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IndustryArena Forum > CNC Electronics > General CNC Machine Related Electronics > Spindle Encoder options for a Smithy Lathe
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  1. #1

    Spindle Encoder options for a Smithy Lathe

    I'm looking at using Centroid's Acorn on my conversion of a Smithy Midas 1220 XL and need some ideas about spindle encoders for the lathe portion. The spindle is driven by step-pulley(v-belt) so mounting a standard shaft optical encoder would be impossible without major Mods. Right now I've come up with an idea, but I was hoping someone might have another solution that may work easier(or more affordable). RLS makes off-axis magnetic encoders like this one, https://www.rls.si/eng/products/rota...encoder-system, which have ring magnets that I could mount on the exterior of the pulley and build a bracket to hold the read head.
    I did do quite a bit of searching thru other build threads, but it looks like all the other Acorn lathe builds are using timing pulleys or gears mounted on the spindle to drive a standard shaft encoder.
    The other idea I had, which seems like a less-than-optimal one, would be to use an encoder with a friction wheel(rubber rimmed wheel) that would sit against the spindle pulley and would be driven by... you guessed it, friction!!! Unless I'm mistaken the friction wheel would have to be the same diameter as the pitch diameter of the spindle pulley, so that it's a 1:1 ratio. Is that correct? If that's the case, it probably wouldn't work for me as I dont think I could fit it inside the gearbox as is.
    Any ideas?

  2. #2
    Join Date
    Nov 2005

    Re: Spindle Encoder options for a Smithy Lathe

    It's not a Smithy but very similar. This is what I did.
    I was also looking at the RLS rings but this route was easier and a lot cheaper.

    Attachment 442520

  3. #3

    Re: Spindle Encoder options for a Smithy Lathe

    What resolution is the encoder you used? Acorn says it has to be minimum 4000ppr(1000 "line"), which seems like ridiculous overkill. The few builds I've seen documented were using 1000ppr.

  4. #4
    Join Date
    Nov 2005

    Re: Spindle Encoder options for a Smithy Lathe

    this one happens to be a 1024 P/R. I paid $22.50 for it. I found this 4096 P/R one but it is a lot more expensive.

  5. #5
    Join Date
    Jul 2011

    Re: Spindle Encoder options for a Smithy Lathe

    If you guys want cheap encoders check out the AMT-102 series. I have used them with success on two projects. They are programmable and cheap. They come with bushings for multiple shaft diameters, 2 different mounting brackets. Under $25 each. CUI also makes some direct mount encoders for larger shafts but I have not tried those ones yet.

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