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Potential tool post grinder spindle

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  • Potential tool post grinder spindle

    Considering this spindle for tool post grinder build. 4” wheels. Also considering it as a possibility for end mill sharpener as seen recently in the magazine

    Looking for any insight into this. I’ve never seen one in person. Wondering about power at 1/2 speed and vibration/balance of spindle

    https://www.amazon.ca/gp/aw/d/B07C1T...XZXP7T50&psc=1

  • #2
    4" wheels probably have a limit of 5000 rpm ( I did not look it up).
    If it is 500w that is like 2/3 hp, probably more like 1/2 hp.
    If you slowed the spindle down to 1/2 speed, I don't think you would
    have enough torque left, due to the radius of the 4" wheel.
    Also, the bearings are for sure not large enough to handle the mass
    of a 4" wheel. I would say this spindle would be good for ID work
    with small stones of 1" or less, but not for a wheel.

    -Doozer
    DZER

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    • #3
      How would the ER 20 2,2kw motor do for the same potential toolpost grinder application?

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      • #4
        Might be more the the range of right.

        I do love helping other people spend their money,
        so I say go for it !


        -D
        DZER

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        • #5
          I've been looking at those packages myself for much the same use. But when I look at the user reviews near the bottom of the page the first two report bad vibration. The first just mentioned the vibration. The second review mentioned that the motor unit became smooth and quiet when the fan was removed. He balanced the fan then all was good.

          Other reviews indicate some successes and some warranty issues. So all in all I'd say it looks promising. And given the low cost perhaps the slight risk is all that we can expect.

          This is not a motor and spindle that I think would be good for use with a 4" cup wheel though. It's a smaller shaft and smaller ER collet. And by extension a smaller set of shaft bearings. Look at the expanded version of the first picture and between the motor casing and the ER adapter you can see the small size of the shaft. I'm going to guess that it's likely a 6mm shaft. Not the sort of size I'd want to use with a larger wheel like your 4" option.

          Plunger, that motor is a lot more money but it looks a lot more sturdy as well. The one I looked at seems to have the ER chuck taper integrated into the end of the actual shaft. In addition from the two small holes drilled into the nut it appears that they even balanced the out of symmetry issue in the snap on feature of the collet nut. Now THAT is attention to detail ! ! So four times the price but along with higher power level it would appear to be a lot more durable and have a higher overall quality.
          Chilliwack BC, Canada

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          • #6
            Originally posted by plunger View Post
            How would the ER 20 2,2kw motor do for the same potential toolpost grinder application?
            I have on of those spindles, they are usually 24,000 RPM and used with a VFD. WAY to fast for a 4" wheel (or anything but tiny wheels for that matter)

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            • #7
              That spindle is meant for a 1/8" router or endmill for a CNC router, and a dirt cheap CNC router at that. I have the 3 phase version of that I am going to experiment with. The included drive with mine is absolutely anemic and faults out trying to get the motor to rotate anything with any mass. Converting it to a servo with an encoder and Odrive.
              As for tool post grinders, You'll want a separate spindle with angular contact bearings with a settable preload driven by an appropriate motor for the needed RPM. I should take pictures of mine.

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              • #8
                Check out youtube, lots videos on this motor. They like it for bench routers. For small wheels 1/8 x 1" diameter it would work. Dont think a 4" would. You would have to make an arbor with the ER tapper to have any chance of it working. Price is right with a speed control, but you dont get something for nothing like a saddle grinder .

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                • #9
                  Looks like its back to the drawing board. How much power would be required for a 4 inch wheel at 5000 rpm I wonder? Probably build a spindle and use a 1/10th hp motor if I can find one. Thinking small timing belt drive. Will poke around and see if I can find a power calculator

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                  • #10
                    It sounds like an interesting project but the advertisement makes no mention of the accuracy or run out of the spindle bearings which is a critical part of any precision quill, especially for grinding.

                    The price of brand name spindle bearings for a quill that size far exceed the cost of that entire set up. And what about replacement parts ??

                    JL..............

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                    • #11
                      JoeLee, I’ve moved on from motor in the link. Now leaning towards 1/10-1/6hp ac motor with belt drive to a shop made grinding spindle

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                      • #12
                        I don’t think you want a timing belt for a grinder. My mill spindle does not cut as smooth as I would like and I think it is the timing belt drive I used.

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                        • #13
                          Originally posted by Captain K View Post
                          Looks like its back to the drawing board. How much power would be required for a 4 inch wheel at 5000 rpm I wonder? Probably build a spindle and use a 1/10th hp motor if I can find one. Thinking small timing belt drive. Will poke around and see if I can find a power calculator
                          This will be for tool and cutter grinding and other light duty jobs, right? So you won't need all that much power. I'd say more than a 1/10 hp for sure though. That's light sewing machine territory. But something like 1/4 to 1/3 would work for light duty precision work. 1/2 hp would be lots.

                          I'd say no to the timing belt too. You don't need the timing and the pulleys for them are either a lot more expensive or they are a lot more complicated to make.

                          For a tool post or T&C grinder that uses up to the 4" stone you're considering I'd suggest sewing machine V belts like THESE . They have teeth but only so they are more flexible for going around smaller pulleys. The pulleys they fit into are regular "V" format style pulleys and the teeth just give the belt more flexibility for fitting smaller size pulleys. The size across the outer face of the belt is about 6 to 8mm wide. And they are VERY easy to find and cheap as a little checking will show. And for the sort of loads you would apply to a small finishing grinder used for T&C style work and similar jobs they are more than strong enough to handle the load.
                          Chilliwack BC, Canada

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                          • #14
                            Those belts look like the ticket. Need to source motor and then we'll see how it goes

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                            • #15
                              That "spindle" is just a generic permanent magnet brushed motor with a er chuck stuck on it. I would use one of the three phase ones that are water cooled and include a vfd that others have mentioned. You should be able to get the speed low enough with the vfd and still have some power.

                              Bearings matter and it will show up in your work.

                              If you want something better look for a used Precise (Now Fischer Precise) spindle. I have a larger one that is very nice, apparently has ABEC 9 bearings in it. Paid a couple hundred for it on ebay.

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