Reprap circuits from scratch

I realise there's probably a lot of people on here who'll think I'm a bit mad for trying it, but I was going to try to build a reprap from salvage as much as possible (for both cheapness and entertainment value). Since I have a bunch of resistors, switches and other basic electronic bits lying about, as well as some unetched circuit board, I was wondering about building the motherboard myself. I know a little electronics, but not a huge amount, and was trying to work out the layout of the board from the photos of the circuit and the schematics.

Does anyone know what the requirements for the components are - can I use the old style resistors (with the coloured bands and pins that go through to the back of the board) rather than having to get a load of the surface mount resistors in, or do the SMT ones have a higher wattage or anything?

Any information anyone can give me on the components would be handy, as I'd rather not get the chips, make the board and solder it all up to discover that the resistors can't take the juice and i have a nice pretty melted thing...

Cheers

Edited 1 time(s). Last edit at 11/10/2010 03:54PM by Mako.

If you're looking for a more hacker-ish version, I'd suggest:
http://reprap.org/wiki/Pololu_Electronics,
or http://reprap.org/wiki/RAMPS

Then you'll have something that works, which you can then extend by rolling your own "shield" to go with a pre-bought arduino-mega:
http://reprap.org/wiki/All_In_One_Electronics

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I response to your original query: basically, you're looking for a through-hole (non SMD) version of arduino/arduino mega. I suspect that you can't find a through-hole version of the microcontroller, so that that chip would be SMD. For all the other components, through-hole would work.

But you will have more fun going with a prebuilt arduino mega and a shield in kit form. Once you have that working, roll your own shield, and start tinkering with microcontrollers.

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Hello Mako

Welcome to the world of RepRap -

It's not a mad idea, and I wish you good luck if you go ahead with building up your own electronics from scratch - and I'm happy to help and advise you as much as you need and can handle.

But my advice is to think about a slightly more standard way to get going in this project so you keep momentum and make it to the end-game of a working 3D printer -

Building a RepRap/Repstrap has many challenges, the electronics are just one small part and you want them to work well. You could easily spend many times more on individual parts so have a think about going down this route -

Get hold of an Atmel MEGA (I bought 2 in the UK for just £22.50 each)
Get some (or just one to start with)- Pololu stepper motor boards ( £12 each)
You may want to get hold of a MEGA Shield Kit so you can easily connect the Mega to the steppers. (google Arduino Shield)
You can make the MOSFET drivers and ADC inputs very easily with just a handful of low-cost components.
Then Take a look at RAMPS here and see if you want to try and etch your own PCB - RAMPS

This will be good fun to make and you will end up with a very good and capable electronics setup that you won't need to worry about. - It will give fantastic results (if the mechanics are also made well).

If you want a ready-made solution look at GEN6, But that's not anywhere as much fun as doing the above

GoodLuck

Rich.

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[richrap.blogspot.com]

Also, What_Tooling_Do_You_Have?

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

- I like the new all in one design -didn't spot that one before, thanks Sebastien.

So much Development is just marching along at the moment !

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[richrap.blogspot.com]

Cheers guys, the premade arduino and RAMPS looks like a good plan - I get a little lost once I get into things much beyond basic, so constructing that should help me understand where everything links up without compromising the main board! And leaving me more space to add extras in and change things round I think?

I've also just found an old printer and a scanner in my loft so might well open them up to see what's inside (hopefully some motors but if they're rubbish I might end up getting some others anyway)

PCB etching for the shield shouldn't be too hard, I've been doing fairly precise brass etching for a while and have access to a fair array of chemicals As for other tools, I can always borrow a garage with power tools, or use the more delicate kit like a dremel etc at my place. But the initial RepStrap will probably be built from whatever is lying around that lends itself to stable construction. Possibly even meccano...

So, where's a good place to get the arduino mega from?

There are through-hole versions of the processor (with fewer pins than an Arduino Mega, but enough to run a RepRap), and an electronics design using one and aiming to be easy to make is being worked on. However, it isn't finished yet, and if you buy the processor on its own (not on an Arduino/etc board) it normally won't have a bootloader installed, which means you will need additional hardware to program it.

> So, where's a good place to get the arduino mega
> from?


That depends on where you are; see Arduino's distributors list.

Frankly, I'd suggest [ultimachine.com] (aka Johnnyr who did up RAMPS).

He contributes quite a bit of documentation; I try to be neutral to all vendors, but in fact I'm strongly biased towards folk who upload and participate in our community.

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

I made my own motherboard and my own firmware to go with it. A significant portion of the really interesting techniques and research have been done on mostly custom machines.

Basically you need a 3-axis CNC machine of some description, a temperature-controlled extruder, a 4-axis controller to drive it all, and some way of getting the gcode into the controller. ANYTHING that fulfils these criteria can be a repstrap

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Wooden Mendel
Teacup Firmware

Triffid_Hunter Wrote:
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> I made my own motherboard and my own firmware to
> go with it. A significant portion of the really
> interesting techniques and research have been done
> on mostly custom machines.
>
> Basically you need a 3-axis CNC machine of some
> description, a temperature-controlled extruder, a
> 4-axis controller to drive it all, and some way of
> getting the gcode into the controller. ANYTHING
> that fulfils these criteria can be a repstrap

Wow, thats a nice thing. Is documented anywhere further please? Would be nice to have it on an alternative electronics page sort of like ramps (just this could be more like raups).
A small schematic would help, for pin assigns and so, etc. Even hand drawn? Better than keeping on checking firmware def in order to have min mods with further versions.
Btw also would be lovely as shield and as simple as it is i would make one to test it besides the gen3. With the other drivers ofc. If you need a dumb bot to make some repetitive tasks as wiki, tests etc - i could be it

Edited 1 time(s). Last edit at 11/13/2010 08:02AM by NoobMan.

Your standard arduino has ~17 GPIO pins available (excluding reset, serial, etc). You need 3 each for X/Y/Z [step,dir,min] (9), 2 for extruder [step/dir] (2), 1 for temp sensor (1) and 1 for heater (1). That's (9+2+1+1) 13 pins, so you have 4 left over. I add one for controlling the power supply (1), and my max6675 takes 3 pins instead of 1 (2), and I have a 2nd heater output (1) so that's (13+1+2+1=) all 17 pins used.

The heater outputs need to use the PWM pins for timers 0 or 2 (I used timer0 pins D5 and D6), and the temp sensor needs an analog pin if it's a thermistor, or the SPI pins if you're using a MAX6675 like me. The rest of them can go to any pin you like. I did point-to-point wiring as you can see.

I had to write my own firmware because the official FiveD won't fit on a '168, and I couldn't think of any reason why not, so I decided to find out.

I will end up rearranging the wiring on my board at some point so I can play with thermistors. The thermocouple is lovely and accurate, but I only get 5 readings per second which makes PID temperature control a bit clunky.

My resultant pinout is the default pinout in the config.h.dist file in the FiveD_on_Arduino repository.

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Wooden Mendel
Teacup Firmware