Plasma cutting with servo System in LinuxCNC

Sorry, I have a error. not 85 kg. Is 150 kg (330 pounds)

wow thats heavy! thats ~1000 lbs of force to accelerate at 3 Gs

with 900 oz-in and 3000 RPM you would need about .2" / turn
gearing to get that force meaning top speed would be about 10 IPS
and the motor would have to accelerate to full speed (3000 RPM)
in about 25 mS (120,000 RPM/sec)
This is tough for bare unloaded motors

Not practical without larger motors or less acceleration

Peter,

I think you dropped a decimal place somewhere. 3000 RPM x 0.2" = 600 IPM,
so he could gear it down some more. (Edit: Oops, 10 IPS = 600 IPM, you
are right on the velocity.) When increasing the reduction ratio,
at some point the motor inertia becomes dominant, you want to keep the ratio
below that.

Assuming 900 oz-in is the peak motor rating, then you have 56.25 Lb-inches
for acceleration. Assuming a .2"/turn ratio, that gives a linear force of
1769 Lbs. So, I don't see a problem, here. he'll get plenty of velocity
and more than sufficient linear force to get his 3 G acceleration.
(The conversion factor for a 5 TPI leadscrew, which gives 0.2" advance
per turn is one I know almost by heart. torque in inch-Lbs / 0.0318 =
linear force in Lbs. The 0.2" advance is the same as an infinitely thin
cord wrapped around a drum of 0.0318" radius.)

Jon

Yes I did it in my head and dropped a factor of 2, but
0 to 3000 RPM in 25 mS is still going to be tough
(and lead screws are out of the question)

Then in this system result better to use lead screw? How this can better my system? And band transmission is not possible? How I can to dimension the transmission ration to reach the speed and acceleration with a reasonable cost in servo motors and mechanical system?

PCW wrote:

Yes I did it in my head and dropped a factor of 2, but
0 to 3000 RPM in 25 mS is still going to be tough
(and lead screws are out of the question)

Yup, either rack and pinion or belt drive would be the way to
go, that is typical on a router, anyway. I wonder why this
gantry is so heavy, most similar machines are maybe half the
weight. It may be necessary to go with a lower reduction ratio
to keep the motor speed down, as that may already be the
dominant inertia. At least he isn't trying to do this with a
stepper motor!

Jon

You have reason. My design is very heavy. I have seen belt drive in quilting machines with gantry mass of aprox 900 pounds with servo motors panasonic of 1KW without lead screw and this works perfectly. How I can down the weight of my design without use aluminum?

At least he isn't trying to do this with a stepper motor!

Jeje. It is not possible with steppers, just looking at speed torque curve can tell that it is not possible

I am confusing.

Any person can explain me or can share with me information about to calculate the motors, drives, ratio of reduction, choose better system of transmission to my application, acceleration, inertia, velocity, etc.

All information is very valuable to me.