Quote Originally Posted by printbus View Post
Seems like an oversight to not include an output that could be used with firmware out-of-filament detection. Various firmware already supports it. Or is that what the sensor contact pins are for? (Sorry - didn't read the external links for details)

How narrow of a spool can be used with this? I think the thinnest I have is around 35mm. How much of a hassle is it to reconfigure from one spool width to another?

I personally don't trust any of the spool mounts where the spool just sits on rollers. As the spool empties, you lose all the weight that keeps it place. The large metal disks might help with this, but I'm still not sure I'd trust it, especially on a few of my spools with really small hub diameters.
Topic 1: output for out-of-filament detection
Yes, it was an oversight to not initially include this signal. I revised the interface to include the following signals:
1) 5-24 V input (OR use the DC jack but not both at the same time)
2) Ground
3) IR sensor 1 raw output
4) IR sensor 2 raw output (sensor 1 and 2 form a basic quadrature signal)
5) Filament error condition via GPIO (0: okay, 1: out-of-filament, jamming, clogging, grinding --> whenever the extruder is not pulling filament)
6) Remote shutdown and hard-reset of the board via GPIO (0: board is running, 1: board is shutdown and held in reset)
I also added a physical switch to enable/disable the buzzer alarm.


People who want to simply connect the board to their printer and use it as a "smart" switch can use signal #5. Developers who want to modify their printer to detect filament speed, etc can use signals #3 and #4. The IR signal output is much cleaner and does not require debouncing like you would with a mechanical rotary encoder.

I would include pictures of my current progress, but I am having trouble inserting them on this board.

Topic 2: small spools
I just revised the platform design so that the rollers can actually touch each other. They will be able to hold your 35 mm spool. I also added a footer to each pylon so the nuts are embedded in the footer. This way, you can adjust screws from the top without having to fiddle with M3 nuts on the bottomside of the platform. Again, I wish I could show you pictures, but I seem to not be able to insert them on this board. If you check my Thingiverse page, I will be updating it this weekend.

Topic 3: spools falling off
The metal disks are actually ABS with gold paint. I need paint to block IR.

https://youtu.be/nfBTYKQTa1g

The long base of the platform allows you to create a more stable wheelbase to hold your spool securely. The tensioner keeps reliable tension through the hub. The encoder on each roller do help prevent the spool from tipping over. I have run multiple spools from beginning-to-end (I don't care about color) and I have not had one spool fall off so far. Granted, the spools I use are ~80 mm wide.

The only problem I have run into is where the last few winds of filament come loose and no longer pull the spool. To solve this, I tape the end to the hub so that the roll completes. The extruder pulls the taped end off the hub and alerts me when the spool stops rolling.

Addendum:
I am currently designing and testing an inline filament roller that can be attached between the extruder and spool. I will attach a link once I am satisfied that it works well.