Re: Plasma table gear reduction

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> Hi all,
>
> Next step is the transmission.
>
> Assuming a 1,000 RPM servo motor (for ease of calculations)
>
> and a rack or belt drive.
>
> It would appear that the lowest gear ratio is about 1:1 and that is
> using a pretty small drive gear.
>
> Assuming one wants 100 inch per min speeds, there is a need for a
> 10:1 reduction.
>
> I can get a pair of timing belt pulleys for about a 3:1, maybe a

4:1,

> and that would indicate that a jackshaft would be in order for two
> sets of belt reduction.
>
> This seems pretty striaght forward and different pulleys offer the
> ability to change ratios.
>
> Obvously, when the surplus motors are spinning 4 times faster, it
> means the need for a reduction is required.
>
> Is there a simplier way to do reduction ?
>
> Dave

Start with a top speed of 200 to 300 IPM for plasma. Depending on
the servo motor and your max drive voltage take about 80% of the max
RPM of your motors. The Ke constant will give you your rpm per volt.
Usually a 3:1 to 4:1 reduction ratio will work for most
applications. You don't have to spin the motors at full rpm all the
time. Most of you cutting on a plasma will be at 50 to 100 IPM with
some thin stuff up at 160 to 180 or faster. As long as most of your
cutting is being done in the middle range of the motor you will get
good results. Servo motors are much more linear in their torque VS
RPM than steppers. One of the problems with rack and pinion and
servos is you can get speeds that are way to fast without gear
reductions. I'm not sure a jackshaft and two levels of reduction are
needed.