What’s the easiest low-tech soft landing for belted-Z that will not affect Z height and doesn’t involve electromagnetic solenoids/latches/etc that you can think of? I see more and more super high corexys out there, approaching and even exceeding deltas in height and they use belts. What’s a good mechanism for soft landing in case of a power outage/other such error?
I have thought about many options but always revert back to thinking about some centrifugal break that is small and is driven by the belt itself but can’t seem to be able to put it together in a effective design…
You could put relays that short the stepper pins when the power goes out. Use electronic breaking.
It could be a normal relay that is normally closed, but when energized it opens. And just hook the relay coil to the power supply directly. The relay would cycle 1 time per power cycle so cycle count isn’t a concern.
Note you want to short both poles of the stepper to get maximum breaking.
If you do hook this up wrong, it will fry your stepper drivers.
Another option is to use counter weights and pulleys so the z axis is at a low energy state everywhere in the print. This is what elevators do. They have a pulley at the top connected to a really heavy weight on the sides. When the elevator is at the top, the weight is at the bottom. It reduces the force required to lift and slows falls.
I know this is probably out of reach but as soon as i saw the question i thought of drop tower rides in amusement parks. They have a interesting way of stopping without power. Somthong with magnets and an induced coil. Mabey you could look into that, might be easier that it sounds
@Matthew_Del_Rosso it is actually really simple. A thick walled copper or aluminum pipe and a really strong neodymium magnet. You drop the magnet into the pipe and it slows down. The tighter the fit. And stronger the magnet the more stopping force you generate
Drive the belts with something like a worm gear or a highly geared down system. Both of those cannot be back-driven easily and won’t allow the bed to fall.
@Camerin_hahn This sounds very interesting but I am not good with electronics, haven’t laid my hands on a relay up to now but I’d try if there would be a proper tutorial I could follow. This is one of the good ideas I’ve came across with regards to my terms for such a solution. Thanks will look into it more.
@Camerin_hahn Regarding the elevator counterweight solution , it is not feasible if you do the auto-leveling which I don’t intend to do but who knows, better not hinder myself.
I didn’t know how amusement parks tackle emergency stops but while it doesn’t sound very complicated it means that I need to sacrifice some Z height to allow a magnetic shoe to get magnetized by the vertical smooth rod. But if one uses alu slot that won’t work.
@ThantiK yes gearboxes are the most common sense response except that printed ones don’t offer enough precision and buying ones means either buying it with the motor (didn’t find wormgear based geared stepper motors or their prices are prohibitive) or buying the two gears themselves and printing a stepper mount. I remember even having even thought of somehow implementing a printed wormgear that would be engaged by the moving belt but will not participate in the Z movement. In case of power loss it would not be able to be driven backwards…hmmm, you might have reminded me of a very feasible idea after all… THANKS.
why not just put a piece of foam at the bottom for the bed to fall on to? Also, if the bed falls with that much speed that you need this, wouldn’t that also cause the motors to generate enough juice that they might potentially fry the stepper drivers?
@Steve_M
That’s why I am looking into a soft landing solution. So far @Camerin_hahn NC relay idea and @ThantiK helping me be reminded about an older idea with idle wormgear somewhere along the belt path are the most appealing to me. Neither of them would create speed into the falling bed. Stopping is best and both are promising of achieving that.
@Florian_Ford , I was driving my whole Z axis with a single motor with worm gear and 5mm ss rod across the bottom. Belt drives gears fit on the ends of the 5mm rod.
@Florian_Ford I don’t have any working 3D printers at the moment any more. Haven’t had time to work on them since I build deltas all day. The Azteeg on my delta went out.
I bought the worm gears off of ebay a long while back, and it turns out I cannot find them again to save my life. I got the pair for $10. And yeah, the ingentis was a belt-driven Z…I took it apart to fix some things, and got busy - so it’s only “was” because that machine is currently in pieces. I’ll be going back to the worm driven Z when I have the time.
@ThantiK
Yeah Deltas seem to have a very high rateof adoption these days. Glad to see that. I am on the hobby side though, and not that fast with that either … but I enjoy the ride as is.
@Camerin_hahn Ok, you got me too interested in this shorting the stepper with NC relay method. Is there any easy to follow literature/tutorial about it?
Edit: I’ve been reading a bit on a few sources (https://is.gd/7viVWO, https://is.gd/3t1Zs1, http://www.opend.co.za/tutorials/steptut1.htm, etc) and it doesn’t sound that easy when you are trying to prevent ANY current from stepstick to motor while the internal coils are shorted by the relay. There should be some sort of add-on circuit board that is interposed between stepstick and motor to prevent any current going to the motor or the relay should be positioned between stepstick and motor which means the current to activate the relay should be VERY small (just guessing here, I am in no way an electronics literate)
… but I enjoy the ride as is.