Z-axis without threaded rod, good idea?

Hi all,

I'm going to start building a 3D printer soon.
I was thinking about doing the Z-axis without the threaded rods.
I want to use just a belt.

Do you think this would be a good idea?
Is this even possible? (does this work with the current firmware?)

Any idea's a greatly appreciated.
If there is anyone who made his printer this way, any pictures, documents etc. would be welcome.

Thank you in advance

Edited 1 time(s). Last edit at 12/05/2011 11:24AM by pinaise.

Certainly that can be done! But it might add more components than you want to fool with. You have to have two belts, one for each side, a set of gears for reduction, two driven pulleys connected with a shaft (or two stepper motors with two sets of gears), Two idler pulleys to keep the belts tight.

I don't know... the threaded shaft gives you great gear reduction and is pretty simple... copied on both sides.

Regards,

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

rossfree Wrote:
-------------------------------------------------------
> Certainly that can be done! But it might add more
> components than you want to fool with. You have to
> have two belts, one for each side, a set of gears
> for reduction, two driven pulleys connected with a
> shaft (or two stepper motors with two sets of
> gears), Two idler pulleys to keep the belts tight.
>
>
> I don't know... the threaded shaft gives you great
> gear reduction and is pretty simple... copied on
> both sides.
>
> Regards,
>
> Ross

You make a few good points there, thanks!
I'm trying to make this one out of wood, so i can print the parts and make a authentic one, in this way i can keep this one as a CNC machine.

I watched a video off the Mendel, and it showed that it uses a bigger gear on the threaded rod.
Would I need such a gear or is it possible to use just the size that is used on the steppers?

Thank you!

Hi,

I'm not sure how you're planning on using the belts on the Z axis, but it's worth remembering that the threaded rods don't just provide movement, but also holds the X carriage in place between movements and when the Z motors are turned off. Had you thought of an arrangement that prevents the X carriage from slipping back down?

---

------------------------------------------
garyhodgson.com/reprap | reprap.development-tracker.info | thingtracker.net

By gear, do you mean timming pulley? Have a look at the Prusa-Mendle. The Z-axis threaded shafts are driven directly on each side by stepper motors wired in series. Simple and it just plain works. So much easier with fewer parts than the original Mendle.

Regards!

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

@garyhodgson:

I was thinking about it, the stepper should hold the belt in place while there is power on the motor.
I have no idea about the kinds of loads that will be on the Y or Z axis, so i don't really know if it will work.

ATM I'm just thinking about it, I ordered the parts and when they arrive I'll try various things and see what will work.
I have no experience with any of this and thats why I'm going to like building this, learning new stuff!

@rossfree:

I was referencing to this video: video
In the video it's not really clear if they are timing pulley's or gears.

I'm not sure yet if I'm gonna use the single motor or double motor setup.
But maybe it will be wise to use a double motor setup, after all, steppers are not that expensive.



Thank you for the suggestions and comments.
I'll keep them all in mind when I'm going to build it.
The input you guys gave me helps me think outside the box and about things i have not considered.

Thank you!

Hi Pinaise,

I agree... they really aren't expensive... and when the power is off, with the threaded rods, the Z-axis shouldn't move. Not so sure with spur gears and pulleys. Check out the video below... what a way to build machines... with everyone at the same time. Two day build! Awesome!

Prusa Mendle Group Build

Good luck!

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

yes this is possible, i have been using 35mm film:



as you can see it's wise to add a counterweight, that way if you lose power or if you want to emergency cut all power, your nozzle doesn't come crashing down into the print. i would suggest dual belts at both ends 2 motors 1 driver like a prusa, that's what i'm doing on another printer now.

with threaded rod set up the z motor actually sleeps whilst the layer is getting printed, you have to change that in your firmware (pretty simple in the sprinter firmware) to make it active the entire print.