Advice Needed: How to control/power my machine

I've made a large gantry (Ultimaker style) machine that I need to control, details below.

I've already purchased a Gen 4 Makerbot Thing-o-matic electronics set with 5 stepper 3.3, the extruder board 3.6 and the main board (mega 256 driven). I now realize that the EC3.6 board needs a DC motor and not a stepper. I originally chose it because of the thermocouple reading, but now not so happy, as I have a stepper design for the extruder. this whole setup seems to be the wrong decision.

Question: how would you control this thing?

X-axis and Y-axis
Lin Engineering 5718-05 Nema 23, 24 VDC, 2 amp, unipolar
18 x 40 inch footprint, 20mm rods and bearings, 15tooth XL on stepper, 30 tooth on rods.

Z-axis
two Lin Engineering 5718-05, driving Parker linear stages, direct drive coupling. 5mm lead screw
threaded rods not ballscrew, so no back drive issues. about 18 inch usable travel.

Extruder Drives
I have 2 Kysan Nema 8, 3.9V, 0.6amp, 16:1 reduction, 17mm hobbed diameter.

2 Hotends
Jhead MK V-B, 5.6ohm resistor, thermistor or thermcouple, 1.75mm, .4mm diameter.

Misc bits like the heated bed, fans, chambering, etc is still TBD.

RAMPs, Azteeg X3, Mach3, ??
Any advice will be appreciated.

Dave

Edited 1 time(s). Last edit at 09/04/2012 02:00PM by davew_tx.

Hey, nice build I am intrigued by your dual extruder design.

For dual extruders, I think I would be looking closely at the Azteeg X3. It is still fairly new, but is an improvement on RAMPS.

If you are interested in the Mach3 route, I would check out SeeMeCnc, they have an active Yahoo group. They probably have most experience in printing with Mach3. They also have a dual extruder board, might be worth looking at.

I am looking at RAMBo and Azteeg X3 now.

both will end up around $180 or so.

It would be nice to get a couple, so it is familiar when I need to power my Delta.

Wait... 24 Volts? I dont think RAMPS does that, dosent RAMPS run 12V?

-Nick

Edited 1 time(s). Last edit at 09/05/2012 08:14PM by N314.

Nick, please read the documentation. RAMPS is happy with up to 35V (http://reprap.org/wiki/RAMPS_1.4#Power_Supply). However if you go over 12V you must remove the diode D1 so that the Arduino Mega does not draw power from the RAMPS board, but instead gets it from the USB.

There are compelling advantages to running above 12V including less current draw, faster heating of the print bed, and the stepper motors and stepper drivers will run significantly cooler.

I just got that 24V off the Lin Engineering charts. Seems they run them there.

Thanks and hopefully I can get on to the correct path soon.

I like the idea of the RAMBo, with the software based stepper tuning.
my NEMA 8 motors are vastly different than the NEMA 23.

Does the Azteeg handle both ranges using their drivers?

As you may have guessed, I am mechanically oriented and don't know much electrically.
It will be the challenge for me on this.

@Davew_tx

Is it the 5718M-05 Unipolar model that you are planning to use?

The SureStepr drivers that come bundled with the X3 can be used with a setting of 1.5amps with fan or heatsink(adjusting the current with the lowest you can get away with) . You can use a secondary supply of 24v on the X3 for the motors and a main supply of 12V. If you have a 24v heated bed then you can use 24v as you main supply.

I just read the sticker on all 4 steppers, and i have a mixture. crap.

2 say 5718m-05p, 2.8amp, which looks like a bipolar
2 say 5718m-05e and they say 2.0 amps, I guessing unipolar.

any advice? maybe I should just replace all 4 with some great NEMA23 from Keling or ??

Uhm. 24V isn't enough for driving a 24V stepper motor. Expect less than the specified tourque, especially at higher RPM (more than 100 RPM).

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

@Traumflug
The steppers are not 24v rated, Dave was looking at the charts that uses 24V to power the motors and picked it up from there. Judging by the ratings they are more like 3.6v.

@davew_tx
The Ultimaker style gantry doesnt seem to require a lot of torque to move around since it's light( Im not sure about the weight of the increased size), what made you go for Nema 23 high torque motors?

So, the weight of each axis is heavy, and it's not because of extruder head weight.
20mm rods weigh a several pounds. I didn't measure the actual number before assembly, but maybe 5-8 lbs for the short side and 10-12 for the long axis?? complete guess.

the 2:1 reduction on the pulley/belt should help.

I chose those motors because they came attached to the linear stages I got for the Z-axis.
Nothing deliberate or calculated, just ended up with them.

I'm leaning towards as much torque as possible because fast moves and infill direction changes might cause a skip with these heavy assemblies.
maybe I should get some 380 ozin Keling steppers. Seems like $50 each. kl23h2100 is 2.5V and 3.5 amp. Can the X3 drive those?

this is what I am leaning towards.

a RAMPs shield on a Mega256, with 2 Pololu drivers for the extruder motors, fans, HBP.
A GenXLab gecs2tc1 dual thermocouple reader, temp controller for the hotends. manual setting of each.
X and Y each driven with Gecko G213V, using the NEMA 23 400oz steppers, at 48V.
dual Z axis steppers, Gecko G251X, at 48V

picture is progress on the extruder head.
Orange PLA with a good bite. ABS seemed similar depth of bite.

Dave,

I saw someone selling a converted Sanguinololu to easily accept external drivers like the gecko you mentioned. That might be an easier solution for your application. Just could not remember where I saw it.

Thanks!
So my assumption of using just the STEP/DIR/EN off the shield is not quite right?

I will look into a Sanguinololu solution also.

Dave

The issue you will run into using normal stepper drivers off any of the arduino based solutions, is that for many of the the existing firmwares do no hold the step signal for long enough, and the delay between a change in the dir pin and the stepper signal pin being triggered is also too short.
This may manifest itself as randomly dropped steps.
You can "fix" the firmwares by adding delays during the writes, but you should be aware of it,

i found this geckostepper library for arduino.
there are some time delays in the .cpp file.

anyone use this?

[github.com]

here is a sanguinololu box that looks promising.

[www.ukcnc.info]

not sure

Edited 1 time(s). Last edit at 09/08/2012 07:46PM by davew_tx.

OK, so the UK dudez have an ebay for that arduino to stepper board
[www.ukcnc.info]

got one coming.

Yep, Thats the one I was talking about.