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Controller Enclosure

Discussion in 'General Talk' started by Sprags, Apr 12, 2018.

  1. Sprags

    Sprags Veteran
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    i tried doing a search for controller enclosure and found the whole machine enclosure. Considering how many chips you get when machining aluminum something like that is necessary.

    But I was looking for a box for the electronics. The nema enclosures I found are way more than I planned on spending but I think I found a Hammond enclosure that is 16 X 16 X 6 for about $110. I have a variable speed spindle so I need room for the VFD which I think will fit along with the stepper drivers, the controller board, the power supply and the switches and stuff. I don't think it's hinged but it is only about $110.

    I don't want a PC case and short of building a box this looks like the best alternative. I will post a link when I get home.

    Thoughts or suggestions please?
     
    #1 Sprags, Apr 12, 2018
    Last edited: Apr 12, 2018
  2. Sprags

    Sprags Veteran
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    whoa...don't all jump in at once! I imagine most here use computer cases....
     
  3. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Many people find cheap plastic project enclosures on ebay or amazon it can be tricky finding the right size but they are out there for about $40 or less.
     
  4. Sprags

    Sprags Veteran
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    Thanks I will look on ebay
     
  5. Wareagle

    Wareagle Well-Known
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    Here's an option and it's less than $40.
    https://www.amazon.com/gp/product/B005T94MQU/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
    It's a NEMA 4x plastic enclosure which is dust tight.

    This box is what I bought for my electronics, and in it I have installed the following:
    1x - 24VDC power supply
    1x - 5VDC power supply
    1x - PMDX-126 breakout board w/ Smoothstepper
    4x - DQ542MA stepper drivers
    1x - keyed switch
    1x - emergency stop button
    1x - selector switch
    1x - fan

    The layout of the electronics has been done in a fashion that keeps the line voltages (125VAC) away from the low voltages (24VDC & 5VDC), communications and stepper wiring. Heat is forced out by cross ventilation vertically from bottom to top.
     
  6. Gary Caruso

    Gary Caruso OpenBuilds Team
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    right, i was able to fit my gear into a 12x10x5" enclosure
     

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  7. Sprags

    Sprags Veteran
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    The 24,000 RPM water cooled spindle I'm using also included a VFD that I want to install in the controller enclosure. Dimensionally it is roughly 5.5" X 6" X 8" so as much as the eclosures you gave showed me look good and on the track with what I'm looking for I need one a bit larger. Thank you.
     
    #7 Sprags, Apr 16, 2018
    Last edited: Apr 16, 2018
  8. Sprags

    Sprags Veteran
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    Thanks to your suggestions I was able to find a Bud Industries enclosure a few sizes up that I'm pretty sure is going to hold all of the components I'm going to need. The one I found is the NBF-32032. I found it on Amazon for about $58 so it's not much more. I'm not really an electronics guy so I hope you can help me with a few questions.

    I have one 24v power supply I got from Open Builds but I'm thinking just to make sure I have enough power for the 4 stepper motors, the VFD, the water pump and the controller board and cooling fans I should add one more. Is that safe to say or overkill? I thought I saw another setup wth two so I'm thinking two would be better.

    I'm assuming the cooling fan or fans should be DC. Is that correct? I'm thinking the standard 120 mm size fan should do it.

    Can someone suggest an Emergency Stop switch? I almost considered a switch with a Paddle on the stop but I want to get a separate power switch for powering everything up and. Mushroom type push button emergency switch would be better. Is that true?

    Any help is appreciated...Thank you.
     
  9. JustinTime

    JustinTime Master
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    I would get the mushroom type Emergency Stop switches. I got two of them on my machine. One on each end. I can hit them faster than searching for the paddle switch and trying to hit it.

    Two power supplies will be better than one, especially if you use one for the spindle and one for the rest of the stuff. It will isolate somewhat the electronics from any potential 'noise'.

    Fans can be 12v DC, 24v DC or 120v AC or any other voltage, depending on what you buy.
     
  10. Sprags

    Sprags Veteran
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    Thanks for the help...

    If I go with a 120V AC fan am I correct in thinking I would plug that into the wall using a separate power cord as opposed to connecting the 12V DC or 24V DC fans to the power supply?
     
  11. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Fans don't pull much power, the 24V psu can easily power the fan and everything else with no problem. 300mA is typical
    The way drives work they will not even come close to using as much power as you would think from the current setting.
     
  12. Wareagle

    Wareagle Well-Known
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    Take a look at the loads that you are putting on the PSU (power supply unit) and add them up. If the total load is less plus a safety margin than the PSU capacity, you're good.

    Example:
    The OBPS 24VDC PSU is rated for 14.6 Amps, so we'll roll with that. The other numbers here are just random and don't reflect reality.
    1) Let's say you put 4 steppers that draw 2 Amps each. 2 × 4 = 8 Amps total
    2) You put a fan motor in that pulls .1 Amp. .1 x 1 = .1 Amp total
    3 ) A light is also fed by the PSU and pulls .5 Amps. .5 x 1 = .5

    Add those up, and you're total connected load in this scenario is 8.6 Amps.

    If you add a safety factor and only load to 75% of the PSU rating (14.6A x .75), the available current (Amps) is 10.95 Amps. My recommendation is to cap the total load to no more than 75%. The PSU runs cooler and the output voltages remain more stable. If your set up goes beyond b the 75% mark, then add a PSU and divide up the loads. Otherwise, it isn't necessary to have multiple PSU'S of the same output voltage.

    10.95A is greater than 8.6A, so you are within the PSU's rating in this scenario.

    Do the calculation and you'll know where you're at. Hope that helps!
     
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  13. Sprags

    Sprags Veteran
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    Thank you for the lesson ...that helps a lot!
     
  14. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Oh and putting the VFD in the same enclosure as the drivers and controler is probably asking for EMI issues..
    I know it's been done in the past (savvas comes to mind) but more separation is a better practice
     
  15. Sprags

    Sprags Veteran
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    I saw a YouTube video where they also included the a Raspberry Pi for the bCNC controller software. I imagine that's also not a good idea right?
     
  16. Gary Caruso

    Gary Caruso OpenBuilds Team
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    The pi would be ok, but the vfd for a spindle is high voltage and high frequency electrical noise. Need to be grounded and shielded well. It’s doable but can cause issues.
     
  17. Sprags

    Sprags Veteran
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    i gave it some thought....the enclosure is fairly large. How about if I put some kind of sheet metal barrier between the VFD and everything else?
     
    #17 Sprags, Apr 21, 2018
    Last edited: Apr 21, 2018
  18. Gary Caruso

    Gary Caruso OpenBuilds Team
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    If you already have the space, give it a shot, just be sure to use good star grounding practices and shielded wire.
     
  19. Wareagle

    Wareagle Well-Known
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    EMI can be a funny thing. It can do strange things to electronics, be unpredictable and tough to troubleshoot in many cases. In regards to EMI generating devices (VFDs, motors, electronic ballasts, etc.), the farther away you can keep them from EMI susceptible electronics, the better off you'll be. General rule of thumb; 12 inches (30 centimeters) minimum for the voltages we would normally deal with.

    This applies to non-shielded wiring to/from EMI susceptible electronics as well. Keeping wiring out of the EMI boundary is a good practice. Along the lines of wiring practices, it is best (not always easy or possible) to keep AC and DC wiring away from each other. When you have two wires (or more) running parallel with one another, essentially it becomes an unwound transformer. Technically this is incorrect as there are many things happening in a transformer that aren't happening in a wire run, but for the sake of an over simplified explanation.....;) Induction can and does happen in parallel wiring, and the induced voltages and currents can manifest into crazy things with electronics.

    It's best to avoid the practice of mixing system wiring, and better to keep mixed (AC & DC) wiring as short as possible. The longer the parallel run, the more chance of potential induction between the two (or more) wires.


    @Sprags In your application the divider may or may not be effective in regards to EMI. It depends on the size of the EMI fields generated by the VFD, the size of the divider, gaps, proximity to susceptible electronics, etc. Lots of variables in the scenario!! If it were me in this situation, the VFD would be in it's own vented enclosure for the EMI factor and to keep line voltage and control voltages separate. This may or may not be a possibility due to space, funds, etc. This is just a "best case, best practice" suggestion.

    You may be on the road with your electronics layout since the posts are a day or two old. If you are, give 'er a go. There's no way to know without firing it up and seeing if everything behaves or not.

    May your build be successful beyond expectation! :thumbsup:
     
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  20. Sprags

    Sprags Veteran
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    After posting my question here another forum member, the guy based my build on, at first had his VFD in the same enclosure with everything else. And he now tells me he he moved the VFD outside of the enclosure. He used a recycled computer tower case for his enclosure.
     

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