Major differences between IR Sensors and FSR Sensors for bed leveling?
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Russ, adding the FSRs on the end effector is similar to what the guys are doing with peizos on the effector, just that piezos are in some ways more suitable in that application (mainly around pre-load)
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And being able to drill the piezo means mechanically the system works far more directly, there are FSR hotend designs with dual fsrs one either side of the hotend. If there is an fsr out there with a hole in it then it might be much more possible. But its also the sensitivity at 50g of force for a typical FSR to reliably record a trigger there has to be quite a bit of compliance in the hotend to get this to happen resulting in the wobbly nozzle, which we have eliminated from the piezo sensor modules by pre-loading the much more sensitive piezo disc, also because of the hole the force is transmitted in the most direct way possible to the piezo meaning 10g is more realistic probing force, Mike thinks he can get down to 1g!
The piezo system is much more sensitive to mechanical noise than an FSR though, so probing has to be done with low jerk/accel. I haven't found this a problem, I want my probing to be accurate not fast.
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I may do the FSR sensors after re-reading this thread.
I wired up all of my motors and sensors last night with the exception of the effector wiring and extruder.
I ended up shortening all of my stock wires and sleeving and crimping them with the included Duet WiFi connectors in addition to labeling all the plugs with Dymo heat shrink. Is there any downside to sleeving with paracord? I had some for a different project and it seems to work almost the same as tech flex - just with a fabric feel.
I have the melamine plate from Trick Laser that I bought with an FSR kit and I may go ahead and use it on the new build instead of upgrading my old Rostock for now.
The Onyx bed is mounted to the melamine and it has to "float" on the three FSR sensors on top of silicone pads that are positioned beneath each tower, correct?
Is there a reason the FSR bed has a single tab that is different from the other two? Does the different tab need a specific orientation to the X, Y, or Z tower?
Also, what are people using to secure the glass? I usually use 3x binder clips - but I would like to find a lower profile method of attaching the glass securely if anyone has recommendations.
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Could you use the type of clip that they use on picture frames
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@Russ:
so Micheal, good stuff, you went over a lot of the concerns and thoughts i'm having at the moment.
I also use PEI so its good to know about CA glue.
let me ask you a question. cant we just move the 3 point FSR to the endefector. I would think if we did that we can get the same or better results as the plate dezighn.
but this just makes more scene. then i would think the weaker beds would be less effected?
any how. just some thoughts.
also if you can run this test for me so i can add your data that would be greate:
https://www.duet3d.com/forum/thread.php?id=1330
Thanks!
~Russ
Russ, this is a good idea and one I experimented with. This is very much like the electronic probes for milling machines work. It is a little challenging to construct a mechanism with X-Y movement constraints and virtually no constraint in Z when the entire apparatus must move all around! I know other have tried this with varying degrees of success. In the end, I felt a bed mounted solution would be less problematic.
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I may do the FSR sensors after re-reading this thread.
I wired up all of my motors and sensors last night with the exception of the effector wiring and extruder.
I ended up shortening all of my stock wires and sleeving and crimping them with the included Duet WiFi connectors in addition to labeling all the plugs with Dymo heat shrink. Is there any downside to sleeving with paracord? I had some for a different project and it seems to work almost the same as tech flex - just with a fabric feel.
I have the melamine plate from Trick Laser that I bought with an FSR kit and I may go ahead and use it on the new build instead of upgrading my old Rostock for now.
The Onyx bed is mounted to the melamine and it has to "float" on the three FSR sensors on top of silicone pads that are positioned beneath each tower, correct?
Is there a reason the FSR bed has a single tab that is different from the other two? Does the different tab need a specific orientation to the X, Y, or Z tower?
Also, what are people using to secure the glass? I usually use 3x binder clips - but I would like to find a lower profile method of attaching the glass securely if anyone has recommendations.
saffi, not sure about paranoid sleeving's melting point. That would be the only concern (flammability too).
Yes, the Onyx and bed are mounted to the the melamine plate I designed and this floats on the 3 FSRs on silicone pads. This arrangement is rigid, insulates the FSRs from the bed heater, doesn't over constrain the sensors, and the sensors are positioned as far outside of the bed diameter as possible (at least for the RMax).
Yes, that single tab accommodates the Onyx LED and wiring. This plate was designed for the SeeMeCNC Onyx heater but can be used for other heaters.
I use three of the hold downs supplied with the printer-one at each "ear". These ears are designed so you can use printed hold downs, or even bent aluminum if you prefer. I do use 3X binder clips on my RMax V3 - it has an earlier version of the plate without the ears. They work fine too. I think the lowest profile would be 1/16" (1mm) aluminum strips bent and drilled. I'll try to make some to photograph on my blog this weekend. Maybe I can convince Brian@TrickLaser to include 3 with the plate!
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Could you use the type of clip that they use on picture frames
Yes absolutely. They may require a little more bending to accommodate the melamine.
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Micheal, thanks so much for that really comprehensive rundown of probing. For deltas this is a critical requirement - I am looking forward to your review of our new method!. #itscomingsoon #spoilers #notsurewhyIamusinghastags
"Hello, I'm Michael and I'm a probaholic…" I really have spent more time with probing than is reasonable. In the beginning it was simply to make sure I could print stuff like this reliably and repeatably:
That "mesh" requires near perfection for first layer height (and bed adhesion too). It wasn't until I climbed aboard the dc42/Duet train with FSRs and PEI print surface that I was able to print these parts (and even more challenging parts) with 100% yield. A first layer height off by even .03mm is "visually offensive" to the human eye - it looks fat and squished.#ontheroadtoprobingrecovery #lookingforwardtothenewprobetotest
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Russ, adding the FSRs on the end effector is similar to what the guys are doing with peizos on the effector, just that piezos are in some ways more suitable in that application (mainly around pre-load)
ah yes, FSR might not be the one here, it dose seem that piezoelectric is a better choice all around. That is if you dont want movement in the attachment. But a flat piezoelectric attached to the PCB in the correct configuration might work. just some random thoughts… using something like this: http://www.imagesco.com/piezoelectric/index.html
Russ
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Russ, this is a good idea and one I experimented with. This is very much like the electronic probes for milling machines work. It is a little challenging to construct a mechanism with X-Y movement constraints and virtually no constraint in Z when the entire apparatus must move all around! I know other have tried this with varying degrees of success. In the end, I felt a bed mounted solution would be less problematic.
yeah i agree with you there. the moment even for a micro switch is also something i have been concerned about.
i think if your bed is mounted rigid, then your good to go with the way you have you bed.
again if you can run those micros and spit back the data so i can add it to the list. from the results you say you are getting it would really help me thing about this stuff. please do it!
https://www.duet3d.com/forum/thread.php?id=1330
~Russ
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That's doable, I have scads of data! I'll need to sort through it. I also have data I've asked a few others to collect for me for comparison.
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That's doable, I have scads of data! I'll need to sort through it. I also have data I've asked a few others to collect for me for comparison.
ok, well for now if you can just get "new" data using those Micros on that thread then i can have equal comparison for the rest of the data
Thanks!!!
~Russ
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Yeah I'd love to see your data using Russ's test too Michael. Given that the only entry for FSR's here is not that spectacular it would be interesting to see how a really well set up implementation performs.
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@Russ:
Russ, this is a good idea and one I experimented with. This is very much like the electronic probes for milling machines work. It is a little challenging to construct a mechanism with X-Y movement constraints and virtually no constraint in Z when the entire apparatus must move all around! I know other have tried this with varying degrees of success. In the end, I felt a bed mounted solution would be less problematic.
yeah i agree with you there. the moment even for a micro switch is also something i have been concerned about.
i think if your bed is mounted rigid, then your good to go with the way you have you bed.
again if you can run those micros and spit back the data so i can add it to the list. from the results you say you are getting it would really help me thing about this stuff. please do it!
https://www.duet3d.com/forum/thread.php?id=1330
~Russ
Now I see why I was a confused about what you were talking about - they are MACROS, not micros. You use "micro" everywhere.
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@Russ:
Russ, this is a good idea and one I experimented with. This is very much like the electronic probes for milling machines work. It is a little challenging to construct a mechanism with X-Y movement constraints and virtually no constraint in Z when the entire apparatus must move all around! I know other have tried this with varying degrees of success. In the end, I felt a bed mounted solution would be less problematic.
yeah i agree with you there. the moment even for a micro switch is also something i have been concerned about.
i think if your bed is mounted rigid, then your good to go with the way you have you bed.
again if you can run those micros and spit back the data so i can add it to the list. from the results you say you are getting it would really help me thing about this stuff. please do it!
https://www.duet3d.com/forum/thread.php?id=1330
~Russ
Now I see why I was a confused about what you were talking about - they are MACROS, not micros. You use "micro" everywhere.
oh man… lol well everyone take note, if your reading my comments do read between the lines… lol
strong points = electrical / mechanical anything, PLC programing and related programing. making anything from nothing (junk)
week points = spelling, typing, high level math, C+ and related programing ( mostly due to my bad spelling and typos)haha the more i post the more you learn what i mean and not what i typed,
my bad!!!!!!!
and to think i own my forums... lol
http://open-source-energy.org/~Russ
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Also we're developing a PCB effector for delta printers with a built-in nozzle contact sensor. See https://www.duet3d.com/forum/thread.php?id=1093&p=1. We're currently waiting for the second round of prototype PCBs to arrive, so they won't be in production for a few weeks.
Thumbs up!
Russ
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I'll post some pictures this weekend of what my printer looks like. The paracord sleeving was only used on the motor wiring and the endstop wiring. The heat bed has regular tech flex sleeving currently.
I know fire safety is an issue for printers. I have a few SeeMeCNC thermal fuses that are 98C. I think I'll solder one underneath the Onyx and then not run the heat bed over 75C (I am almost exclusively PLA and 60C heat bed temps). I also have a fuse box that I can wire into the heat bed and hot end as well - but that may be redundant. I'll probably make a fire safety thread once I get closer to a working printer to explore some ideas I have.
One other question about the FSR arrangement, what is the bed weight limit for the John's FSR kit? The reason I ask is that I have a very heavy round aluminum disc that I may use for a printer bed but it weighs nearly 3kg - which might be 2.5+ kg too much for the sensors (I saw a 500g limit number somewhere online).
I may have to save it for a future printer to experiment with the upcoming PCB effector.
Are there any plans to make the effector and carriage PCB with mounting holes to use the stock $1 SeeMeCNC plastic ball-cup joints?
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There certainly is not a 500gm limit to using 3 FSRs equidistant around the perimeter of a bed. I do not know what the true upper end is but I have done experiments testing probe sensitivity and even with 2kg of mass put on the bed to load it, the FSRs worked perfectly. I doubt that 3kg will be an issue. That must be some bed!
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A flat piezo element used in the same manner as a foil strain gauge element certainly sounds lie it is worth trying. I would think that most places that you could put a single element on a PCB effector would have differing sensitivities in the X and Y planes but that would not be likely to have any effect on a straightforward Z probing operation. Thermal effects may be more of a problem but they can probably be worked around as they are with piezo diaphragms.
Another one that may be worth looking at are thickness mode piezo rings such as this one from Steiner and Martins https://www.steminc.com/en/piezo-ring-18x12x12mm-18-mhz-2-wl At $5 per ring they are a lot more than diaphragms but still not very pricey.
Mike.
p.s., I am the Mike that DjDemonD mentioned a few postings ago. I haven't yet got to 1 gram having hit the wall at 5 grams but will try again over the next few days.
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