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CNC Add-on: Rot. Laser Soldering Paste applicator

Using a cheap tire compressor, driven by a stepper motor, to apply solder paste from a syringe and then soldering small wires to components.

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It's possible to melt solder paste with a 1.8W blue laser diode, but this assembly will contain 2x 3W laser on each side cooled with 4 heatsinks.

In the middle there is a syringe which contain the solder paste and is connected with a flexible tube to the compressor, which is driven by a stepper motor: the goal of this is to get better control of the pressure/ vacuum pulses needed to get good dosage. (also remove the need of an air compressor and also the Venturi vacuum generator).

On both side are mounting holes for a Cu-wire feeder (momentary manual feed) and a UV led if I wish to use UV-curring paste with composite fibers (the laser is then used to cut the fibers).

The whole assembly rotate, where the angle is calculated ( with the Teensy 3.1) from the coordinate values given out by UART from the CNC-Controller, the Teensy control directly the compressor motion (pulses) and transmit data via UART to an Arduino which then drives the laser modules and stepper for rotation.

System Design:

The assembly is built for my mini-cnc-mill (see my other project), it has a mount diameter of 65mm like my Chinese spindle (0.8 & 1KW have the same size) which means to be compatible with other small CNC.

The syringe is 10ccm, mounted in a brass body, 2 bearings 6005 2-RSH O.D. 47mm, are compressed with a M24x1.5 threaded ring on top.

The 2 bearings are mounted in an Alu. part O.D 65mm by 32mm height. A ring OD 47mm ID 40mm keep both outer part of the bearings apart, it permits to put tension on them with the threaded ring and the syringe holding body.

The laser diodes came mounted in 12mm barrels, 2 alu. blocks 20x20x20mm have a 12mm hole with a blocking set screw M3.

These blocks will be pinched between 2 heatsink (30x35mm), on each corner of these heatsink there are 2.5 mm holes.

The horizontal beam have M2 threads where the heatsink get fixed, 4x M3 threads to lock it to the syringe holding body. These M3 are also used to mount the wire feeder and/or a UV led.

Atop of this horizontal beam is a spacer ring and the 24T Alu. Hub Sprocket. 

A chain will link this sprocket to another one 13T which is mounted to a Nema 17 stepper motor.

  • 2 × Laser Diode with copper barrel Nichia NDB7875 445nm 9mm
  • 2 × PWM- Laser diode driver FlexMod P3 Laser Driver
  • 6 × Heat-sink 50mm x 63mm x 20mm
  • 1 × Microcontroller Teensy 3.1
  • 1 × Microcontroller Arduino pro min 328
  • 1 × Stepper motor driver chip ULN 2003
  • 1 × Toroidal Transformer 2x 7V 50VA
  • 3 × Darlington TIP 127
  • 2 × Rectifier 8A
  • 2 × Voltage regulator LM 340-5V

View all 23 components

  • The UV curing liquid

    AltMarcxs09/29/2014 at 03:59 0 comments

    Good news it's seems that the 445nm laser can also cure this, but  using only 2x 385nm LED isn't enough, the 415nm laser is much faster, have to make a heat sink for the last.

    Keep bottle upright.  

  • Putting electronics together

    AltMarcxs09/29/2014 at 03:50 0 comments

    4 axis or compressor stepper driver mounted: see

    Laser control unit mounted on the Y axis:

    The main control unit been tested.

  • Pictures

    AltMarcxs08/20/2014 at 22:49 0 comments

    Both 3W Laser diode mounted

    Laser on but picture with flash

  • Wire feeder

    AltMarcxs08/20/2014 at 22:33 0 comments

    Small spool of Cu-wire (or other fibers) going through a needle.

    This needle is just a bit lower than the dispensing needle, it keeps the wire on the PCB while Z goes to the solder position.

  • More electronics

    AltMarcxs08/20/2014 at 14:06 0 comments

    This board drives the laser drivers (Flexmod P3), the stepper motor which turn the assembly and additional 5V output used to switch on/off the UV laser mounted aside of the assembly ( will be used to expose PCB traces to UV ).

    It's receiving it's data, the values of laser power and an angle value to move the stepper, from the coordinate board with the Teensy 3.1 on it.

    It's also take care for E-Stop and Interlock.

    It contains some opto isolator because each laser driver get it's own 8.5V (at 2.4A) but the stepper motor need more the 8.5V, bridging them and he get's 17V.

    And it does work.

  • Update on Working on the electronics

    AltMarcxs08/05/2014 at 02:04 0 comments

    Here the schematics of the Teensy controlled board, which receive via UART the coordinates and "Spindle Speeds" from the USB-CNC card, the VFD feedback, and 6 buttons with leds. STOP PAUSE PLAY are transmitted back to the USB-CNC card (also an E-STOP), then LEFT ENTER RIGHT will be used for navigating through menus and setups, displayed on the 2x40 char LCD.

    Also 2 external valves are driven, a stepper driver ( the one for the compressor) also, a ref.position sensor for zeroing the stepper motor (again compressor).

    And most important are the values send via UART to the Arduino mini-pro which sit on the machine with the laser driver and the ULN2003 for the other stepper motor (rotating the whole assembly).

    Update: Small modification in the schematics AND building it on perf. board.

    On this it misses the Teenys 3.1 for clarity ;-) 

  • Compressor & Stepper Motor

    AltMarcxs07/30/2014 at 22:28 0 comments

    Mechanical parts: Scavenged compressor ( or buy a dirty cheap 12V car tyre compressor), a base plate, a pinion and a stepper motor.

    And assembled it does look like this:

  • More pictures

    AltMarcxs07/25/2014 at 16:40 0 comments

    Blue, Green, Red Laser on

    These are only for better view, blue and green crosses and red vertical (will be the UV-laser.

  • Got more stuff, received ordered electronic parts.

    AltMarcxs07/23/2014 at 23:27 0 comments

    10 Opto-coupler, ULN 2003, 2 rectifier, 2 heat-sinks, Transformer 50VA, cables and other stuff.

    I have 2 driver boards for the laser diodes, they need a power supply, each laser diode run a max current of 2.4A at this rates the forward voltage get to 5.5V, the driver board need min. 1.5V more, = 7V. Transformer has 2x 7Vac rectified = 8.1V.

    The transformer/rect./cap. stays in the CNC case, but the laser driver board have to be near the diode, that why I'm going to mount the heat-sink/driver behind the Z and atop of the Y axis. Will be great!

    An LM 340 will produce the 5V for the Arduino and also provide Voltage for the UV Laser/LED which will be commutated with an TIP 127.

    The ULN 2003 drives a small 5 wire nema 17 stepper used to rotate the whole assembly, it will get it's power from the bridged 8.1 +8.1 V supply.

    I got to be careful with this setup, at least one of the laser driver board needs 2 opto-couplers for the PWM signal and on/off. The boards are nice you set the max. current for the diode at 100% PWM and at 0% you leave just enough current to keep the diode in a lasing state. (the diode will last longer)

    The arduino will receive via uart, the calculated angle, the power of the lasers, and UV laser/Led on/off. Also it should receive/act to the emergency stop interlock. 

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Enjoy this project?



Chaz wrote 08/27/2014 at 15:32 point
You should consider using a screw extruder to meter the paste out. You could drive a drill bit in reverse. Then use a pressurized syringe to supply paste to the screw feed. a bit more involved but will be more consistent

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AltMarcxs wrote 08/27/2014 at 19:06 point
Paste dispenser use compressed air, a Venturi vaccum generator and valves. (also make great noise).
I asked myself how to improve this, electric regulated air pressure, valve timing… too complicated.

Using a stepper to create pressure pulse is way better, it's way faster than open/close pressure valve and open/close vacuum valve.

But most important: I can't have a compressor in my apartment (the flow rate for the Venturi being the biggest issue)

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Deadbot1 wrote 08/27/2014 at 20:44 point
My thought here would be to use a stepper and drive a peristaltic pump. With a setup like this you could precisely control the amount, offload the pump to a remote section of the bot(reducing weight at the head), and utilize multiple pumps to use multiple materials.

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[this comment has been deleted]

AltMarcxs wrote 08/27/2014 at 00:50 point
I got from my CNC card a serial out but no serial in, it has also 3 digital inputs for buttons (Pause, Start, Stop) and 1 E->Stop.
With this I receive the coordinates and spindle speed via Uart but have to feedback to the CNC it's digital inputs.

From Teensy to the Arduino mini I use an other serial port (this time bidirectional), to set the laser power, rotation and the additional output values, also I get Status information back (mainly E-Stop and which Add-on is connected).

I had to do this because the laser driver have to be mounted near the diodes, and it's simplify the wiring (4 wires for power supply and 2 serial TX/RX).

BUT later I want to build another Add-On: 3D printer extruder, were I keep my Teensy board as it is within the CNC ctrl-unit, but have another Teensy/Arduino, outside, taking care for temperature, heating element and so on.

It all began with the wish of an coordinate display, then set spindle speed, then getting torque feedback from the VFD (in milling mode), then pick&place, paste soldering and in future printing 3D with extruder.

I want this modularity/expandability , Just connect the Add-on required and go.

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davedarko wrote 07/23/2014 at 07:19 point
Wait, lasers in a project and no video? Interesting project, "Laser soldering paste syringe - without sharks (yet)" would probably get more attention though ;)

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AltMarcxs wrote 07/23/2014 at 22:38 point
But it could be used for much more… Video coming soon.
Well I hope the title is now better. English is not my main language, please pardon my errors and strange formulations.

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davedarko wrote 07/23/2014 at 23:00 point
It does not have to include every function and you should consider that will cut off the name after an amount of characters in some places (lists and on mobiles) so make sure it features the coolest stuff first to get the deserved attention and let the crowd read the rest in the details :) the picture is a bit blurry. But it is really interesting and i'm looking forward to the video! It's not my native language either, but nobody cared around here, don't bother :)

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davedarko wrote 07/25/2014 at 16:42 point
Much better pics now :)

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davedarko wrote 07/27/2014 at 19:14 point
much much better pics now :)

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AltMarcxs wrote 07/27/2014 at 21:12 point
And there is a video too.

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davedarko wrote 07/27/2014 at 22:35 point
You should give the video its own log... the link list might be nice but having an embedded video is twenty times better to see for everyone :)

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PointyOintment wrote 07/23/2014 at 05:28 point
Your title doesn't make much sense, but your project itself sounds interesting.

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AltMarcxs wrote 07/23/2014 at 22:26 point
I know, there aren't enough char allowed in the title, it's so diverse: solder paste, UV curing epoxy, conductive ink, ceramics, pick and place, experimenting with wires/fibers and even more. But how should I name it?

  Are you sure? yes | no

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