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  • I need some disc sander advice.

    I've been wanting a bigger disc sander (only have a little hobby 4" one now) in my shop and have now accumulated enough good junk to start putting one together. I have enough 1/2" aluminum plate and larger chunks to make a very solid mount/base, adjustable table and disc & hub. I came across an old (50's - 60's?) Westinghouse 110v 1/4 hp 1725 rpm motor today for free. It says "Type FHT AC Motor 56Z Frame" on the name plate and when I cobbled up a patch cord and plugged it in it sounds smooth as silk and feels plenty powerful.

    Anybody have any advice as to what diameter I should make the disc? I want to run it direct drive and would like to choose a size that uses a commonly available (translation: cheap) disc that wouldn't bog down the 1/4 hp motor.

    I'm also curious about zirconium oxide discs. Anybody got a line on a good supplier and do they really last a lot longer?

    What say you'uns?
    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

  • #2
    I have a 12" disc sander that's direct drive(no belt losses)that runs a 3600rpm 1hp motor and the power is borderline not enough.

    If it were me I would go no less than 1hp and no less than a 12" disc.Direct drive is also nice since you don't need any pulleys etc and they run much smoother as a result.

    I also bought a 12" Grizz disc sander for a whopping $140+shipping that's darn hard to beat.

    Yes the Zirconia discs last a long time,6 maybe 7xs what AOX does.I just by mine from McMaster Carr,$4.25/disc for US made heavy cloth backed discs with good glue.
    I just need one more tool,just one!

    Comment


    • #3
      Hi,

      I'll second Wierdscience, 1hp is barely enough on a 12" disc. I can trip out the heaters on mine. That 1/4hp isn't much better than what you already have.

      dalee
      If you think you understand what is going on, you haven't been paying attention.

      Comment


      • #4
        since we are on the subject.....

        I am kicking around the idea of building my own disc sander as well. I want something in the 16"-20" range. Is there a formula for calculating horsepower to disc size?

        Also, whats the best choice of material for the disc, aluminum or steel. What about disc thickness?

        I hope you don't mind me stepping in your thread Dickeybird with questions of my own.

        Lee

        Comment


        • #5
          Thanks for the input guys and no sweat Lee on the big sander question. I'm curious if there's a rule of thumb calc for hp/disc size as well.

          I don't have the extra $$ to just go out & buy one right now but I do have the stuff gathered up to build one for nuttin'. I suspect that old American iron 1/4 hp motor has way more than 1/4 the power of a modern Grizzly (Chinese) 1 horsepower motor. My Chinese 4x6 bandsaw has a "1 hp" motor on it and it won't pull the skin off a rice puddin'.

          I grabbed the pulley with a rag, plugged it in and tried to stop it by hand and let's just say it feels pretty stout. I'm guessing an 8" disc would be pretty close; maybe even 9" or 10". I'm thinking the slower (1750) rpm motor will need a fairly large disc to work properly. I guess it's all just a crapshoot 'til the metal hits the wheel and the sparks start a'flyin!
          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

          Comment


          • #6
            A few years ago I bought one of those combo 4"x36" belt/9" disc sanders at a sale. The motor was clearly "underscoped" and operating the thing always p*ss*d me off.

            I finally ripped off the the belt part and now it works very well as a disc- alone sander. Can't tell what HP the motor is but now it takes a determined effort to slow it down.

            I also have a 1"x42" belt sander with a 1/4 HP motor that I installed. It needs to be handled carefully to prevent stalling so I would echo what others have said regarding more power. On the other hand those old motors were very conservatively rated so you may be ok.

            Regards,

            Geoff

            Comment


            • #7
              Dickybird, --- I've got an 8" disk off a deceased 1x42 - 8" belt/disk sander that expired rattling around here that youre welcome to, it'll ship on USPS for cheap ---- IIRC it has a 5/8" hole

              And, I think youre right about that old motor, I bet it'll handle an 8" easy ----the Chinee motor that was on that sander was 'rated' at 3/4hp but it was pretty wimpy.

              Several yrs ago the company that makes those "3 in 1" sorta woodworking machines (Shopmate??) offered a 12" disk to adapt to the motor on it for $25-30 and I built a sander up off a 1hp scrapyard motor .... that thing has got to be one of the more handy tools in the shop! Course this was long before HF offered their 12"er for $99!, I probably spent that much on making that one up.

              Anyway, if you want that disk, DickyB,--- send me a PM
              If everything seems to be going well, you have obviously overlooked something........

              Comment


              • #8
                Your expectations may be different than mine- but I have a horse and a half on my 12", and would never go for a smaller motor.

                Of course, I also dont use cheap sandpaper- only Klingspor CS411, which is a blue zirconia alumina paper. Its false economy to buy cheap paper, in my opinion- you just tear thru it. A good zirconia, from Norton or Klingspor, will last you months of sanding stainless. We can take a piece of 3/8" round stainless, and feed it into the disc til there is nothing left but your glove smoking.

                As for bigger ones- for 16" to 20", the cheap imports start at 2hp, the decent domestics usually run from 3 hp, up thru 5hp for the beefy ones, to a rare 7 1/2hp model or two.

                More power is good.

                Comment


                • #9
                  I have several three phase 16" and several 12" machines the big ones are best.Alistair
                  Please excuse my typing as I have a form of parkinsons disease

                  Comment


                  • #10
                    Thanks Bill, PM sent!
                    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

                    Comment


                    • #11
                      Hey Milton,

                      I made a disc sander a while back primarily for use with wood but lately has been getting used for metal work too.

                      I started with a 9" replacement disc for a Sears disc sander - ordered it from their parts department and cost all of $15. I could have made one but for the time and trouble it wasn't worth it. Motor is an old GE 1/2 HP with a 5/8" shaft and the remainder being made of plywood and pine. It has three feet so it sits flat - I used Hocky pucks for the feet (bore a small socket with a Forstener bit and screw on to the wood frame) cheap, solid and works.



                      cheers, Graham

                      Comment


                      • #12
                        Originally posted by DICKEYBIRD
                        Thanks for the input guys and no sweat Lee on the big sander question. I'm curious if there's a rule of thumb calc for hp/disc size as well.

                        I don't have the extra $$ to just go out & buy one right now but I do have the stuff gathered up to build one for nuttin'. I suspect that old American iron 1/4 hp motor has way more than 1/4 the power of a modern Grizzly (Chinese) 1 horsepower motor. My Chinese 4x6 bandsaw has a "1 hp" motor on it and it won't pull the skin off a rice puddin'.

                        I grabbed the pulley with a rag, plugged it in and tried to stop it by hand and let's just say it feels pretty stout. I'm guessing an 8" disc would be pretty close; maybe even 9" or 10". I'm thinking the slower (1750) rpm motor will need a fairly large disc to work properly. I guess it's all just a crapshoot 'til the metal hits the wheel and the sparks start a'flyin!
                        Unless that motor was built in the steam era it's nothing special.The 12"Grizz sander I have is a sure enough 1hp,I can radius the end of a 2x4 in seconds,that's a full radius 1-3/4r.The other sander is 1hp3~ and "old arn",it's still close to being weak.

                        Not arguing,just saying that in this case more IS better.
                        I just need one more tool,just one!

                        Comment


                        • #13
                          I was all geared up to build a disc sander in the neighborhood of 16-20"s with an old tablesaw I had kicking around the shop. I saw the price of media for a 20" sander though, and that kind of turned me off. I run a little 6" disc/belt sander right now that I use only as a disc sander and zirconia alumina discs are about $1 a piece. I am still going to build something bigger, but no where near the original plan. Maybe a 12" one, I intend to run a 3hp motor on mine. My little one has a 2/3 HP motor, and it is built into the base of the sander. I had to take it apart, because I couldn't believe a 2/3hp motor could fit in there. The motor is a odd frame, but it is a pretty big devil for going into the base.

                          I have never had trouble with that motor and the 6" disc, however I have an identical sander that I lengthened to take a 4x54" belt and use that for belt sanding only, the motor is seriously under sized for that application.

                          Later,
                          Jason

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                          • #14
                            disc motor H.P.

                            I agree a 1H.P. is a minimum, a 1/4 H.P. would be pretty Wimpy, and Very Slow!!

                            Ray in N. Ont.

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                            • #15
                              What thickness are the larger 16-20" disk?
                              Whats the ideal material; steel or aluminum?

                              Lee

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