Electronics & Enclosure

Design & Suppliers


Controller
There are a lot of systems sold for controlling 3D printers. It's clear (from forum postings) that the Ardunio based RAMPS controller supplied with the A1 is about at the end of it's useful life. It's fine for the A1, but not beyond. We were promised the Smoothie Board with the A1. Apparently it was not quite ready when TL needed it, and we never got the promised 'free upgrade'. Right now, I'm inclined to go with the Smoothie Board for my Nextgen system unless someone can convince me otherwise.
Smoothie Project - http://smoothieware.org/smoothieboard
installing Smoothieboard in a 3D printer - http://smoothieware.org/3d-printer-guide
installing Smoothieboard in a CNC Milling Machine - http://smoothieware.org/cnc-mill-guide
installing Smoothieboard in a Laser Cutting machine - http://smoothieware.org/laser-cutter-guide
buy from - Uberclock - http://shop.uberclock.com/products/smoothieboard
Kickstarter page - https://www.kickstarter.com/projects/logxen/smoothieboard-the-future-of-cnc-motion-control

Power Supply
The A1 had a problem with it's heated bed. The resistance of the Kapton heater was ~ 1 ohm. At 24 volts thats 24 Amps for a power load of 576 watts. That was more than the power supply provided could deliver.

Here's the power calculations for the nextgen printer.

Heated Bed - 2 8x8 in 12v silicone heaters in series - each heater measures ~ 1 ohms, so the pair will be ~ 2 ohms.
At 24 volts that's 12 Amps for a load of 288 watts.

Extruder - I'm going to move to using cartridge heaters, instead of resistors, in my hot ends. I purchased an E3D heater with a 24v cartridge heater.
It measures ~12.6 ohms. At 24 volts that's 1.9 Amps. Using 2 Amps that's a load of 48 watts.

Stepper Motors - The Kysan 1124090 motors I'm using in this design are rated at 1.5 Amps/phase. For load calculations I'm going to use 2 Amps (which is the limit of the drivers on the smoothie board). At 24 volts, that's 48 watts/motor x 5 motors (X,Y,Z1, Z2, X1 & X2 ) that's 240 watts. [I'm aware that the dynamic load calculation is more complicated than the simple DC current figure I'm using here but I've got to use something!] If you counted motors you will have noticed 6, but the Smoothie Board only supports 5. In conversation with Mark Cooper (SmoothieBoard designer, shop.uberclock.com) I asked about it. The answer is: "Driving both of your Z axes from one driver is perfectly normal and does not pose a problem. Electrically, if you wire the two steppers in series, they each split the 24V source voltage so what effectively happens is each stepper gets 12V at whatever the current setting is."

after a google products search for 24v 400w power supplies I purchased 2 units from
http://www.aliexpress.com/w/wholesale-power-supply-24v-400w.html

Enclosure
If you've looked at what I did to re-locate the A1's electronics from inside the base - http://www.r2-3d.media-conversions.net/printer/A1.rebuild.1.html
or how I packaged up the controller for my CNC router - http://www.cnc.media-conversions.net/electronics.html
you'll already know that I'm partial to re-purposing obsolete PC chassis. I intend to take that route this time as well.
I was looking for two identical chassi. While you can usually find one at garage sales, flea markets, etc. finding two the same is difficult. I did stumble across a line of chassi being sold by Tiger Direct.
http://www.ultraproducts.com/applications/category/category_tlc.asp?CatId=32
at the time I found it, their ULTRA XBlaster Pro U12-42350 Mid-Tower Case - was selling for $39.99 - less $20 rebate - less $5 cupon - with free shipping.
at $14.99/chassi you simply couldn't beat the offer. - I bought two.

This choice created a minor dilemma. These chassi came without PSU's. I had 'cleaned up' my basement and tossed most of my salvaged PSU's so I didn't have a scrap pair that I could canabalize for parts to use for the power cord termination. I would not have wanted to disassemble brand new PSU's in any case. First I looked up the ATX specifications at:  http://en.wikipedia.org/wiki/ATX from this I downloaded:
ATX Motherboard Specification, v2.2 from which I extracted a drawing of ATX MOBO mounting hole location
 ATX12V Power Supply Design Guide, v2.31 from which I got an outline drawing of an ATX PSU.

I had in my 'junkbox' a pair of Corcom 6VM1S power entry modules, so I decided to print a simple panel that would fit in place of the PSU, hold the power entry module and perhaps a fan (TBD). Then I decided not to because that would put the power switch at the back of the chassi. So I picked up a pair of Interpower 8301213 - IEC 60320 C14 Screw Mount Power Inlet modules - drawing. I decided to mount these units at the top of the chassi where the ATX I/o connector panel would normally be and to modify the front panel bezel to accomodate a circuit breaker/power switch.
Endstops
http://reprap.org/wiki/Mechanical_Endstop
http://www.3dmakerworld.com/store/parts-accessories/electronics/mechanical-endstop-microswitch
http://www.ebay.com/itm/GE-Mechanical-End-Stop-Endstop-Switch-Module-V1-2-3D-printer-Reprap-Mendel-Pursa-/221278436596?ssPageName=STRK:MESE:IT#ht_2510wt_1221
http://reprap.org/wiki/Gen7_Endstop_1.3.1
http://www.ebay.com/itm/3pcs-3D-Printer-Optical-Endstop-end-stop-with-cables-Rerap-US-Seller/261412161850?rt=nc
http://www.amazon.com/JMT-Optical-Endstop-Makerbot-End-stop/dp/B00EUTURFU

Cabling
For this project I will need cable for:
6 stepper motors 4C (x,y,z1, z2,x1,x2)
3 endstops 3C (x,y,z)
3 thermistors 2C x1, x2, bed,
2 extruder fans 2C x1, x2
2 extruder heaters
The Extruder, with heater, fan and thermistor requires 6 conductors, otherwise everything else can be served with 4 conductor wiring.
AWG 22 GA wire is capable of handling 7 amps. The motors are 1.5 Amp, the extruder heaters (40W@24V) are 1.66 amp, all the other loads are negligible except for the bed heaters.



Contact Information
Contact me using: fpirz (at) media (dash) conversions (dot) net

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