ADDING a 3-Wire Laser to a CR-10S 3D Printer

I wanted BOTH a 3D Printer AND a Laser - in one device.

With minimal switcharoos necessary to go from one to the other.

So, I modified my wonderful Creality CR10S 3D printer (an Instructables prize!) by adding an inexpensive "5.5W" 3-wire laser. Today, I'll show you how.

Objectives:

1. Mount a 3-wire laser on my CR-10S 3D printer
2. Control it via the incredible LightBurn software
3. Keep the CR10 still completely operable as a 3D printer without having to remove the laser.
4. Cut 1/8″ Baltic Birch plywood (even if it takes multiple passes)

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Main Parts

• Creality CR-10S 3D printer
• 5.5W Laser w/ 5V PWM. Options: (notes in next step)
  • Along with this 3018 CNC kit as I did, or
  • Standalone SainSmart Laser on Amazon
• 12mm x 3mm Neodymium magnets
• 3mm Screws
• Kill Switch

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Other Parts & Supplies (further explained in the following steps)

• 6" Flex Hose
• 6" Self-closing exhaust vent
• 6" In-line fan
• Fan speed controller
• Dark green laser safety glasses
• Laser panels from JTech
• Soldering iron
• Fire extinguisher

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Amazon links are affiliate links. They're how I afford name-brand sandpaper.

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Buy with a 3018 CNC Kit

I bought my laser w/ a $~250 CNC Kit (this one). I dedicated the CNC to CNC-ing, and put the laser on the CR10S.

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Or, Buy Standalone

I did a bunch of digging to find a standalone laser that has a verified 5V PWM signal.

The SainSmart Laser Kit from Amazon has standard 5V PWM control as verified on SainSmart's website here. This laser has a separate control board which is fine (and probably better).

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NOTES ABOUT POWER & CAPABILITIES

"5.5W"

According to popular opinion, "real" lasers like the JTech 4.2W (~$475), the JTech 7W (~$675), Endurance lasers, etc have considerably more power than these cheap "5.5W" lasers. Therefore, the quotes.

Don't expect a GlowForge outta this thing.

Area

Considering offsets, the CR10S is capable of laser-ing a 11" x 12" area.

Thickness

I've cut up to 1/8" Baltic Birch plywood (see pics above), which took some fine-tuning and several passes. If *cutting* is the primary task you have for your laser, consider getting a dedicated machine or a higher power laser such as the 7W version from JTech.

There are many tutorials about hooking up a laser to a 3D printer. But, in my quest to mount a 3-wire laser to my 3D printer, I found most tutorials cover *conversion* rather than *addition*. In other words, it's a pain to switch between laser mode & 3D printing.

I'll focus on:

A) Easy Mode Switching

I'm going to focus on an approach that allows quickly changing between 3D Printing & laser modes.

B) 3-Wire Laser Hookup

The specific setup I'll be covering today is for a 3-wire laser w/ separate power & PWM signal wires as follows:

• 12V
• 5V PWM/TTL
• GND

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This is probably common knowledge but I want to make sure it's clear: Components differ. 3D printers differ. Motherboards differ. Lasers differ.

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To help with this, I'll be very specific about the components I'm using, and I'll also make note of the technical function/feature of each so you can more easily adapt this Instructable to fit your specific scenario.

Example: Instead of saying:

Hook the white wire to Pin A

I'll say something like:

Hook the white wire to Pin A (which has the 5V PWM signal for the Part fan at the GATE of the MOSFET in my case.)

That way, if you have a different printer, you can ask your printer's Reddit/Facebook user group "Where can I find 5V PWM signal used for the part fan?" and they can point you in the right direction.

Hopefully this helps mitigate the problem of internet irrelevancy.

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Sorry to spam you with 5 safety bits, but things could go seriously wrong if you don't think this through. I'll try to keep them short.

I'll point you elsewhere for details, but basically you have at least these safety topics to get familiar with:

1. Fire
2. Fumes & smoke
3. Eye protection
4. Lasering yourself

Good articles to read up on safety:

MIT's Laser Cutting Safety

Laser Cutting at Home from Maker Freedom

In the next few sub-steps, I'll make note of the actions I, personally, took for each. Not recommending anything specific for you. Please do your own research and determine what's right for you, or wait 30 years to see how my approach worked out for me :D.

Here's what I do to try to reduce the risk of fire. Not necessarily what you should do. Research & decide for yourself! I:

• Bought this fire extinguisher and have it on hand.
• Bought a fire blanket in case a fire breaks out and I get cold.
• Stay in the garage while the laser is running to keep an eye on it.
• Clean my laser area out before usage.
• Added a kill switch on the outside of the printer enclosure. I very much like this Fulton switch with a huge stop button and doesn't need to be hardwired.

Fume exhaustion is essential, and big enough to be its own Instructable. Here, I'll point you to 2 Instructables that cover ventilation that exhausts to the outside.

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1) Kev_MTL's Easy and Cheap 3D Printer Fume Hood Enclosure

https://www.instructables.com/Easy-and-Cheap-3D-Pr...

It's pretty primitive, but gives a basic idea of simply capturing fumes and sending them outside.

My notes on Kev's design:

• Instead of the case fan, I'd recommend a 4" in-line exhaust fan.
• Drill intake holes low in the box so air can get in...then flow up and out of the box.

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2) PatternMusic's FumeCoffin

https://www.instructables.com/Fume-Coffin-Laser-Cu...

Though I think it's overkill, it's probably the proper and responsible way of doing things. In this Instructable, PatternMusic gives some very good explanations of what's going on with air flow, air pressure, and air filtration.

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Check out DIY3DTech's Video

DIY3DTech has a very informative video about air displacement considerations for exhausting to the outdoors. It's about 7 minutes.

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Okay, and here's what I did:

Not saying it's what you should do. My setup was intended to be flexible for welding exhaust, some fine dust extraction, and sending laser smoke and fumes to the outside. So I used a 6" setup to move the equivalent volume of air more slowly than a 4" system would. (example: 100CFM through a 6" hose moves more slowly than 100CFM through a 4" hose, and is therefore less disruptive to the welding shielding gases....in theory.)

• 6" Flex Hose
• 6" Self-closing exhaust vent
• 6" In-line fan
• Fan speed controller

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Here's what I did. (not necessarily what you should do)

You need to protect yourself and others who might get a glimpse of the laser. For this, I used a 2-part approach:

1) Laser Glasses

After trying several from Amazon, these dark green glasses make my laser appear far darker than the green glasses that came with my laser, and the color is more neutral to look through (less green) so when I take them off, things look far less pink.

Safest bet would be buying from a reputable laser company such as JTech below, but I use mine as part of a 2-part approach, and I don't laser often, so I'm pretty comfortable with the ones from Amazon, but make your own decision there!

2) Laser Panels from JTech

I ordered 3x of the 12x12 Panels from JTech to surround the laser area. I *wish* I'd bought 2x 12x24 panels instead to reduce seams.

This may sound stupid, but believe me, when focusing the laser, it's tempting to reach in there and move the board around instead of jogging the controls w/ Lightburn. Don't do it. And if you ignore that advice and do it anyway, at least reach in there with a stick or something.

With laser glasses on, you don't see the laser beam so it's hard to remember it's there.

But with beer goggles on...

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Extend your 3-wire JST connector's wires if necessary and run them down the length of the sleeve running from the hotend to the mainboard.

We need 12V, GND, and 5V PWM. This turned out to be simple:

• 12V -> Case fan (always on)
• GND -> Case fan
• 5V PWM -> Part fan’s 5V logic signal PRE-MOSFET!!!

Go ahead and splice the 12V and GND to the case fan’s 12V and GND.

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The 5V PWM is the tricky bit. Find this MOSFET in the pic above.

TEST.

Grab your multi-meter and test this pin CAREFULLY. On the CR10 screen, set your PART FAN to 0, 128, and 255. Your multimeter should show voltages of 0, 2.5V, and 5V respectively.

Unplug printer from the wall.

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Carefully solder your PWM/TTL wire there.

That pin on the left is the Gate pin for the MOSFET. On the Creality v2.1 Mainboard in the CR10S, this is where the 5V PWM logic signal comes from the ATMEGA2560 to control the MOSFET (which then uses trickery to modulate the 12V signal for the fan....but that's a different topic)

I put a bit of extra solder on the MOSFET’s pin, then tinned the wire w/ some solder, then melted the two together…wire in left hand, soldering iron in right. I’m mediocre at soldering small things, and this technique is low risk.

Keep in mind: when the PART FAN turns on, so will the laser. Obviously you’ll want to turn OFF the laser (button on top…at least for my model) when you’re 3D printing. Might as well unplug the laser using the top plug.

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SIDE NOTE: How does LightBurn control the laser's PWM natively?

M106 and M107, baby. LightBurn controls the laser using the same Marlin commands Cura uses to control the part fan.

I'll spare you the stories, but ultimately, to get LightBurn and Marlin talking, I had to make the following super simple changes in Marlin.

//Configuration.h

#define INCH_MODE_SUPPORT

//Configuration_adv.h

#define CNC_COORDINATE_SYSTEMS

These file changes are the same in Marlin 1.1.9 as well as Marlin 2.0

If you're unfamiliar with flashing Marlin on the CR10S, here's a good video on that.

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I designed & 3D printed a part that holds the laser UP high enough to avoid interfering with 3D printing mode, and OUT far enough to avoid interfering with homing. Download it form Thingiverse here!

You’ll also need 2x 12×3 Neodymium magnets, and 2x 3mm screws.

Use epoxy to secure the magnets in the recesses, then screw the plate on the laser.

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COMPATIBILITY NOTE! This is one of those places where your laser may not line up! This design relies on the holes being 40mm on-center. Recommendation: Print at 100% infill (the part is small enough anyway) so you can drill custom holes if necessary.

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This excellent laser-cutting software has a free trial, and is only $40/year. It's feature-packed.

https://lightburnsoftware.com/

More on using it in a later step. But just make sure to get it installed for now.

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Homing the Carriage:

Before placing the sacrificial board, home the carriage in Lightroom.

This may sound counter-intuitive, because the laser won't be homed to the plywood.

But, the objective of homing (at least, in the case of the laser) isn't so much to position the laser perfectly (that's in the next step) - but rather to let Lightburn know where the laser is.

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Sacrificial Board:

When using the laser, you'll want a sacrificial board underneath the board you're cutting. I use a 1/2" thick piece of plywood, cut to 11.5" x 11.5" to fit between the binder clips.

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After homing, put the sacrificial board back on the bed.

*put on your eye protection before turning on the laser*

This is where I do things differently to ease the homing process in the future!

1. Focus the laser (Using LightBurn's "Fire" button)
2. WRITE DOWN THE Z POSITION. (and turn off the laser)

Now you know the Z-position for the sacrificial board. This will ease future homing operations when switching from 3D printing back to laser-engraving.

Setup for engraving cutting:

1. Add the wood you want to engrave/cut.
2. JOG the Z-axis UP the thickness of that wood.

Example w/ 3mm thick wood:

• If you focused your laser just now, move the Z-axis up 3mm.
• If you just HOMED your printer, move your Z-axis up 3mm + the Z POSITION you wrote down earlier

This allows you to skip the step of focusing the laser each time you home it!

Since the Z-limit switch is still set up for 3D printing, and the 3D-printed bracket keeps the laser out of the way of the X-axis motor and up away from the print, switching between 3D printing and Laser modes is simple!

Switch back to 3D-printing mode:

1. Unplug (or switch off) the laser - Important!
2. Remove the backer board.

Switch back to Laser mode:

1. Auto-home in Lightburn
2. Jog the Z axis to: Focused Z (you wrote down earlier) + thickness of wood you're engraving
3. Plug in (or switch on) the laser

There are many Instructables about Lightburn, so I'll point you to my favorite:

Darkly Labs' Wood and Thread Pendant Necklace

Darkly Labs does a great job explaining many features of Lightburn. It's very clear, has great screenshots, and covers the bases I think are very helpful to learn from the start.

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Take the Instructables Laser Cutting Class

Also Instructables has a whole course on laser-cutting that will get you started with hands-on projects. Keep in mind that the laser used in this Instructable is limited to cutting 1/8" plywood and even then it will take several passes to actually cut.

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Check out my Instagram and YouTube places, as well as the Smoking LED Candle Instructable that resulted in the 3D printer you see above!

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