Indirect (bearing) laser filament monitor concept

Adrian52

@brunofporto I finally got a sensor, and have fitted it. It seems to be working OK, although giving high percentages - 103 minimum, 147 average, 203 max, on a roughly 3000mm print. I have made the following changes to the design

The cutout for the board components needed an extra 1mm - maybe because I have the v2 sensor?
The jaw bearing is lowered by 0.3mm. The hinge only bends a little, but enough to grip the filament
The ptfe tube slot is widened to 4mm diameter. I was finding the filament was sticking because of compression of the tube. I also made 3 narrow cutouts 4.2 mm diameter in the slot to make the inside ridged - the tube seems to hold quite firmly without occluding the bore
I think I already mentioned giving 0.1mm clearance for the bearings, and 1mm extra for the hinge
I roughened the outside of the upper bearing with an emery board - feels a bit more grippy, and maybe seen better by the sensor?
this is what it looks like

I could post my changes on thingiverse, but didn't want to steal your thunder

Will update as I get more experience with it.

dc42

@adrian52 said in Indirect (bearing) laser filament monitor concept:

I finally got a sensor, and have fitted it. It seems to be working OK, although giving high percentages - 103 minimum, 147 average, 203 max, on a roughly 3000mm print. I have made the following changes to the design

I think you have the new version laser filament monitor, that's why the movement percentages are so high. Firmware versions 2.03beta and 3.0beta recognise the newer version and give the correct percentages.

Adrian52

@dc42 I'm actually on 2.03beta3 (2019-03-25b6)

dc42

@adrian52 said in Indirect (bearing) laser filament monitor concept:

@dc42 I'm actually on 2.03beta3 (2019-03-25b6)

When you send M591 D0, does the response include the sensor version?

Adrian52

@dc42 ahhh - it says v1

dc42

Do you know whether it is a V1 or a V2 ?

Adrian52

@dc42 its a v2

Adrian52

@dc42 looking at previous monitor readings on the console, it was reporting v2 earlier. I sent M591 D0 A0, to see if it made any difference. After sending M591 D0 A1, still shows v1. Will reboot and see if this is reproducible

Adrian52

@adrian52 It went back to reporting v2 - here is the console output - I did an M122 at the end
0_1556743869145_20190501console.txt

dc42

I think there may be a minor issue with the filament monitor firmware. If the filament monitor detects continuous movement then it will not send its version word again after startup. You can tell that this is happening because the LED on the filament monitor will give green flashes only. Whereas when it is sending status words, the LED flashes red.

So if the filament monitor starts up faster than the Duet, and vibration is causing small amounts of spurious motion to be detected, then the Duet may never see the version word. But if you see red flashes too then the Duet should get the version right.

TheLightSpeed

So any success with this? The reason I ask is I have a SeeMeCnc Artemis, and I bought 2 Filament Laser Monitors from Duet. Yesterday I spent all day wiring and pulling the wires etc. I finally got them hooked up, and working. So far I am only testing with one. But it just keeps stopping my print saying "Extruder0 has detected minimum movement"... I ran the M591 D0 and it came back with a range of 5% to 200%, so I changed the range to 1% to 215%? but didn't seem to make a big difference.

Here's the thing... I don't want filament "movement" monitoring... I just want RUNOUT sensing. If I am out of Filament, it stops... simple. I was told this was the only sensor I could use... so that's why I have it.

Help please!

wilriker

@thelightspeed said in Indirect (bearing) laser filament monitor concept:

Here's the thing... I don't want filament "movement" monitoring... I just want RUNOUT sensing. If I am out of Filament, it stops... simple.

I think this would have been easier with a simple microswitch-based sensor. Is there anything special with this printer that would prevent this solution?

I don't think the laser sensor can act as a simple run-out check reliably because that's not what it is intended for.

3dmntbighker

@adrian52 My 693ZZ bearings are 4.3mm wide. Is your version suitable for this width bearing? The bearings on Amazon don't seem to be 4mm as the specs would indicate. Judging by the pictures of most of them. Also, my first print doesn't come close to fitting Capricorn tubing.

Adrian52

@3dmntbighker I don't think so - my slot is 4.2 mm wide in the stl, so 4mm wide bearings run freely. I think you will need a 4.5 slot for a 4.3 bearing. With 4mm diameter cutout for the tube, I find the capricorn fits firmly - I think its 3.8 on the original design.

pkos

@adrian52 Yeah I had to do the same. When I opened the original stl's in either Fusion or FreeCAD, they show up as 4mm exactly - which is why I had to make the slot larger to 4.2

Oh and my bearings are exactly 4mm wide, but I bought them locally and not from amazon or aliexpress. They cost like proper bearings should cost too

That said, after making the slot larger and painting one bearing with a sharpie - I can now report a tentative success! Needs more testing, but so far so good. Values range between 73% and 97%. Will update as I go on.

0_1557140983024_4mm slot.JPG

3dmntbighker

@adrian52 said in Indirect (bearing) laser filament monitor concept:

@3dmntbighker I don't think so - my slot is 4.2 mm wide in the stl, so 4mm wide bearings run freely. I think you will need a 4.5 slot for a 4.3 bearing. With 4mm diameter cutout for the tube, I find the capricorn fits firmly - I think its 3.8 on the original design.

I think I'll be looking for bearings that are actually 4mm. Will you be posting STL or cad files?

brunofporto

Here are the source CAD files for anyone to modify it Please be kind and if you publish your mod mark it as a remix.

https://cad.onshape.com/documents/02526ef3896956555223f675/w/99601476c3f07fcbd93694c3/e/a0eb7bd691b19b6f2d63ac54

brunofporto

@3dmntbighker said in Indirect (bearing) laser filament monitor concept:

Will you be posting STL or cad files?

Done!!!

brunofporto

@pkos said in Indirect (bearing) laser filament monitor concept:

I can now report a tentative success!

I was thinking of trying some heat shrink tube around the bearing, or some way to make the bearing surface rough (some carefully made chemical attack to the metal).

SteveYYC

@brunofporto I was wondering if something like a commercial anti-slip coating would work - most of them say they'll stick to metal. Unfortunately they come as a spray so the bearing would have to be carefully taped off before painting.