Accelerometer option OR option to Configure for Weight added due to Mods
I would LOVE to see an option to purchase an accelerometer. This would be for a few reasons.
1) It allows fine tuning the printer head, bed, and belt tensions for each individual printer. This would especially be true for those of us that may add weight to the bed (handles) or the printer head (fan guards) or other mods that a stock 'factory' algorithm will not compensate for.
2) may make the entire process of input shaping have better results.
Hey... the XL has it, so, there should be some good reason... right? ....
OR... a lower cost simpler idea at a compromise.
Other option would be to allow users to input a value for any weight they might have added to the bed and/or printer head (guards, handles, covers, etc ... all of which commonly found on Printables for the MK4). For example, within reason, Prusa could simply add some weight in small increments and run their internal tests for algorithms for the added weight. For example adding increments of 5 or 10 grams weight up to 30-40 grams would allow at least small amount of compensation for such modifications.
Just a thought... curious of what the community things... feel free comment 😉
RE: Accelerometer option OR option to Configure for Weight added due to Mods
I think that the option of entering the masses is not viable, as it is not the only factor affecting the resonant frequencies of the printer.
An accelerometer is the answer. ADXL sensor is just a couple of Euros. I use it with success on my Voron printers.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
If the 'mods' are mostly rigid and it's mostly just added weight, then the resonant frequency of a dummy weight verses the actual mod might be 'close enough' ... but Bad Buchauer, you are totally right... it's probably not the real solution. The best solution would simply be the accelerometer(s). I really hope and pray there is some paid upgrade in the future to help. With my Input Shaping on, I am not getting the best results that I see folks on youtube getting (such as www.youtube.com/watch?v=bT0Rj_d801o )
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Let's look at this from the other side.
Is there something wrong with the MK4 prints during input shaping? Or does it really change that much if I have a few grams more on the print head in relation to the weight of the head? Has anyone already changed something and the ringing got worse?
Of course the ADXL sensor brings accuracy. But what are the actual practical effects on the print?
There is also the option of doing a test print. There you can also see the effects immediately.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
For a standard, adequately tuned printer, I agree that an accelerometer might not bring much (especially when printing using standard profiles).
For modded printers, printing outside the standard print profiles, or simply having a printer that is old and worn, the accelerometer could help fine-tune the input shaping for the particular printer state and specific use case.
Also, we need to remember that for input shaping, there is no one solution that fits all. There are different mathematical models that one can choose to correct the motion. What we've got on Prusa is a model selected by developers as optimal for a typical use that they had thought would work for most of us. And again, after applying mods or trying to use a printer outside of the standard process envelope, that might not be the case anymore. The only way to set up input shaping in such cases would be to use an accelerometer.
From my experience, using an accelerometer on a Klipper-based printer helped me to find out that the printer build had issues (the belt's motion system had loose screws) and also to find the influence of the belt tension on the maximum attenable accelerations.
Now, the question comes to an ADXL sensor that costs around 5EUR. How much would the Prusa version cost? And how much freedom to influence the input shaping functions Prusa developers would give us in the future?
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There is no question that an ADXL sensor is basically a good thing. But you not only have to measure, you also have to be able to interpret the data correctly. That's why Prusa goes the way of keeping everything as simple as possible for the user.
I can't imagine that it's because of the costs. Rather because of the additional effort in development and especially the technical support at the moment. It may well be that something else will come. The connection is there and the developers have used it. The menu in the printer is otherwise pointless. Of course I would order one straight away 😉
You can already try out all the input shapers today and also change the frequency and the damping.
In the beginning it was also the ZV, now it's the MZV.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
I was wondering if there is any way to translate the Klipper accelerometer output to something useful for Marlin and therefore the mk4?
I have an ADXL and a raspberry pi sitting there and I could easily flash Klipper to the mk4, run the input shaping tests, get the result graphs and flash back to prusa firmware if I could then say ‘X needs 1.4 from Klipper equals 37 for Prusa’ or whatever the numbers are.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Any experience with Klipper on the MK4?
Of course you could use the data obtained in this way on the MK4.
The Klipper version of the input shaper runs on the Mk4. You can enter the values with the Start Gcode.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
So the values from tbe resonance tester graphs are the same in Klipper and Marlin?
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Prusa does not use the Marlin input shaper. They have compiled the klipper code so that it is executed directly in the processor.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Very interesting. I’d pay money for Prusa to do their own full fork of Klipper…
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Of course, Prusa only used the input shaper code from klipper. Not the entire firmware. That was misleadingly written by me.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
No no, you wrote it perfectly. I was just adding I’d love them to do a full Klipper fork as well as just taking the input shaping but I’m glad they have and I’m glad I understand now.
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I feel like prusa needs to keep up with the tech and innovations on this front. I have a MK4 i love it. However i've also been keeping my eye on what bambu is doing lately and they seem to be progressing their tech quite quickly. Whether they could get the same thing by tuning the input shaping just for the MK4. I do wonder what innovations an accelerometer would make in the future with more advanced code and innovations. I would have hoped the designers would have at least left this as an 'option' or feature in the future.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Wouldn’t the mk4 need an accelerometer on both the extruder and the bed?
RE: Accelerometer option OR option to Configure for Weight added due to Mods
They are easy to move and if you really wanted they are cheap enough to permanently mount two.
RE: Accelerometer option OR option to Configure for Weight added due to Mods
Good deal! Proprietary info notwithstanding, I wish Prusa would publish data showing that they have input shaping dialed in good enough w/o equipping every printer with an accelerometer and software to calculate it for each individual printer regardless of the user’s set up. Maybe someone w/ enough time and expertise will run the trials and publish the results for this type of stuff on YouTube and get a bunch of views.