Treadmill To Belt Grinder Conversion Worked Out

[Mike] had a bunch of disused fitness machines lying around. Being a skilled welder, he decided to take them apart and put them back together in the shape of a belt grinder.

In particular, [Mike] is reusing the height-adjustment guide rail of an old workout bench to build the adjustable frame that holds the sanding belt. A powerful DC motor including a flywheel was scavenged from one treadmill, the speed controller came from another. [Mike] won’t miss the workout bench: Once you’re welding a piece of steel tube dead-center on a flywheel, as happened for the grinder’s drive wheel, you may call yourself a man (or woman) of steel.

The finished frame received a nice paint job, a little switching cabinet, proper running wheels and, of course, a sanding belt. Despite all recycling efforts, about 80 bucks went into the project, which is still a good deal for a rock-solid, variable-speed belt grinder.

Apparently, disused fitness devices make an ideal framework to build your own tools: Strong metal frames, plentiful adjustment guides, and strong treadmill motors. Let us know how you put old steel to good use in the comments and enjoy [Mike’s] build documentation video below!

33 thoughts on “Treadmill To Belt Grinder Conversion Worked Out

  1. I’m more of a Murphy’s law expert than a belt grinder expert, but isn’t that path length a little unnecessary? Like it can reach out and rip the face off the guy standing 4ft behind you.

        1. I believe, and I may be wrong, the length is to decrease belt temperature and extend belt life by having more surface area.
          Looks like a great design to me.

          also its probably not going to cause much damage when it lets go…its not stretched, it’ll likely just flop on the ground

        2. If you are building your own, you can add a belt brake. Wouldn’t be hard to do. A switch with a roller on it and a solenoid operated clamp. But I agree that this one wouldn’t need it.

    1. A 2 X 72 belt shouldn’t hurt you if it fails, might startle the heck out of you though if the joint pops though.
      I used to sell sanding belts to industrial / commercial customers and I did have a client switch to our belts because they had problems with one of our competitors belt joints failing. Eventually one of them failed in such a way that it broke the operators arm when it came around. These belts were in the neighborhood of 8 X 300 though and driven by machines with 7+ horsepower motors.

      1. With thicker belts you start getting air resistance more on your side, but they get heavier and carry momentum.

        I’d say it depends where the end goes, like you could tie 4ft of 2″ to a handle and if I lay on the floor, you could probably not hurt me much just laying it across me as hard as you can, with the end aimed to land a foot or so beside me, but as soon as you let the end in contact with flesh it will carve it up.

        1. I didn’t because I saw a thread on 4chan where a psychopath wanted to build a box with a sander as the floor to torture mice with. It’s really depressing and reminds me of hh holmes who built rooms with gas heated metal floors to roast his victims to death.

  2. What a terrible waste of a perfectly good bench. Should have sold the bench to someone who would use it and buy a 8 foot section of 4 inch square tube.

    The treadmill, good riddance.

    1. Fitness hardware is a 3 part system, which is supplied only 2/3 complete. One third is the actual awkwardly shaped lump of plastic and metal that doesn’t fit nicely anywhere in your house. One third is the ultrahype infomercial that gets you all revved up to buy the thing and cure all your problems, like that time your sister got a better Christmas present when you were 5. … and that creates the remaining third… the good intentions of the purchaser to actually use it.

      So when only the hardware is left, it’s cluttering up the damn basement, it’s not in demand because the last of those infomercials was 3 years ago, and it’s basically hard to get rid of junk… unless you have a yard sale, and someone with a good memory for infomercials will give you $10 for it.

  3. What a great idea:- I found a treadmill not the other day with a 1.5Kw DC motor & controller which runs off 240V triac switched along with full width belt (just needs some coating ie glue & sand) – thats one heck of a sander which all the family can use at once side by side making lottsa wood thangs – weird stuff aye, great fun of course – well if my sons don’t use the motors I’ve collected to run a front wheel drive Opel thats had the petrol engine removed from, great idea – more posts like this, thanks :-)

    Hrrmm, an edit option on the way at some point, maybe with a 5 min period ?

  4. This is absolutely amazing, it was like I made a wish and it came true on HAD.
    No really! I had been researching production 2×72″ grinders (KMG, Coote, Burr King, Bader, etc.), and DIY versions – EERF, “grinder in a box”, “no weld grinder”, etc.

    I was just thinking about that treadmill motor that I hadn’t used for anything, went to HAD, and up pops this!!

    As Hannibal said, “I love it when a plan comes together..”

    1. ” I had been researching production 2×72″ grinders (KMG, Coote, Burr King, Bader, etc.), and DIY versions – EERF, “grinder in a box”, “no weld grinder”, etc.”

      Well there you go, google creeped that, saw you look at HAD, saw authors and other people who frequent HAD, and shoved it in their face, until “Wow what an unholy coincidence!!!” an article was made.

      1. Guess I don’t understand, do you mean google’s “tailor made” search results off of what I had been looking at in my browser, or do you mean targeted ad-crap?

        Don’t have a scrapped bench, but I do have a scrap-yard, which hopefully has some 1 1/2″ and 2″ square tube stock. A free bench would be cheaper though.

        It would also be nice to build it for cheap myself vs. buy a pro unit. Though the “plug-in-and-go” of the pre-made grinders is nice.

        Of to the yard!

    1. The whole point of a ground wire is to ground the metal, all the metal, so that if it becomes energized as it goes to ground rather than grounding through you.
      When you tear apart a treadmill motor you’ll notice that everything is grounded except for one circuit board and that one is standing on plastic insulated feet.
      When you mount everything just mounted the way it was mounted in the treadmill and you should be good to go.
      I just wish I could figure out the RPM counter so at least I would have a reference as to some sort of speed and I would know which number to search for when grinding a specific item.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.