40W Chinese Laser: Brain Transplant!


I’m removing the stock controller board. The proprietary software is terrible. It is getting replaced with the Open Source RapRep RAMPS G-Code controller. Thanks to the customized Marlin firmware by TurnkeyTyranny, this gives us several new advantages:

  • open source software chain (thanks again to TurnkeyTyranny and the Inkscape G-Code Export Extension)
  • programmatic control over the laser output power (ditching that terrible manual pot)
  • A slick new LCD control panel
  • I’m surprised I’ve not seen this elsewhere, but I plan to use a thermistor in my coolant tank to monitor the coolant temperature. Hopefully I can hack the firmware to stop firing the laser if the tank temperature rises beyond the set threshold.

    I ordered a new ribbon connector and made a new transfer cable to connect to the RAMPS pins. I was too impatient to design and order a wiring harness board, so I just soldered the cable right to the pins on the connector. I covered the contacts with some Liquid Electrical Tape.


    Below is a diagram of the wiring. Thankfully this was my exact power supply, so I didn’t have to get creative. Now, on the RAMPS, the servo pins are marked 2B 2A 1A 1B and the diagram has A- A+ B- B+. Here is the translation:

    A- -> 2B (ribbon cable pin 9)
    A+ -> 2A (ribbon cable pin 10)
    B- -> 1A (ribbon cable pin 11)
    B+ -> 1B (ribbon cable pin 12)

    It’s also not very clear on the diagram, but the XHOME goes on the first Signal pin on the endstop header and YHOME goes to the third signal pin. Even though it shows the 5v and GND going to the AUX-3/SPI header, you can use any 5V/GND connections on the other AUX or SERVOS header blocks.

    The Y stepper cable connects the following colors to pins:

    red -> 2B
    blue -> 2A
    white > 1A
    yellow -> 1B

    I’m borrowing this photo from TurnkeyTyranny’s git repo and putting this here so I can find it later:


    This is not the greatest photo, but some of the wiring choices can been seen here:


    I made sure to test the steppers and homes before I even hooked up the laser fire and PWM controls to the RAMPS board. Once everything was moving as I expected, it was time to test the laser! Something about this screen preparing to push the button had me feeling like a mad evil genius set to take over the world: “FIRE ZEE LAZOOR!”


    As you can see by the burn, the initial tests were a success:


    Now its time to mount the board and get the wiring cleaned up to make room for more upgrades!

40W Chinese Laser: First cuts!

Today I finally wrangled a Windows XP machine back into shape so that I could run the stock software that works with the stock controller board.

I did the test cuts on 1/8″ thick hardboard.

We immediately see the value in having an air assist cutting nozzle. Without one, the exhaust fan pulls the smoke and heat up and across the work.

No problem – a couple hits with the sandpaper and its clean! Not bad for a machine out of the box with zero calibration!

The RAMPS arrives Monday. That’s when the teardown and upgrade will begin. Honestly, I can’t wait, because the stock software provided is terrible! Perhaps I’ll experiment with different power settings in the meantime.

40W Chinese Laser: Improvements

This is currently just a list of the upgrades I intend to make on my new machine. I’ll add links as I complete each item:

Add LED interior lighting
Remove controller and replace to RAMPS CNC controller
Replace controller panel with RAMPS LCD and switches for cooling, lighting, etc
Change chassis bolts to proper length
Add Air Assist head and pump
Upgrade Water Cooling
Enlarge build area
Upgrade Exhaust Assembly
Add fan to interior of power supply

LINK: Click here for a link to my post that contains a shopping list of parts required for the various upgrades.

40W Chinese Laser: Upgrade Parts List and RAMPS conversion

All of the following links are for items on Amazon. With a few exceptions, all qualify for Prime free shipping.

RAMPS Parts:
RAMPS + Arduino + Stepper Drivers
E-Stop Switch

Power Supply Cooling:
60mm 24v Fan for P/S

Exhaust Upgrade:
Exhaust Fan
Fan Hose
Hose Clamps

Laser Cooling Upgrades:
Water Reservoir
Heat Exchanger
Heat Exchanger Fan
Cooling Hose

Air Assist Upgrades:
Air Pump – hold off on this: waiting for pump to arrive to see if it can produce sufficient air flow.
Manifold – hold off on this: waiting for pump to arrive to see if I can reroute three of the four outlets internally.
Air Assist Hose
Drag Chain for Air Assist Hose

Interior Lighting:
LED Strip
LED Power Supply I chose the 2A model, only slightly more expensive, and the terminals have more substance.

40W Chinese Laser: Unboxing

I ordered mine from the San Leandro, CA facility. It shipped on a Monday via FedEx. It arrived two days later, on Wednesday.

I was surprised at the size of the unit – I had imagined it to be about 75% of its actual size. The wooden box was a bit beat up, half the screws were missing and the lid was otherwise held on by packing tape.

The second (cardboard) box inside was in very good shape.

The entire machine was tightly surrounded by 1″ thick, cheap styrofoam. I’m pretty sure they just broke up the pieces by hand to make them fit in the shipping container, as there were small bits of foam all over the place. Get your shopvac handy to pick up all the snow!

Unpacked. Back of the unit. Covered in broken styrofoam. The cooling hoses are very soft and were crushed and deformed by the tight stryofoam packing. They function ok, but some parts seem to have melded themselves with the foam somehow. Notice the lines are filled with water, so they did actually do some testing before they shipped it out.

Front. Covered in packing cellophane wrap. For some reason the lid is jammed open a bit. Perhaps because of the items packed inside.

Removed the wrapping film and we now see the accessories inside. This bag contained a tube of silicone paste (I’m assuming for lubricating the rails), a roll of cheap double sided tape (the manual mentions using this over the mirrors to check alignment), a DVD-R (containing instructional PDF, CorelDraw and CorelLaser software) and a USB key – I have read elsewhere that this is a dongle that allows use of the Corel Laser software.

USB A to B cable, exhaust fan and aquarium pump (for laser cooling).

Took me a moment to notice the exhaust fan hose (blue, behind the lens head). Hose expands to about 6 feet in length. Also hidden under the platform is the 110v power cable.

Closeup of the cooling hose. Note they are still very wet inside. Some sections are more opaque than others. I’m assuming their test water also had some sort of antifreeze in it, as my pump was also covered in some milky white residue around the outlet connection.

A bunch of styrofoam “snow” trapped in the power connector.

Some of the frame bolts are MUCH longer than they need to be. I will be replacing these with bolts of the appropriate length. Some are so long that they are offsetting the ability for the machine to sit flat on the four rubber corner stands.

The interior of much of the machine was VERY dusty with brown dirt. No telling how long the chassis parts might have sat in an open warehouse or even outdoors prior to assembly.

Laser tube. While a but dusty (probably from the dust falling from the top of the bay door that was pictured above), it looks to be in very good condition.

More styrofoam snow in the back of the power/control compartment. All the wiring is wrapped and appears to be tidy. Not the horror show rats-nest or unshielded wiring that I’ve seen arrive on other Chinese laser builds.

Back of control panel.

Power supply.

They obviously test-fired the laser as there was a good amount of soot on the bottom of the lens carrier. I have yet to remove the lens. I plan to take it out for inspection and cleaning – mirrors too. I’ll add to this post with those details later.

They must slap these things together very quickly. The shield acrylic (in addition to being very scratched up by the stored accessories mounting) is crooked as all get out.

Here’s a shot to show the size of the thing on my workbench. Again, much larger than I anticipated it would be. Pretty crazy for such a small work area of 12″x8″. I’ll certainly be making modifications to make for a larger build area.

I did some checks to make sure the mirrors were aligned (I forgot to take pictures of that process). Turns out everything was in line and I successfully fired my first hole in a piece of thin cardboard!

New owners note: The way the switches work are not very clear in how they are labeled

Power: This is obvious. Nothing will happen unless this in On and glowing.
Laser Switch: This is an up/down locking toggle pushbutton. This essentially arms the laser.
Laser Power needle indicator: This will only indicate the read amperage of the laser *while it is firing*. Turning this, even when the Laser Switch is On, will not result in the needle moving. I suggest no more than a quarter turn clockwise when first test firing the laser.
Laser Test: if the “Laser Switch” is in the on/down locked position, this momentary switch will fire the laser. A quick pulse is usually sufficient.

That’s it for the unboxing.

LINK: Click here for a WIP/TODO post that lists the improvements I’d like to make.

LINK: Click here for a shopping list of all required upgrade parts available on Amazon.com.

New solution for getting PLA to stick to your print surface

I’ve been tipped to a new solution for PLA adhesion that works incredibly well. I’ve printed objects with square corners that cover nearly the entire print bed (190mm) and it works like magic. No curling or lifted edges. Compared to Kapton on “blue tape”, it is easier to apply, has a nicer finish and is infinitely less expensive.

Solution: one (1) part white glue to ten (10) parts water. Turn up the heated bed to your PLA print temp (~60-70c). Mix the solution throughly – should look like thin milky water. Dip a folded paper towel in to get it damp, then swab the printer deck. Make sure it coats the deck evenly. Yes, it will appear streaky. Wait until the heat from the bed dries up the solution – you’ll see it go from shiny to flat/opaque.

I usually run 10-20 prints before I feel the need to re-apply. If you go days between prints, its probably a good idea to re-apply to get the standing dust off the print surface.

Yes, it is true that the glass-side finish of the prints is not as smooth at bare-glass prints – but you’ll notice that its nearly impossible to remove the parts from the glass until you let them (part and glass) cool to room temperature. I’ll take a 10% reduction in surface quality any day over a lifted print.

I’m curious to see other’s results with this method.

OLI Project: Polargraph – Arduino UNO Version

I was recently reminded it would be nice see a write up of my experience of building a Polargraph that is controlled via a Ardunio Uno.

The kit from polargraph.co.uk is wonderful, but for a few reasons I decided to skip the kit and do the DIY thing:
1) I can print my own parts
2) I already had an Uno laying around
3) I’m generally a cheapskate and I decided I could source less expensive parts

Parts list:
Arduino Uno
motor shield
2x NEMA 17 Stepper motors
one (1) 9g servo
fishing line (had this on hand – I figure anything over 10lb test would work)
wood board for printing surface (MDF recommended something at least 2’x2′ should work fine for 8.5×11 paper prints)
sharpie pen

3D printed parts:
Arduino clip – this was fortunate to find, as the board I had on hand was 3/4″ thick MDF) http://www.thingiverse.com/thing:17882
quick change pen holder http://www.thingiverse.com/thing:28854
2x fishing line spools http://www.thingiverse.com/thing:16384
2x motor mounts http://www.thingiverse.com/thing:288271

Polargraph Arduino Uno source: https://github.com/euphy/polargraph_server_a1
Polargraph Controller program (multi-platform): https://polargraph.googlecode.com/files/Polargraph%201.7-1.6.zip

full assembly


gondola (reversed, so you can see how the dummy CD was attached with hot glue)


gondola (pen holder)


Arduino Uno with motor shield


motor and mount


OLI Project: $50 radio control transmitter: from meh to yeah!

My cheap 4-channel TX needed an upgrade, so I went large ($50!) and got myself a Turnigy 9x v2 for Christmas. Months later it arrived.

I just got to messing around with it a couple days ago. The main reason I wanted the upgrade was to get “clicky” switches for changing flight modes (rather than having to rely on a inaccurate pot to set between 6 modes). And… that’s when I noticed the best manual I could find was a google translation of the original Chinese text.

When I bought the transmitter, I had no idea it had a ATMEGA64p in it… let alone some handy soldering pads on the board… and TONS of custom, open firmware mods! Enter er9x custom firmware!

Out comes the screwdriver, soldering iron and AVR programmer:

TX with old (slow!) firmware:


ATMEGA64p – thanks for the massive solder pads! (hot glue > duct tape)


New firmware flashed!


Now, when I originally installed the wire harness, I figured it’d a one-shot deal: flash and done, then close up the case with wiring inside in case I needed to flash it again down the road (which would require cracking the case again). But then I quickly realized the power of being able to plug into the flash at any time, change some EEPROM settings with EEPE, and flash the new config. It is a ton easier than navigating on the LCD to make settings changes.

So I soldered another length of wire after some sawing, filing and hot glue work, I had an externally accessible port:



And here’s the finished product, ready to read/write, looking no worse for wear. Next up will be the oh-so-popular LCD backlight. It seems pretty necessary, as the LCD’s contrast is not the greatest. It’s an inexpensive addition, and seems to be a lot less effort than this hack!


I added LCD backlight. Much easier to read! I highly recommend adding to to your HobbyKing cart for $5. I ended up paying $15 from an eBay seller in the US.
Here’s the new LCD backlight: