The Documentation Last update: 2019-08-13
This Lasercutter is -more or less- a
copy of the cutter constructed at hackerspace Bitlair*,
Eightdot* started this copy for Hack42, Arnhem, NL, around 2014,
but due to personal circumstances he was not able to finish the
Early 2019 JanBee* started to finish it, taking a lot of advises
and suggestions for improvements from HobbyBob* (HB) and Eightdot*
An important design criterium for this machine was to allow
materials of size 1220 x 610 mm to be handled. This is (at least
in NL) a standard dimension of widely available materials such as
This documentation is primarely meant to maintain the machine at
It is NOT an instructable to build a Laser Cutter, but those who
are involved or are planning to build one may profit from the
The LaserCutter at Bitlair, Amersfoort, NL.
The "FatMan" under construction at Hack42. (Photo
To the very right, partially visible the smaller laser cutter
It was very helpfull to have a smaller working laser cutter at
hand (kind of K40-clone) so we could make many smal parts from
either plywood or polyacryl. Also we are in the lucky position to
have a metal workshop with a lathe and a milling/drilling machine
with accurate X-Y-Z positioning. This made it possible to make
several parts from metal, mostly aluminium, in stead of
3D-printing which gives less sturdy parts.
When I (JanBee) started to work on this machine early 2019 most of
the parts were present; the frame was mounted, the X- and Y motors
and drive belts were mounted, the cover could be opened and closed
and several panels of either metal or plywood were present. There
were Power supplies and motor drives and even a Laser Tube
specified for 100 Watt optical output.
Advised by HB* and EightDot* we decided to implement a number of
improvements over the Bitlair unit.
The frame of the machine itself is not stiff enough, it needs
support of a very rigid and stable structure. We constructed a
frame from welded 40 x 40 x 2 mm square steel tubes, the whole
thing on wheels. The frame is dressed with some 18 mm thick MDF
plates, on top, bottom, backside, left and right side, leaving
space for storage of materials and on the right side the cooling
Integrated in this MDF construction is the exhaust fan which sucks
air from the laser space and blows it out of the building through
some large diameter hoses.
HB* advised us to mount the X-motor and the return pully on the
X-beam itself, and not on the endplates which carry the Y-wheels.
This prevents the endplates to bend in response of the
X-movements, de-alineating mirror 2.
Also we kept the drivebelt connection as low as possible to
prevent wobbling of the mirror-3 plate.
The beam of the X-rails has been reinforced in the Y-plane with a
25 x 25 x 2 mm “U” profile over nearly the full length. This
profile is also used to guide the X-caterpillar.
In the original design the drive of the Y-axis was done by the
motor at the back-center side, with two M5 threaded rods to the
sides where two dented belts were driving the X-beam. We replaced
these M5 rods by 10 mm aluminium tubes. Some lath-work was done to
interface the tube to the 5 mm rods carrying the Y-pullies and the
We choose to implement a laser bed which can be motorically
adjusted in height, to adapt to different thichknesses of
materials or workpieces. The bed is now supported by 4
M10-threaded rods which end in bearings and pullies. A closed belt
drives the 4 pullies synchronically. 1 of the rods is directly
driven by the Z-motor. End switches limit the travel of the bed.
BugBlue* designed new tensioners for the X- and Y drive belts.
The surface on which materials to be cut or engraved can rest is
the usual honycomb structure. The honycomb is supported by
aluminium L profiles 25 x 25 x 2 mm positioned with the
hypothenusa in the horizontal plane. The frame of the bed rests on
the L-profiles of the Z-axis mechanism and can easily be taken out
to clean the area below. It can be replaced at exactly the
original position by a few notches.
Winch / Cover
We decided to implement a motor driven winch to open and close the
cover of the machine. The size of the cover is such that people of
moderate size find it difficult to open or close it.
The frame of the machine was modified such that the opening on the
front of the bed area is now lower, making the placement of
materials easier. The corresponding part on the cover is provided
with slits to allow air from the room to enter the bed-area, but
in such a way that (laser) light cannot go through there. The
front plate of the cover has a little overlap such that no laser
light can go through the slit.
In the original design the exhaust was on the right side of the
channel below te lasertube. This causes a sub-optimal airflow over
and below the laserbed. In the new design the exhaust fan is below
the table top, in the middle of the laser area, and sucks over the
full width of that area.
During the construction we had a small He-Ne laser available which
was mounted on the place where the CO2 tube should
come. With this visible light most of the mirror adjustments were
done. Doing so the CO2 laser tube needs to be mounted
only in a very late stadium of the whole construction process and
there is less need for adjustment-shooting with the CO2
Mounting the Laser Tube
The 3-D printed mounts which were already made allowed adjustment
in the horizontal plane, but not in height. The commercially
available mounts for a 80mm diameter laser tube were to heigh,
they would not fit into the machine. We designed some mounting
plates allowing vertical adjustment of the tube.
We decided to implement a red LED-laser based pilot light, to help
adjusting workpieces on the bed.
The Beam Combiner stuff we bought throug the AliExpress channel
did not have enough adjustment possibilities, so it was modified
in several ways. Basically two independent adjustments are
required: First to aim the pilot laser such that it hits the
combiner mirror exactly at the place where the CO2 beam
leaves this mirror (should be the center of the mirror), secondly
to adjust the combiner mirror such that the pilot beam is exacltly
aligned with the CO2 beam.
Also it was positioned in a non-perpendicular way to have more
margin for the CO2 beam width.
The usual mirror mounts have adjustment facilities only for
rotating the mirror in the horizontal and vertical planes. However
also adjustments for translation in X, Y and Height are required
to have the beam hit the mirrors in their center. We realized this
by mounting the mirror-mounts on laser-cut acryl plates which
allow adjustment in X, Y and Z directions by adjusting nuts on M5
threaded rods through 5.2 mm wide slits.
The safety facilties of the usual laser control boards (we chosed
fort he Smoothie Board because it supports fast streaming of
raster data) are quite marginal. Advised by HB* we implemented a
“Safety Board” (SFB) which monitors and controls most of the
functions in the machine and tells the Smoothie Board (SMB) with a
few signals that all is safe, job can be started/paused/stopped,
etc. The SFB talks by ETH/UDP with the RaspberryPi which runs the
GUI displaying data and allowing control on a 7-inch touch
We use a Smoothie Board V1.3 from BigTreeTech. A special interface
board was created to route signals from / to the Safety Board
(SFB). The SMB talks with the LaserWeb Server running on the
Raspberry-Pi (Pi) through
the serial port on the Pi's GPIO connector.
A functional description of the interfacing with the HVPSU.
The Safety Board (SFB) monitors and controls most of the functions
in the machine. It listens along with the signals sent by SMB to
the HVPSU, with Home and Endswitches etc. It measures water flow
and temperatures. The SFB is a quite dumb board, it measures and
controls, but most decisions are made in the GUI program running
on the Pi
The Crydom board hosts up to 8 solid state switches. It is used to
switch mains power under software control to several sub-units.
A motorized winch is implemented to open and close the cover. The
open / close commands are given through a serial connection
between the SFB and the Winch Control Board (WCB). Commands
originate from the GUI on the Pi.
Cooling the laser tube is extremely important. When operated at
the specified maximum output power the tube dissipates around 450
Watt. The tube is designed to use water cooling. Optimal
temperature for the tube is around 17 °C, which is generally lower
than room temperature. So passive cooling by air is insufficient,
an active cooling system is a must. A second thing is that we must
prevent a temperature shock for the laser tube when the system is
The water flowing through the laser tube must have a very low
electric conductivity, otherwise there is a risk of flashing at
the high-voltage side of the tube. This can be achieved by using
destilled water. There is discussion in the laser community
whether to use demineralized (DM) or destilled (DS) water. Well,
the difference is that DM water may contain non-ionic contaminants
on which algea might grow. Destilled water surely is free of such
contaminants. Both may absorb gasses from the air, in particular
CO2, which makes the water slightly acidic, and so
conducting. Also metals might dissolve a bit.
We use destilled water with addition of a little anti-algea
solution, and we continually monitor the conductivity of the
The AirAssist is a nozzle from which air is blown onto the cutting
Bitlair: Hackerspace in Amersfoort, NL.
Bugblue: A participant of Hack42.
Drive Power: The part of power circuits that must be explicitely
switched on, and will be switched off by the Emergency Button.
EightDot: Participant of both Bitlair and Hack42 who initiated the
construction of the Hack42 Lased Cutter.
FatMan: The name we (#42) gave this machine. In contrast with the
smaller laser cutter named Little Boy.
n.b. Little Boy and Fat Man were the names of the atom bombs on
Japan in 1944.
Fpc / Lazarus: Free Pascal and the Lazarus IDE (Integrated
Development Environment) to make programs with a GUI, Graphical
Lazarus / FPC is freely available for many platforms, Wxx, Mac,
Linux, Raspberry Pi, etc. The slogan is “Write Once, Compile
This is true for the larger part, but running an application on
different platforms can give supprisingly different cosmetic
GUI: Graphical User Interface. Something like Windows on a screen.
Hack42, #42: Hackerspace in Arnhem, NL. Location of this Laser
HB: HobbyBob, participant of Bitlair having much experience with
buiding laser cutters.
HVPSU: High Voltage Power Supply Unit for the CO2
JanBee: A participant of Hack42 who is finishing the Laser Cutter
and made the (this) documentation.
MDF: A cheap plate material consisting of fine wood grains and a
lot of of binding material. Available in a range of thickness.
Pi: the Raspberry Pi which runs the LaserWeb-server and the
SFB: Safety Board.
SMB: Smoothie Board.
WCB: Winch Control Board.
Winch, Winch Controller:Mechanism for motor-driven opening and
closing the cover of the machine.