Why get rid of an old, high quality Japanese machine when it can be upgraded? That’s what Dutchcreen thought when they contacted me. They have a Brother TC-324N CNC machine that works great, but is a pain to program. They asked me to check if it’s possible to generate programs in 3D CAD software and transfer it directly to the machine..

The problem

Brother TC-324N CNC machine

The true problem behind this, is that the programs are written on the machine itself, which makes it very labour intensive and therefore costly to write even a single program. Also, not everyone knows how to write such programs, which means Dutchcreen had to hire someone to do it for them - making it even more costly and time-consuming. This defeats the purpose of the machine for in-house prototyping.

In a modern workflow, you can do most (if not all) of the programming on a PC and generate the machine codes based on existing 3D CAD models. Our goal was to check if we could have such a workflow using the old machine.

Research & options

The first thing we checked is whether it’s possible to connect a computer to the CNC machine. Turns out it has a RS-232 port, which is found on old computers until it was replaced by USB. In short, this is no longer a standard on modern computers.

RS-232 serial port

Picture: the RS-232 serial port

Now, there are multiple ways to solve the RS-232 connection issue:

  1. Replace the on-board computer on the CNC machine with a modern PC running CNC software such as Mach4. This also requires hardware that drives the machine motors (stepper controller + breakout board) and modifications to the machine.
  2. Use the CNC machine’s on-board computer as “slave” and control it from an external computer over the RS-232 port.
  3. Use the CNC machine’s on-board computer as “master” and find a way to transfer the programs to the machine.

Apparently option 1 is a popular option, as it’s well-documented on the Internet and there are a lot of hardware options for this. But it’s also the most complex option. Instead, I wanted to explore option 3 as this requires minimal additional hardware.

The solution

I found a simple device that handles the communication with the CNC machine over the RS-232 port and reads/writes to USB, the Shop Floor Automations Portable USB Connect.

This is what it looks like in the factory:

Final solution is comparable to how most desktop 3D printers work: reliability of running the program from the machine itself with the flexibility of transferring programs on a USB stick.

All in all, it’s a very cost-effective and pragmatic solution to the problem:

  • No hardware modifications: low-cost solution and easily reversible.
  • Low risk of machine failure since it still uses the machine’s on-board computer.
  • Workflow doesn’t change for the factory workers. The programs are still on the machine.

With this simple addition to their hardware setup, Dutchcreen is now able to generate their CNC programs with their CAD software and transfer them to the CNC machine with a USB stick. As a bonus, they also have a backup of all the CNC programs that were on their machine.

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