Building a 3d printer because parents won't let my get another off the shelf one

[sharp musk]

Also the whole printer will be modular so i can choose what part to build

[naive elbow]

I like the title

[spare needle]

malicious compliance 😄

[mellow lodge]

Those profiles looks massive

[sharp musk]

4040

[fallen nymph]

These are Nema 23s? The mounts will flex from the tension and drive force, shafts won't be happy either

[sharp musk]

ok? what are some suggested solutions

[fallen nymph]

Make stepper mounts stiffer, check if you can stay within max radial load rating of the stepper or if you need to go for double shear

[sharp musk]

thicker motor mounts?

[fallen nymph]

Add trusses etc

[sharp musk]

example?

[fallen nymph]

https://en.m.wikipedia.org/wiki/Truss

[sharp musk]

hmm, i feel like theres some potential in this idea

[fallen nymph]

Yes, that's why you see trusses everywhere, because they work and they're great

[sharp musk]

ok

[sharp musk]

good?

[fallen nymph]

The mount will bend like this

[sharp musk]

trussed

[fallen nymph]

It'll bend right here

[sharp musk]

im designing a plate like thing to connect both the top and bottom mounts from the right

[fallen nymph]

You want it to work in shear

[sharp musk]

what that mean?

[sharp musk]

Bed tilt leveling and maybe multi axis printing? idk will this work

[fallen nymph]

Plate won't be stiff in this direction

[spare needle]

Look up maxwell kinematic mounting, far easier

[fallen nymph]

Especially considering that this one is overconstrained as
w = 7 × 6 - 9 × 5 = -3 (it's removing 3 degrees of freedom more than it should)

[spare needle]

no idea what you just calculated so I'm taking your word for it 😄 I just looked at it and my brain said " Nah, doesn't look right. Hows that supposed to be moving? Tilt "

[fallen nymph]

w is mobility
Every moving assembly gets 6 degrees of freedom at the start, hence 7 × 6 (2 pieces for each arm and the bed, gives 7 total)
From this we subtract the amount of degrees of freedom each joint takes. There are 6 linear rails that remove 5 DoFs each and 3 simple rotational joints removing 5 DoFs total
Both of these give 9 × 5
So we're starting with 42 DoFs and we're removing 45 DoFs

[sharp musk]

im a kid with a printer and i don't understand this stuff. please elaborate

[spare needle]

Thank you. I have to say, I love reading your replies in general. Learning every time 😄

[sharp musk]

um... what does this mean

[spare needle]

was a reply to Deddy

[sharp musk]

i just copied the stuff off hevort printer cad

[sharp musk]

i just need tips on how to improve lol

[fallen nymph]

Hevort uses spherical bearings

[spare needle]

they use these short rail segments instead of a steelball and 2x2 cm of steel rod

?

[fallen nymph]

Yep

Hevort Z assembly

[spare needle]

to my untrained eye this seems overly complicated......they probably have a good reason for it

[sharp musk]

yeah thats what i tried to copy

i just used a ball bearing because i don't know what the weird screw thingy is

[fallen nymph]

Rod end spherical bearings

[fallen nymph]

Now replace simple rotational joints (which remove 5 DoFs) with spherical joints (which remove 3 DoFs) and recalculate

[sharp musk]

they look like this? are there standard part numbers or something?

[fallen nymph]

Yes to both

[sharp musk]

nice, but i think il probably use the thing i designed for now because i don't have the patience to wait for hardware to arive

[grave coral]

It wont work

The issue is that if the bed tilts you only have forwards backwards rotation in the bed mounting so at a minimum 2 of the mounts are going to be twisting in an axis they dont like

You need the spherical bearings for the design you have

Oop somewhat late reply, didnt notice the dates

[spare needle]

Still relevant

[fallen nymph]

Yep, missing 6 DoFs freed to run triple Z

[grave coral]

^

also is there any benefit to gearboxed nema 23s on this

[fallen nymph]

N32s don't seem gearboxed

[grave coral]

what's this thing then?

is that not a gearbox?

[fallen nymph]

Probably couplers to get 5 mm shafts since N23s tend to have 8 mm

[grave coral]

I just assumed it was a small reducer or something

[grave coral]

ah that would make sense

I feel like it would be easier to just bore out pulleys though

fairly easy on a drill press

[sharp musk]

i don't have drill press,

[sharp musk]

no

[sharp musk]

yeah

[fallen nymph]

Remember that it causes high radial load

[sharp musk]

i don't understand this stuff elaborate.

[fallen nymph]

Belts will be pulling on these shafts in a radial direction, this load will be a significant distance from the stepper flange, so the stepper shaft will have a high bending load that'll be changing directions (as the stepper rotates) which causes fatigue breaking of the shaft

[sharp musk]

so fix it at the top as well

with a beating

*bearing

[fallen nymph]

Remember that you need to align this bearing to not cause binding and extra radial load