Using Rev D Printrboard to test some motors; no extruder

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Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Sat-23-Mar

I want to eventually figure a way to use the Printrboard to drive my CNC router, but for now I just want to use it to test motors. XYZ. When I plug my motors in I get the Extruder Switched Off/ Min Temp Triggered error. Can I just plug a motor into the extruder motor slot to fix the issue? Or is this a temperature issue since I don't have a hotend?
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Using Rev D Printrboard to test some motors; no extruder

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Re: Using Rev D Printrboard to test some motors; no extruder

Postby thawkins » 2015-Mar-Sun-00-Mar

etxbkst wrote:I want to eventually figure a way to use the Printrboard to drive my CNC router, but for now I just want to use it to test motors. XYZ. When I plug my motors in I get the Extruder Switched Off/ Min Temp Triggered error. Can I just plug a motor into the extruder motor slot to fix the issue? Or is this a temperature issue since I don't have a hotend?


Find a 270ohm resistor and wire it across the thermistor pins. It will fool the board into thinking the heater is at about 200c.

You may have adjust the resistor, so you may be better geting a 1k trimpot and using a screwdriver to set the precise temp. But no matter what the fixed resistor will stop the error message.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Sun-00-Mar

Thank you! I'll give this a try.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Sun-00-Mar

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Re: Using Rev D Printrboard to test some motors; no extruder

Postby RetireeJay » 2015-Mar-Sun-07-Mar

Yes, you could do that. But simple non-adjustable resistors are cheaper. It's up to you.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Sun-16-Mar

What sort of wattage does the resistor need to be? Just perusing Amazon and RadioShack websites shows a few different varieties of 270ohm resistors.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby RetireeJay » 2015-Mar-Sun-19-Mar

You can use 1/8 watt or greater.
The thermistor circuit is fed by 5 volts. The formula for power dissipation in a resistor is (V^2)/R. So if you had 5V applied to the resistor, you would dissipate about 1/10 of a watt. But in fact, there is a series 4.7k resistor on the board so the dissipation will be MUCH less than that. Basically, you don't need to worry about it.
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Printrbot Plus operational January 2013
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GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby Mooselake » 2015-Mar-Mon-11-Mar

If you're not using the E (extruder) axis why does it care if there's a thermistor (or resistor faking one)?

Check your gcode, including any automatically generated startup gcode, for extruder commands. Remove them. No resistor necessary... Manual commands should work without any problems, as long as you don't try the extruder ones - and even if you do just ignore the error. While the E axis won't move, X, Y, and Z will work just fine.

I'd be very hesitant to fake a thermistor with a resistor - if you forget to remove it, and you (or some future owner) connect a real extruder, you're taking a chance at converting your device into a firestarter and needing to find a new residence.

Kirk
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby thawkins » 2015-Mar-Mon-12-Mar

Mooselake wrote:If you're not using the E (extruder) axis why does it care if there's a thermistor (or resistor faking one)?

Check your gcode, including any automatically generated startup gcode, for extruder commands. Remove them. No resistor necessary... Manual commands should work without any problems, as long as you don't try the extruder ones - and even if you do just ignore the error. While the E axis won't move, X, Y, and Z will work just fine.

I'd be very hesitant to fake a thermistor with a resistor - if you forget to remove it, and you (or some future owner) connect a real extruder, you're taking a chance at converting your device into a firestarter and needing to find a new residence.

Kirk


Standard marlin wont startup unless the first extruder has a temperature reading of between 15c and 275c, it will stop with an error message and require an m999 reset or powercycle.

Even with a temperature registering within that range, any extrusion command wont work and will throw an error if the temp is below 170c

If you want to see this in action, just unplug your thermistor and try to start your bot up. You will get an undertemp error, put a jumper across the pins and you will get an overtemp error, in both cases marlin stops processing any further commands until reset.

Note: he is driving a CNC machine with this board not a 3d printer, it does not have an extruder to catch fire, he just wants the board to be able to start up. The resistor allows him to use standard marlin for driving the xyz chassis and perform homing etc.
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-------------------------------
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Dual heated beds.
RAMPS 1.4 running Marlin 0.98
-------------------------------
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby Mooselake » 2015-Mar-Mon-15-Mar

Well, that was interesting... It took some work and zip tie cutting to disconnect the thermistor, plus waiting through a W10 update, but with reasonably current firmware (unified V3 iirc) it will connect and home, but any other motion commands will cause the firmware to halt. I moved my PB around without an extruder during my initial assembly back in late 2012, but that was different firmware and some time ago. Is the thermistor check a somewhat recent feature? Guess I've contributed to Brook's misinformation.

For motor testing only you can use G28 home commands to make them spin, but not for any real motion. M203 (disable cold extrude) didn't help. Don't forget disconnecting motors with the power on will potentially blow the board, so power down between motor changes.

Still don't like the idea of potentially bypassing the thermistor if there's any chance the board will end up in a printer, maybe I'm too sensitive after dealing with the aftermath of multiple fires. Make sure it's obvious and can't be accidentally overlooked. A better way would be to recompile and reflash Marlin (will PREVENT_DANGEROUS_EXTRUDE disable the test, and can you completely disable the extruder?) , or use grbl - it's better suited for CNC use, anyway, and won't require faking out the extruder checks.

Kirk
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Mon-19-Mar

@Mooselake, I'm of the same mindset, and so I think I'm going to invest in a Smoothieboard since it is dual purpose. But until I can get the cash together, I'd just like to use the printrboard to test movement.

I got the resistor wired, and now I don't get the temp error. In Prontrface I can move the Z axis (the only one attached at the moment), but inputting code like M501, G0, etc, result in an "Unknown Command" error. Strange that it moves the axis when I jog it, but it accepts no commands? I can't remember the last things I may have done with this board before it went into storage, so maybe a firmware reflash is in order?
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Mon-23-Mar

Image

I bought one of these at RadioShack as well. Can anyone advise on how to wire it up? I used the resistor method, and it works, but it reads a constant 270 degrees. I don't know if that matters or not, but if it does I'd like to install the pot trimmer to lower the temp it reads.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby thawkins » 2015-Mar-Tue-00-Mar

Wire the center pin and any of the other two to a connector and plug into the board, you should be able to adjust the resistance and vary the fake temperature.
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225mm x 200mm - Heated Bed
RAMPS 1.4 running Marlin 1.1.0
Full Graphic display.
-------------------------------
Zen Toolworks CNC/3d printer
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Dual j-head hotends.
Dual heated beds.
RAMPS 1.4 running Marlin 0.98
-------------------------------
Flashforge 3d Creator Pro
Dual Extruder
220x143x150mm
Mightyboard rev e, runnimg Sailfish 7.7r1234
-------------------------------
Photon, self designed printed printer.
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby etxbkst » 2015-Mar-Tue-01-Mar

Thanks, @thawkins!
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Re: Using Rev D Printrboard to test some motors; no extruder

Postby RetireeJay » 2015-Mar-Tue-06-Mar

A 1k variable resistor will only get you down to about 170 degrees. To go to lower temperatures than that, you will need a higher resistance. 10k would get you down to about 85 degrees; 100k will get you to 25 degrees. Any of these variable resistors will be able to take you off the top end of temperature (when they are set to less than 100 ohms); the difference will be how much resolution you have. With a 100k variable resistor of that "single-turn" construction, it will be very "twitchy."
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S
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