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Comment by cassac | Hacker News Reader

Well we don’t really know that an accelerometer is needed for input shaping for a nozzle that is only accelerating across a single plane. The mk4 nozzle only moves on one horizontal axis when printing not two like the XL and the Bambu. Not that I don’t trust your take, but Prusa usually has their ducks in a row and I expect this to be no different.

I don’t care about any features of the Bambu line and would continue with Prusa line. They are nice sure but they aren’t that much cheaper with that much better features. You didnt really mention these jaw dropping world changing features so feel free to fill me. I hope it’s more spaghetti detection.

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You’re forgetting that z hops are a thing. Even in a single axis the load from Eg the filament reel depends on the actual weight of the reel, and there’s almost certainly some variation in the cast aluminum frame parts (internal voids are I’m told an inevitable happening in aluminum/metal casting at scale). I assume the input shaping also would be needed on the bed slinger element as well.

As for the bambu, I’m getting voron level performance out of it, though admittedly with a much less open machine. I was using a prusa mini much of the past year but I quickly hit a lot of rigidity issues with its frame that were impossible to address without a total rebuild.

I guess for me the issue is simple: most of the plastics which I want to build stuff with (whether for engineering reasons or haptics of how they flex and feel) really require / benefit from enclosed printing. Pla is an incredibly strong material, but it can’t really handle any flex without brittle failure. And I just don’t like that.

I’m also in the process of putting together a voron v0, which I expect I’ll use even more due to sheer speed and ease of heating.

Nylon and asa and tpu are just so much more gratifying in my use cases.

What do you think about CPE/Chlorinated Polyethylene? Works fine for me on a Prusa i3mk3s in a room heated to 75 degrees F, with limited drafts (make a tent/enclosure if you have to)

I’m not familiar with it! If it’s a fun material great! While the fumes from any filament require serous caution for long term health risks, I’d assume anything with chlorine or fluorine pose some acute health risks? (I make sure I run these machines in a fully ventilated area that is rarely occupied with a person, in my case a spare bathroom )

I built an enclosure for my prusa out of a 20 dollar tub, so I don’t consider an enclosure like a big thing because they are easy to make. If I didn’t bespoke my own I would have made the ikea enclosure.

I can print tou all day, you can’t really compare the mini because it’s not direct drive and it’s a Bowden. I bet if you had a proper MK3 you wouldn’t have any issues with your filaments. The mini is the mini for a reason. I want to do asa and nylon but the fumes… eww

Very true!

What I was trying to articulate is that a bed slinger motion system requires a much larger enclosure than a core xy motion system or other fixed/z axis bed designs. So that if you have any real estate constraints and want an enclosure, bed slinger becomes non viable. :)

I agree that the fumes are bad, I use a spare bathroom with always on ventilation for mine.

The unfortunate thing is that the volatilized chemicals/ and particles in pla and petg are also not super great for people, they’re merely less terrible smelling

>Well we don’t really know that an accelerometer is needed for input shaping for a nozzle that is only accelerating across a single plane.

Input shaping requires an accelerometer for calibration. On a bedslinger like the Mk4, you need two sets of measurements - one for the toolhead and one for the bed, because both are moving and both can experience different resonances. The Prusa solution is to pre-calibrate input shaping from the factory; this is less than ideal, because printer resonances can be substantially affected by the surface that the printer is sitting on. The user could re-calibrate input shaping, but that would require them to connect their own accelerometer module to the motherboard and find some means of jury-rigging it in place.

https://blog.prusa3d.com/announcing-original-prusa-mk4_76585...

I’m not sure what you are trying to say. It sounds like you are saying that because they are factory calibrating it, it’s not needed… so then it’s not needed? What does it matter if it’s less than ideal if it produces satisfactory results? Results are the only thing that matter and Prusa is consistent with producing them so I’m not sure why this is different?

>What does it matter if it’s less than ideal if it produces satisfactory results?

Input shaper calibration is affected by the surface that the printer is standing on. If your workbench happens to be more or less rigid than the surface the printer was calibrated on at the factory, the calibration won't be accurate. The input shaper could fail to correct for some resonances, or correct for resonances that don't exist. This will cause visible artefacts in the print.

Other printers at a similar price point offer one-touch calibration of input shaping, or automatically calibrate before each print as part of the homing and warmup routine. On the Mk4, you need to buy an accelerometer module, figure out some way of attaching it to the printhead and the bed, then run the calibration routine twice.

Yes we do, because the accelerometer is used to measure resonance on all axis when the printer vibrates at speed. Check the Klipper documentation to see how it works.

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