Laser filament monitor

dc42

One disadvantage of installing the filament monitor after the extruder drive is that there is an increased risk of filament dust contaminating the image sensor, especially after there has been a jam and some filament had been ground up.

punamenon

@dc42 said in Laser filament monitor:

One disadvantage of installing the filament monitor after the extruder drive is that there is an increased risk of filament dust contaminating the image sensor, especially after there has been a jam and some filament had been ground up.

A good point! What about a redesign so that when you split it apart, you can access the sensor with a cotton swab? Would repeated wiping damage the sensor?

brunofporto

@dc42 That is is true.....

celulari

@dc42 said in Laser filament monitor:

Today I've been trying out a laser optical sensor to see if it is accurate enough to use instead of the rotating magnet sensor we use in the beta test filament monitors. The good new is that in tests with several different filaments including black and transparent, first indications are that it works adequately, provided that the filament position is sufficiently well constrained. So we will go ahead with making prototypes. We may have a very small number (between 2 and 4) available for beta testers

This does however mean that production of filament monitors to the existing design is on hold until the prototypes are ready and tested, so that we can make an informed decision on which design to use.

The laser filament monitor would have a much simpler housing design. Basically it just needs to clamp PTFE tubes on the inlet and the outlet, to ensure that the filament is constrained to be in the centre of the field of view of the sensor.

Is the filament monitor available for purchase?

Thanks.

Phaedrux

@celulari not yet

brunofporto

@dc42 @T3P3Tony

As a first suggestion I would say to put the leds at the same side as the connectors or at least put a standard pcb hole right below them to allow better view of their status not at the sensor side.

For now I am reading their status from the SW holes

Thanks!

robobobob

Just ordered my duet this morning for an idex printer build. Definitely interested in a filament laser sensor, if there are spots for any more beta testers in the future. I would also like to put forward a design for a different type of filament sensor, using not lasers, nor ultra sound, but an electric motor. Would it be possible to mount a very small electric motor, and a wheel to rub up against the filament, and then read the voltage output? Surely if this was done correctly, it would allow you to read everything necessary, with no calibration required. Again, I'm just thinking, and haven't done any testing, but in principle, a zero voltage reading would indicate either a jam or that the printer has run out of filament, a sudden dip in the voltage would indicate grinding, and the overall voltage could be used to monitor the flow rate. It does occur to me for better accuracy, more than one motor would be ideal, but I don't see why this would be such a problem. The only other issue I can identify is that this sensor would be very large compared laser sensors, and therefore harder to install in a printer.

brunofporto

@robobobob https://duet3d.dozuki.com/Wiki/Duet3dFilamentMonitor_RotatingMagnetVersion

robobobob

@brunofporto I had seen they had made something similar, though I also saw earlier in the post that it was susceptible to dust, and I presumed this was to do with the sensor. Surely monitoring voltage output by a motor would be simpler? I have no clue whether there is any way of reading a dc voltage input however. I simply had this idea because I was looking at anemometers for the raspberry pi, and saw one that worked in this same way. As far as I can recall, a motor's rpm has a linear relationship with voltage put in. Presumably the inverse is true for the voltage output, with the rpm put in.

brunofporto

@robobobob The issue is not the type of signal, IMO, but the mechanical reading of the movement itself.

Filaments can slip the wheel, the reading may vary based to the spring compression of the reading wheel relative to the hardness of the material, the mechanical sensor adds drag that can influence the reading, etc.. Also the casing design, quality of bearings, type of hob wheel, etc may vary if the end clients are the builders of the mechanical part of the system. And it will be much more expensive if they sell the bundle.

Optical movement sensors are widely used ( i.e. your mouse) even in industry to feedback motion. They are cheap and precise enough. And they do the job without touching the material (at least the sensor ) So they are very good candidates for this job.

With enough data from the beta testers they can fine tune the sensor for a wide range of materials and learn the behavior of the sensor to fine tune it.

peirof

hi,

sorry but i have not read all post, its a long post...

One question

The filament monitor. Detect when run out of filament only? or too detect when filament, for a jam, not its extruded?

thanks

Phaedrux

@peirof Yes it will detect a jam and under extrusion as well I believe.

p.tyers

From the list it looks as though testing is proceeding well.
Is there an estimated date for commercial release yet?
Alternatively is there any chance of getting a beta version?

pkos

I'm also interested in either buying it or signing up for beta testing.
Got loads of black PLA, got a functioning printer with duet wifi 1.04 (and just started ordering parts for a HEVO). Am slowly learning OpenSCAD and can program arduinos (home automation fully based on printed PCBs of my design and arduino on them). Not in the UK, but would gladly pay for shipping.

stewwy

I'm also interested in beta testing if it's still possible.
I print mainly in PETG grey,black and transparent red, and in PLA violet( more like pink) wood and black.

I'm mainly a chemist , with just enough electrical/mechanical knowledge to be dangerous

T3P3Tony

@stewwy they are now available for sale :
https://www.duet3d.com/laserfilamentmonitor

stewwy

Thanks, now I know what I'm getting for my birthday in a couple of weeks

BlueDust

Now that the laser filament monitor is for sale, does that mean you guys were able to resolve all of the open concerns?
Saying that, from the last list I read, it's not enough to make me not buy it. I am just wondering how beta the product still is, or if this is now the finished product.

Thanks!

T3P3Tony

@bluedust it works variably with different filaments, that is a function of the laser sensor itself.

It's definitely worth reading the testing thread:
https://forum.duet3d.com/topic/6092/laser-filament-monitor-test-results/

I have had it work well enough with all the types I have tested it with but others have had very bed results with PETG for example.

siblues

I hope they get it straightened out since I am very interested in purchasing one myself.i also am in the process of switching over to the Duet WiFi and PETG.