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Author Topic: gear measurement for servo motor  (Read 800 times)

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Offline pedenskiTopic starter

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gear measurement for servo motor
« on: July 14, 2013, 08:18:18 PM »
im quite new in the mechanical engineering and not familiar with gears and motors yet, few days ago, i bought a second-hand GWS servo motor for my project, and it didn't include gears.

can someone help me how to know the correct measurement of my motor so i could buy the correct gear that could fit on my servo motor. specifically, the measurement of the gear 'hole'

here is a pic http://i43.tinypic.com/2ekktw7.jpg

Offline waltr

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Re: gear measurement for servo motor
« Reply #1 on: July 14, 2013, 10:08:22 PM »
What you need is called a 'servo horn' to put on the servo's output shaft.
The gears are already inside the servo housing.

Google "GWS servo horns" and you'll find lots available from many sources.
You will also need a screw that goes into the end of the output shaft to hold the horn in place.

Offline pedenskiTopic starter

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Re: gear measurement for servo motor
« Reply #2 on: July 14, 2013, 10:49:15 PM »
hi waltr,

im actually looking for a gear, instead of a horn. i need to directly attach a "gear" on the shaft.

upon searching for servo gears, there are various sizes of "middle holes" and i need the specific diameter of "middle hole" that could fit on my servo motor.

there were suppliers that provides plastic gears and rack, but they were too big for my servo.

is there a standard way on measuring the middle hole diameter so i could give the correct specs to the supplier?


Offline jwatte

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Re: gear measurement for servo motor
« Reply #3 on: July 14, 2013, 11:03:31 PM »
Yes; standards are typically in fractional inches, or in whole millimeters (e g, 1/4", or 3mm, or whatever.)
Get a good set of calipers, and measure your output shaft diameter. Note that 1/4" will be 6.35mm, whereas 6mm will be 6.35mm.
Also note that holes are often "press fit" which means it will be very tight -- you may need an arbor press or similar to actually mount the gear.
Anything with a set screw in it will not have that problem; there will be slop (slip fit) but I don't know of a series of pinion gears that come with set screws.

The specifications for your servo should specify the output shaft dimensions, btw. Reading that would be safer than measuring yourself.

Offline pedenskiTopic starter

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Re: gear measurement for servo motor
« Reply #4 on: July 14, 2013, 11:21:24 PM »
thanks jwatte,

the picture attached, didnt seem to indicate the shaft dimension, ive also looked for the datasheet but it didnt mentioned anything about the shaft measurement. i guess i just have to measure it myself.


Offline pedenskiTopic starter

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Re: gear measurement for servo motor
« Reply #5 on: July 15, 2013, 01:54:05 AM »
am i safe to say that the diameter of the shaft is 5mm?


Offline jwatte

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Re: gear measurement for servo motor
« Reply #6 on: July 15, 2013, 10:05:44 AM »
That's not a shaft, that's a spline. And, looking at your ruler, it looks like the outer diameter of the spline is about 5.5 mm.

I think the best thing you can do is to get a round servo horn that is known to fit, and then put (glue? expoxy? screw?) a gear of some sort onto that horn. integy.com has a number of round servo horns for 23T, 24T and 25T splines. Do you know which of those your GWS servos are using? (Google ought to know, at least)

Offline waltr

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Re: gear measurement for servo motor
« Reply #7 on: July 15, 2013, 05:25:06 PM »
Ahh...a gear output instead of a horn. ok.
Start googling and looking at any company that sells servos and Robot parts. I recalled one of them have gears that fit onto servo splined shafts.
Also be sure to check with the companies that advertize on this web site (on the right side of this screen).

 


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