CNC Plasma Table THC Torch Height Controller?

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t8017e
Posts: 25
Joined: Thu Jun 06, 2013 2:25 pm

CNC Plasma Table THC Torch Height Controller?

Post by t8017e » Wed Jun 12, 2013 3:16 pm

Hey guys I just ordered this off ebay. [/url]http://www.ebay.com/itm/281085923996?ss ... 1439.l2649 Has anyone used it or connected to their systems. I have a custom made pretty trick vertical
2 x 2 plasma table and now need the Z adjustment to cut multiple parts with out babysitting the machine.

I got the control in and now have to figure out how to connect it. I'm using a Miller Spectrum 375 plasma cutter running Mach3 and Sheetcam. Any input or help will be appreciated.

I attached some pictures of my machine and controls

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JJsCustomDesigns
Posts: 607
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Location: Nebraska

Re: CNC Plasma Table THC Torch Height Controller?

Post by JJsCustomDesigns » Wed Jun 12, 2013 3:22 pm

Am i see'n this right? Vertical Plasma Table??
"There are bigger things planned for you in your life, be patient"

Im on the prowl for a good used Hypertherm Plasma with hand torch.
PM me with details
Thanks

t8017e
Posts: 25
Joined: Thu Jun 06, 2013 2:25 pm

Re: CNC Plasma Table THC Torch Height Controller?

Post by t8017e » Wed Jun 12, 2013 3:47 pm

Yes you are! Saves a ton of space in my shop. You can set it up horizontal also but I use it vertical.

t8017e
Posts: 25
Joined: Thu Jun 06, 2013 2:25 pm

Re: CNC Plasma Table THC Torch Height Controller?

Post by t8017e » Wed Jun 12, 2013 5:21 pm

Well I got the answer from eagle plasma, this is what they say. I will be trying it tonight if time allows.

"connect a wire from a 5volt line on the input group to the common on the THC then connect wires from the torch up , torch down and ark connection too inputs on the breakout board one on ech numbered pins must use only pins 10,11,12,13,15 no others. then set inputs on mach3 for thc up , down and torch on to the input pin you selected.
Next set the pins to red x under active low that means that the inputs will be high when in use.
the leads to your torch one goes to the clamp lead inside of the cutter and the other to the tip voltage."

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Cbrbarnes
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Re: CNC Plasma Table THC Torch Height Controller?

Post by Cbrbarnes » Sun Sep 08, 2013 9:21 pm

Please post how this works out. I've got a 4x4 table without thc and don't want to upgrade to a better table quite yet but for the $250ish it would take to add this, it's quite compelling. Thanks

t8017e
Posts: 25
Joined: Thu Jun 06, 2013 2:25 pm

Re: CNC Plasma Table THC Torch Height Controller?

Post by t8017e » Mon Dec 23, 2013 12:54 pm

Well my conclusion is it works, I'm sure there is something better, but for the money and running the machine with out one really suck. So It was worth the money.

I can get through longer runs now with out to much baby sitting of the machine. I would ultimately like a sensor of some sort to see where the material is at all times, the only problem I still have is during a move if the plate is real warped you can still hit the Z limit switch, because there is no sensing unless the torch is on and cutting.

What do other machines use for THC?

jimcolt
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Re: CNC Plasma Table THC Torch Height Controller?

Post by jimcolt » Tue Dec 24, 2013 9:37 am

Most torch height control systems available on cnc machines have the ability to sense the surface of the plate before each cut, then retract to pierce height, pierce, then index to cut height and start cutting in the x and y axis. Once the x and y get above 80% of programmed cut speed the arc voltage control then becomes active, correcting the torch to work distance while cutting. The better THC systems are also tied into the motion control so when the machine decelerates (below 80% of programmmed speed) the z axis freezes (to prevent diving into the material). Further, the THC recognizes anomalies such as kerf crossings and ignores the momentary increase in arc voltage, eliminating diving in these areas as well.

To sense the surface of the plate there are three major techniques, Torque sensing, limit switch sensing, and ohmic sensing.

-Torque sensing measures the amperage (or steps in a stepper drive) of the z axis motor to sense a collision with the plate. Once sensed the drive reverses and retracts to the proper pierce height. This process works well on plate that is thick enough so it will not deflect upon collision, plates that deflect (thin) will often follow the torch upwards on the retract, and the sensed location is not accurate. Most of these systems have "adjustable" torque to minimize the deflection.
-Limit switch sensing, also know as a "floating head sensor" uses a limit switch that senses contact with the plate. The torch then retracts to the pierce height (an usually has an added offset to compensate for limit switch hysteresis). This process also deflects thin materials as the torque method does.
-Ohmic contact detects an electrical resistance change when the torch shield contacts the plate. This provides instantaneous sensing of the surface, and properly designed can eliminate plate deflection evn on very thin materials. This process works in most applications where the surface is dry and relatively clean (minimal rust, no primer). On water table applications the ohmic contact often senses the water....so if there is a bead of water on the material, or if the water is above the surface of the material the sensing may be too high.

Most industrial cnc plasma machines use a combination of ohmic and torque sensing for best performance and reliability.

Good height control with full plate sensing capability allows you to program many parts on your machine and then do other jobs in your shop while the parts cut, unattended. This is what cnc plasma cutting is all about! Productivity!

Jim Colt Hypetherm


t8017e wrote:Well my conclusion is it works, I'm sure there is something better, but for the money and running the machine with out one really suck. So It was worth the money.

I can get through longer runs now with out to much baby sitting of the machine. I would ultimately like a sensor of some sort to see where the material is at all times, the only problem I still have is during a move if the plate is real warped you can still hit the Z limit switch, because there is no sensing unless the torch is on and cutting.

What do other machines use for THC?

Vmastergage
Posts: 1
Joined: Sat Feb 13, 2016 10:44 pm

Re: CNC Plasma Table THC Torch Height Controller?

Post by Vmastergage » Sat Feb 13, 2016 10:50 pm

Do you have any pics of how this is hooked up in yoir specific application? I have a miller spectrum 375 also and seeing this would make it much easier to hook everything up right! Thanks in advance!

cncplasmaworkz
Posts: 5
Joined: Mon Apr 15, 2019 6:30 pm

Re: CNC Plasma Table THC Torch Height Controller?

Post by cncplasmaworkz » Tue May 14, 2019 6:42 pm

Im also using a spectrum 375 pictures would be sweet!

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