New machine build - block and tackle style belt drive for z axis?

I am working on a new build. I was considering using a belt drive for my z axis. The following image shows a system of pullies that move the gauntry up and down. The belt would be attached to the gauntry on the right side.

This will give a mechanical advantage of about 6:1. The block and tackle style pulley system would reduce the required torque at the motor and give a smaller minimum layer height. Has anyone tried something similar? Do you see any problems with this design?

Thought about a similar principle but with another background -

Building a cross axis Y on X normally requires a motor for the y axis on the X axis - which increases mass on the X axis
The upon method could ( in case that x and y motors would be installed on the baseplate and the y motor would be driven in differential way in relation to the X Mmotor prevent this mass. problem ( the y Motor would have to work somway more but the x axis would just have to carry the building plate load + the someway longer belt!! ( and cabling would also be easier!)



However this would probably need coding as I dont know, if differential drive would be embedded in any Firmware...

Hj

Edited 1 time(s). Last edit at 08/16/2013 04:32AM by Optimist.

Hi quickness,

i guess it would work, but to my opinion it's a very complicated desig. Which advantage do you see in using a belt for the Z-axis instead of a screw?

Optimist,

there is an implementation for differential drive in some firmware, but id don't know if this would suit your setup. The implementation i know of is for the CoreXY-Setup. If it does not fit driectly it could possibly be adapted.

best regards

--- Lars ---

@quickness

HBot has a routing similar to what you have.

Hbot
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I see a combination of two problems. This will exert more force (by a factor of 3:2) on the end of the gantry to which the belt attaches, and it relies on bearings that may be widely separated to keep the gantry level. So, I think it will pull one side of the gantry higher and bind the bearings.

Have you seen the belt arrangements on some of the Tantillus variants?