[burpg] Re: Measuring Servo Spline
- From: Armor Harris <armorharris@xxxxxxxxx>
- To: "burpg@xxxxxxxxxxxxx" <burpg@xxxxxxxxxxxxx>
- Date: Sun, 17 Aug 2014 15:36:14 -0700
Yeah you only have to get one tooth of the spline, the diameters, and then
revolve it. So just get super close up on one tooth
On Sunday, August 17, 2014, Mehmet Akbulut <meak@xxxxxx> wrote:
> Alessandro is right. To get the least amount of skew/distortion,
> perspective crop will help.
>
> Unfortunately there is no data sheet. I'm not in Boston, otherwise I would
> have done it.
>
>
> On Mon, Aug 18, 2014 at 12:46 AM, Alessandro Cesar Dias Gomes Filho <
> acgfilho@xxxxxx <javascript:_e(%7B%7D,'cvml','acgfilho@xxxxxx');>> wrote:
>
>> Do they not have a datasheet?
>>
>> Also, whoever does this might want to do a perspective crop on the
>> picture in Photoshop to make sure it is isometric.
>>
>>
>> On Sun, Aug 17, 2014 at 2:24 AM, Armor Harris <armorharris@xxxxxxxxx
>> <javascript:_e(%7B%7D,'cvml','armorharris@xxxxxxxxx');>> wrote:
>>
>>> Hey guys,
>>>
>>> We need someone back at the lab to measure the old e-regulator servo
>>> spline. Looks something like this
>>>
>>> http://www.servocity.com/html/hitec_servo_splines.html#.U_A6QvldV8E
>>>
>>>
>>> I think the best procedure here is to use a high resolution camera
>>> (read: not an iphone) to take a perfectly 2D picture of the servo spline
>>> with a pair of micrometers set to a known distance on the same plane as the
>>> servo spline (calipers probably aren't accurate enough unless they're
>>> really nice ones).
>>>
>>> Then, someone can use imageJ to measure the length in pixels of each
>>> spline tooth and use the distance between the micrometers in the same plane
>>> as a pixel to length ratio. ImageJ makes it really easy.
>>>
>>> I've done this before on another application, I used an SLR with a stock
>>> lens and a tripod and it worked pretty well. The setup was in a difficult
>>> environment but I was still able to get accuracy of less than .001" You can
>>> probably do better since it's in a well lit lab environment and you can
>>> control the photo a lot better. I would suggest is setting up the camera
>>> for maximum contrast so that when you zoom in, you can still see sharp
>>> lines.
>>>
>>> Once we get that measured, we want to try using wire EDM to machine our
>>> own attachments for high precision valves like the thrust vector control
>>> and the throttle valve. This could potentially make our servo driven valves
>>> a lot more reliable and rugged, so it's a really big deal if we're able to
>>> do this.
>>>
>>> Anyone up for it?
>>>
>>> Armor
>>>
>>
>>
>
--
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