This section is for info on the electronics we're using with RepRap. This mainly relates to our control boards, but may include supporting electronics, like the Thermocouple adapter boards we're using with RAMPS.
Parts Inventory A list of electronics parts we're using-- or intended to.
Thermocouple Adapter Boards
Instead of using thermistors for temperature monitoring, we currently use thermocouple adapter boards based on Analog Devices's AD595 IC. We connect the thermocouple board to pins 1,2,3 of AUX1 (5V, GND, and A3), and change TEMP_0_PIN to 3.
We have found that connecting the AD595 backwards results in the destruction of the IC. To avoid this, we use keyed connectors (digikey 487526-2-ND and A28527-ND). The connectors have a slot/key that divides one pin from the others; we use this pin as 5V and the others for signal and ground (which swap pins from one side of the cable to the other). This allows the cable to be reversible.
Two of the new printers this year are using RAMBO electronics. RAMBO is an integrated Atmel ATmega 2560 micro-controller and RAMPS board. It also contains the the stepper controller boards on device instead of having them plug in. The benefit of using RAMBO is that it is slightly cheaper to have everything on device. The downside is that if anything breaks you will need to get a whole new board (or very carefully use a hot air rework station to remove the smd chips) since everything is surface mount. In addition, one must send g-code to set the motor current since there is a digipot instead of real potentiometers. More info (especially on the firmware) can be found here: http://reprap.org/wiki/Rambo
Currently, M907 (set stepper motor current) cannot be used to change the extruder motor current (M907 E$ does nothing). As a work around, use M907 S$ to change the current of all stepper motors, including the extruder motor, to some value (represented by $) then change each other motor individually by using M907 X$ Y$ Z$.
Enter these commands at the start:
M907 S70 ;sets all motor current levels to 70
M907 Z100 ;sets the z motor current level to 100
Here is a compiled list of information about hot tips for extruding.
Information includes electronics used, number of thermocouples and operating temperatures we have found effective.
General Electronic Components
Comparison of Electronics
Once we decided that RAMPS seemed to be one of the best choices for electronics on the Prusa-style RepRaps we were building, we compiled a list of prices from various possible sources: RAMPS
Generation 3 Electronics
We currently have two Mendels on site (Alpha and Beta), created from Techzone kits. They use the Gen 3 TechZone Remix hardware, but we use an extra Stepper Driver board instead of running the extruder from the Extruder Controller.
Building Custom Motherboard
One of the goals of our program is gaining the ability to produce RepRaps to distribute to other groups at the university. To do this we need to bring build costs as low as possible. To this end, we are researching alternate electronics systems in hopes of finding one which we can produce ourselves, without needing to purchase kits or completed boards from third parties. This section serves as an index for that research.
- Heated bed support
- Multiple head support
- 2 Z motors
- protected outputs
- Would be nice
- High step count
- SD Card support
- Control panel (computerless)
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