Problems with new Laser Filament Monitor

brunofporto

You can use a hobbs wheel and use the laser sensor to measure the hobbs movement instead. The it will work independently of filament type.

3dmntbighker

I have two BMG's and Bondtech DEFINITELY suggest using it with filament going in either direction. Especially based on the 3D printable parts they suggest using. I thought it was odd when I realized what they were suggesting too. In my case they are both direct drive to E3Dv6 so I have to figure out how to use my laser sensors. I ordered one for both of my printers.

Making filament move a wheel for the sensor to watch adds complexity but it might be the best way to use optical sensing? I may have to remix something on Thingi. You probably want to gear UP the movement, or make the wheel diameter where the filament runs past a lot smaller than the sensor part of the wheel. Aren't you skirting very close to just using a purpose built optical encoder though at this point?

insertnamehere

@T3P3Tony I want to hold off on the RMA until you can try the eSun filament. There is a chance it may work for you and the problem is mine.

I really like the concept of the filament sensor and really would like it to work. Can you let me know if you have been able to test with the filament I use?

insertnamehere

@T3P3Tony Just a question on the design of the laser monitor.
Looks like the optical sensor is mounted perpendicular to the filament.

Am I correct?

If so, I'm wondering why this design choice was made, given that laser sensors and the LED in optical mice are positioned opposite each at angles to the surface so the light source can illuminate the surface irregularities better.

Out of interest I ran the problem PETG filament length-ways over the sensor on a laser mouse. Had no problems sensing movement.

I know, not exactly rigorous testing, but interesting.

deckingman

@elmoret said in Problems with new Laser Filament Monitor:

@deckingman It does seem odd, and I'm not sure why Bondtech recommends it (unless there's not space to mount it conventionally, hard to tell), but I would say from the photo that @insertnamehere is correct, the filament travels from right to left in that photo. Otherwise, putting the microswitch on the (typically) discharge end of the Bondtech wouldn't do any good, as it would never see that filament had run out.

OK I concede and apologise. I was using my 'phone so didn't look at the picture. In my defence, I did say in my OP that it might work. However, it still seems an odd thing to do especially as the BMG is available in both left and right hand versions to enable access to the release lever for any installation.

dc42

@insertnamehere said in Problems with new Laser Filament Monitor:

@T3P3Tony Just a question on the design of the laser monitor.
Looks like the optical sensor is mounted perpendicular to the filament.

Am I correct?

If so, I'm wondering why this design choice was made, given that laser sensors and the LED in optical mice are positioned opposite each at angles to the surface so the light source can illuminate the surface irregularities better.

Out of interest I ran the problem PETG filament length-ways over the sensor on a laser mouse. Had no problems sensing movement.

I know, not exactly rigorous testing, but interesting.

In the sensing chip, the image sensor is mounted next to the laser. So we can't control the distance between them, only the distance to the filament and the direction that the filament runs. At present we have the filament running over the centre of the laser and the centre of the image sensor, which I thought would give the best response. I guess we could try running the filament at right angles to that direction, in which case it would have to run over the centre of the laser but would not run over the image sensor at all.

brunofporto

Have you tried my casing design? I have a large exposed length of filament based on a hypothetical aperture I calculated from some datasheet parameters.

I had no issues with shiny metallic petg or translucent materials with it. Just make sure you cut the filament tip diagonally so it enters the exit hole nicely

alt text

https://www.thingiverse.com/thing:3119908

T3P3Tony

@brunofporto Thanks, I have not tried it but will do!

insertnamehere

@brunofporto said in Problems with new Laser Filament Monitor:

Have you tried my casing design? I have a large exposed length of filament based on a hypothetical aperture I calculated from some datasheet parameters.

I had no issues with shiny metallic petg or translucent materials with it. Just make sure you cut the filament tip diagonally so it enters the exit hole nicely

https://www.thingiverse.com/thing:3119908

In fact I used your design first. I liked the look of it.

After I found that I had problems sensing shiny petg I switched to the Duet reference design.
I found both yours and the reference casing gave the same results.

Since you and @T3P3Tony have had reasonable results sensing petg maybe it's just that I have a faulty sensor?

When @T3P3Tony can test the same filament type this may prove to be the case.

T3P3Tony

David has also suggested we test filament at an angle.

@insertnamehere I have ordered the esun filament but it is not on a fast delivery here in the UK for some reason (Amazon - next week) so will test ASAP.

brunofporto

@insertnamehere said in Problems with new Laser Filament Monitor:

I found both yours and the reference casing gave the same results.

Thanks!!! I will make a shorter version then, this one sometimes is very difficult to feed the filament. And I will adopt your hold solution (use the groove mounting as I have a similar extruder setup).

timcurtis67

@brunofporto said in Problems with new Laser Filament Monitor:

Have you tried my casing design? I have a large exposed length of filament based on a hypothetical aperture I calculated from some datasheet parameters.

I had no issues with shiny metallic petg or translucent materials with it. Just make sure you cut the filament tip diagonally so it enters the exit hole nicely

https://www.thingiverse.com/thing:3119908

I modified your housing to run the filament through at a 10 angle to see if it makes any difference in the accuracy. I don't post on Thingiverse but here is a link to the STL files. Note I have not printed these yet so there could be fit issues.

https://drive.google.com/drive/folders/1b8wBl5uZ1qwoimONZLIcWlFULOlNsJaq?usp=sharing

0_1540999841589_Angled Filament Sensor.JPG

0_1540999850268_Angled Filament Sensor Cutaway.JPG

Once I confirm if the angle approach works I will go back and "pretty up" the housing.

timcurtis67

@t3p3tony said in Problems with new Laser Filament Monitor:

David has also suggested we test filament at an angle.

@insertnamehere I have ordered the esun filament but it is not on a fast delivery here in the UK for some reason (Amazon - next week) so will test ASAP.

I will be testing this theory by Friday. I'll report back.

brunofporto

@timcurtis67 It is already pretty

insertnamehere

Since the prusa laser filament monitor uses the same sensor as the Duet, I did a few searches and turns out that the prusa sensor has problems with black petg also. Prominently eSun.

https://www.reddit.com/r/prusa3d/comments/83sq1f/problems_with_mk3_filament_sensor_with_black_petg/

insertnamehere

I'm finding problems detecting eSun Yellow PLA also.

Duet3D laser filament monitor on endstop input 3, disabled, allowed movement 50% to 145%, check every 3.0mm, current position -6.8, brightness 92, shutter 17, measured minimum -15%, average 50%, maximum 130% over 479.8mm

@T3P3Tony can you tell me what the min, average and max percentages represent?
What causes a negative percentage?
Is the filament monitor still usable with numbers like this?

3dmntbighker

@brunofporto Thanks, I'm starting with your design on my Ender 3 printed with eSun black PLA. I think you need a bit more surface area "bite" on the tubing.

insertnamehere

@t3p3tony, @dc42
The last 2 days I've been printing with eSUN black PLA, not the PETG I've been having problems with but a filament that has worked ok.

I have been getting value like:
minimum 83%, average 95%, maximum 112% mostly, I thought the sensor was working ok with this filament.

Then today I tried a print and the print paused twice with "Extruder 0 reports too little movement".

I ran a M591 D0 I now get this and now it is
minimum 46%, average 71%, maximum 93%
with the same roll of black PLA

Why so inconsistent?
Do I have a faulty sensor?

It doesn't work with some filaments and when it does it gives inconsistent result.

Did you have these problems in testing?

insertnamehere

@insertnamehere said in Problems with new Laser Filament Monitor:

@t3p3tony, @dc42

look, I'm a customer who is having problems with your product. I've been asking questions to help me determine if I have a faulty device. Two previous posts of mine have gone unanswered.

I would like to know if the inconsistent readings for the same filament over time (as much as 50% variability) were common in beta testing or if you think the sensor is faulty?

What do the the min, max and average percentages represent, and what values (I get some negative percentages) are unusable for sensing movement?

I get a lot of false detection even with quite wide M591 Raa:bb values. Was this seen in testing?

What should I do RMA for a replacement or get a refund?

dc42

How did you mount the filament monitor? Might dust have go on to the image sensor, reducing its sensitivity? The instructions on our wiki advise against mounting it with the image sensor facing upwards, to guard against dust building up on it.