Hi- we've been having a long discussion about the use of the ARC window in the new release of Dragonframe, - for, oooh, about 8 months now...

The thread got very lengthy, meandering, chatty- and well, warm and fuzzy, but perhaps a little LONG

So I thought I'd breath some life into it on the new board.

Most of those involved how now built some kind of motion control rig- pioneers include Jim, Mark, Doug and wrongboy- as well as myself.

here is the link to the original thread if anyone wants to head backwards- a lot of ground has been covered already.

my news is that i have some footage of current tests of the 3 axis rig I have built- like a cage to surround the sets on my next pieces.


the rig seems fairly reliable so far, after a rebuild last month on the vertical section- in the test footage we struggle a while to find a cleaner slower track, until the steps per revolution setting was increased to 3200- although i'm sure we can get even cleaner moves yet out of it...

I am still using the original DFMoco sketch for Arduino, and wonder whether any of the other guys have any thoughts on differences between the two?

I also think the curves used during these early test moves could have been designed better themselves- too many keyframes for each seperate axis i suspect...obviously 3 axis moves are going to be a very rare occurence anyway...

Anyway, the thread- it lives!


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Alright guys I've upgraded to DF 3.04 and got the DFMoco Sketch working on my Arduino Uno and I wired up one motor with the circuit found here. It's all working fine with arduino's built in stepper class. When I hook it up to DF I get connection confirmation and can see messages in the Moco log so I'm certain it's hooked up ok.

But here's the thing, when I try to add an Axis to the Moco window I only have the option to add ArcMoco or Digital focus. I added it as ArcMoco #1 and jogged it on every channel and didn't see anything going across the communication log.

I feel like I'm missing something big, but the DF user manual seems to concentrate more on ArcMoc and just refers me to the DFMoco sketch.

tl;dr: Is there a specific way to set an axis to the Simple Serial Interface (Arduino)?

when you connect the arduino over usb do you get a connection message on your computer, (mac or pc?)...

when you set the channel to arcmoco 1 you did right- you just need to set a channel number to the arduino too- the next setting down is channel- check your channel output on your arduino, but usually we connect to the channels from 1 onwards- it depends where you have wired into the arduino...but 1,2,3,4 etc is easy and best...

this caught some of us out first time round.

EDIT- you may need to check you are actually connected to the right arcmoco channel too- different usb ports have different addresses, and sometimes it seems arcmoco1 goes to the first, etc...

the way to check os to go to the connections window in dragonframe, and look down your list of connections- if you are successfully connected here, it should say 'connected' over on the right hand side, and there should be a message in the relevant channel saying 'connected to dfmoco__(may be different versions of the sketch software- i have both- the original , and 1.1.2)

but you should be able to see in this list what you are connected to, in order, and work things out- and if you arent yet connected- then connect.

good luck.

ps- one for Will-


great results.


Thanks John. It turns out I had it on the Simple serial interface >_< which is just for the remote stuff I guess. So now it's on Arcmoco #1, communicating as it should. But now I have a new problem.

I bought three stepper motor drivers and motors(really my school bought them, we're building it for use in the animation department). It turns out that they are unipolar motors and the DFMoco was built to use bipolar motors. So now I can either try to rewrite the sketch or buy new boards and motors.

What drivers does everyone use? Are you all on Big Easy Drivers, or is there a cheaper alternative? I probably should spring for what I know will work, but the previous drivers were only four bucks and that included the motor, so it seems like a huge step up to 22.95 for just the board.

Hey Sam,

I think a lot of us are going with the BEDs because we know they work and are fairly simple to hook up to the Arduino. What boards are you using? As for the unipolar motors, that is not a big deal. Are they 6 wire? If so then you find the centre tap wire for each side. For instance I have in front of me a 6 wire motor, the colours are as follows, black-green blue-red. The other 2 wires white and yellow are left unconnected. So the BLK-GRN are one set and the BlU-RED are the other. On some drivers you will see A- A+ B-B+, you have to determine these points on your board. If for instance you are using a BED the wiring sequence is as follows, as you hold the BED with the motor connections on the board pointing away from you:

A-A+ B+B-

Now if I wanted to connect this motor I have to this BED, it would connect using the following sequence: BLK=B- GRN=B+ BLU=A+, RED=A-

Never connect a motor to your board/driver while powered. Chances are you will blow the board. Never hook the motor directly to the power supply as this will probably blow the motor.

Hope this info helps Sam.

I was using this board from Geetech, but it wasn't wired exactly as I hoped. So, I pulled the transistor array off and wired it like this.

That's great to hear that I can still use the motors I have. They're five wires, and I have the data sheet so I know which one is the common. So the center doesn't have to be hooked up to anything at all?

Has anyone used the original easy driver? It looks like it'd work, I think the "Big" just handles more amperage.

That sounds right for the motor. You can use an Easy Driver but since it can only handle .750 AMPS or there a bouts it is better to go with an BED in case you want to drive some stronger motors.

Hi Sam,

I was using the easy driver for one axis, having bought it by accident. It was mixed with two BigED's on another two axises (axii?), but there were so many trial-and-error things to work out I swapped it out for a third BED in the end to keep everything consistent.

It wasn't working for me, but at that point nothing was, so worth giving it a try since you've gottem.

Hey guys, Long time no see.

So my instructor built the rig, we got some 12v cnc motors, easy drivers the whole shebang. We tested it with a some weights and it all worked fine, but when we put the real equipment on, which weighs less than the test weight, it just shudders and misses steps.

What are some ways to make sure I'm getting maximum torque out of the motors? It'd really suck to have to order up to some bigger ones. I will if I have to but I just wanna make sure I'm getting all the torque I can before I shell out some more clams.

I've increased the potentiometers on the ED to the max. Switched from 1/8th microstepping to Full steps. And I've slowed the movement down as much as I can go.

Anybody got any tips/voodoo that might help?

Without having a look it sounds like the EDs are turned down to low for the weight. I say this as that is what I would get when adding a new motor/axis to my rig. Then I would power up the motor and fine tune the BED to the proper power setting. Take a pic Sam so I can see the rig and the controller.

Hi Doug... I just found your post and went over to check the videos out... they're down?  Bummer, I hope you put them up again soon... only recently did I realize I could do what I need to do with a jib style moco rig and was really curious to see how you went about it.  

Previously I was focused on more of a CNC router bed style approach because I needed absolute XYZ positions, and Dragon doesn't feature virtual axis... but I found a work-around.

Congrats on the rig!  It's quite impressive!


Jim Arthurs

Douglas J Kropla said:

If anyone is interested I am doing a series of DIY videos for how I made my rig. I have them over at my Youtube channel - RunningRabbitFilms1. There are only two so far but they may give some insight or trigger an idea for you. 


Depending on the version/batch of driver-module, you might need to adjust the trimpot in the other direction because the label is back-to-front.

This info from https://www.sparkfun.com/products/9402

"Note: Version 4.3 of the PCB has an error on the Current Adjustment silkscreen. The Min/Max labels are reversed. The correct direction for maximum current is counter-clockwise."

The Pololu stepper drivers are better than BEDs, IMHO: http://www.pololu.com/catalog/product/2128

To play it safe, attach a small heatsink to the chip (regardless of what brand of driver you use).
This photo from Douglas Kropla shows his circuit enclosure includes a fan aimed across all the drivers for additional cooling, and I think it's a smart arrangement: http://www.stopmotionanimation.com/photo/motion-control-interface-i...

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