4th axis- planetary vs harmonic?

[walter]

I`m interested in adding rotary 4th axis to DIY-CNC Router Table Machine.

Some people use planetary gearhead for that purpose, others claim harmonic drive is better because it`s zero backlash. Has anyone here had any experience with harmonic drives?


Thanks

[Evodyne]

Originally Posted by walter I`m interested in adding rotary 4th axis to DIY-CNC Router Table Machine. Some people use planetary gearhead for that purpose, others claim harmonic drive is better because it`s zero backlash. Has anyone here had any experience with harmonic drives? Thanks

Walter,

Hi! There are a few discussions about this going on right now-look at some of the 5-axis threads. Personally I plan to use the harmonic drives-for exactly the reason you meantion. I suppose it really depends on what you are planning on making (required tolerances, etc.) on the one hand and cost on the other. At any rate, take a peek at the other threads-it may help. Good luck!

Lance

[walter]

Thanks Evodyne, good info.

I read about harmonic drive accuracy and low backlash. I`m a bit concerned about longevity... Some estimastes say 3000 hrs vs 30000 hrs with planetary gear based systems. Seems like a big difference, harmonic drives are not cheap..

[Evodyne]

Originally Posted by walter Thanks Evodyne, good info. I read about harmonic drive accuracy and low backlash. I`m a bit concerned about longevity... Some estimastes say 3000 hrs vs 30000 hrs with planetary gear based systems. Seems like a big diffefence, harmonic drives are not cheap..

You may want to look at Harmonic Drive Technology's site for more info on expected life.

Lance

[walter]

Yeah... They mention the 3000 hrs number too. And say that actual life would be 5 times longer. Not bad.

By the way, Evodyne. Do you have any good harmonic drive source?


Thanks