Hello everyone! I'm running into an issue sometimes with my Taz 5;

Hello everyone! I’m running into an issue sometimes with my Taz 5; Every once in a while, for whatever reasons, my filament will stop extruding. I know when it happens what to check and how to fix the problem, but here’s what I’d like to do to help prevent a ruined print when I find out that my printer continues to move as if it is extruding but has moved onto higher layers and is air printing.

I would like to mod my Taz 5 with a filament movement detector, so when the extruder gears keep moving but filament is not, I can pause the print immediately to fix the problem and pick up where I left off and not waste precious time by having to start over.

There are several low filament sensor alerts out there, but that’s not so much of an issue for me as filament not moving.

Anyone have an idea, or know of a preexisting sensor setup that I could make myself?

I thought of a color sensor looking at a striped gear that would turn as the filament moves into the extruder, and when the stripes stop moving, the sensor prompts an alert of some kind to get my attention, or sends an M Code to the controller to pause the print in progress.

Is this possible? Maybe there is a simpler solution?

I think your foundation is a sound one. A wheel that contacts the moving filament, with the wheel itself striped for an optical pickup integrated into your system. The wheel need not be very large, only large enough to have separation from black and white appropriate to the sensor pair. If the wheel was made of a clear plastic, the sensor pair could be on opposite sides, rather than counting on reflection.

I can think of a number of methods that involve something like an Arduino, but do not have enough experience to suggest how to interface it with your printer.

Thanks @Fred_U , I know that just because I have a vague idea of how to solve a problem, it’s not always possible in real life to make happen.

The Lulzbot Taz 5 uses a modified Marlin firmware with a Rambo board, which may complicate things if I try to mod it. I am very familiar with a Ramps 1.4 setup, and while I’m sure Rambo boards have a lot in common with Ramps, I’d have to dig in a little deeper, and see if I can get the source code for Lulzbot’s flavor of Marlin, see which pins are available for adding mods, and if there is a section of the firmware to add on to it. I’m starting to wander way out of my expertise with this, but hey, who doesn’t like a project?

Please keep the feedback coming, I’m happy to hear any ideas you all have.

I found the manual for the Rambo board. It’s 80 pages long but was an interesting quick scan. The Rambo is based on the same chip family as the Arduino and one can use the Arduino IDE to modify it.

From what I’ve learned, the more common means of providing an external action is to use a spare end-stop input on the main board. If you are able to examine your board and determine you have an open (un-used) end-stop connector, that’s half the battle.

I did not see the typical Arduino input pins, but that only means I don’t know what to look for on the Rambo board, not that they don’t exist. I’m not a programmer, so I would not attempt to add code to your programming, but someone else may have the smarts.

Because the end-stop input is open/closed, you’d probably have an external mini-board to convert "filament-moving - OK’ and “filament-not-moving - Not OK” to open and closed for the happiness of the end-stop pins.

During my research, I discovered a link for someone building an out-of-filament detector. His trigger code put the printer into pause mode, but my alleged mind went into pause mode as soon as as I saw the body of the programming.

I hopped over to the lulzbot web site and found that the source code is available, which is a bonus over locked-down printers. I’ve also popped into their forum and found this thread:

which points to a pre-made filament movement detector:

which is listed at US$65.00

I did not see the Taz 5 on the supported printer list, but it does allow for other printers by referencing that it works on “Other printer controllers that supports external pause signaling.” A google search for that phrase specific to the Taz 5 came up empty.

You could contact Lulzbot directly, point them to the Tunell monitor link and ask if they can tell you how it would work with your printer.

@Fred_U This is some great information, I was hoping to stay within the scope of Lulzbot, since, well, this wasn’t a cheap printer and if I broke it because I have obsessive compulsive tinkering disorder, I’d not forgive myself, ever.

I’ll look into this and ask Lulzbot directly if the Tunnel filament monitor is compatible. If not, well, maybe there is another workaround I could do that wouldn’t compromise the stock hardware. Thanks for your help!

I hope you’ll post here with your results.

Where else? Even if I don’t apply this idea to my Taz5, I do have pet “Pimp My Printer” project that I’ve been working on casually for a while now, that would be a better candidate for experimentation. I’ll post info about that at a later time.
Thanks again for all the info, looks like I have a lot of reading to do tonight.

You could have a sensor wheel on the filament and a sensor on the extruder drive. Then compere the movements, if not in sync then trip the endstop

I think the mechanicals aren’t so much of a question or problem as the interfacing to the printer. Michael hasn’t specified what action he would like when the filament stops moving, but my guess is that a pause response would provide the best results for a given print.

I would like a pause in the print, maybe a buzzer to sound to get my attention so I can get the issue fixed and get back to printing. I often print as fine of details as I can, .35 nozzle, .1-.2 layer height, so the obvious ways of knowing quickly and at a glance if, beyond the first layer, filament is still moving through the extruder. 5 hours into a 6 hour print, and realizing that i’ve been air printing for the last 20 minutes, now that’s a frustrating, sad moment. Over the weekend I was working with precise architectural models and kept running into a clogging issue, had I known when the issue was happening I wouldn’t have had to print each piece six times before I finally got one.