>>> If you make a disk, the number of slots per revolution will be limited
>>> to something like 30kHz/3k RPM = 10
>> Note the common thinko here: 3k RPM is not the same as 3k RPS.
>>
>> 3kRPM = 50 RPS, so if you assume 30 kcounts/sec, you have 30000 Hz / 50
>> = 600 counts/rev to play with.
>
> &*%$#& it, I've been doing this all day. Thanks for correcting me.
> Someone might have taken it as being correct. "Question everything"
> seems to be good advise. Plus, writing out your units in equations.
Or you could use the GNU 'units' program which is available for windows [1]
or any linux distribution, [2] like so:
$ units 30kHz/3krpm 1/rev
* 600
> I would think 50 slots per revolution would be plenty, making 200
> quadrature counts per revolution, so with the correction, we go from
> being on the edge to being well within limits (10 kHz (?)). For Penance,
> I should build an encoder and test it. Let's see, a 3" disk is ~ 9" in
> circumference, 9"/50 = .180" slot width, piece of cake. Although, I seem
> to remember someone has a bright yellow lathe with a disk like this.
It also works in reverse:
$ units 3krpm*50*4/rev kHz
* 10
Now, isn't that handy?
-fenn
[1]: http://gnuwin32.sourceforge.net/packages/units.htm
[2]: 'apt-get install units' or http://ftp.gnu.org/gnu/units/units-1.87.tar.gz
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
