Laser cutter and engraver

Laser Cutter and Engraver

Laser Cutter and Engraver

I purchased a K40IV laser engraver directly from China through eBay for $660. I have seen lots of posts about what “cheap” units these are and how “crappy” the software is that comes with them. I have a different opinion about these lasers. I for one am really impressed that the individual hobbyist can get in to the laser cutting and engraving game for less than $1000. I personally found that the customer support from “shmilyshop2011” was fantastic. They sent me a replacement part for something that was damaged in shipment, and I think they tried very hard to make me happy with the purchase. Sure, the construction is not fancy, but it is solid and functional. It’s up to you to add on bells and whistles or fancier components. The laser tube and supply have been very solid performers so far. If you price out each part individually, you will find that buying the package saves you some serious money. Fancier systems which ultimately have the same performance are 10x the cost. As a hobbyist, the gamble with inexpensive gear was worth it to me, and I am happy with the result so far. I am doing some serious work with the gear that I purchased.

Please read my note of caution on the main N6LYU home page

Amateur hobbyists, please read the following carefully!

To my general note of caution, I will add quickly that the fumes produced during plexiglass cutting are really nasty. I have a two-stage pusher-puller ventilation system, but the garage quickly fills with a bad smell once the cutting starts. I have been wearing a gas mask or exiting the room during the cutting process. I understand that the fumes are very, very toxic and that they should be taken seriously. I intend to upgrade the puller part of the ventilation since I think the pusher is the source of leaking gas.

Also, when switching from engraving to cutting, the chance of setting things on fire increases dramatically. The 40 Watt laser is on continuously, and dwells for a much longer time in the same spot as it cuts. My engraver sits on a wooden work bench. There is a round port at the bottom of the machine through which the defocused CO2 beam passed during one of my cutting runs. It set the table top wood on fire! I added an aluminum heat sink below the work area to absorb laser energy that cuts through my working part.

Pictures of laser engraving results

Wood
engraving of the Taj Mahal

Wood engraving of a Flamenco dancer

Video of
engraving of Flamenco dancer

Plexiglass engraving for an office gift

20120514-123922.jpg

I added a more powerful air ventilation system and a stronger water recirculating system with a filter. I added a cup of bleach to the water just to avoid having anything start to grow in there. While the sump pump that came with the unit worked fine, I just have a better feeling about dissipating the hundreds of Watts in the laser tube with a higher water flow rate. I also added a paddle wheel indicator so that I could visually verify coolant flow. I have the laser, water pump, and ventilation fans all switched by the same power strip, so one can not run without the other. The paddle wheel has an interlock output that I plan to utilize down the line.

I had intended to modify my new laser engraver to become a laser cutter by replacing the stepper motor controller board with one that could be controlled from Mach3. As it turns out, there is a software solution that works very well. The solution to the laser cutting problem did not require cutting a single wire! I thanked the blog author for his post.

In principle, all the parts are on the table for laser cutting. The engraver is a 40 Watt laser with two stepper motors moving the last optics to direct laser light to the intended target location. In engraver mode, the laser head follows a raster pattern like a dot matrix printer and burns little spots. A laser cutter needs to follow a vector path and move much more slowly so that the beam has enough dwell time to cut through the intended material. The trick is making the raster engraver software perform slow vector movement. The blog that I found to solve my particular problem on my particular machine is the following.

Combined Cutting and Engraving in Moshidraw

I know that many, many people have exactly the same laser engraver that I purchased and use Moshi Draw. I hope to enable many of you to perform cutting operations that you probably thought would require you to buy a machine for multiple thousands of dollars. The blog gets you started, and has already produced some great parts for me.

Here is a Plexiglass trinket that I first engraved, then cut.

Frog picture

Here is the Stepstruder Mk 6 “Part A” which has open source drawings available. MakerBot Industries charges $5 for the plate plus $7.75 for shipping. When I heard that, I thought “Hey, just ship it, don’t handle it!” Now I can cut as many of these as I want. My plastic “Part A”
cracked, and now I can easily replace it.

Stepstruder Part Picture 1

Stepstruder Part Picture 2

Video of Stepstruder part cutting

I have sold one of these on eBay. I will probably make more parts and diversify.

This guy appears to have figured it out in a ;similar
way
.

There are companies that will sell you a packag of board and software

but the packages cost more than my laser engraver!

A stepper controller board costs less than 100 bucks on eBay.

There are YouTube videos of people who have performed hardware conversion to directly control the engraver stepper motors using Mach3. It is a straightforward solution, and a good one to be sure. A good implementation would include an easily switchable system to change between engraving and cutting (Moshi Draw and Mach3), and will also
require laser power control through some G-Code implementation.

Since any laser cutting or engraving involves only two stepper motors, I am not particularly compelled to converting the operation to G-code and Mach3. Honestly, if I can take a CAD file and end up with a nicely cut part, I don’t mind using a funny combination of software steps. The other advantage of leaving the hardware alone is that sometimes I want to engrave a surface, then cut out the part. By using the software steps described below, I can make that switch without any trouble at all.

In summary, to perform laser cutting using the K40IV, do the following:

Create a DXF file using Autocad, or generate one from an image using
software such as Img2CAD

Use CorelDraw or any other program you can find to convert the DXF file
in to PLT format

Use the PLT file as input to MoshiDraw (as described in the above
referenced blog)

Adjust your speed settings to slow down the laser movement depending on
the material you want to cut.

Here is a video showing the engraver cutting out a foam part.

Although the first laser cut parts that I made look pretty good, I want to add air assist to both cause less heating of the plastic and to make even cleaner edges. I will design the air assist fixture for the ;laser engraver and make the drawing available to others. The lens assembly is not adjustable on this laser, so the part is easy to make. I just need to add a funnel with a tight fit around the lens fixture held in place with a set screw, a port for compressed air, and
an exit nozzle for the laser beam and flowing air. The air blows away melted or burned material and also cools the surface during the cut. Additionally, the compressed air in front of the lens keeps vapor and burned junk from collecting on the lens. I cleaned a pretty good film off of the lens as I was measuring the mount in preparation for the air assist part design.

There are air assist parts available on line as well. At the moment, I am hesitant about modifying the CO2 laser beam path since the beam is invisible, even to a standard IR viewer, and I am worried about successfully realigning if I completely remove the lens assembly. I am sure I will dive in to that process at some point, but for now I just want to ramp up my laser cutting ability.

An eBay search for “CO2 Laser Head Mount” results in many appropriate
items ;for sale.

Here are pictures of one such item

Air
assist drawing

Air assist picture

Now just think about the possibilities! I can both engrave and cut arbitrary images and patterns on a variety of materials. So far I have engraved wood, anodized aluminum, plexiglass, ceramic tile, marble, and glass. I have cut 1/4″ plexiglass very successfully.

Here is a commercial air assist

Here is commercial conversion software for sale

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