Announcing the ORDuino !

[frob]

As i know a lot of people here are ordering or about to their Orduino's + RAMPS + Pololu's etc. for the ORDbots,
I thought i should tell you about what i'm doing on this front now even if its a little early -
I dont have any board rederings yet, but the schematics are done and i'm half-way through the board layout already.
The board will be about 160mm x 60mm - it may change a little along the way, but thats pretty stable now.
i might grow it to 80mm wide if it saves time for the prototype layout but then the production version will be smaller.

Here are the basic features :
100% surface mount or as much as possible to keep the assembly costs down;
- this also allows the board to be bolted flat against makerslide or aluminum plate and use that as a *very* efficient heatsink
- Arduino Mega / RAMPS software- compatible, but no Arduino stacking headers
- Micro-SD card socket
- FTDI-based USB interface like previous arduinos for easier programming.
- RS-485 serial interface
- Local switching 5V regulator can take 24V in;
- up to 5 stepper axes @ 30V 3A max.
- also has connector header footprints for Pololu/stepstick a3988 drivers, in case you accidentally blow up one of the on-board drivers
(it is designed so you can easily use an exacto to isolate a blown driver and install and new driver board over it )
- Robust design with protection features, so its very unlikely the above scenario will happen in practice, unless one is extremely careless.
- All motor outputs connect with 3.5mm pitch pluggable terminal blocks; these also include connection for limit switches for that axis:
one terminal block per axis.
- 3 high current transistor outputs; Transistors are SMT and are rated 50A max, designed in system to easily handle 20-30A @ 24V.
- extra protection features here too, and current & temperature monitoring in software as well.
- 5mm pluggable terminal blocks on Power input and Heater outputs.
- FFC connector to directly drive the heated build plate that way, if you prefer.
- Buzzer for alarm / "done" signal.
- 4 "R/C style" servo headers
- 3/4 thermistor inputs (3.5mm pluggable terminal blocks )

Some options i may add before i'm done if you tell me it would be useful:
- Thermocouple interface?
- LCD interface ? ( i have a lot of new old stock of 128x64 monochrome LCD, about credit card size)
- ATX supply connector, or other connectors for common power supplies: Barrel jack, 6-pin mini-fit, or DIN.
- Joystick or other user control interface ?

I was trying to add SMT-style 1/4" faston tabs for power & heaters as well but that probably wont happen because they take so much space.
Its hard to find low cost, compact pluggable connectors that can handle 20-40A for the power and heater connections- especially surface-mount ones. It also requires special consideration in the board layout. As it is this board will probably use 2 or 3oz copper; a bit more expensive but at least it helps with heatsinking. If you agree the 1/4" Faston tabs are a good compromise, i will add these, though making the board 80mm wide rather than 60mm. The alternative power connectors are through-hole only so standoffs will be needed to mount it, and possibly a heat-sink in more demanding applications, although the board is designed to run cool when driving an ORDbot, so heatsink should be unnecessary.

What do you think so far?

PS my target price for all this is $130 for 4 axes / 2 heaters and $150 for an "all dressed" 5 axis 3 heater version.
Possibly less if i get enough interest / reservations.

I'm hoping to finalize the design by the end of the coming weekend so i can order prototypes along with the Heated build plates, so please dont be shy to give me your opinion and suggestions right away!

Cheers

[Zat German]

One of the problems with the RAMPs design(with pololus) is that the stepper drivers' ICs are supposed to have their heat drawn from the bottom, not from the top with heatsinks. If you could account for this in the design, that would definitely be a step in the right direction. I believe this is one reason why some people are surface mounting the drivers on their designs, instead of using modules. However, having replaceable modules is a good thing in my book.

[frob]

One of the problems with the RAMPs design(with pololus) is that the stepper drivers' ICs are supposed to have their heat drawn from the bottom, not from the top with heatsinks. If you could account for this in the design, that would definitely be a step in the right direction. I believe this is one reason why some people surface mounting the drivers on their designs, instead of using modules. However, having replaceable modules is a good thing in my book.

Correct -
that is accounted for in my design, in fact it is one of the main reasons to go to a 100% surface mount layout, allowing the mounting surface to be the heatsink as well. The other reason is cost. When assembling more than a few dozen boards, its a lot cheaper at contract assembly houses when you avoid through hole / manual assembly & soldering- automated assembly of through hole is only cheap in very high volume. I'm attempting to give people the best of both worlds - the low cost and thermal efficiency of an all-in one SMT board, but keep the option of replaceable modules if something goes wrong.
Or to upgrade that 4axis board to 5 axes..
Or plug in a high-current, high-voltage stepper driver instead. or a Servo driver.... etc...

One thing i failed to mention below is i'm using the new advanced driver IC's which are software configurable, a lot more powerful, and have much better built-in protection features. they also support 1/32 microstepping and switching modes on the fly through software control.

I'm also using the soldered-in M3 threaded mounting bosses - mounted on top so you just add screws from the back to clamp the board against the mounting plate / heatsink. or if through hole connectors are used they can be installed on the bottom instead to clear their pins, and still transfer some heat to the mounting plate.

[Enraged]

I haven't purchased my electronics, so I would be interested in this. Running at 24V would be nice.

Regarding the LCD, check out the Adafruit LCD Shield: http://www.adafruit.com/products/714

It only uses 2 pins to control the LCD and buttons. Something similar this would be a great add-on for your board, allowing you to mount it in an accessible spot. Maybe have the buttons on the LCD board control functions such as start, stop, loading a file, adjusting speed (maybe % based so you can adjust speed on the fly?) or extruder temperature (tweaking the temperature of the extruder without changing software would be nice).

[frob]

I haven't purchased my electronics, so I would be interested in this. Running at 24V would be nice.

Regarding the LCD, check out the Adafruit LCD Shield: http://www.adafruit.com/products/714

It only uses 2 pins to control the LCD and buttons. Something similar this would be a great add-on for your board, allowing you to mount it in an accessible spot. Maybe have the buttons on the LCD board control functions such as start, stop, loading a file, adjusting speed (maybe % based so you can adjust speed on the fly?) or extruder temperature (tweaking the temperature of the extruder without changing software would be nice).

Not bad for the price -
what i'm not crazy about though is the seperate power supply connection and cabling ;
The LCD i had in mind is a graphic "chip on glass" unit 2mm thick that would directly plug into a small ffc connector on the board ; thus if the ORDduino is mounted in the expected place you'd only need to make a small extra slot or hole in the mounting plate and stick it on the front side opposite the board with double-sided tape. I think it would look very clean and nice installed that way.
Since i have hundreds in stock i can sell them as an extra option for cheap - like $10 ea. with a board.
This is what it looks like:

pressAGM1264H.jpg (7.24 KiB) Viewed 184983 times

It could be backlit but that would be a little more tricky for lighting & mounting it.

[Hibernator]

I am definitely interested. The extruder + electronics part of the ORD bot has me still a little confused though. There seem to be a lot of options (not necessarily compatible with each other) and therefore a simple one-stop alternative would be very welcome.

Definitely vote for having a display.

[IPvFletch]

Is that $130 including the Arduino Mega and drivers, sensors, etc?? Many proven (complete) kits are selling for $180, so you'd have to beat that, for an apple to apples complete kit. The LCD is nice, probably a $25 add-on though as not everyone would want it. The idea of exposing the LCD through a square cut into the upper panel is great, and using the upper panel (aluminum handle part) for the heat sink is an amazing idea! I do wonder though how hot it will get, but you could just print a plastic handle grip if need be.

[butterfingers]

You might want to consider something like this:

http://www.goodluckbuy.com/3-2-tft-lcd- ... duino.html

http://www.goodluckbuy.com/2-4-tft-lcd- ... duino.html

That would be very cool.

[frob]

Is that $130 including the Arduino Mega and drivers, sensors, etc?? Many proven (complete) kits are selling for $180, so you'd have to beat that, for an apple to apples complete kit. The LCD is nice, probably a $25 add-on though as not everyone would want it. The idea of exposing the LCD through a square cut into the upper panel is great, and using the upper panel (aluminum handle part) for the heat sink is an amazing idea! I do wonder though how hot it will get, but you could just print a plastic handle grip if need be.

Yup, $130 all-in. AND you're getting something a lot better, in my humble opinion, at least

Thanks for the positive feedback!

I don't expect it to get noticeably hot on the ORDbot, driving small lightly loaded nema14 / 17 motors.
If you have a 100W extruder hot end and 300W heated build plate it might get a little warm but not enough to be any kind of issue.

Hmm as a printable accessory, a plastic frame / bezel to hold the LCD along with a small PCB with cursor buttons next to it and LED's to backlight the sucker would be really cool got any blue filament ?

[dzach]

This sounds really interesting at that price. I'd like to see the LCD interface included as well as the ATX connector, although this might mean the 160x80 size will become unavoidable.

Some questions:
- Are the SD card and (optional) LCD display going to be supported by the software?
- Does the software support the new current limiting capabilities of the A3988 driver?
- Is the PCB going to be a 3layer one? Alegro MicroSystem recommends it as a low point ground and thermal path.
- The chip manufacturer gives a 1.2A per phase current rating, i.e. 2.4A per axis. How is the 3A max achieved?

Considering the combined heated bed + ORDuino PCB, could that be a kit with all SMT parts (including the ones for the heated bed) pre-soldered and all the non SMT parts supplied with the uncut PCB?

That would make it an unbeatable offer (at present at least)for the ORDuino + heated bed!