Generation 6 / other electronics questions

Hi,

I am currently designing a 3d printer based on the Mendel design except:

• The frame uses a very accurate compound slide table, driven by lead screws not belts (which acts as the X and Y axis)
• It is machined from metal not plastic, and therefore cannot self-replicate
• It extrudes both a build material and a support material (so 2 extruders are necessary)
• The gear ratio is set to accurately print very small parts slowly
• It extrudes jewelers wax and water soluble wax to make wax parts that can be used in lost-wax casting to make parts for jewelry (rings and what-not)

However, I am using the same type of electronics, software, firmware, and actuators as Mendel; because these would be immensely hard to design, and write/make from scratch.


So, my questions are:

Do the generation 6 electronics support driving 2 separate extruders (and if so – how) or do I need to use gen 3 electronics

Are there any obvious problems that you would see in doing this?

Does the standard RepRap program support making the stepper motors rotate X number of steps at each direction change, to compensate for the lead screw’s backlash? (and if it doesn’t then how can I make it do this)

Can multiple extruders be daisy chained together to do the same thing (so multiple parts, which are exactly the same, can be printed at the same time) – this is unrelated to my first question


Thank you in advance, Sean Lang

slang800 Wrote:
-------------------------------------------------------

> Can multiple extruders be daisy chained together
> to do the same thing (so multiple parts, which are
> exactly the same, can be printed at the same time)
> – this is unrelated to my first question

Can't comment on the rest, but this should be possible, and something I was thinking about.

You need to drive each motor with a separate stepper controller chip, but there is no reason that a few stepper controllers could not be run in parallel. I've been thinking about this as a way easily use two extruders to print two sets of parts at once, thereby doubling the output speed of the printer for jobs where multiple parts are required.

One disadvantage is that if one extruder fails in some way, you can't easily stop it without stopping the other one. If the stepper controller chip has an enable line, you could technically disable the extruder with a problem that way, but the head will of course still physically move around, which might cause other issues.

Another issue (physical) would be making sure the heads are the same height (Z).

gen 6 currently only supports 4 steppers (X, Y, Z and one E), 1 heater/thermistor, and 3 opto endstops. there are future plans for add on boards to drive a heated bed, but currently there isn't anything planed for additional steppers, as far as I've read. It's a great solution for a stock 3d printer (even a basic repstrap), but currently inadequate if you are going to experiment with different designs / multiple extruders.

in regards to your last question, you'd be doubling the load on the stepper driver. I have a hunch that this would be a problem.

Sean,

You're calling it
http://reprap.org/wiki/Punnett
right?

Any napkin sketches or CAD renders? Are you using extruded aluminum?

---

-Sebastien, RepRap.org library gnome.

---

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!

Thanks for the advice, However after looking at [www.mendel-parts.com] more closely I found that it says that it has a "RS485 bus connector with the possibility to link through the extruder step and dir signals (2nd extruder)". So now I am completely confused.

Second:

Yep, it's called punnett (for now) and is a repstrap that is intended to be very accurate (though not very portable, small, or cheap). As for napkin sketches/cad renders - not yet, but a better description will be posted on the wiki soon. And I haven't used extruded aluminum (at least not yet), instead all mechanical components have been made on a CNC mill.

Third:

Since it seems that generation 6 will not support a second extruder easily, what is the next best electronics set that will?

Since it seems that generation 6 will not support a second extruder easily, what is the next best electronics set that will?

Looking at
http://reprap.org/wiki/Mendel_Multiple_Extruder
http://reprap.org/wiki/Hydra-MMM_Prototype

I'd suggest
http://reprap.org/wiki/Pololu_Electronics

Email rhys and clayton, cc'ing reprap-dev?

---

-Sebastien, RepRap.org library gnome.

---

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!

Using Pololu electronics sounds good, however after reading more about the RepRap Motherboard v1.2 I think that it can support multiple extruders (see [reprap.org]) and PLEASE correct me if I'm wrong. Also, this generation seems better tested, and I don't intend on printing the electronics with a Reprap.

Do you know if anyone has used the gen 3 electronics for multiple extruders?

Hmmm ... email Rhys and Clayton, cc'ing reprap-dev??

---

-Sebastien, RepRap.org library gnome.

---

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!

Gen 6 can control extra extruders: on the RS485 connector the step/dir signals are brought outside to connect another stepper driver.

All it needs is an enable pin, you can control this via RS485 or use the I2C port which is also available on the board (and not used).

The rest is firmware: about the same as using any other firmware. You should implement the commands to select an extruder and I think you`re done by then.

Hi Elmar,

great job you've done

Do you think the next batch will have a heated bed control?


regards,
Tom

---

regards,
Tom

Tom,

The currently produced batch of electronics has the same functionality, so not yet heated bed on board. However Camiel will have another solution for this, that surprisingly seems to work quite good.

Thx, I'm looking forward to it!!

---

regards,
Tom

scion_imports at ebay have very good gen 6 boards

nearly half the price of mendal parts

and free freight

i payed $135 for my boards and no problems so far

the email for scoin_imports@msn.com

Hi,

Do you know if anyone has used the gen 3 electronics for multiple extruders?

i asked this question also 1 month ago on the IRC channel and then i got the advice to waste no time on searching how to steer 2 extruders with the Gen3 Electronics because the extruder controller is designed to use a DC motor and today everybody is using steppers for better accuracy.

The advice they gave is to use RAMPS 1.4 if you wanna have a quick result without having much knowledge of electronics, because it's designed to use 2 extruders.

So i have one litlle problem. Some while ago i also bought Gen6 electronics, so before i should decide to buy RAMPS 1.4. Anybody having a proposal how i should connect a second extruder?? I already know that the steering of the stepper can happen by the RS485 but what with the heater??

Greetings.

I am currently working on an extension for GEN6 that will control a heater and a fan via the I2C connector.

The board is designed, but not etched yet, so I have not made the design public. I hope to do so in the next few days. My build Blog.

Geoff

---

---

How often I found where I should be going only by setting out for somewhere else. - R. Buckminster Fuller

[apapageek.com]