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Author Topic: Set up steps on Bridgeport Series II NC  (Read 1425 times)

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Set up steps on Bridgeport Series II NC
« on: December 31, 2014, 11:20:02 AM »
Need help setting up motor steps on a Bridgeport Series II NC.
I used gecko drives with Mach 3 software using the existing
Superior Step Motors.
To get to run one inch I had to put in 80,000 steps and
the fastest I could get it to run was around 20 inches per minute.
It seems to be microstepping.
Would prefer it to step .001" instead of .0001".
I have set one up before and I used 2000 steps and got 120 ipm.
This one won't take it.
What am I doing wrong.

Offline Hood

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Re: Set up steps on Bridgeport Series II NC
« Reply #1 on: January 01, 2015, 05:11:17 AM »
It will depend on the gearing between motor and screw and the pitch of the screw itself.
I will assume it is a 5 TPI screw rather than metric so that means that your gearing must be 8:1 which seems extreme.

BTW Geckos are 10 micro steps and you can not alter that. Almost certainly your motors will be 1.8 degree which is 200 steps per rev, so for one rev of the motor you need 2,000 steps. Now if the screw is 5TPI then you would need 5 motor turns to move 1 Inch, so that would be 10,000 steps per inch if it was direct coupled, so that is why it seems you have 8:1 gearing as you say it requires 80,000.

Now your Max Velocity, that is determined by the steps per unit and the Kernel you have set, so at 25KHz the max Velocity you would get is 25,000/80,000 x 60 = 18.75IPM
If you increased the kernel to say 60KHz then you would get a max velocity of 45IPM, increased to 100KHz and you would get 75IPM. Be aware though that things may get unstable the higher the kernel you use.
If you can you should look at reducing the gearing, that may not be possible however as it may mean your motors do not have enough torque to move the axis as they are quite heavy on a seriesII.

Hood
Re: Set up steps on Bridgeport Series II NC
« Reply #2 on: January 01, 2015, 10:01:09 AM »
Yes, 18.75 IPM is the fastest it will run.
What is the kernel and why does it change the velocity?
it will be Monday before I can try.
Thanks

Offline Hood

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Re: Set up steps on Bridgeport Series II NC
« Reply #3 on: January 01, 2015, 10:10:39 AM »
The kernel is the max frequency that Mach will output per axis.
You get to it from Config menu then Ports and Pins. You will need to restart Mach when you change the kernel then you will need to adjust the Velocity. As said however you can end up with an unstable computer if you set it too high. Most computers should manage 45KHz but it will depend on your specific computer how high you can set the kernel.
Hood