What electronics to use for my machine?

Hi, i'm building an 3D printer, but I'm a bit confused as to what electronics I need to be using. The machine is using Nema 23 3A/Phase stepper motors for X, Y, Z and the extruder.

Pictures of the machine can be found here;

http://rappronz.blogspot.com/


I've purchased a RAMPS V1.4 board but have since found that the stepper drivers that go with it are rated at 2A per coil (is this the same as per phase??) So I don't think this will work? And how does this connect to the PC.. what am I missing?

If someone could point me in the direction of what gear I need to be using.

I would prefer out-of-the-box solutions rather than a kit I have to solder as engineering is my expertise not electronics.

Any advice is much appreciated here because admittedly I'm a bit lost.





Regards,

Nigel.

Just having a quick look round another thread I saw this image,

[forums.reprap.org]

I didn't realise the board I have (the top one) needs to connect to the lower board. I don't have the lower board.. what is it and where can I get it?

If there's a guide someone can point me in the direction of regarding what's what when it comes to the electronic side of things I would really appreciate it.



Cheers.

The standard stepper drivers (pololu's and stepsticks) won't reach 2a, I think nophead or someone said around 1a is the max you actually get.

You should be able to power the nema 23's with standard drivers however you'd only be getting about a 1/3 of the rated torque.

---

My Reprap blog

jds-reprap.blogspot.com

I think you can get up to 2A a coil with the Pololu drivers, but you will need a decent heatsink/fan combo on them

[www.pololu.com]

They offer higher power drivers but it will require modification to the board.

I'm using a Sanguinololu - [www.reprap.org]

I found it to be the cheapest/easiest solution.

Nigel_NZ Wrote:

>
> I didn't realise the board I have (the top one)
> needs to connect to the lower board. I don't have
> the lower board.. what is it and where can I get
> it?
>

Its an Arduino Mega and you should be able to find a supplier fairly easily.

Hi Nigel,

Impressive machine! Robust baby! I like it a lot. You have quite a show piece going there.

We have a Dimension printer at work. Also a nice machine. Press print and walk away. Never fails. Works beautifully and makes outstanding parts. They did there homework.

The Dimension printer is built in a cabinet... fully enclosed, with vibration mounts. When it prints, the whole machine shakes. It has a fairly robust head as well... but you my friend have outdone yourself. :-) I think, once you get that baby up and running, you're gonna have some fun keeping it on the table. :-) No... probably not but I think worth mentioning is the head could be a lot lighter I think. The lighter the head and table, the less start and stop forces going on, and perhaps the easier to control with cooler electronics. You certainly have chosen some nice motors to drive it and I'm sure they will do the job... still... you're not holding a milling bit... you're feeding plastic filament.

When you do get this thing going, you're gonna want to speed it up. That's when mass becomes your enemy. As you move forward you might consider ways to lighten things up without sacrificing control and accuracy. Maybe a die spring and thumb screw instead of pneumatic cylinders, or a light weight frame instead of a solid aluminum table. You might also consider a smaller stepper for driving the filament to reduce weight (keeping the X, Y and Z the same).

I tend to look at things with a very critical eye... and I hope I haven't offended you. That is a really sweet machine and I really look forward to seeing what you do with it! I wish I had some of your tools at my disposal!

On the plus side, I can see you're putting inter-changable heads on that machine. Extrude plastic today, mill traces in a circuit board tomorrow, cut wooden puzzles with a laser next week.

I can't help you so much with electronics other than to say, it shouldn't be too hard to take the present control electronics and use larger stepper controller boards to handle your chosen motors. Find a geeky electronics friend in New Zealand to help you bump up the power handling and you're good to go!

Cudos!

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

Hi, thanks for the replies I really do appreciate it. A lot of useful information already.

I've purchased an Arduino Mega controller from a supplier in New Zealand, and have looked into stepper drivers some more. Ideally I would want to be able to run the motors at maximum output -what's the point in having a 3A motor and only running it at 1A current. Is it possible to run wires from the RAMPS board to an external stepper driver such as the link below? Essentially are they just Step / Dir connections between the two?

http://www.geckodrive.com/g251x-p-38.html


Ross - some very interesting points you've made regarding the weight of the head and table assemblys. I think once I get the machine up and running I will look into getting weight out of the head where possible. I could possibly mill pockets into the underside of the table to take mass out of it and work something out with the head too.

I don't plan on using the machine for milling or anything once it's built. I work as a programmer and setter on large Okuma CNC 4 Axis Machining Centres and Mill-Turn Lathes so really have all my bases covered there


Thanks for the input it really is a big help.



Cheers,

Nigel.

The point of running a motor below its rated current is to bring the operating temperature down. A stepper at full power runs hot enough to soften an ABS bracket.

If you are willing to produce a metal bracket, then you can take step and dir signals from RAMPS to any controller you like. In this case, it may be worth building a custom shield on top of the mega, a lot of the space on RAMPS is devoted to supporting the pololu controllers.

Hi, thanks for the input. If you have a look at the link I've posted to the blog of the machine above It's all aluminium framed and I can install fans and / or water cooling if heat soak from the motors becomes a problem.

I've ordered 4x Gecko G251 Drives from Australia.




Cheers.