Testing Resolution / accuracy , Your results wanted! Z Probe Results
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My take on the issue of validity of results is the same as youtube Thomas' in that an aluminium bed should be used as a control, with direct electrical contact (the most accurate probe possible) between nozzle and bed. That should be as accurate as your mechanics/electrics/electronics and firmware (your printer/rig in short) can manage.
Then stick your probe on there and do it again, now you have the measure of your probe. Otherwise you are measuring your printer/probe at the same time and some printers/rigs are more accurate than others.
My test rig is not great for accuracy testing as I said above, but it is great for making sure a newly made piezo module can do 1000 probes reliably and not breakdown mechanically or electrically. A really scientific rig, which I'd love to build, would have linear guides, ball screws, be made of thick aluminium with bracing etc… and be run from a 1/256 microstepping motor/controller.
And yes probing is more of an issue on a delta. But only because manually calibrating one is tedious and time consuming and the awesomeness of delta autocal is available to us with RRF, to use it we need the best probe we can muster. On a cartesian or corexy, if the bed is truly mechanically level and flat you just need 3 endstops and off you go. This is an age old (for 3d printing anyway) debate between those of us with super high precision machines with all metal build (or deltas as they need more calibrating) and those with slightly less perfect machines which benefit from auto/grid levelling.
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It could be the best to use aluminium bed and the nozzle - bed contact method to make a dead flat calibration for reference, then swap the bed for the one to actually print on and manually adjust the nozzle offset with babystepping (I totally adore babystepping and it's persistency !)
Then the probing would be more precise and delta calibration better.
I'd give it a go but have to write down some testing procedure just to be sure what to look for.Even Stratasys machines use plastic bed which is all but flat and level then they melt in the first layer of raft following by two more.
As soon as delta geometry is correctly measured, this way of laying down first layer is fool proof and easier on final user.I'm not sure if it's not a thread hijack I do here, perhaps it should be in another thread.
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Separating probe accuracy from printer build accuracy is tough to do. On my delta I'm fighting a mechanical issue right now which makes any sort of probe repeatability tests futile, as it quickly falls into the noise of the printer itself (I have a bearing or something that's gone out, makes a grinding noise during some moves, but for the life of me I can't track it down yet)
In addition, if you're probing two points at any distance apart, then you're actually adding your current calibration accuracy into the probe data, since you're really comparing against the currently calculated plane.
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If Russ doesn't mind a discussion here about how to test probes (since it is pertinent to his project) then lets continue otherwise yes lets make a new thread.
DuetUser yes adding an aluminium bed surface to do a sample probing on is valid, but as kraegar said only if you are probing over and over at bed centre, for example, since calibration will affect accuracy of your result if moving around the bed. Since calibration accuracy (for deltas) is determined by probe accuracy in part then it can become a difficult loop to break out of. I can see the effect in my calibration deviation from one probe to the next on my kossel XL but its got linear rails, 0.9 deg motors, 16t pulleys, duetwifi and 6mm tooling plate for a bed (with printbite bonded evenly on top). It should be a quite precise platform to test probes on, but its also my main printer so I built a rough and ready rig to free my main machine up to print client parts.
So I'd propose as a "scientific" test, probe 30 times onto aluminium, electrically with a pullup enabled for z_probe, and the aluminium and nozzle connected to GND and Signal on the probe connector. Make sure there is no voltage from anything else on the hot end first, to avoid any damage to the controller though their shouldn't be. That's your baseline. It should produce very low numbers.
Now install your probe and do another 30. Your range and standard deviation here will be higher but if you subtract the first set of values from the second, you have your probe's accuracy and repeatability measured minus the inherent accuracy of your setup.
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If Russ doesn't mind a discussion here about how to test probes (since it is pertinent to his project) then lets continue otherwise yes lets make a new thread.
DuetUser yes adding an aluminium bed surface to do a sample probing on is valid, but as kraegar said only if you are probing over and over at bed centre, for example, since calibration will affect accuracy of your result if moving around the bed. Since calibration accuracy (for deltas) is determined by probe accuracy in part then it can become a difficult loop to break out of. I can see the effect in my calibration deviation from one probe to the next on my kossel XL but its got linear rails, 0.9 deg motors, 16t pulleys, duetwifi and 6mm tooling plate for a bed (with printbite bonded evenly on top). It should be a quite precise platform to test probes on, but its also my main printer so I built a rough and ready rig to free my main machine up to print client parts.
So I'd propose as a "scientific" test, probe 30 times onto aluminium, electrically with a pullup enabled for z_probe, and the aluminium and nozzle connected to GND and Signal on the probe connector. Make sure there is no voltage from anything else on the hot end first, to avoid any damage to the controller though their shouldn't be. That's your baseline. It should produce very low numbers.
Now install your probe and do another 30. Your range and standard deviation here will be higher but if you subtract the first set of values from the second, you have your probe's accuracy and repeatability measured minus the inherent accuracy of your setup.
ill let you hijack this thread but only if you run my macros and give me your results..
hehehe!!! ( I run my own forums so i sure know how this hijacking can happen
(http://open-source-energy.org/)so here's the thing. I'm not looking for the best of the best, I'm looking to find out what people are using and how accurate there probe + printer is…
If you watch my video at the top of this thread i go in to talking about tom's video and how he did it and what i wanted different Ect.
so yes, we can test probes like Tom did and do it even better as you mentioned DjDemonD. however i think that's not necessary. Tom did a good job with the exception of Davids optical senor (any one got one please test it!!)
we are looking at 2 things here,
1. using a contact to contact test ( I did not do this in my video but did do this after and posted the results)
This test will give you your current configuration base line for your printer its self.
2. Test your Z probe like you normally use it. this value will be a +/- of what your contact contact test was.From my tests it seems that trying to achieve a contact contact Z probe is silly. most of us do not print directly on an AL bed. I use to use glass and still do but the PEI works the Treat! so all my tests show that most of the micro switches I tested are about 2x the error of my printer any how. and at .003mm that's not much to worry about...
my problem is that I'm using my delta to CNC and so i need something that i can be used in more than just the printing.
OK, now do post some more Z probe values!!! i'm quite interested to just see what everyone is probing at!! ( i want to build a small database of tests. so do post them!)
~Russ
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I am using thin film pressure sensor on the hotend which can only do cold leveling
https://ae01.alicdn.com/kf/HTB1J7l3LpXXXXc3XFXXq6xXFXXXY/3D-printer-accessories-set-kit-thin-film-pressure-sensor-leveling-pressure-sensor-kossel-delta-leveling-baseplate.jpg_640x640.jpgI am also looking forward to the piezo sensors
Jackal,
your data added to the workbook.
Higher rez http://open-source-energy.org/rwg42985/russ/Projects/3D%20printer/micro%20switch%20Z%20probe%20Data/Bed%20Probes%20accuracy%20others%20added.jpgcan you give me a few more details like motor steps and the Duet Board your using?
also, do you have any photos / drawings of your setup? It seems that your getting quite a good result. so that answers my question on how a SFR will do on the hotend.
but how you have it set up is also important. so the more details the better
It also seems that your single point is way more accurate than when you move around first. Theses are the kinda results i would expect if your parameters change when things slightly shift. and it makes sense. if your looking at force, and your hot-end shifts even slightly, then the force will change. and that's why your results better with a single probe no move.
This is where a solid setup is needed. However even with that, its VERY good.
total deviation from mean 25 move
7.46 umtotal max / min 25 move
28 umtotal deviation from mean single point only
1.79 umtotal max / min single point only
10.5 um~Russ
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Separating probe accuracy from printer build accuracy is tough to do. On my delta I'm fighting a mechanical issue right now which makes any sort of probe repeatability tests futile, as it quickly falls into the noise of the printer itself (I have a bearing or something that's gone out, makes a grinding noise during some moves, but for the life of me I can't track it down yet)
In addition, if you're probing two points at any distance apart, then you're actually adding your current calibration accuracy into the probe data, since you're really comparing against the currently calculated plane.
This is correct. this is why i wanted only a single point. even when moving around the point is still 0,0
do you have a motor bearing bearing out? take off the tension and wiggle the shaft… or turn it and see if you hear and noises??
even with your error, can you run the tests, just for fun then again after you find the problem. just to see if it even changed anything?
I will not add the data till after you find the problem, but just for fun sounds interesting to see how much it is effecting your setup ?
~Russ
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Kossel XL Duetwifi, tooling plate, 0.9 degree motors, 16t pulleys, 1/16 stepping with interpolation
Bed Temp 75, hot end temp 130 (to ensure no filament at the nozzle affects results)
Using Lykle design 64mm magnetic effector with 27mm "hole drilled" piezo disc, 3 rods, 3 screws support.I could not run this at full speed, piezo requires the probing itself to happen very smoothly so I run
;slow down movement to improve accuracy of probing, and lower motor current in case of incident M906 X500 Y500 Z500 E800 I60 ; Set low motor currents (mA) and increase idle current to 60% M201 X250 Y250 Z250 E1000 ; Accelerations (mm/s^2) M203 X15000 Y15000 Z15000 E3600 ; Maximum speeds (mm/min) M566 X100 Y100 Z100 E1200 ; Maximum instant speed changes mm/minuteBefore probing and did the 4 runs at 60 % speed. Piezo is accurate not fast, this is due to mechanical noise and vibration which will cause false triggers if its too great.
Okay so 100 to -100 test run 1:
Bed probe heights: 0.002 0.002 0.002 0.002 -0.003 -0.003 -0.003 -0.003 -0.008 0.002 0.002 -0.003 -0.008 -0.008 -0.003 -0.008 -0.013 -0.003 -0.008 -0.008 -0.008 -0.008 -0.008 -0.008 -0.013, mean -0.004, deviation from mean 0.005
Run 2:
Bed probe heights: -0.013 -0.008 -0.013 -0.013 -0.013 -0.013 -0.013 -0.018 -0.023 -0.018 -0.013 -0.018 -0.018 -0.023 -0.013 -0.023 -0.018 -0.018 -0.013 -0.013 -0.018 -0.023 -0.018 -0.018 -0.018, mean -0.016, deviation from mean 0.004Single point probe run 1:
Bed probe heights: -0.018 -0.013 -0.018 -0.013 -0.018 -0.013 -0.018 -0.018 -0.018 -0.018 -0.018 -0.013 -0.018 -0.018 -0.018 -0.018 -0.023 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.023 -0.018 -0.023 -0.018 -0.018 -0.018 -0.023 -0.018, mean -0.018, deviation from mean 0.002
Run 2:
Bed probe heights: -0.018 -0.023 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.023 -0.018 -0.023 -0.018 -0.023 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.023 -0.018 -0.023 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.018 -0.023, mean -0.019, deviation from mean 0.002Please be careful with the 100 to -100 test if you are not using a delta!! I am, but just saying
Since the values above appear to be microsteps limited I also tried a run at 1/256 of the single probe test:
Bed probe heights: -0.034 -0.026 -0.021 -0.024 -0.022 -0.020 -0.023 -0.022 -0.024 -0.022 -0.020 -0.021 -0.018 -0.020 -0.021 -0.016 -0.019 -0.018 -0.016 -0.017 -0.020 -0.016 -0.017 -0.020 -0.018 -0.018 -0.020 -0.017 -0.016 -0.018 -0.016 -0.017 -0.018 -0.015 -0.016 -0.014, mean -0.019, deviation from mean 0.004Interestingly probably a more accurate test I wonder if using 1/16th and interpolating is essentially smoothing the result but please add them I think piezo has proved its worth.
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I will try to find the time to do an electrical contact test on this printer for a baseline. Plus looking at the data for microswitches, of which some did very well, the issue here is you are deploying them by servo, in the real world? So how do they do on repeatability from one run to the next? This is the reason I love piezo, its permanently mounted. If you attach a microswitch to probe then remove it afterwards, how repeatable is that between runs?
Maybe add a third test probe, home, probe, home etc…
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Kossel XL Duetwifi, tooling plate, 0.9 degree motors, 16t pulleys, 1/16 stepping with interpolation
Bed Temp 75, hot end temp 130 (to ensure no filament at the nozzle affects results)
Using Lykle design 64mm magnetic effector with 27mm "hole drilled" piezo disc, 3 rods, 3 screws support.I think piezo has proved its worth.
Yeah Nice !
Here is the results:
very nice!
If you run the contact contact, run it at the same slow speed, then again at the 5mm/s speed.
I'm going to run the contact contact slower on mine to see what it looks like.
Thanks!!!!! keep em coming guys and gals! i would love to have a database of this stuff!!
~Russ
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To be honest I don't calibrate too often, I print on three printers now and haven't recalibrated them for almost a week.
Our print surfaces are quick swappable so after finishing a print I swap a glass bed and start printing next part, without any recalibration. Of course these beds are more or less distorted, thus it's good to use raft.What I was thinking is to make an initial precise calibration with aluminium bed just to receive good part precision, then forget about calibrating anything, just swap the bed to glass, production one and refine nozzle offset with babystepping if required.
I only have to check if it really does improve anything to have deviation less than say 0.03. -
I will try to find the time to do an electrical contact test on this printer for a baseline. Plus looking at the data for microswitches, of which some did very well, the issue here is you are deploying them by servo, in the real world? So how do they do on repeatability from one run to the next? This is the reason I love piezo, its permanently mounted. If you attach a microswitch to probe then remove it afterwards, how repeatable is that between runs?
Maybe add a third test probe, home, probe, home etc…
yeah i wanted to do a home probe home probe test but that is i think for another day… because then your adding the tolerance of your homing switches. its more than i wanted to test at first.
If we all set up a contact contact and got a 0 deviation... we could then test the accuracy of our Homing... ( however i cant even get a 0 deviation even when running very slow)
if anyone has a servo controlled micro switch probe do please test. i think that we will find a lot of error in that.
for me tho i want a direct switch with the hot end. like your piezo system.there are already deigns out there like this.
https://www.youtube.com/watch?v=e119OXzkk7s
but, like i said with a micro switch you have to back it off x amount and that means that you need a part that moves a lot more than lets say your piezo system. this means there is more chance for error and your nozzle moving around while printing.there are micro switches that dont need much movement, but nothing like a FSR or the piezo system. where you can basically hard mount everything but know that you are measuring this force…
dose anyone own a seemecnc rig with the accelerator probe??? That i do want data for!!
~Russ
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well, i finally was able to get a 0 deviation with the contact contact.
using theses settings
[c]M558 P1 X0 Y0 Z1 H1 F1 T10000 I1[/c]But only a few of Manny try's….
most of the time its always .001mm deviation ( max / min of .003mm)
[c]2:39:14 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: -0.003 0.000 0.000 0.000 0.000 0.000 -0.003 -0.003 0.000 0.000 0.000 0.000 0.000 -0.003 -0.003 -0.003 -0.003 0.000 -0.003 0.000 -0.003 0.000 0.000 -0.003 -0.003 -0.003 -0.003 0.000 0.000 -0.003 -0.003 -0.003 0.000 0.000 -0.003 -0.003, mean -0.001, deviation from mean 0.002
2:22:29 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -0.003 0.000 0.000 0.000 -0.003 0.000 0.000 0.000, mean -0.000, deviation from mean 0.001
1:58:42 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 -0.003 0.000 0.000 0.000 0.000 -0.003 0.000 -0.003 0.000 0.000 -0.003 -0.003 0.000 -0.003 -0.003 0.000 -0.003 0.000 0.000 -0.003 -0.003 -0.003 -0.003 -0.003 0.000 -0.003 0.000 -0.003 -0.003 -0.003 -0.003 -0.003 0.000, mean -0.001, deviation from mean 0.002
1:54:49 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 -0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -0.003 -0.003 0.000 0.000 0.000 0.000 0.000 -0.003 0.000 0.000 0.000 -0.003 -0.003 -0.003 -0.003 0.000 -0.003 0.000 0.000 -0.003 0.000 -0.003, mean -0.001, deviation from mean 0.001
1:52:50 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -0.003 0.000 0.000, mean 0.000, deviation from mean 0.001
1:50:54 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000, mean 0.000, deviation from mean 0.000
1:49:18 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 -0.003 0.000 0.000 -0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.003 0.000 0.000 0.000 0.000 0.000 0.000, mean 0.000, deviation from mean 0.001
1:47:39 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000, mean 0.000, deviation from mean 0.000[/c]so its possible but i still cant hit 0 all the time…
~Russ
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well that's interesting, even at fast speeds its till quite accurate.
M558 P1 X0 Y0 Z1 H10 F500 T10000 I1 ```[c]3:27:33 PM M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode Bed probe heights: -0.003 0.000 -0.003 -0.003 -0.006 0.000 -0.006 -0.006 -0.003 -0.006 0.000 -0.003 -0.003 0.000 -0.003 -0.006 -0.003 -0.003 -0.003 -0.003 -0.003 -0.003 -0.003 -0.003 -0.003 -0.006 -0.003 -0.006 -0.006 -0.003 -0.003 -0.006 0.000 -0.006 -0.003 -0.003, mean -0.003, deviation from mean 0.002 3:26:33 PM M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode Bed probe heights: -0.003 -0.003 0.000 0.000 -0.003 -0.003 0.000 0.000 -0.003 -0.003 0.000 0.000 -0.003 -0.003 -0.003 0.000 -0.003 -0.003 -0.003 -0.003 0.000 -0.003 -0.003 -0.003 -0.003 -0.003 -0.006 -0.003 -0.003 0.000 -0.003 -0.003 -0.006 -0.003 -0.003 -0.003, mean -0.002, deviation from mean 0.002 3:25:00 PM M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode Bed probe heights: -0.031 -0.031 -0.034 -0.034 -0.034 -0.034 -0.031 -0.031 -0.034 -0.034 -0.037 -0.034 -0.031 -0.037 -0.037 -0.034 -0.034 -0.037 -0.037 -0.034 -0.034 -0.037 -0.034 -0.034 -0.037 -0.034 -0.034 -0.037 -0.034 -0.034 -0.037 -0.037 -0.037 -0.034 -0.037 -0.037, mean -0.035, deviation from mean 0.002M558 P1 X0 Y0 Z5 H1 F300 T10000 I1
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode Bed probe heights: 0.000 0.000 0.003 0.003 0.003 0.000 0.000 0.000 0.000 0.003 0.000 0.000 0.000 0.000 0.003 0.003 0.000 0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000, mean 0.001, deviation from mean 0.001 3:23:35 PM M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode Bed probe heights: 0.003 0.003 0.003 0.003 0.000 0.003 0.000 0.003 0.000 0.000 0.000 0.000 0.003 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.003 0.003 0.000 0.003 0.000 0.000 0.000 0.003 0.000 0.000 0.000 0.003 0.000 0.003 0.000 0.003, mean 0.001, deviation from mean 0.002 [/c] ~Russ -
and now we are losing it…
M558 P1 X0 Y0 Z1 H10 F1000 T10000 I1[c]3:30:41 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: -0.009 -0.019 -0.009 -0.015 -0.006 -0.012 -0.012 -0.019 -0.009 -0.015 -0.019 -0.019 -0.015 -0.015 -0.019 -0.009 -0.015 -0.009 -0.012 -0.019 -0.015 -0.015 -0.019 -0.012 -0.015 -0.019 -0.019 -0.015 -0.019 -0.015 -0.019 -0.012 -0.012 -0.015 -0.012 -0.012, mean -0.015, deviation from mean 0.004
3:30:02 PM
M98 P0:/macros/probetesting/Probe Testing Single Point 36 probes P values .gcode
Bed probe heights: -0.006 -0.003 -0.012 -0.006 -0.006 -0.009 -0.012 -0.019 -0.009 -0.009 -0.009 -0.012 -0.009 -0.015 -0.009 -0.012 -0.012 -0.012 -0.012 -0.012 -0.015 -0.009 -0.009 -0.012 -0.015 -0.012 -0.015 -0.009 -0.015 -0.012 -0.019 -0.009 -0.015 -0.009 -0.012 -0.019, mean -0.012, deviation from mean 0.004[/c] -
so for me contact to contact above 500mm/min we start getting out of a nice range.
~Russ
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@Russ:
I will try to find the time to do an electrical contact test on this printer for a baseline. Plus looking at the data for microswitches, of which some did very well, the issue here is you are deploying them by servo, in the real world? So how do they do on repeatability from one run to the next? This is the reason I love piezo, its permanently mounted. If you attach a microswitch to probe then remove it afterwards, how repeatable is that between runs?
Maybe add a third test probe, home, probe, home etc…
yeah i wanted to do a home probe home probe test but that is i think for another day… because then your adding the tolerance of your homing switches. its more than i wanted to test at first.
If we all set up a contact contact and got a 0 deviation... we could then test the accuracy of our Homing... ( however i cant even get a 0 deviation even when running very slow)
if anyone has a servo controlled micro switch probe do please test. i think that we will find a lot of error in that.
for me tho i want a direct switch with the hot end. like your piezo system.there are already deigns out there like this.
https://www.youtube.com/watch?v=e119OXzkk7s
but, like i said with a micro switch you have to back it off x amount and that means that you need a part that moves a lot more than lets say your piezo system. this means there is more chance for error and your nozzle moving around while printing.there are micro switches that dont need much movement, but nothing like a FSR or the piezo system. where you can basically hard mount everything but know that you are measuring this force…
dose anyone own a seemecnc rig with the accelerator probe??? That i do want data for!!
~Russ
It would be nice to have an endstop repeatability test of some sort? Any ideas?
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@Russ:
Separating probe accuracy from printer build accuracy is tough to do. On my delta I'm fighting a mechanical issue right now which makes any sort of probe repeatability tests futile, as it quickly falls into the noise of the printer itself (I have a bearing or something that's gone out, makes a grinding noise during some moves, but for the life of me I can't track it down yet)
In addition, if you're probing two points at any distance apart, then you're actually adding your current calibration accuracy into the probe data, since you're really comparing against the currently calculated plane.
This is correct. this is why i wanted only a single point. even when moving around the point is still 0,0
do you have a motor bearing bearing out? take off the tension and wiggle the shaft… or turn it and see if you hear and noises??
even with your error, can you run the tests, just for fun then again after you find the problem. just to see if it even changed anything?
I will not add the data till after you find the problem, but just for fun sounds interesting to see how much it is effecting your setup ?
~Russ
My printer is partially dismantled to find the source of the grinding sound, and to do some work on my piezo probe setup. Once I find the time to work on it again I'll try and run your tests.
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Just been thinking about the endstop test. The issue is reference points isn't it? Since the endstop is the reference point for the axis the only way to test it would be to create a hard limit somewhere, for example with rails, clamping something onto the rail say 5-10cm from the endstop, then moving the carriage/s manually to sit against the hard clamp point, then homing and then move back under power to the hard stop noting the distance travelled. Repeat this process 20-30 times and you have an endstop repeatability measure which is not dependant on the sensor at the other end of the travel (in the case of a delta say). Sure you could do this potentially with endstops at either end of the axis, but I have never had this setup even when I had a pure cartesian machine, and I certainly don't now I have 2 delta's and a corexy.
You could then swap in a different endstop - Idris has a piezo endstop system in the works which I'd love to compare to microswitches and opticals.
Can anyone think of any easier way to do it?
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I think the best thing to do is just test it agents its self.
that's kinda what your doing on the Z probe. ( home > test distance from home > check against the average)
so, for fun you could home the printer, disconnected Z probe, connect the end stop in its place, reverse the motor. and send the same z probe commands. This would tell you how repeatable "going home" is…
you could probably do all this in software configuration with out ever moving a wire around...
just some ideas for you to chew on
~Russ
