Upgrade: Mod your POWERWASP to support variable fan speed


A controllable fan (on/off and speed) it’s a nice feature that really improves your prints and, once setup, it can operate without any assistance.
In the POWERWASP, fan is directly connected to the regulated 12v output that’s always on. Since this printer it’s really well made you can attach or detach you fan anytime, also during the print, basically turning it on and off as you like. For example you can add the fan after the firsts layer, but still you need to assist you printer and… is just off or full power. To take advantage of the features of your slicer software (like cura or slic3r) and your Marlin firmware, just follow this tutorial.
After your hardware upgrade you may want to update your firmware to support this feature in a better way, but I will tell you about this later on.

SKILL: some confidence with your printer and ability to solder trough holes components
TIME: 1h (actually I don’t remember how much it took, but it’s more than reasonable)
TOOLS: nothing special, just scissors, screwdriver and a soldering iron
COMPONENTS: one BD679 transistor and one 1k resistor

The POWERWASP printer comes with an Utlimaker shield clone (rev. 1.5.4) that uses a dedicate pwm pin (D7 on Arduino) to operate the fan to cool the hot-end.
You can find more info and schematics here: http://reprap.org/wiki/Ultimaker%27s_v1.5.4_PCB

Ultimaker shield rev. 1.5.4

Ultimaker shield rev. 1.5.4

Power Wasp Shield

POWERWASP shield

As you can see from the pictures above the two boards are identical except for one thing: the POWERWASP shield has all the components needed to run the printer and not those unused (in perfect WASP style ;-)) so to run this feature I had to add them by myself. A really easy operation if you know how to solder trough hole components.

Step 1:
Open the cover on the bottom of the POWERWASP and disconnect all the wires from the shield (I suggest you to mark them carefully to easily put them back on the right places 😉

Step 2:
Cut the power supply wires that are directly soldered on the pcb. Once terminated the mod, instead of solder them back, I added a connector just in case I will ever need to remove the board again, but that’s optional: you can just solder them back to the pcb without any problem.

PowerWasp shield update for variable speed fan

POWERWASP shield modified to use pin 7 to control a variable speed fan. Sorry I took this picture upside down compared to the others…

Step 3:
Solder the transistor BD679 in the right position (see picture “number 1”) (Q4 in Ultimaker pcb schematics)

Step 4:
Add a resistor of 1K (see picture “number 2”) (R20 in Ultimaker pcb schematics)

Step 5:
Disconnect the fan from its current position (originally the fan pins are connected to the 12v regulated output, one of the three pair of connectors on the top left corner of my picture) and connect it to pin 7 (see picture number 3, first connector on the left). Pay attention to the correct polarization, + is the pin closer to the transistor (in the picture the one on the left). If your printer has a led strip you may have two pairs connected to the 12v regulated output, one for the fan the other for the led, just disconnect one to discover wich one it is 😉

Step 6 (optional):
If you have the components I also suggest you to install the Molex headers for expansion 1 and 2 and some pins for the other expansions (3 and 4) for future use so you don’t have to open your printer anymore… oh, well.. mmm.. I don’t know..
I’m on the way to complete a new control panel with many interesting features in addition to those already in the utilpanels, etc.. Just stay tuned for that 😉

Step 7:
Re-connect all the wires in the right places as noted before and put the cover back

Step 8:
Don’t forget to modify your firmware to handle you fan correctly!
You fan now gets tension directly from your VIN (VIN2 to be correct) that’s 18v!! and an unmodified firmware can potentially output 0-18v.
You can find how to update your firmware in my previous post https://mcmos.wordpress.com/wp-admin/post.php?post=104&action=edit
Alternatively you can limit max speed accordingly in your slicer program but I don’t like this workaround at all, see my post to read why.

If my tutorial it’s not clear enough (it’s my first one) just ask me!

Have fun 😉

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Categories: 3D Printer, Improvements | Tags: , , , , | 4 Comments

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4 thoughts on “Upgrade: Mod your POWERWASP to support variable fan speed

  1. Great tutorial! I’ll try to implement this on my wasp and will report back should any issue arise during the mod!contact

  2. Modding done, everything went perfect following your guide!

    Just one note: looking at the schematics I noticed that the transistor that drives the fan is connected as open connector. This means that you can just power the fan with the regulated +12V (the line where the fan is originally connected to, then just use the PWM on the negative to control the fan. This is how the PWM fan output should work according to the schematics, I don’t know why they didn’t make that connection when they designed the PCB :-/

    I exploited this in a very easy way: i split the wired fan connector in half, so that I had two single “connectors”, one for the positive and one for the negative. Then I just connected the negative to the PWM output and I left the positive on the +12V rail it was before the modding. This way you don’t have to solder any wire to the PCB nor to mess with the firmware, yet the fan is regulated from 0V to 12V as it should be.

    Here it is a couple of pics explaining what I did. They aren’t as good as yours tho: http://imgur.com/a/ysPwe

    • Glad you fond my guide useful 🙂
      when I decided to perform the mod I sticked to the original schematic but this is a very clever workaround for the missing connection. And if I’m not wrong it also add a plus (I need to check it out and I’ll tell).
      Great job!

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