Whelp, IGentUS is looking like it’ll be taking another diversion before making that first print. There’s NO way GT2 belts and 40 tooth pullies are going to be able to haul about 6+ lbs of build plate, insulation, glass, heater, and object-to-be-printed.
So…metric leadscrews. times 2. Aliexpress?
Problem the first: 10mm shaft. Problem the second: it was jumping teeth with nearly a static load. And DEFINITELY jumping teeth just trying to lift the assembly by turning the shaft.
Might be able to use a @Shauki method of four pullies and one worm screw…but I liked the one method with two screws, one motor, and gt2 belt. (@Eclsnowman ?)
@Mike_Miller I love the joined drive lead screw. It’s the only way I will ever do it moving forward. The bed on HercuLien and Eustathios have been bombproof (zero maintenance). I have not adjusted either for a long time. HercuLien has been printing non stop since it came online and I haven’t touched bed level since. Go 20 tooth on the motor and 32 tooth on the screw. Its a great ratio.
@Mike_Miller also I really like the Misumi screws and nuts (HercuLien has composite nuts, Eustathios has brass). And get some superlube silicone lubricant from Amazon for the screw… You will thank me.
The 8mm screwes from open builds are nice. Multi start so that will hurt you a bit on efficiency but they are fast. The LulzBot have moved to 10mm misumi screws and poly nuts. I’ve been running 7 machines at work for the last two months without a hiccup. They are nice screws but about twice the price of open builds.
In a pinch I used 8mm fine thread on my corexy when it was first built. Worked great, no real quality improvement from them to lead screws… Just had to decrease max z acceleration to avoid issues at first. But superlube made them really nice too.
1mm pitch so crazy z resolution http://www.mcmaster.com/#98861a320/=tn55vn
Not that I recommend belt-driven Z, but you could probably get rid of the belt skipping problem by using an idler bearing (or two) against the back of the belt on your belt pulley, the same way we grip filament between a drive gear and an idler bearing.
@Whosa_whatsis Probably, but I’m getting the feeling I’m approaching the material limits lifting 6+ lbs with two GT2 belts and there needs to be an added mechanical advantage…what’s disappointin is: I think I had the drop concerns solved…belt of filament wrapped around the shaft with a spring tensioner in one direction would allow it to move in one direction freely, then grip the shaft to provide drag going in the other direction.
@Eclsnowman Lots of good ideas there, I’d pick up a little vertical travel (I’m gave up a few inches to have a single length order from IGUS). Gotta ruminate a bit.
@Mike_Miller Why don’t u use 3 vertical shafts? Think about it. That way you divide the load for each stepper not by 2, but by 3, and you can also level your bed very easily. No need for springs etc. I have this setup working on a build plate measuring 45 X 45 cm, with heated bed, and it works like a charm. For heating i’m using a bread-toaster which I installed underneath it, so its a bit heavy. I could not get it to work reliably with two big nema 17 steppers, but could with 3 small nema 17 steppers. Solved a lot of problems.
Wow…that’s an outside the box thought. Run all motors from the same wrong harness, then turn whichever leg you need to for leveling.
let’s just say I’m allergic to boxes. Sometime that works, sometimes I hate myself for it.
I’ve got three optical endstops, i could see it auto levelling innately.
Do you have all three motors on the same driver? I like this idea.
Yes, I do. But I’m using fairly big drivers. TB6600’s.
@Mike_Miller you can duplicate or slave drivers on a number of boards, but I am not aware (looked for a while) of anyone having a smooth way to use 3 endstops on one axis.
Hope you post the direction you decide on, great topic!
My desires are waffling all over the place. Today, I’m thinking of keeping the two rods for guides, and staggering two wormdrives to offset any potential racking due to lifting some distance from the Center of gravity.
O = worm gear
o = guide rod
—O---o—
BED
–o—O–
@Mike_Miller try @Whosa_whatsis gear tension idler first. It might fix the skip. Also if the gt2 gears are printed skipping might be an issue. I find printed gt2 gears to be problematic.
All of the gears are machined, and I’m awaiting a few more because I’m a couple short. I may be able to drive the z stage with belts and two motors, but that may not be necessary.
You can always hook up multiple endstops to the same input. If they’re normally-open, wire them in parallel, if they’re normally-closed, wire them in series. Either of these ways, the endstop pin will be triggered when any of the switches is triggered.
Now, if you want to be able to home each one individually, that’s a different story, and would require significant firmware modification to treat each one as a separate axis. I’ve looked into the same thing, and I think Smoothie is a better starting point for implementing that than Marlin.