[raychar1234]

Hello everyone,

I bought an used harmonic drive from Ebay, it claimed to be a model of SHF-17-50-2UJ and of reduction ratio 50:1. Because there was worn out in cross roller bearing, I needed to disassembled it and replace a new one in it. At first, I didn't check the reduction ratio before I did the disassembly....

After everything done and also installing it to my 5th axis. I checked and found the ratio is incorrect! It actually is 51:1.

From the outside looking and the marking on the housing, it looks an original "HD" brand. What is the wrong with the ratio? Is it due to my incorrect assembly of spline into the inner gear ring, but the drive runs smooth?? Will one of the gear inside is not an original brand and of incorrect teeth number?

Can anybody help?

Thanks,

[Alan XR8]

Hi Raychar1234,
Do a search on cnczone for hd drives. I do recall it mentioning about the drives being 1 out on the ratios.


Alan

[RCaffin]

Hi Raychar

The drive is fine. That sort of HD can be mounted in several different ways. One way gives a 50:1 reduction, while another way gives 51:1. Get the manual from Harmonic Drive and read all about it.

See http://www.cnczone.com/forums/linear...gineering.html for how I used a similar HD to make a (very nice) rotary table for my CNC.

Cheers
Roger