servo wheel compaibilty fut,jr,hitec ??? - Page 2 - RC Groups
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Jun 06, 2009, 03:35 PM
Registered User
Quote:
Originally Posted by A Useless Geek
Let's get this thread back into operation, fellas. We need to collect as much data as we can about all brands of servos and their output shaft characteristics as we can reasonably do. Anybody who has taken good measurements or who has access to manufacturer's data please post up here, eh?
Servo - Horn arm Spline Count and Inter Brand Compatibility will continue to update.
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
Last edited by A.T.; Jun 07, 2009 at 07:13 AM.
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Jan 10, 2012, 06:07 PM
Registered User
Hi everyone, this is my first post here.

I was searching on the Net for "servo spline dimensions" and could not find what I wanted, so I did my own measurements. I took a Hitec HS-422 servo and measured the spline shaft. This shaft has 24 teeth, and has a 0.2263 inch diameter.

I then took the servo horn and cut the female spline , so I ended up with a "Donut" shape part. Took the part to where I work and used a optical comparator to measure the inside of the spline ( magnified 50x ) and I came up with this: major diameter = 0.224" and minor diameter = 0.204".

I also measured the female part with a "Gauge Pin", the 0.207" pin was loose and the 0.208" was "snug" .... so a difference of 0.003 - 0.004" between optic and micrometer...not so bad...

I could not measure (other than with the optical comparator) the inside major diameter. but the 0.224" measure is close enough to the 0.2263" of the shaft, meaning that there would be an interference fit of 0.002" which is a lot (I think !).

I'll try to put some drawing when i find how.

JP
Jan 10, 2012, 06:16 PM
Registered User
here are the picures....
Jan 10, 2012, 09:39 PM
Registered User
Evan D's Avatar
I use alot of different brand servos, many being rebranded Chinese servos. I have a very large drawer of Futaba full size servo arms/ wheels and a large drawer of JR full size arms and wheels. I have a small collection of other arms and wheels in plastic baggies with what servos each set uses. I think I have about 15 different sizes/ splines.
Jan 11, 2012, 11:28 AM
just Some Useless Geek
JP, you are the man! This is exactly the kind of data we need for this thread, and the kind of stuff that the OEMs don't bother to publish. More info along these lines will allow us all to mix 'n' match servo components from differing OEMs. Keep it up, eh?

Oh, and don't forget to follow the link in Alan's post, above. He's got some number listed there as well.
Jan 11, 2012, 03:16 PM
Registered User
The reason I need the spline measurements is to be able to draw the spline in google skethup and keek on drawing a timing pulley around that, and then send my drawing to shapeways and have my pulley made in plastic !!! (3d printing) . I will be using continous rotation servo. my next task is to measure a 23 teeth spline ( Spektrum servo).

JP
Jan 11, 2012, 04:42 PM
Registered User
Quote:
Originally Posted by jappie
The reason I need the spline measurements is to be able to draw the spline in google skethup and keek on drawing a timing pulley around that, and then send my drawing to shapeways and have my pulley made in plastic !!! (3d printing) . I will be using continous rotation servo. my next task is to measure a 23 teeth spline ( Spektrum servo).
JP
Why not utilise the standard Hitec pulley? as attached. must be cheaper
unless a specific size is required for direct drive
JR also provide various size disc horns which are easily joined to make a drum.
If more than simple marks are required, glue or bolt on a timing disc .
. Servo - FAQ - Resolution - 1 Degree Wheel & Arm for testing.
Refer also to the pictures, especially that showing servo with protrator which includes source
of many online printable units under:
Servo - Horn Arm Spline Count and Inter Brand Compatibility

much more under sub section
"Servo - Alterations, Calculators, Databases, Leads, Repairs, Convert to an ESC or winch & FAQ."
of
"Radio Systems, Accessories, Alterations and FAQ." at:
Alan's Hobby, Model & RC FAQ Web Links

Alan T.
Jan 11, 2012, 05:22 PM
Registered User
Thank for the links !!

my final goal is to have something like this , http://www.shapeways.com/model/33126...ml?gid=sg55747

but for different servo brands.

I could also use available gear or pulley and glue them to a horn...etc...but I'm having fun right now
Jan 12, 2012, 07:34 AM
Objects in mirror are losing
1000MPH's Avatar
I just started a thread on the slope forum about my inability to set Hitec servo arms to 90 degrees when the servo is centered. My problem is the offset is not equal when preparing mirrored left and right servos for wings. I know I can "fix" with subtrim or a digital programmer but I wanted to ask here to see if I missed something simple or the servo arm offset is something well known.
Thanks,
stuart
Jan 12, 2012, 03:04 PM
Registered User
Quote:
Originally Posted by 1000MPH
I just started a thread on the slope forum about my inability to set Hitec servo arms to 90 degrees when the servo is centered. My problem is the offset is not equal when preparing mirrored left and right servos for wings. I know I can "fix" with subtrim or a digital programmer but I wanted to ask here to see if I missed something simple or the servo arm offset is something well known. Thanks, stuart
Servo Horn Centering - Spline Count. quote:
"Unfortunately, simply turning a servo horn around does not work with all servo types, especially standard Hitec servos which have a 24 count spline - Only those servos with odd numbered splines (say 25 spline) can be turned around to aproximate center position. Even then some sub trim may still be required. Gone are the days when servos were hand assembled and hand set for centre point to be at 90 degrees. There will always be variables with current production methods, no two pots absolutely identical. -(excludes digital servo.)

Use best mechanical setup and never max out all trims:
. EPA, ATV, Dual Rates & Expo Differences & Caution + ESC BEC Set Up

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links"
Jan 12, 2012, 04:34 PM
Objects in mirror are losing
1000MPH's Avatar
Thanks, Alan, I checked your FAQs first but must've missed that entry.


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