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Is it possible to get a DC output from the printer ?  

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TheExtruder
(@theextruder)
New Member
Is it possible to get a DC output from the printer ?

Hello,

I'm trying to connect a different device - a simple DC motor - instead of the extruder stepper motor on my printer, using only 2 wires and not 4 and I cannot find a guide for this switch.
I'm really struggling with the ouptut, the closest I've come is to consider it as a PWM output and use a DAC converter (PWM to DC) which is already a good solution but I'm wondering if it is possible to control the output voltage in an other way ?

Thanks a lot !

Posted : 26/02/2019 11:12 am
Chocki
(@chocki)
Prominent Member
Re: Is it possible to get a DC output from the printer ?

If your good at coding, you could use the RPi header (J19) to interface with say a raspberry nano or even another ATMEL based solution, then add one of the many available motor controllers to this. I would also look at upgrading the existing 24v PSU and use a 24v to 5v module for additional 5v power.
Bear in mind the current RAMBO firmware is quite full, but if your really looking for some sort of custom printer, you could strip out what you dont use and fit your own code. Most of the control code for your motor control would be done on the daughter board anyway.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 26/02/2019 11:37 am
TheExtruder
(@theextruder)
New Member
Topic starter answered:
Re: Is it possible to get a DC output from the printer ?

Alright I'll try this, I'll let you know as soon as I can get a RaspberryPi

Posted : 26/02/2019 11:51 am
TheExtruder
(@theextruder)
New Member
Topic starter answered:
Re: Is it possible to get a DC output from the printer ?

I found that the simplest solution to get a DC output is by the fan pins which give a 100 % PWM at max speed ie DC 5V and is easily controlable.
Although I need to get two output so I might change my mind but I'll search in the fans way more than trying to add a raspberry controler.

Posted : 26/02/2019 4:55 pm
michael.c110
(@michael-c110)
Eminent Member
Re: Is it possible to get a DC output from the printer ?

you could use a dc to dc converter and use power from the psu

Posted : 26/02/2019 6:03 pm
scott.b47
(@scott-b47)
Trusted Member
Re: Is it possible to get a DC output from the printer ?

An advantage of using the raspberry pi is that you probably want to run Octoprint on the pi anyway (who doesn't want to run Octoprint?). So run Octoprint, write some python plugin to do your custom motor control, and get your PWM directly from the pi. There's plenty of spare pi gpio free when using Octoprint. If you need high current to control your DC motor, the robotics guys have all sorts of high current driver (H-Bridges, etc) boards. This is probably what I'd do.

I'm curious what your application is? You're replacing the extruder with a different tool?

Posted : 27/02/2019 8:30 am
michael.r52
(@michael-r52)
Eminent Member
Re: Is it possible to get a DC output from the printer ?

That is exactly what the PWM is for. You just need to filter it. What kind of current are you looking for and what kind of ripple in the DC?

Posted : 27/02/2019 9:10 pm
TheExtruder
(@theextruder)
New Member
Topic starter answered:
Re: Is it possible to get a DC output from the printer ?


An advantage of using the raspberry pi is that you probably want to run Octoprint on the pi anyway (who doesn't want to run Octoprint?). So run Octoprint, write some python plugin to do your custom motor control, and get your PWM directly from the pi. There's plenty of spare pi gpio free when using Octoprint. If you need high current to control your DC motor, the robotics guys have all sorts of high current driver (H-Bridges, etc) boards. This is probably what I'd do.

I'm curious what your application is? You're replacing the extruder with a different tool?

You are right this is the most complete setup, I got my Pi today so I'll let you know if it works well.

I want to put two pumps for nanopowders as a first experiment of automation in my lab and with other tools if it is conclusive!

Posted : 28/02/2019 3:36 pm
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