Z axis: ball screws vs belts

o_lampe

@3dpmicro said in Z axis: ball screws vs belts:

And lastly it's good practice to consider using whole steps when setting resolution as micro stepping once was shown to be far from accurate. Maybe that's changed with the new drivers in the last few years but I doubt the motors have.

The counterweight idea is interesting.
I'm using a mix of 3x cheap ballscrews and a belt reduction with a single motor. The bed never drops, but I have 2500steps/mm at 16:1 microstepping. I'm sure, with three motors, it will not drop either with belt reduction or without.
I reduced u-stepping to 4:1 once but than the mesh-leveling moves of the Z-motor turned from the common sizzling/hissing sound to farting.

3DPMicro

@o_lampe what is the lead on your ballscrews?

o_lampe

@3dpmicro
1204 from robotdigg

cdl1701yahoo.com

@mrehorstdmd I am using ball screws with a 300x300x10 bed and they do not drop when the motors are disengaged, but, the bed does move easily when pressed with I would say about a pounds worth of pressure.

3DPMicro

@cdl1701yahoo-com how many ballscrews and what is the lead?

fma

@sebkritikel said in Z axis: ball screws vs belts:

I believe your next problem will be potentially destroying a driver on your board from the back EMF.

I never destroyed a driver, even by moving hard the gantry.

Have a look at this vidéo (from quebec): https://www.youtube.com/watch?v=PCpfXJV89WA

fulg

@fma said in Z axis: ball screws vs belts:

I never destroyed a driver, even by moving hard the gantry.

It depends on your driver... Twice I have killed a TMC2100 by moving an axis while unpowered (and not fast either). Granted those were the old Waterott boards, you can buy an extra board to protect them now.

I have not blown a driver otherwise, and not for lack of trying. But it can happen (if rarely) depending on your hardware.

On an unrelated note: I think I remember you from the ORDBot days, do I?

zapta

@fulg said in Z axis: ball screws vs belts:

Granted those were the old Waterott boards, you can buy an extra board to protect them now.

Some boards such as SKR use small driver modules that can be easily replaced with no tools. Not as elegant and dense but functional.

fulg

@zapta I believe Waterott was actually the first provider of Trinamic drivers in Pololu Stepstick form-factor (with the chip on the back side so you could put the heatsink on the correct side of the PCB!), but the lack of physical space means no protection diodes. They are easy to replace but they are also quite fragile, at least the TMC2100 model.

Dad003

to get good quality you will have ot spend a lot for a good ballscrew , belt is cheaper but platform will go down when not powered , i went from cheap leadscrew to belt and belt made my printer 1000x better on Z for quality

fma

@fulg said in Z axis: ball screws vs belts:

On an unrelated note: I think I remember you from the ORDBot days, do I?

Yes! What a memory!!!

fma

@dad003 said in Z axis: ball screws vs belts:

to get good quality you will have ot spend a lot for a good ballscrew , belt is cheaper but platform will go down when not powered , i went from cheap leadscrew to belt and belt made my printer 1000x better on Z for quality

Good to read that!

fcwilt

@dad003 said in Z axis: ball screws vs belts:

belt is cheaper but platform will go down when not powered

Not necessarily. I have 3 Z steppers with 5 to 1 integral planetary gear boxes. The bed does not drop when power is removed.

Dad003

@fcwilt i have 2x60mm nema 17 in a pulley box going from 20>60:20>60 , but i know my platform that hold the bed is heavy which is why it goes down when off

timcurtis67

@fma
I have a 450mm X 450mm bed (.250" thick) on 2 lead screws with 8mm travel per revolution. They are the 4 start style lead screws. I drive it with a nema 23 stepper.

No issues with the bed dropping when the power is off but I can push it down with some slight pressure.

mrehorstdmd

The 30:1 worm gear reducer stops the 3.5 kg bed assembly (tested to 4kg additional load) in my printer from dropping when power is off, and I can't make it drop by pushing down on it. It has one motor, driven by the Duet board driver, and two belts that do the lifting. Worm gears FTW! There are no sync issues, and the bed is in in tram at all times. No sensors, no extra motor drivers, no extra wiring, no configuration issues. It all "just works" every time. The only downside is that I can't make youtube videos of it. There's just no excitement at all...

o_lampe

@mrehorstdmd
I remember your worm drive was quite expensive and not easy to get outside U.S.
What was it's name? Rhino-something...

zapta

@mrehorstdmd said in Z axis: ball screws vs belts:

no extra wiring...

It was replaced with extra belting.

mrehorstdmd

@o_lampe https://www.ebay.com/itm/Rino-Motorized-Rotary-Table-Stage-CNC-4th-Axis-Sherline-Milling-Engraver-Router/191714031261?epid=711126295&hash=item2ca30bf69d:g:A7UAAOSwPhdVB2f0
$108 shipped. You get the motor and worm drive already integrated. Compare that to the cost of a motor and brake, or buying a motor and separate gear box. This type seems to work fine, too, and can be bought via aliexpress in whatever country you're in: https://www.ebay.com/itm/NEMA17-Turbine-Worm-Gear-Stepper-motor-Hybrid-2-Phase-4-wires/324001642095?hash=item4b7000b66f:g:HTMAAOSwEGVd50j1

@zapta Yes, belts instead of wires and connectors. How often have you heard of wiring problems vs how often have you heard of belts failing? I suppose ineptitude in wiring can translate to ineptitude in mechanics, so they're probably even by that measure.

zapta

@mrehorstdmd said in Z axis: ball screws vs belts:

How often have you heard of wiring problems vs how often have you heard of belts failing?

Chances are your printer has many more wires than belts so more room for failure.

BTW, I just started to collect parts for a Voron V2.4. If I got it correctly, the design has 8 (eight) belts and 16 puleys/idlers just for the Z movement, so belting can be fun.