Re: [CAD_CAM_EDM_DRO] Trak cnc 2 control replacement

seb fontana wrote:

> To retro using what is currantly availible, affordable for home
>use/limited production. Machine is Sharp brand; B'port clone Series
>1 size, very nice ways/condition. Reason for change: control must be
>run in 3 axis, no option; RS232 port not enabled, not capable/no
>means to store/write/retrieve programs with PC. I can assemble
>replacement with instruction, limited electronic experience and have
>been following article in HSM magazine. Would welcome suggestions,
>comments, thoughts. I am in CT. Can E me if prefer. Following is a
>list of what the present control [Trak cnc 2 made by South Western
>Industries] works with.
>
> 1) Has dc servo motors, 4" dia x 6" long, 4 brush, with encoder.
> Motor volt, amp, torque not listed on label.
> Encoder count not known. Should be around B'port
> Series 1 size. Belt drive of 2:1 reduction.[All Good?]
>
> 2) For DRO{?} has another set of Encoders[?] that pick up x&y
> movement by contact wheels on bed and sadle; attached
> to leadscrew [at quill] for z. Newer Traks use
> same units on x&y..May work somehow in combination
> with encoders on motors. [Good ?]
>
>
>

Are you sure it has encoders on the motor AND on the axis? That presents
a "sensor fusion" problem - like the guy with two watches who wonders
what time it really is? I wonder if the motors have DC tachometers instead.
That is a much more common arrangement.

Using wheels to get position information from the table sounds pretty
strange.
A little dirt could cause it to skip or jump, and the absolute position
reference
would shift.

Jon