accessory bar as well and has an adjustable platen and work table shown attached to the slack belt bar.



            this bit was just fun



            I used an air cylinder as a tensioning spring. A builder had this idea on another board and some guy was flaming him cause it needed shop air to work... so what, it needs electricity too. ITS IN YOUR SHOP... probably never find an air line there. :~)

            That is a impressive collection of grinders in your link...
            Last edited by ironmonger; 01-13-2016, 09:19 PM.
            paul
            ARS W9PCS

            Esto Vigilans

            Remember, just because you can doesn't mean you should...
            but you may have to

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            • #7
              Another "junk" belt grinder build, actually 2 of them... Did buy a real contact wheels and 3hp vfd's though. Even the vfd control heads were from parts scrounged from old sonar displays. 3 hp isn't overkill at all.





              Lots of details/pics here : http://s238.photobucket.com/user/lak...?sort=4&page=1
              Last edited by lakeside53; 01-14-2016, 01:33 AM.

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              • #8
                lakeside, that is a "nasa build", i will try and keep it simple. im planning to only crown the drive pulley.

                http://s238.photobucket.com/user/lak...ml?sort=4&o=26

                so you are adjusting tracking with the horizontal knob, tilting the whole assembly? does that work? im thinking the belt has to run parallel to the rotation of the wheel. but maybe not?

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                • #9
                  The horizontal knob (front) rotates the arm and wheel assembly in the horizontal plane. The top knob locks it in place (not really needed to "lock" - just some friction). Works well. Tilting the wheel in the vertical plane also works; I just choose the former method.
                  Last edited by lakeside53; 01-14-2016, 11:49 AM.

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                  • #10
                    Lakeside those grinders are really well made. How long did it take you to figure out everything? I bet you hated to put paint on all those really cool machined parts. Paint covers up all the great work that went in to build those grinders. Next time spray them with clear polyurethane.

                    I am really impressed with the work you did.
                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #11
                      Originally posted by dian View Post

                      it will be "junkyard" in the sence, that i will try and use only the stuff i already have or can find around the shop. any purchase will be a failure. it will also be a very crude build, i will not derust the metal, break any edges, ream anything for fit nor will i paint it. its suppsed to be a grinder with the least effort and investment possible. will it be ugly? for sure. will it work? we will see.

                      Why?

                      I have built 3 grinders, the cost/time is in the motor, vfd, bearings, wheels and contact wheel.
                      Don't think making an intentionally ugly, rusty framework with finger cutting sharp edges to hold 3 or 4 wheels in proper alignment is going to save you much money or effort.

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                      • #12
                        lakeside, doesnt the belt then not run true to the wheel? so maybe it doesnt mater to have a slight angle difference? im asking because it would spare me fabricating a swiveling tracking contaption.

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                        • #13
                          cij, in my experience it will. it usually takes three times the effort, money and time to make my stuff look good. and then priming/painting is annother effort im going to avoid. i just want to grind.

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                          • #14
                            Originally posted by dian View Post
                            doesnt the belt then not run true to the wheel? so maybe it doesnt mater to have a slight angle difference? im asking because it would spare me fabricating a swiveling tracking contaption.
                            In the KMG grinder the the idler swings in an arc perpendicular to the plane of the belt, observing from the end of the motor shaft it has freedom in the pitch plane with no yaw.



                            you can make out the small blocks that the pivot pin goes through just to the left of the idler wheel. The idler is bolted through the block opposite the adjustment screw that are between the two .5"X2"X2.5" blocks bolter to the winging tensioner frame. It's a .75"X2"X2.5" block pivoting near the top and the 2"X2.5" face is drilled for a 1/2-13 bolt that carries the idler.

                            See page 5 of 7 at the first part of this file

                            This entire grinder is made from flat stock. And while I am perfectly capable of welding, the mounting tunnel that carries the tool bars was fabricated from flat stock. The fit is quite close and I didn’t want to take a chance on a very slight warpage in the 10" long tunnel that would impede the insertion of the tool support bars, which are 1.25" square stock.
                            paul
                            ARS W9PCS

                            Esto Vigilans

                            Remember, just because you can doesn't mean you should...
                            but you may have to

                            Comment


                            • #15
                              Damn Lakeside, have a little mercy? You set the bar really high, those things are PURTY! I don't need a 2" grinder for the AL & Delrin I use, but now I want one.....

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