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Appreciate A Review of proposed architecture...

Posted by mars bonfire 
Appreciate A Review of proposed architecture...
May 09, 2011 09:26AM
I have been wandering through the reprap wiki, trying to figure out a path to a 3D printer for my particular interests and resources. I would appreciate comments and/or design review of my proposed plan. Here goes:

Since I own a small 2 1/2 D Taig CNC mill, I will start with that for the translational axes. So I understand this would be called a Millstrap.

I am designing a variant of the mini-extruder (stepper drive, 1.8mm ABS) as the extruder to mount to the Z axis of the mill.

I looked into using Turbocnc as the stepper driver SW but it really does not look very compatible with the extruder commands...

so, I plan to use a Arduino Mega for all positional axes and for the extruder control (Question: as I understand it, one Arduino Mega is up to the task of commanding **all** steppers and heat control including the extruder....some wiki discussion seems to indicate that there is a separate positional controller and a separate extruder controller...my hope is that one Arduino Mega can handle the whole problem???).

The Arduino outputs step/direction signals (correct?) as well as interface to heater related signals/control (need more research here). I will wire them into a connector (25 pin sub D) on my existing mill stepper driver for the X,Y,Z controls (which now receives step/dir signals from my PC via the parallel port. I will separately wire from the Arduino Mega to a Pololu stepper driver to drive the extruder stepper.

This is where it gets hazy...I will find appropriate Arduino firmware to drive the four steppers and heater control (which firmware should I use...help appreciated).

Does this all seem reasonable?

By, the by, what are typical move speeds that one would use with a mini-extruder....I want to make sure my little mill can move fast enough to keep up with typical extrusion rates.

Thanks in advance,

Steve
Re: Appreciate A Review of proposed architecture...
May 09, 2011 11:12AM
For the electronics, I recommend RAMPS. It's a very compact, clean device, and has everything you need right there. I use a firmware called Sprinter. It supports hardware-based motion acceleration, which give really smooth operation at high speeds.

The extruder can go slow or fast, depending. I don't think you will have too much problem with that. I would recommend that you start with proven designs, and venture into experimentation after you've got the basic system working.

Temperature control is a no-brainer. The electronics takes care of that. Just make sure you get at least a couple of 200k thermistors. Most firmware has defaults for that type.
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