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  1. #1
    Join Date
    Nov 2013
    Posts
    12

    Method for Adjusting Tip Voltage for THC Control

    Got my first table up and running and starting to look like I know what I'm doing but the DTHC is still kicking me in the teeth. Everytime I think I have it figured out, it bites me. Otherwise, I can run with it turned off and things look pretty good.

    I've been under the assumption that you can just turn on THC after you've dialed it in and walk away, but I think I need to pay closer attention to what I'm doing. So I need some feedback. My setup is PPLLC SDB gantry, DTHC IV and Bladerunner from CandCNC and Hypertherm Powermax65. Sheetcam and Mach3.

    Today I switched to fine cut consuables for a 16ga project. I had been running on the same electrode for a while but put in a new nozzle. I didn't pay any attention to the tip volts or torch height and the torch dove during a cut mid project. I turned off THC and did a straight line test and saw tip volts around 90 instead of 75 at 0.06 cutting height. I'm guessing the electrode is wearing down and I need to adjust the volts up in Mach while watching the Z DRO to get it back up to 0.06. My 16ga plate is pretty flat.

    I see where some folks cut a small part of the job in manual mode first to see what the tip volts are and adjust it before doing the rest with THC turned on - the objective being setting the tip volts to get the right cutting height. Is this a pretty standard process to follow? I guess I was hoping I wouldn't have to baby it that much. Also, how much of a voltage adjustment can you make before you say "that's just to far out of whack" and look for something else that's messed up?

    Thanks

  2. #2
    Join Date
    Jun 2009
    Posts
    226
    Gary
    I use the LCTHC from Candcnc and I can't cut at the recommended voltages listed by Hypertherm with the finecut consumables (the voltage is very close on the 45A and 65A regular consumables). I cut at 88V on 16 GA and this gives me the correct height and I get great cuts. I've been using my setup for over 3 years and have learned that the recommended cut voltages are just that, a recommendation. Find out what works for your setup that will give you the cut you want and stick to it.

    Willy

  3. #3
    Join Date
    Nov 2013
    Posts
    12
    Thanks Willy, that helps alot. I was thinking there was something wrong with my setup. Today, I cut 20 pieces that were small 4"x4" parts. I did them all with the DTHC turned off and just watched the screen. I came to the conclusion that 88 to 90 volts was the average of what I was seeing. I just couldn't figure out why FC/16ga was so far off from the charts compared to 45A cutting 10ga, 1/4", etc. Hence, my thinking I was doing something wrong.

    Thanks again for the tip.

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