Alternative electronics for Ordbot

Topics Related to the ORD Bot Printer

Rendering of it mounted.

Postby bdring » Mon Mar 05, 2012 2:10 pm

Here it is on the Quantum. You would need to drill a hole pattern for it. I could add a pattern on future orders. I prefer the vertical connectors (shown) , like a RAMPS.

azteeg_ord.jpg
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Re: Alternative electronics for Ordbot

Postby Oli » Mon Mar 05, 2012 2:20 pm

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Re: Alternative electronics for Ordbot

Postby dzach » Mon Mar 05, 2012 2:49 pm

Oli wrote:I think the problem with the stepper drivers is that people even have an expectation for them to blow. Designed properly, it could be made impossible to do so (thermal shutdown, current limiting etc.) . There has been so much capitalisation on the allegro family of parts, my impression is people are cautious of using anything else.


I completely agree. Having just bought a RAMPS system, my worst fear is that the stepper drivers will blow by some accidental disconnection of the cables. This fear is worsen by the fact that the 0.1" terminals (not the same as in the Azteeg X1 prototype) attach rather insecurely to their female counterparts, although they seem to make good contact. The terminal blocks used in the Azteeg X1 board provide lateral support and lock the female connectors and are much better than the simple ones (like the ones that are hosting the stepper drivers).

If the matching female connectors will be provided along with the board this will be a good solution. Otherwise I'd much prefer screw terminals.
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Re: Alternative electronics for Ordbot

Postby royco » Mon Mar 05, 2012 6:02 pm

Thanks for your interest.

I tried using the Terminal blocks during the design but went with the MTA/CST type for cost, ability to provide right angle and vertical connectors cheaply and commonality with what is currently out there. Also, some testers worry that the screws on the terminal blocks would loosen because of vibration when mounted on the printer. Altho I really like just screwing in the wire and be done with it.

I also think that the allegro based drivers are placing a closed wall on controllers. The chip itself is pretty cheap but is a pain to get a hold of.

@Oli - No plans of changing the boards size for a V2, I'll look into the ATX connector, I would like to stick with the allegro as a plug in as its supported by most firmwares and easily replaceable.

I contacted my connector supplier and checking the price on those mating connectors, Im hoping it doesn't impact cost that much so I can include it. Making it easier for the user is a win win for all.

Thanks for all your inputs.
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Re: Alternative electronics for Ordbot

Postby Enraged » Mon Mar 05, 2012 6:18 pm

Just ordered, I think this setup is exactly what I want.

Have you considered designing your own Pololu compatible stepper drivers that can handle higher current/have better heat management?
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Re: Alternative electronics for Ordbot

Postby Enraged » Mon Mar 05, 2012 7:10 pm

Can you post what type of connectors are used/how many? I'd like to source them locally.
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Re: Alternative electronics for Ordbot

Postby bdring » Mon Mar 05, 2012 7:13 pm

Why did you choose the Mega644P processor? That has less memory than the Arduino Megas. Will that be a problem with some firmwares now or in the future?
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Re: Alternative electronics for Ordbot

Postby butterfingers » Mon Mar 05, 2012 7:44 pm

bdring wrote:Why did you choose the Mega644P processor? That has less memory than the Arduino Megas. Will that be a problem with some firmwares now or in the future?


The Melzi Ardentissimo successfully uses the same CPU. Just as an aside, the form factor for this is perhaps ideal for the ORD Bot:

http://reprap.org/wiki/Melzi#Melzi_Ardentissimo

I'm not saying, "stop, somebody already did it", but maybe there are some ideas to leverage from this design?
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Re: Alternative electronics for Ordbot

Postby royco » Mon Mar 05, 2012 8:31 pm

@ Enraged - Thanks! I tried ta remix the Pololu drivers to have better thermal dissipation but again its the sourcing of those A4988 thats a bit of a problem. Altho i can place an order with my rep and wait for 16 weeks to get them @ 2K quantities. Ouch!
The mating connectors are 1375820-2, 1375820-3, 1375820-4 and crimp pins 1375819-1. I may include them in the package if it doesn't cost too much(will know in a day or two).

@bdring - It was chosen for cost over the ATMEGA 1280 and 64K has still a good reserve for the new full featured firmwares. The chip has pretty solid arduino support too.

@butterfingers - I saw that design a few weeks back, i liked it being complete but I prefer the drivers to be plug in. If somebody improves the design/cost of the A9488 drivers then we can take advantage of that, its actually a pretty good chip except that supplies are hit and miss at best.

The driving force behind the design is Cost and features that create a good value for the user, Thats why I added enough features to make it sit right between the Sanguinololu and the RAMPS and price it below an assembled Sanguinololu.

Thanks for all the inputs.
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Re: Alternative electronics for Ordbot

Postby Oli » Mon Mar 05, 2012 9:10 pm

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