Indirect (bearing) laser filament monitor concept
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@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.
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@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.
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@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.
Voron 2.4 (Duet 3 6HC + 3HC standalone), Voron SW (Duet 3 mini 5+ standalone), Voron Trident (Duet 3 mini 5+ standalone), Voron 0.1
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@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?
Scratch built CoreXY with Maestro
Heavily modified Ender 3 with Maestro
MPCNC work in progress with Duet WiFi -
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. -
@3dmntbighker said in Indirect (bearing) laser filament monitor concept:
Will you be posting STL or cad files?
Done!!!
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@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).
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@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.
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@steveyyc woul be easy to tape both sides only. No need even to trim the tape.... That should do the trick! Do you have a link for such product, please, so I can look for something similar around here?
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@dc42 I am still having an issue with the version number recognition. I find that if I send M591 D0 A0, the monitor is reported as v1, having previously been recognised as v2. The console output illustrating this is here
0_1557422029306_20190509console.txt
I am still getting rather high results, even having tried 2.03rc1. An earlier print gave min 113, avg 157, max 247 over 754mm print -
@3dmntbighker I have just put the files on thingiverse, 3618968
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@brunofporto I was considering something like this stuff from Rustoleum
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Got mine printed and assembled, but I'm getting an extremely large range of values for min & maximum. Does this mean my bearings are slipping?
M591 D0
produces the following:Duet3D laser filament monitor on input 4, disabled, allow 25% to 440%, check every 3.0mm, current pos 5.7, brightness 110, shutter 35, measured min 4% avg 181% max 492% over 994.7mm
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@steveyyc Unfortunately yes....
The direct bearing seems too slippery for this use.
I'll think about another solution.
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@brunofporto I've put a ring of electrical shrink-wrap tubing around the upper bearing - it's now dark grey but it's not exhibiting any slipping when I push filament through manually. Will let you know once I do some testing with it how it calibrates.
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@brunofporto said in Indirect (bearing) laser filament monitor concept:
@steveyyc Unfortunately yes....
The direct bearing seems too slippery for this use.
I'll think about another solution.
The best answer would be a garnet blast or something similar on the external diameter.
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Update: Shrink-tubing around the bearing worked for a short while, but since the tubing is soft it quickly developed a groove and began to slip again.
Still much better than using the bare shiny metal, but I did wind up getting a negative movement on a section of complex infill. Since negative values for R do not seem to work, even setting minimum to 0 I will still get pausing without actual jams/issues on a job.
Next attempt will be to use salt water and electricity to etch the outer rim of the bearing. I have done this with other SS items and the result is usually an even, "frosted" surface. I don't know if this will be enough "texture" to grab the filament or not.
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@steveyyc Update: Salt Water Etching didn't touch the stainless so I resorted to an emery board and the garnet abrasive took the shine of the bearing very quickly.
It's definitely going to be hard to get negative values now - the range has shifted to min 555% and max 588%
Provided this result lasts through a few more jobs I think sanding the bearing may be the solution to the slippage.
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I have some preliminary results on the effect of changing the working distance of the sensor. The sensor Web page suggests 5 - 60mm for glossy surfaces, and 20-40mm for white paper. I printed some spacers to go between the top and middle sections of the indirect sensor, and checked the results after printing about 700mm of filament. I have been using A0, and 5mm measuring interval. With no spacer I got 72%(48), 149%(100), 243%(163) for min, average and maximum, normalised to average =100 in the brackets. With the 10mm spacer, I got 180(49), 370(100), 390(105). With a 15mm spacer, it was 472(97), 487(100), 505(103), and the 25mm spacer 575(81), 708(100), 749(106). I need to do more tests, but it looks like a longer working distance may be better - the 15mm spacer result is quite good. Perhaps this is worth investigating with direct sensing too.
I am still getting the sensor reported as v1 after sending M591 D0 A0, sometimes reverting to v2 after a number of M591 D0 s (it is a v2 sensor) -
@adrian52 said in Indirect (bearing) laser filament monitor concept:
With a 15mm spacer, it was 472(97), 487(100), 505(103)
Yeah, 15 looks really good, unless you actually want a slightly broader range. At least it looks like a sweet spot should be close at hand.
Scratch built CoreXY with Maestro
Heavily modified Ender 3 with Maestro
MPCNC work in progress with Duet WiFi
