What are the constraints on cutting aluminum?

New Home Forum Mostly Printed CNC – MPCNC Advice – MPCNC What are the constraints on cutting aluminum?

This topic contains 49 replies, has 8 voices, and was last updated by  David Rabbit 1 month ago.

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  • #54673

    David Rabbit
    Participant

    Here’s the manual for it:  https://www.casogo.com/Manual/DS_NVBD_EN.pdf

    #54678

    David Rabbit
    Participant

    This morning I used a piece of white tape, a photo resistor, and an oscilliscope to measure the unloaded RPM of the spindle that came with my 2418.  It came out at 8333RPM.  It wouldn’t be hard to come up with something more permanent, using the same technique with an Arduino Pro Mini instead of an oscilliscope, to capture RPM for a PID.  It’s plenty accurate, and it’s certainly cheap to make, that’s for sure.  You could do this, or similar, with almost any spindle I would think.

     

     

    • This reply was modified 1 month, 2 weeks ago by  David Rabbit.
    • This reply was modified 1 month, 2 weeks ago by  David Rabbit.
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    #54683

    thesfreader
    Participant

    Something like that ? https://www.v1engineering.com/forum/topic/hardware-needed-for-a-software-fix/ ? 😀 (see latest posts) Ryan has done some work n something like that indeed, which gets the RPM and feed it into a PID algorithm + get the PWN for cntroling a target RPM, and some triac to adjust power fed to the router… Not yet finished, but SOOOO promising.

    1 user thanked author for this post.
    #54684

    Ryan
    Keymaster

    Wow, I was just reading a crazy long github post involving servos…..

     

    As for the PID thing, there is another coming along on the social page on instagram. I have no idea how he is getting the reading as he is pointing the lights at a metallic surface though. So one way or another a new PID will be available soon.

    The controller in that spindle is not a PID but does have some acceleration control. Hall effect sensors are needed for the brushless spindles to start up going the correct direction, and then can be used for speed detection.

    1 user thanked author for this post.
    #54689

    Jeffeb3
    Participant

    Brushless motors have built in speed control, in that they have to move the current through the motors at a certain speed, not the current based approach DC motors use. So it’s still possible that spindle will have speed control, not just “torque control” for lack of a better word. It depends a little on the software in the box.

    1 user thanked author for this post.
    #54692

    Ryan
    Keymaster

    I used a large high torque brushless without sensors in another project and it was kinda of a bummer that you needed to give it a bump to get it going and a big enough bump to make sure it went the right way. That is the most promising out of the box solution I have seen yet and looks to be leaps and bounds better than the quiet cut. Add $50 or so for the power supply and it might be a solid solution for under $200 if the quality is there.  I need to triple check the specs but I would like to try one.

    1 user thanked author for this post.
    #54697

    David Rabbit
    Participant
    Something like that ? https://www.v1engineering.com/forum/topic/hardware-needed-for-a-software-fix/ ? 😀 (see latest posts) Ryan has done some work n something like that indeed, which gets the RPM and feed it into a PID algorithm + get the PWN for cntroling a target RPM, and some triac to adjust power fed to the router… Not yet finished, but SOOOO promising.

    Wow, talk about synchronicity.  I just now read that thread (thanks to you) and it felt like deja vu.

    I wonder why all the high speed spindles are AC rather than DC.  I guess a spindle needs higher voltage than 60VDC to get to the >24,000RPM speeds?

    I’ve heard that for milling PCB’s, those high RPM’s tend to work better.  I found some aliexpress spindles that go up to 60,000RPM, but they’re all AC.

    Anyhow, doing a PID for a DC spindle does seem like it would be a little easier than for an AC spindle, so I guess I’ll start with a DC PID.  Maybe by then Ryan will be done with the AC PID.  🙂

    • This reply was modified 1 month, 2 weeks ago by  David Rabbit.
    • This reply was modified 1 month, 2 weeks ago by  David Rabbit.
    #54700

    David Rabbit
    Participant
    #54705

    Ryan
    Keymaster

    Have you convinced yourself yet why I am trying to make a less expensive PID controller for any AC router?

    Links and things you have read are nice but really, try it out. Tell us if it works or if it burns out, or if it ships at all, is it really enough power, does the control work? Do the instructions actually tell you how it works? We have all bought things from aliexpress, and the experience is not always good.

    For hopefully right around $100-$120 total you would get a 660, WITH a warranty, and a PID and it’s code that you can change and edit the way you want.

    1 user thanked author for this post.
    #54710

    David Rabbit
    Participant
    Have you convinced yourself yet why I am trying to make a less expensive PID controller for any AC router? Links and things you have read are nice but really, try it out. Tell us if it works or if it burns out, or if it ships at all, is it really enough power, does the control work? Do the instructions actually tell you how it works? We have all bought things from aliexpress, and the experience is not always good. For hopefully right around $100-$120 total you would get a 660, WITH a warranty, and a PID and it’s code that you can change and edit the way you want.

    Well, sure, that sounds great.  I hope you do.

    #55239

    David Rabbit
    Participant
    #55240

    Jeffeb3
    Participant
    If anyone has interest, I can post the results.

    In case I haven’t said this already, I am very interested in the results.

    #55245

    David Rabbit
    Participant

    Well, I can confirm that the spindle itself weighs 2# 4oz.  A power supply should arrive later today that I can use to power it up.

    In terms of actually testing it in actual use, my 3D printer hasn’t arrived yet, so I’m not sure yet if I can mount it on my 2418 or whether that will have to wait.  I should be receiving the 3D printer in about  2-3 weeks from now.

    If there are other tests you can think of, though, that you’d like run in  the meantime, I could maybe do some.  I mean, for instance, I could check to see how loud it is, and I could maybe form a rough opinion about how good or bad its runout is.  I could maybe even try loading it to see whether it maintains RPM, but I’m not exactly sure how I should  do that.

    • This reply was modified 1 month, 1 week ago by  David Rabbit.
    #55259

    David Rabbit
    Participant

    Power supply arrived, and I hooked it up.  It runs very quiet.  The motor itself is pretty much sealed.  On the positive side of that, little if any dust will ever get inside it.  On (maybe) the negative side, the fan basically directs air at the back of the motor, and not really anywhere else.  I’m only guessing, but keeping other parts of it cool may prove challenging if doing a lot of heavy milling.  For milling PCB’s, I don’t think it will be a problem though.

    #55382

    David Rabbit
    Participant

    I found a very similar motor being used on a printed CNC machine on thingiverse, so I think it will probably work without issue:

    https://www.thingiverse.com/thing:1001437

    and

    https://www.thingiverse.com/thing:1750276

    • This reply was modified 1 month, 1 week ago by  David Rabbit.
    • This reply was modified 1 month, 1 week ago by  David Rabbit.
    #55527

    Carson Roff
    Participant

    Here is a pic of 9” x 9” x 3.5” build.

    1 user thanked author for this post.
    #55533

    Jeffeb3
    Participant

    That looks great.

    #55931

    David Rabbit
    Participant
    Power supply arrived, and I hooked it up. It runs very quiet. The motor itself is pretty much sealed. On the positive side of that, little if any dust will ever get inside it. On (maybe) the negative side, the fan basically directs air at the back of the motor, and not really anywhere else. I’m only guessing, but keeping other parts of it cool may prove challenging if doing a lot of heavy milling. For milling PCB’s, I don’t think it will be a problem though.

    Epilog:  I ran the motor unloaded continuously at its maximum speed and monitored its temperature using a DS18b20 temperature sensor beneath the holding bracket (so, getting the *least* amount of circulated air onto it).  It reached an equilibrium temperature of around 31C.    Also, it turns out that it actually does have pretty good air flow.  So, I’m no longer worried about this spindle getting too hot.  🙂

    #55950

    Jeffeb3
    Participant

    I’m curious to know if it shows down, when not at Max speed, when running through material. Maybe you can’t test that until you get the cnc finished…

    #55964

    David Rabbit
    Participant
    I’m curious to know if it shows down, when not at Max speed, when running through material. Maybe you can’t test that until you get the cnc finished…

    I think I’ll stick with the mainstream build, at least for the first build, so maybe much later….

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