Upgrading a Laser Cutter from China…

by Stephen Hobley on April 15, 2011

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I recently wrote about some of the problems I’d had with the Chinese Laser Cutter I bought over eBay. It became apparent that I was going to have to replace the X/Y controller board, as this was not functioning correctly.

The Challenge – adding a new controller

I just pulled my old CNC out of storage, the board is a bi-polar 3 axis driver and parallel port breakout from www.easy-cnc.com.

Old CNC board

This differs from the laser controller as it needs to be driven by pulsing the output pins on the parallel port.

CNC controller

I also pulled the gantry out of the laser cutter – unfortunately this has a “Flat Flexible Connector” hooking up the two home sensors and the X stepper motor. It’s going to take some work with a multimeter to figure out the connections.

The Gantry

The motors need 24V, and the controller requires 5V – both of which are available from the laser cutter power supply board.

Connectors

Since I don’t want to change the connector, and FFC connectors are a bit tricky to find, the first step is figuring out a way of hooking it up…

…done!

?

The motors are bipolar, 4 wire, running at 24V and 0.5amps – I had to create an improvised ribbon cable connector, but it didn’t take too long poking around with a multimeter to work out the hookup.

UPDATE (Sunday) : Earlier today, I tried to discover exactly how the home sensors were wired, but after plotting it out on paper and running a few exploratory tests, I’m going to have to admit defeat. 🙂 The home sensors are tucked away inside the chassis, and are difficult to access without some major dismantlement.

They obviously work, but according to the wiring I’ve plotted out, 5v and Gnd are actually shorted out across them. Which is not good. Additionally the 5v supply runs at an offset of 120V – I don’t want this anywhere near the parallel port.

A home sensor is most useful when you need to change cutting heads – and this is not something that happens with a laser engraver. So…. the more I thought about it, the more I thought it’s not worth the effort to continue examining them. The X/Y motors work, and that’s the main thing.

Now to decipher the laser power controller…

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{ 9 comments… read them below or add one }

Jelle April 20, 2011 at 4:30 am

Hi there,

Your problem is one ‘we’ are working on. the chinese built controller board is nice (potentially) but the software to drive it with really sucks. replacing it with mach3 is not a good solution either, we think.
So ‘we’ the LaOS-laser project, aim to develop a separate driver board (easier than reverse engineering those newlydraw things) and develop software that works just as a regular printer driver (cups). The cups server accepts all PS data, and converts these to movement commands (either gcode or something similar) that are sent (over ethernet or USB) to the cutter. So far two lasers have been freed from their chinese brains, and are developing a version 0.1 of a ‘real’pcb.
http://www.laoslaser.org/

Stephen Hobley April 20, 2011 at 8:15 am

I have a lot of experience with Mach3 and so far have found it to be excellent. To use it properly you need to be comfortable working with CAD/CAM, and provide an adequate host computer, but the scripting/plugin environment is nicely designed, and well supported on the public CNC forums.

Jelle April 27, 2011 at 12:46 pm

Mach3 is overkill to the max for a laser cutter. You should not need experience with CAD/CAM to cut some pieces of acrylic. How would you engrave a picture with gcode only?

Stephen Hobley April 27, 2011 at 1:33 pm

Agreed. But it’s much better than a none-functioning controller card :-).

I was using stuff I already have – the controller and a copy of Mach3. I’ve got a bunch of CAM software for running my mill and the only thing I couldn’t do was raster engrave a photograph…

…Until now – I just found the Acme Profiler – a bit of source-code that does exactly that, I was able to rewrite the milling routine to produce laser ready engraving code.

I think the conclusion to my article(s) is simply “you get what you pay for”. Buy a cheap laser cutter, expect to have to work hard to do anything with it – your mileage may vary.

If I were laser cutting for a living, I’d get a loan, get a $20K machine, and have a business plan to pay it all back…

Lawrence November 22, 2011 at 11:04 am

Hi Stephen.

Have exactly the same model from a cursory look at the connectors.
Want to clue me in on the pinouts so I can be lazy 🙂

Otherwise its an hour or two messing around..
Pretty please? 🙂

Stephen Hobley November 22, 2011 at 12:27 pm

Actually I don’t really have anything left – I replaced everything so I don’t have the pinouts for the steppers – although they’re bipolar and so pretty easy to work out with a multimeter.

mark January 18, 2012 at 10:57 pm

How did you end up making electrical connections to the flexible flat cable? Direct solder?

I’m about to go this route…

Stephen Hobley January 19, 2012 at 12:02 am

I actually etched some PCB to match and then used a spring clip to hold the flat cable against it.

mark January 21, 2012 at 12:44 pm

Thanks Stephen. I’m also curious what steps per unit you ended up using in Mach3 and how you came about that number?

great articles, thanks

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