Plasma Digital Torch Height Controller

This page last updated Jan 2023

A microprocessor controlled DTHC specifically designed to work with selected models from the Hypertherm Powermax range and similar plasma cutters from other manufacturers and where your table is controlled by Mach3 either with the parallel port or with a supported controller.

Please read carefully to see if this DTHC is suitable for your system.

Other aftermarket THC systems need either interface electronics or the whole system to be installed inside the plasma cutter power supply. However, most Hypertherm models come with an interface already built in as standard. (Hypertherm refer to this variously as the robotics interface, the mechanized cutting interface or the machine interface). The Razordance DTHC is exclusively designed to connect to that existing interface so you don't need to install anything inside the plasma cutter power supply case. If you have one of these Hypertherm models then this DTHC is the one for you.

So which models are supported?

Hypertherm are constantly bringing out new models but the simple answer is - any model that has an interface built in with a 50:1 voltage divider. If in any doubt I suggest you contact your dealer and simply ask whether your system has the same robotics interface as the Powermax45. If it does then all is well. If it doesn't, ask if there's an update pack for your model.

Please note that to use this DTHC you must have the machine torch. This is because for safety reasons, Hypertherm disable their robotics interface when the hand torch is connected.


Since around 2016, manufacturers other than Hypertherm are now producing plasma cutters with built in interfaces. Please check with your plasma unit supplier. If the interface is the same, then this DTHC will work fine with them. Feedback from users to date is that the THC works fine with Thermal Dynamics / ESAB / Victor machines and that the cable and pinouts are identical to Hypertherm

What else is needed in order to use this DTHC?

  • A Hypertherm Machine Interface Cable with a D-sub Connector that includes the wires for the Voltage Divider Signal. If you don't already have one of these then they can be purchased from your local Hypertherm dealer. Ask for part# 223048 (7.6m) or 123896 (15.2m)
  • A CNC table controlled by a licenced[1] Mach3 (VR3.043.022 or later) via the parallel port or one of the external motion control cards that FULLY support THC functionality.[2]
  • Some method of performing Initial Height Sensing (IHS). Floating head and/or Ohmic sensing are two popular methods. You should be doing this anyway even if you don't yet use a THC.
  • A USB port with a USB to RS232 Converter Cable. (OR on older PCs you can use a spare SERIAL (RS232) port and a straight-through RS232 extension cable.
  • 1 spare output pin on your parallel port/BOB.
  • 3 spare input pins on your parallel port/BOB.
  • Note that you don't need a second parallel port to use this DTHC.
  • A REGULATED 5Vdc supply - what you use for the logic supply of your motor drivers should be fine.

[1] Mach3's internal THC functionality is crippled in demo mode.

[2] These days, any decent external controller should fully support THC. Examples, reported by users include the ESS (Ethernet SmoothStepper), The UC100 and UC300ETH range and CSMIO. However note that user supplied 24V to 5V level shifting is required to interface the CSMIO.

What is the sample rate of the Razordance DTHC?

1kHz or 1000 times per second e.g. at a cut speed of 6 metres/min a reading is taken every 0.1mm. I mention this here because there is a myth repeated from time to time on various forums that Mach3 can only handle THC updates at 10Hz i.e. ten times per second. This is completely untrue and comes (I believe) from confusing input speed with either the macropump refresh rate or the screen update period. Neither of which have anything to do with Mach3's THC functionality.

What do you get if you buy the DTHC?

  • The DTHC card itself of course, which measures approx. 100mm x 90mm (4" x 3.5").
  • A custom Mach3 plasma Screenset with associated setup and control files.
  • Comprehensive and easy to follow hardware and software installation instructions.

The Razordance DTHC

The Razordance Digital Torch Height Controller

Custom Mach3 DTHC Screenset

Custom Mach3 DTHC Screenset

How do you operate the DTHC?

  • Set the required voltage for your job. You can do this either in the Mach3 screen DRO, set it in gcode with the S word or use the "Sample & Hold" feature.
  • Switch on Mach3's THC control via the on-screen button.
  • Optionally but recommended, switch on Mach3's anti-dive control via the on-screen button.
  • Run your job.
  • If neccessary, you can fine adjust the required arc voltage on-screen in real time whilst your job is running.
  • The actual arc voltage is displayed real-time throughout the cutting process. This makes tweaking your optimum arc voltage and hence your optimum torch to work height a snip.
  • Once you've tweaked your system you can pretty much enter your required voltage or even better put it in your g-code and forget it, the DTHC will keep your optimum cut height without further intervention. No knobs to twiddle or madly flickering LCD displays to try to chase.

What does it cost and how do you get one?

The Razordance Digital Torch Height Controller costs £190 (GBP). This price includes FREE shipping worldwide. (UK - first class signed for, International - tracked and signed for)

Razordance working hours are 09:00 to 17:00 GMT Monday to Friday. Orders will be shipped the next working day. Orders received at the weekend will be shipped on Monday.

Shipping normally takes from 1 to 3 working days within the UK and a week or two elsewhere.

Please note that by buying this THC you are agreeing that:

  • Any local import taxes or duties are your responsibility to pay.
  • The item must be signed for on delivery.
  • You have read and accept the Terms & Conditions of Sale. (If you don't have a PDF reader I suggest Foxit PDF reader)
  • You will check your PayPal email address from time to time for order and shipping updates.

Payment is via PayPal. If you don't have a PayPal account you can pay with your debit or credit card as a PayPal guest. Just click Buy Now and follow the instructions.

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