It will not work for X at all, and no need trying for Y either, it will hit the Z stuff. Trying to make it work for everything means you might as well start a whole new printer. I think it’s best if you just focus on Z, but that is up to you.
There are Z max stops, no point in a soft landing you drive it to max 99.9% of the time. If you have failure, the brake will let it down slowly. So in either case there is no need for a landing pad. If it drops too fast you pop something.
If you want a backup for the backup a USP is a better option. If your power goes out enough to worry that much get a UPS and if it gets tripped, have it immediately stop and drive to Z max.
There are only so many redundancies that are worth it.
I have had MULTIPLE bed drops and never blown up a board (damn, i just threw that out to the universe…). I AM using the M8P so maybe it has better protection built in… not sure.
What is different is that I am not using the plate to connect the z drives. I did a 2020 T. Depending on what the stock plate is could make a difference in the weight enough to drive the drop faster than the standard stepper drops at.
Also, through a screw up I used smaller steppers in the beginning. I had to replace the AB steppers as I had issues but the Z steppers are the same. Amazon.com. They are 42nm and are 10mm shorter bodies. This also adds up to less weight but no issues with lifting. I have a 1/4 inch 300x300 bed with magnet and pei sheet on the printer.
Yes great point, we could easily get away with tiny Z steppers to lighten the load and generate less back current, and the new design is already a T extrusion.
That combined with a spring or basic relay and I think we care more than safe.
The other idea I had but have not been able to get a chance to try to make it is an inertial catch lever. Basically if the bed drops the inertia causes a lever to swing into one of the rail holes and and arrest the drop.
Might not be able to access the holes due to the belt but it could be a printed rack on the side of the upright,
So I have the M3 trick on the bottom of the Z belt, and I had this style for the top…I don’t like it. It seems flimsy. I am going to do the M3 on the top as well. It is pretty easy to get the length right that way and there is a ton of adjustment room if you’re lazy, like 10+mm.
I think I have the geometry right, pretty sure this is going to work well. The angles do vary a bit I will do some size changes and see how it looks. Pretty sure it is only a degree or so, probably not enough to really matter. If the build is remotely near 300mmXY.
Need to find some nice squishy silicone for springs and spacers.
That could work for the bed frame to Z steppers, but need something for the bed itself to the extrusions.
Like 5mm silicone standoffs, it can be cut hose, but that is actually hard to get nice and accurate. I do have some springs.
Ummmm, It is just about done.
So I need the X rail to plate nut holder and Y endstop bracket and this thing is just about there. Put in some frame and see what it looks like. There have not been many optional things to ask about so I have just been chugging along.
Oh and swap that top Z belt mount to a M3 style.
I think most of the parametric stuff is finally working. Might need to catch a bug or two with the new bed stuff.
If you are not interested in the extrusion style bed frame it would not take too much to make it a plate.
If you do not have or want to drill a middle hole (three point mount) a bed plate is probably the better option, although you could obviously add the extrusions to support the bed corners on that T.
28 days since the first post, slow but not horrible. Worth the extra time to get all the feedback and opinions.
I fine tuned the height of mine with sandpaper. Since the bed self levels anyways, having the bed slightly higher by a mm in one corner auto corrects itself.