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 Dragonframe - eMotimo shields 
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Joined: Tue Aug 09, 2016 10:31 am
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Post Dragonframe - eMotimo shields
Hey Folks.

Just a heads up, I have an eMotimo TB3 that I am retrofitting into a dragonframe controller.
The PCB's are on order, it is designed to replace the innards of the eMotimo and will give the ability to run 6 motors. It can also easily work as a stand-alone motor controller without the emotimo as long as you have an Arduino Mega.

I know i know, the eMotimo is already dragonframe compatible right?
Yes. but problematic. I constantly ran into connection drops with the stock eMotimo firmware. It seems to have a hard time staying connected for more than a day. A friend of mine gave me a copy of the DFmoco/DFremote sketch that worked with the existing pin-outs on the eMotimo and now it runs flawlessly. There was something about the rest of the eMotimo firmware that causes stability issues. I figured I may as well just replace the PCB in the eMotimo with one of my own design that allows for control of 6 motors.

The minimum order for these prototypes is 10. I plan to keep 2 of them for myself, the other 8 will be up for grabs. 3 are spoken for. If there is enough demand Ill order another batch.

Cost would really depend on how much work I need to put in. Ill part with a bare PCB for $10, but I am also willing to go all the way and do a full retrofit on an emotimo for a price. Keep in mind, this setup would make it 100% reliant on dragonframe, and it will probably require AC power. But if anybody wants to get some more axis control without breaking the bank, this may be a great way to do it.

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Wed Jul 05, 2017 8:24 am
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Joined: Wed Nov 11, 2009 10:45 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: Dragonframe - eMotimo shields
I see spots for six motor drivers, are the other connections in the right places to snap onto the mega as a shield board? We use nanos and teensies so our boards just have another two rows of headers similar to those for the motor drivers. We wound up using the copper pour feature in eagle cad to make the power traces cover an entire side of the board for each. Little channels get etched to separate our conductors from the rest of the surface which serves as the power conductor. There is plenty of room at the edges of your board for a continuous sheet of copper to connect all drivers. One side of the board becomes ground and the other side becomes power.

The "poured" board surfaces do two things. They allow the board itself to dissipate more heat than you'd expect it could. The pour also increases the size of the power conductors to the drivers. Although the traces for your driver power lines are wider than the signal lines, its still possible to get power-starvation in the tail-end drivers as well as supply side noise especially toward the end of the power daisy chain. Depending on what drivers you put on the board, it helps to have a big capacitor right at the power pins for each driver.

Not sure how much of this is just being paranoid. Every time we make a little money, we spend it all developing the next product. We wasted so much on PC boards that things like copper pouring both sides of the boards for power distribution has become the standard way even if it isn't needed.

With the mega and this driver board, you have a controller that can run a lot more than just an eMotimo and other MOCO. This could run a 3-D printer, router or any CNC machine. Have you thought about selling these as machine controllers? Have you thought about porting your firmware to an existing CNC controller? Many of them use Arduino-compatible micros. I think your script could run on them if the pin assignments are changed to reflect which pins on the micro are connected to step and direction on the drivers.


Wed Jul 05, 2017 9:46 am
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Joined: Tue Aug 09, 2016 10:31 am
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Post Re: Dragonframe - eMotimo shields
Dang that's a really good idea about large copper pour areas.. I did not even think of that. I will certainly remember it for the future :)

The design is already being fabricated, in case I goofed up and have to remake them I will certainly take your advice.

I have not considered selling them for CNC either. I got kind of burned out on fulfilling sales and orders and such. This is probably going to be a very limited run. Once the design is proven I may just release the files online so people can have their own boards made if they want.

I remember years ago somebody had done this with big-easy drivers, i think it had a total of eight. I remember running into that design quite often then it just vanished from the internet. I am surprised there is not already something like this available for purchase online. (aside from your DF stepouts), I just wanted something that would fit inside the eMotimo shell :)


Mon Jul 10, 2017 1:29 pm
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