Welcome to LinuxCNC.org

hi again im wanting to retro fit the above machine and think it should go all smoothly (the control has died buy the way just seams sensible to upgrade and not just replace )

was going to use a 5I20 with 7I33TA and 7I37TA (the servo dirves are built in the head and on the gantry motors)

and aslo would like to upgrade too voltage sensed hight control the machine currently has a capacitance sensed hight control and is driven with a servo but it has no feedback ie encoder or such as the initial hight set would be for the pierce only could i not just fit a touch-off switch and then Z up for a timed bit to set pierce hight then let thc take over ?

many thanks john

to make it clearer a like to a vid of the machine and current hight control setup

Hello John,

How does the current control use the THC?

I'm sure you could replicate the same function in EMC.... my homemade plasma I use steppers with the THCAD card to sense torch voltage and adjust the height with the THC comp.

John

hi john

as far as the electronic side of it im not sure as you see in the video it just seams to sense when near and object and this sensing range is on a pot of the control screen im not sure how i could interface this to emc however i would like to upgrade to voltage based control as it makes for a better square cut but would it mean making a new z axis or at least making it stepper drive.

or would i say get away with the fitting of a probe to touch off and then almost guess as too how far to back off for the pierce and then switch to the volage reading as it would normally

is there an axis interface already set up for plasma john ? ie with an input box for the requested cutting volts, pierce delay time and pierce hight settings ?

thanks john

Hi John,

This is everything about my plasma that I have documented to date.

gnipsel.com/shop/plasma/plasma.xhtml

I think I fixed one thing but have not uploaded it... If your Z is servo you should not have to change to stepper just add an encoder so EMC can control it. I use a floating head with a micro switch and it is quite accurate for pre-positioning the torch for pierce. Once the arc has started (Hypertherm has an arc ok output) I start the cut and start using voltage feedback to control the Z height.

John

any encoder supplers you would reccomend?