On Mon, 28 May 2007, Rod Welland wrote:
> Date: Mon, 28 May 2007 09:08:25 +0100
> From: Rod Welland <[EMAIL PROTECTED]>
> Reply-To: "Enhanced Machine Controller (EMC)"
> <emc-users@lists.sourceforge.net>
> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
> Subject: Re: [Emc-users] How to
>
> Alex have taken a photo of Chips and will send it as soon as I get it off
> the camera. If his feathers look a bit ruffled its because I did'nt have a
> 10mm ball nose cutter with flutes long enough (at least 31mm) to cut down
> his feet in fact the only cutter I had which would do this was a 1\4" 4
> flute end mill, but it proved the motion was OK and thats what I was looking
> for.
> As an aside I have been thinking about making a jogging handwheel I have
> seen a few drawings and circuits for doing this but all are built around
> rather pricey encoders some of which are only avaliable from the States. I
> was wondering if it was possible to use a small stepper to do this instead
> as I have a number of these, I think they came from 5" floppy disc drives
> they are various formats i.e. 4 wire, 6 wire, steps range from 100 to 400
> per rev. the 400 appear to give about 8-10 mvs the 100 about 15-18 mvs a
> step. Has anybody ever done this or thought about it, while I .have no
> difficulty making my own circuit boards and populating them my electronics
> knowledge is limited. Also of course if this is possible is it difficult to
> configur this in EMC.
The floppy step motors will give decent quadrature output if you feed the
windings to a comparator (say a LM393). You will need some input protection on
the comparator, perhaps a diode (to prevent reverse biasing) and a input
series resistor (the stepmotors in floppies will generate _many_ volts if spun
quickly)
+5V
|
/
\
/
|\ \
M0-\/\/\/\/---*--------|+\ /
| | \_____*___ A
| | /
| --|-/
___ | |/
/ \ |
| |
| |
--- ---
\ / \ /
- -
You need two of these circuits (M0 is step motor winding0, A is quarature
output A, so you need the same for B)
A sleaszier way is just to us a NPN transistor as a comparator, but then you
would have a fairly high minimum rotation rate of your jog wheel before any
signals were generated.
EMC can read the quadrature...
(pls excuse my sloppy ASCII art...)
Peter Wallace
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