*soon to be* ORD Bot owners, assemble!

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Re: *soon to be* ORD Bot owners, assemble!

Postby Boxcar » Mon Jun 25, 2012 5:02 am

I have an ORD Bot Hadron on pre order. I'm going to be using the dual extruder with 2x40W heater cartridges from the current Kick Starter campaign, Ramps 1.4 with Arduino Mega 2560, and A4988 stepper drivers. I haven't decided on a PSU or heat bead yet. I'm really excited since this will be my first 3D Printer if they meet their July 15th goal!

Could someone please tell me what size power supply I'll need?
Last edited by Boxcar on Mon Jun 25, 2012 7:42 am, edited 1 time in total.
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Re: *soon to be* ORD Bot owners, assemble!

Postby Liberty4Ever » Mon Jun 25, 2012 6:57 am

Boxcar wrote:I have an ORD Bot Hadron on pre order.

Me too! It'll be my second 3D printer... after the Hadron I'm finishing now!


Boxcar wrote:I'm going to be using the dual extruder with with 2x40W heater cartridges from the current Kick Starter campaign, Ramps 1.4 with Arduino Mega 2560, and A4988 stepper drivers. I haven't decided on a PSU or heat bed yet... Could someone please tell me what size power supply I'll need?

I mostly laid it out in my previous posts in this thread. Here are the likely maximum wattages and currents.

120W 10A Heated build platform
80W 6.67A Two 40W QU-BD extruder heaters
36W 3A Two QU-BD extruder stepper motors
72W 6A Three axes of stepper motors
12W 2A Worst case guess (too lazy to search) at the Arduino & RAMPS controller stack
--------------------------------------------------------------------------------------------------------------
320W 26.7A Total

The Z axis has two motors, but they're wired together, and if they're driven by one stepper driver, both of them together won't draw more than 2A.

The control electronics probably pulls less than an amp. Most of it is very low power, but the stepper drivers do run a bit warm, so that should be a conservative estimate as well.

The motors on the BOM provided by Automation Technologies are rated at 1.68A, so you'll need to set the stepper motor drivers below this current. Counting them at 2A each is a conservative estimate.

The big deal is the heated build platform. I'd expect it to be on less than half of the time once it's warmed up, so that should be 60W or less on average, not 120W.

I'd say a 12V @ 25A power supply should do it. That's a 300 watt power supply if you're buying a dedicated 12V only power supply. Realistically, 20A should be fine given all of the erring on the conservative side when sizing each load.

Note that a PC power supply will be rated for total wattage as well as maximum current for each voltage. Using only the 12V part of a PC supply, you're unlikely to be able to extract the full rated power of the power supply, so don't size a PC power supply by watts. Look instead at the current rating (amps) for only the 12VDC portion of the supply.

The math is actually very simple. Add up the amps for every load and buy a power supply capable of continuously supplying that many amps or more. To convert between watts and amps, use the following formula.

Watts = Volts X Amps

Example: 300 Watts = 12 Volts X 25 Amps

I'm at the point where I just spent 20 minutes moving my modified PC power supply all around the Hadron. It doesn't fit well anywhere. I'll probably mount it about halfway up the back of the right Z axis piece of Makerslide. It really screws up the aesthetics, but I can't find a better place. I saw where someone used a Yaesu ham radio 12VDC supply for their ORD Bot. It was short and flat, and it fit nicely under the Y axis Makerslide in the front, where the power switch was easily accessible. That was a nice touch. A 350W PC power supply might be short enough to mount in the back, on the bottom, and have the Y axis platform pass over top, although it looks like most PC power supplies are 3.4" to 3.5" tall regardless of power output. My 650W power supply was about half an inch too tall. Maybe I should make new feet that are 3/4" taller to accommodate PC power supplies mounted just below the Y axis platform? I think it'd be better to have the weight of the power supply down low, for stability and to avoid shaking the frame if the extruder carriage is moving back and forth at some resonant frequency. Or maybe I should buy a dedicated power supply that's shorter and mount it low in the back?

http://www.ebay.com/itm/110904173777
Apparently, I didn't build that! :-)
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Re: *soon to be* ORD Bot owners, assemble!

Postby Boxcar » Mon Jun 25, 2012 8:27 am

@Liberty4Ever

Thank you for the complete breakdown. I ordered a 12V 33A 400W Regulated Switching Power Supply since it was only a few dollars more than the 30A power supply, and about the same size as the 30A you showed me. I like having a little room to grow.
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Re: *soon to be* ORD Bot owners, assemble!

Postby Liberty4Ever » Mon Jun 25, 2012 3:24 pm

After participating in this thread, I talked myself into buying a dedicated 12V switching power supply last night.
http://www.ebay.com/itm/261024310859

I just couldn't tolerate the idea of a boxy PC power supply bolted to the back of the Hadron. I want to hide the power supply in the back, on the base of the printer, and the 8.5" X 4.5" X 2" size should allow me to do that. It's also flat enough to mount centered on the electronics plate on top, with the controller mounted to its back with stand-offs (being careful not to interrupt the air flow through the power supply. That would be a nice tidy installation.

I'm buying a lot of ORD Bot components twice. First I buy what I think I want. Then I buy what I really want. Maybe I'll donate the modified PC power supply for another Hadron part giveaway on BuildLog.net. Watch my Hadron build log for details. I'll use it to remotely power my Hadron for testing until the new low profile power supply arrives and is integrated. Of course, I can only do the finished wiring now if I opt to mount the new power supply at the base. If I wanted it under the control electronics on the top plate, all of that would need to be wired together. Neat as that would be, I probably won't do that. If the power supply ever needed to be replaced and it was under all of the other electronics, that would be a big pain. Details like this can drive me crazy. As I keep telling myself, my second Hadron will be a lot easier.

The ORD Bot was well considered from the perspective of an integrated mechanical design, but the electronics are left to the builder so the mechanics weren't optimized to include the variable and unspecified electronics. That makes it challenging to integrate the electronics and not mess up the looks of the Hadron. I'm doing my best to rise to the challenge. I'm ordering cable track today and it'll be here for my wiring tomorrow, to keep the wiring to all of the moving parts neat and organized. I have some other tips for neat and easy Hadron wiring that I'll be sharing, after I know they work well.

V Wheel Tip: Sneak up on the eccentric V-wheel adjustments very gradually. I thought I was making very small adjustments, and everything felt great yesterday - fairly low rolling resistance (although definitely a bit higher than when the V wheels were loose) without any binding. This morning, I can feel very slight flat spots in the Delrin V wheels when I move the Y axis, and almost imperceptible flat spots in X and Z. It's subtle, but it's there. I apparently had the V wheels a few thousandths too tight and the Delrin compressed while sitting overnight. I don't think I did any permanent damage. I'll loosen the eccentric spacers a very small amount and the Delrin wheels will probably return to their round shape by themselves. I don't think there was any permanent plastic deformation.
Apparently, I didn't build that! :-)
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Re: *soon to be* ORD Bot owners, assemble!

Postby kwando » Tue Jun 26, 2012 2:15 am

@Liberty4Ever

Cool, that's the exact same one I got too. It will be great to assimilate this into the overall 'look' of the ORD bot.

I'll definitely be following your build, I'm sure it will save me from many mistakes during my set up. Thanks for taking one for the team!
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Re: *soon to be* ORD Bot owners, assemble!

Postby kwando » Wed Jun 27, 2012 10:37 am

Hey All,

So the power supply came today, and I need to figure out how to wire it up with a power cable.

I watched this video, and the guy has recommended to use an ultimeter to determine which colour wires reflect what (ground, neutral, live).



My question is, is it possible to determine what is what just by looking at the colours of the wires? Will blue always be neutral, brown live etc? Or does this change from cable to cable?

Secondly, is stripping a PC cable the best way to connect the PSU to the AC? Are there any cables available with the wires already exposed which I can whack right on?

Thanks,

Kwando
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Re: *soon to be* ORD Bot owners, assemble!

Postby loopingz » Wed Jun 27, 2012 2:00 pm

Normally blue is the zero, yellow green the earth/ground and brown the phase. You can easily double check with a mulitmeter measuring the voltage between earth and the others.
Anyway a lot of country does not protect their outlet from being plugged both way (at least spain and portugal in my experience). I dont know what difference it can make on some particular products, can somebody explain the danger of switching blue and brown?
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Re: *soon to be* ORD Bot owners, assemble!

Postby Liberty4Ever » Wed Jun 27, 2012 2:52 pm

In a few older appliances, the neutral (zero) line might be internally connected to the chassis. If you wired the hot (line voltage) wire to the neutral in those appliances, and the chassis was connected to ground, you'd have a direct short between line voltage and ground. You'd blow a breaker or fuse in your building wiring.

Even worse, if the chassis wasn't connected to ground, the chassis would be energized at line voltage. The device would work properly, but if you ever touched the chassis and a grounded object like a cold water pipe, your body would complete the connection, which would be very dangerous.

Most modern products ground the chassis and do not internally connect the neutral to the chassis. Many products are double insulated, so there would need to be two faults of the internal grounding to allow line voltage to be exposed to the user. This is often sufficient for regulating agencies to allow an AC appliance to be wired without a ground connection, using a two wire cord instead of a three wire cord.

In the US, black is the line voltage, white is neutral, and green (or yellow & green) is ground.

There are online diagrams that show the plugs and outlets used in different countries.

In general, the ground is the longer of the three terminals on the plug, and often is a different shape from the other two. If you were very careful, even without knowing how outlets are wired in your country, you could unplug the cord, strip the insulation from the ends of the three wires, use an ohm meter to determine which wire color is attached to the ground terminal (near zero ohms, or beeping on the continuity test), then KEEP THE WIRES SEPARATED FROM EACH OTHER, plug the cord into the wall outlet and use a voltmeter to measure the voltage between the ground wire and the other two wires. The neutral wire will be within a few volts of the ground, and the line voltage will be a much higher voltage.

It's scary, and you probably shouldn't be learning stuff like this over the internet :) but if you are careful not to short anything and you don't touch any part of the wires when the cable is plugged in, and unplug it immediately after the brief test, you should be OK. But safety is always YOUR responsibility. Line voltage can kill. If you are the least unsure, get some help from a skilled electrician.
Apparently, I didn't build that! :-)
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Re: *soon to be* ORD Bot owners, assemble!

Postby kwando » Thu Jun 28, 2012 1:01 am

Thanks for the tips.

I was hoping for a way to make the determination without having to get my hands on an multimeter. Guess I'll need one sooner or later anyway...

Are there any cables pre-stripped with the 3 wires at the end? Or does everyone just strip a PC power cable like the guy in the vid?
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Re: *soon to be* ORD Bot owners, assemble!

Postby Liberty4Ever » Thu Jun 28, 2012 3:09 am

kwando wrote:I was hoping for a way to make the determination without having to get my hands on an multimeter. Guess I'll need one sooner or later anyway...

I sold one of my multimeters that I wasn't using. Now I only have three. :)

kwando wrote:Are there any cables pre-stripped with the 3 wires at the end? Or does everyone just strip a PC power cable like the guy in the vid?

Sure, you can buy a power cable with pigtails (stripped wires) on the other end.

http://www.ebay.com/itm/280887514555

It's usually easier and cheaper and faster to chop off the female end and make your own.
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