why servo ratings in kg/cm not oz/in?

[fz1dave]

Why is the hpi sf50 servo rated at 12kg/cm? Does that calculate to1077.03 oz/in? My math must be wrong because that would be the strongest servo inthe world and no slouch in speed at .18 seconds transit speed. So does anyone have a rating for this servo?

 

[xtremsavage]

That's because HPI is based out of Japan, hence the rating on the servo. I believe it equals to 423 oz in. but, I could be wrong.

 

[xtremsavage]

I was wrong. According to tower hobbies, it's 266.6 oz in of torque.

 

[FastEddy]

The USA is the ONLY country that measures in imperial.
The rest of the world (A majority of the people in the world) use metric.

If you have been in the hobby for a while a majority of the companies have switched to metric size screws and bearings as well.

 

[X]

The problem lies in how it's calculated. For the case of a servo 1 kG cM = 13.88 Oz. In.

So the servo is 166.65 Oz. In.

 

[fz1dave]

Why is it converted differently? Anyway is that servo any good?

 

[X]

I'm no expert, but here is a good explanation I found on another RC site:

"It helps in figuring out how to do the conversion if you write the units correctly. Units written as kg/cm and oz/in imply that torque is force divided by distance, but it's not. Since torque is actually multiplied by distance (you get more leverage with a longer arm), the correct units are kg-cm and ounce-inches.

Since there are about 35.2734 ounces in a kilogram and 2.54 centimeters in an inch, the correct conversion factor is 35.2734 / 2.54 = 13.88 ounce-inches/kg-cm."

 

[fz1dave]

So, you can't convert oz/in to lb/ft just by converting ounces to pounds and inches to feet then?

 

[X]

Yes, but again you are calculating incorrectly for a servo. oz/in does not mean the same as oz-in.