Openbuilds Table Top 50w Co2 Laser Cutter/Engraver

Openbuilds Tabletop Co2 Laser










Laser Controller
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The laser controller is a RUIDA 6445 DSP "Digital Signal Processor", this type of controllers are very common and installed on most big co2 lasers around, the controller consist on two principal modules, the controller main board and the display panel, the main board is where you make all electrical connections to the laser primary components, like stepper motor drivers to control motion signal, Co2 laser tube power supply for pwm control, limit switches "end stops" for homing purposes, other connections are available for other type of accessories, communication with this board can be set for normal USB or via the Ethernet port thru a network switch or a wifi router, wifi with an Apple express wifi extender was my choice, and a direct USB thumb drive to upload files without a tethered PC. The display panel have a very good size color screen, and a numeric keypad for direct value entries and not on increments like the RDC6442, able to change current cutting/engraving parameters, machine settings etc.

X Y Stage (The Gantry Motion System)
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The Co2 laser X Y stage or the gantry it is a bit atypical to the normal setups you may see on other type of CNC builds, the Y axis must be operated by a single motor instead of two like the Acro Laser or a C-Beam cnc Router rig, this is for safety reasons, as you notice in this type of build and other traditional commercial Co2 laser machines the laser tube is fixed in a steady base then the laser beam travels bouncing on mirrors and a focusing lens before making contact with the work piece surface, meaning that a perfect mirror alignment must be maintain all the time, that is why we want only one motor moving that axis in case of a motor or a stepper driver failure that can compromise the mirror alignment and having a Hi power Class 4 invisible laser missing a mirror and start a catastrophic fail, resulting on complete machine losses or even your own house, but if the laser tube is mounted on top of the X gantry and having all mirrors in the same moving platform should be a safe move to use a dual clone motor setup on the Y axis.

So for the size of this build I decide to use Nema 17 1.8deg motors, one Dual Shaft for the Y axiz, and one Single Shaft for the X axis, on both axis a 20 teeth Gt2 10mm wide pulleys were used, also using the same OpenBuilds nema 17 mounts I make 2 bearing supports for the 8mm shaft, and 2 mini V gantry set to mount the X axis rail on top.

For the X axis I decide to test a different motion system with the HIWIN type linear rails the model used is MGN12H, but a mini V gantry set will do the job ok, both axis motion are mounted on 20x40 extrusions, laser head mount/belt tension is a laser cut acrylic model available on the files section of this build as well the Y axis belt mounts.

A good way to do this X Y stage is making it as a module, and test it several times before mounting it on the machine frame, always try to avoid using your machine frame structure extrusions as a motion rail, it will be a very bad "cut corner" move when the time comes to the mirror mounts alignment process.

Z Motion System and Working Bed​

The Z axis motion on a laser cutter is mainly used to correct focal distances between the laser head lens and the working piece to be cut or engrave on the working bed, so we need that vertical movement of the working bed to precisely achieve that focal point distance, good focus is the main key for success on laser cuts.

In this build I also decide to make the Z axis motion a bit different from conventional commercial machines, that consist in the principle of 4 lead screws on each corner of the working bed area and mechanically actuated by one motor and a timing belt and pulleys on each lead screw, in my case I decide to drive "actuate" each lead screw by a direct connection to a stepper motor using normal aluminum flexible couplings 5mmx8mm and 250x8mm Metric Acme Lead Screws achieving a travel distance of 200mm from the laser head tip.

Why and How 4 motors? The main reason of the 4 motors is force, in my case I have a Chuck type rotary device "attachment" that weights 19.5 pounds so lift force is a big concern, how you can connect them is very simple, one pair of motors connected in series or parallel to one stepper driver (2 drivers are need it), then clone the Z axis signal from the main laser controller to each stepper driver, also a dedicated 24v power supply is connected to the stepper drivers to keep main electronic components in a separate circuit, so 2 24v PSU were used. The lead screw nut plate is on the files section of this build.

Electronics Components​

List of electronics and electrical devices:

1- Co2 Laser tube 800x50mm 40-50w
2- Co2 Laser tube power supply (LPSU) HY-T50
3- 24v power supplies, X2 Meanwell 14.6A
4- Main Laser Controller, Ruida RDC6445G
5- X5 Nema 17 Stepper motor 1.8 step angle (X axis)(Z axis)
6- Dual shaft nema 17 motor 1.8 step angle (Y axis)
7- X4 TB6600 Stepper motor drivers
8- DM542 Stepper motor driver (rotary plug driver)
9- X2 Water flow indicators with temperature probes and digital display
10- Analog ammeter 30MhA
11- 2 On OFF rocker switches
12- 1 On-On Toggle switch

Machine Frame
A quick look of the frame and a tip how to use a laser pointer to pre-align the mirror mounts





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