Need help setting up KL-9082 stepper driver with 1200 oz KL34H2120-60-4A motors

[vwhotrod]

Hi members,

I need help setting up my motors
A Little background:
I built my machine a few years ago and I have been using it once in a while (I wish I had more time to play with it)
I'm running mach3 and vectric
Occasionally I miss steps and I think that I'm not getting the power that I should from 3 large 1200 oz steppers, I would think that a machine with such large motors should be very powerful and the missed steps seem to be caused by week motion (or that's what I think at least as if I even try to stop it with a finger it will miss steps) the machine is large to accommodate a full 4' x 8' sheet of material, I used it last yesterday pocketing thru soft mdf and it missed steps.

gantry moves freely and x axys as well, machine is well balanced and very precise in terms of motion

These are the electronic components:

C10 Break out board
3 KL34H2120-60-4A, 1200 oz-in motors step angle 1.8 deg 6 amps
KL-9082 stepper driver, 90VDC, 9.2A
KL- 7220 72V/20A 72VDC power supply

my question is in terms of resolution settings
the stepper driver has the following dip switch settings and it reads something like this:

microstep resolution is specified by 5,6,7,8,dip switches

Steps/rev. (for 1.8deg motor)
400
500
600
800
1000
1200
1600
2000
2400
3200
4000
5000
6000
6400
8000
10000

what should I go for in terms of resolution?, I know after making changes I need to re-set up mach 3 etc that is no problem
any of the above settings better or recommended in terms of avoiding missing steps for more power?
I'm willing to lose speed if that is a trade off as my machine as is, is capable of moving faster than I ever would need to as I have to crank it down to avoid missing steps.
motion is done with 1" wide toothed belts, motors have 2" gears and drive pulleys that are 4" so gearing is 1:2

Movement is somehow jerky also and I'm thinking that it may be caused by the same wrong settings
thank you for any help in advance.
Recommended by Keling was:
ou can set the micro step at 8 ( 1600 ), current at 5.5A
But can I get more torque/less missed steps with lower resolution or higher resolution settings? What about power should I increase amperage?

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[Torchhead]

1. What it the diameter of the drive pulley for the belt? Better yet what is your steps per inch setting.
Microstepping loses torque. Speed loses torque. Bigger motors lose torque faster with RPM.
2. What speeds are you trying to run at?
3 What kind of bit and depth of cut are you using?

Some drivers has "step morphing" (goes to full step above a set RPM) because microstepping becomes ineffective above about 100 RPM and eats up torque . Since you are limited by the driver for the total current it will allow if part of that is burned pulling against the rotation to smooth it out will not apply all of the torue to the load. In steppers, voltage = RPM and Amps = torque. Losing steps means your required torque to move the load and all of the forces of cutting exceeds the torque the motor can provide at that RPM and the motor "stalls" (loses steps)

There is a fine balance between getting max torque at the feedrates you are cutting and getting the upper speeds you need . One would think that just buying bigger motors helps but if the gearing is wrong it can actually hinder. You have more torque in low end but you run out of torque quicker at higher RPMs

[jalessi]

Vwhotrod,

It might help if you posted a few detailed pictures of your machine that show the belt drive arrangement and gear reduction.

From what you are describing it sounds like there isn't anywhere near enough gear reduction for the weight, mass / stiction etc... that needs to be overcome.

Jeff...