Build Log: Laser CNC cutter for R/C Modelers

[ujjwaana]

Disclaimer: Please note that this is more of a Prototyping of a CNC Cutter using high power Laser LED, mounted CNC made form salvaged Printers. I might never be able to complete the build due various Financial/Technical/Time/Family hurdles. I expect the reader would spend its valuable time reading this thread understanding  challenges faced by hobbyists. As a true FSF/OSS believer, I would try to extend all my help/guidance/collaboration to others  interested in such a wonder tool.

Epilogue: Ujjwal received the Laser Diode from an E-bay seller. TCO = $26. Its time to move forward to make the CNC.

It was hard to resist the USPS packet lying for over 24hrs on my workbench and me caught in other stuff. It seems USPS is far better than HK post- they travel thrice the distance in 1/4 time. I received my 1 Watt Laser in flat 6 days after payment, way far form US.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180434964392&ssPageName=STRK:MEWNX:IT#ht_1695wt_939

The seller mentioned that he used 2 'D' cells amounting to 2.2V (must be NiMh, Zinc based dry cell give 1.5v/cell) and used a 1E1W resistor to limit the current. I do have small inventory of electronic component and luckily had a LM317T voltage regulator. Too lazy.. I stole 2 D batteries from my flat mate's flashlight and  started with only 1 Cell (1.5v - middle path). I connected the diode in series to my Multimeter in 10AMP mode. I saw a very faint red glow, way feeble than popular Laser pointer. The current reading on the DMM was mere 20mA. My heart sank! Then I recalled some zenner  voltage concept which needs a threshold voltage for m semi conductors to work. I soldered two cells in series , put the the cover of recently dismantlement Futaba Charger in front of the LED and connected the Ammeter.
Voila!! the current surged to 1.2AMP !!! and I saw a much, much brighter laser beam! 2 seconds and I smelled something. Touched the diode (C-mount resembles TO-20 package) which was pretty hot. 2 seconds and the diode went KAPUT with heat and smell!!!!

I removed the diode and examined the charger cover! By JOVE!!! there as a good 1mm cut/burn made by the Diode in just 2 seconds!! and that in a very hard plastic!!! The smell was of burning plastic and not of the diode itself!!
<Edit> The diode is alive and kicking. the burning plastic left some residue on the diode glass window which I cleaned using Alcohol. But I fear using without a driver circuit (control current) and heatsink.<Edit>

The results seems to be kind of promising. The Diode can deliver quite amount of energy, in the beam, to  object on which it incident. 1 mm cut on hard plastic is a nice output.

Next Step:
1. Make a stable 2.2V/1.2Amp regulated power supply (Easy)
2. Put a heat sink/Cooling system for the diode (Easy)
3. Make a Focusing system using Glass lens/Quartz  which would concentrate power to at least 10's of time.(somewhat challenging as the material science is unknown to me. Losses in glass lens may heat it up/defract)
4. Try cutting Depron/Balsa. It should cut and not reduce them to Ash/Smoke!
5. It things goes fine, start hunting/stealing salvaged Dot Matrix Printer/Scanners


Attaching the photos of the cut made by the Laser.
<Any member interested in donating his dumped/junk Inkjet/Flatbed Scanner/DMP are welcome . I would post if things go fine>

Wish me luck!!
 

[vinay]

Good to know, wanna see in person today, will definitely come to your place Any plans to build a laser gun like the one in Startrek?

[ujjwaana]

Why not!! As long as I get a BIG target like you, during prototyping!!   

[ankur]

gr8 work
As per what i think i to carry out forward the only problem u will face is this:-
http://www.rcindia.org/rc-general-topics/thermocoleps-casting/msg10002/#msg10002
http://www.rcindia.org/rc-general-topics/thermocoleps-casting/msg10004/#msg10004
http://www.rcindia.org/rc-general-topics/thermocoleps-casting/msg10126/#msg10126

u'll need to first get deep into the printer and then try using it
since u have a laser u can just use it instead of the cartridge and use a reprogramed system to sent hte required current only when it has to do some cutting job
rest all i have already mentioned in those posts

[ujjwaana]

Thanks Ankur. thankfully, out of 3 requisite, I am at least good in 1 and 3. I have a good mechanical Engineer  colleague whom I am inspiring to help me.

My present hurdles are Laser/Cutting head, Salvaged Printer or Carriage Rail raw material (shaft, long drive bolt and special 'Nut') Servos are not a problem so are drivers and interfacing with computer. I hope i will get over the first one soon to start hunting the CNC mechanism.

I have seen Inkjet printers with Belt and pulley system and would also consider since Laser setup, if it works, would circumvent the need of a carriage system made of bold and Nut which are specialized to carry heavy load like a Dremel or Saw. Still any pointers to find these long bolt and Nut in India would greatly help me.

Sadly I would be home for Christmas (the only festival of happiness for us) and am busy wrapping the current assignment at office. So the CNC would see light only early next year.

-Ujjwal

[ankur]

Well thats good if u have some poeple helping u around
well i dont know the weight of the laser could u tell me

[ankur]

Also u can place the laser on just one place and make the apparatus move the balsa/foam that will be a good idea the tackle the weight problem of the carriage system
for laser u need no servos just the ordinary 'reprogrammed' mechanism
get 1 second hand working injet printer and perhaps 2/3 dead printer and it will do ur job
also it will not be xpensive
i had a old lexmark inkjet which i sold for rs200[non working] and bought an all in one
i would have never done that if i knew i could make cnc out of it...
all the 4/5 printers including a living one would cost not more than 2000 rs
and a new inkjet will cost about 2000 i guess

[sushil_anand]

2 seconds and the diode went KAPUT with heat and smell!!!!

Why did the laser go kaput? I think you need some sort of current limiting. Also, are you certain that the diode does not need a pulsed source? What do the specifications say?

[ujjwaana]

@Sushil : sorry for missing this vital detail. The laser is intact. I have updated my post.

@ankur the whole benefit of laser diode is the ease of moving the head as it very light and just required 2-3 wires (max 18SWG), much easier than putting a 1 pound Dremel or a CO2 laser with all the cooling pipes.
Moving 50gsm A4 paper on a drum is easy. Its quite difficult to have a moving mechanism for the base as it would require clamping, larger throws and power. Balancing the platform (moment of couple/torque about the carriage axis) when the platform moves the extreme end would be a mechanical engineering challenge, my weakest department.

If you see, most of the DIY/Hobby CNC DON't use moving base platform, including the most famous and successful ones.

[ankur]

If anything is popular doesn't makes it always right and others always wrong[or we would been still thinking that  the earth is in the center of the solar system lolz]
anyways u can make the assembly move but that wouldn't suit,as per my sense
use good geared motors and there will be no problem in moving the base

[SORAV]

i think this can answer all the doubts .plz have a look on this. http://www.8linx.com/cnc/online_store.htm

[ujjwaana]

i think this can answer all the doubts .plz have a look on this. http://www.8linx.com/cnc/online_store.htm

And you think some one would start investments in the CNC like me without ever seeing the Site! You are hit the nail on the head Sourav. This has bee my major inspiration! they have awesome plans and kits!!

@Ankur. The Diode is standard C mount transistor (SL100 etc) , measure 15mmx12mm and weights barely 5gms. even if I move the driver circuit, the whole setup with focusing lens/heat sink wouldn't weight more than 100g - lighter than even Inkjet print head. And I am sure, moving head is more appropriate than moving base platform. I am anyway not doing a POC of moving platform design. Think again. For moving laser head, I would need only 3 carriage system : 2 parallel on which I would mount the 3rd which will hold the Laser. Moving platform would need at least 4 such carriage + Servos

Okay some of the 'Bill of Material' (BoM) for the project: (Anwar, can't I get the 'modify' button back on my first post of the  thread ? it would be great to put imp thing at top).

1. Laser LED - Got it. Will it work ?

2. Ball Screw and ACME threaded Rods (3/8-12) - 3 nos each : http://www.tradeindia.com/fp342457/Ball-Screw-Rod.html
OR ACME rods with ACME Nuts:  http://www.threadedrod.in/index.php

3. TODO: Guide Rods with Bush, Servos with mount, Servo Driver, PIC based USB interface for controlling the Servos and laser driver.

[RotorZone]

Ask for a quote on acme thread and linear guide rails. You'll fall off your chair I was quoted 20k for a linear guide just about a ft long. I suggest using the rails used in modular kitchens. Ebco (in Indian brands) and Hettich (german) are supposed to be good. Using ready made solutions where available will help the project from getting stuck forever. Take it from a guy who went that way after collecting parts.

For the threaded rod I was planning to use normal 10mm threaded rod (sp rd). To take care of backlash, use two nuts(brass) spring loaded. Fix one to the carrier. The other should be free floating, but not allowed to turn. This thread will make your machine precise, but slow if you are using 200 step steppers. There is a bipolar stepper motor (no specs, but found to be very strong) salvaged from printers that you could get form sunday market with less steps. This should be more suitable with this type of threaded rod.

[ankur]

i went to a local computer store today and found the rates of old used printer
here are they:-
old working dmp/inkjet:-1000 rs
old non worrking dmp/inkjet:-500 rs
old working laser printer:-2500 rs

[ujjwaana]

i went to a local computer store today and found the rates of old used printer
here are they:-
old working dmp/inkjet:-1000 rs
old non worrking dmp/inkjet:-500 rs
old working laser printer:-2500 rs

Fundooo!! I would try same in Bangalore tomorrow. I am going to my home time any way (next state capital on Ganges downstream after your city), I have lots of computer AMC/Repairers contact. would try there as well - I might things for free as well!! Rs 1K for DMP is not bad as long as the carriage and Servos are intact!
Thanks Ankur for giving some indicative prices

-ujjwal

[ankur]

i think the laser printer setup will be good for ur laser cutting device
am i right?

[ankur]

(next state capital on Ganges downstream after your city)

u mean patna right

well these prices i m getting because of good contact with the dealer

Rs 1K for DMP is not bad as long as the carriage and Servos are intact!

he said they will be working it means that they are intact

[sahilkit]

hi ujjwaana

what kind of results do u get with balsa or biofoam ??

[sahilkit]

http://www.parallax-tech.com/cutting.htm

[vksingh]

Hi Ujjwaana,

Have you bought the threaded rods. can you please tell me the price for each rod.

[ujjwaana]

Sorry Mr VK Singh but I have been relay caught up with office work since Jan this year.

Barely could make few Planes. not much time to make the CNC (still a in wish list).
I tried to get old Dot Matrix printer (large 136 column one) but no success.

I still have the laser diode + lens mechanism. But its time before I can start the CNC.

[Bilal]

ujjwaana sir,
i have build a cnc hot wire foam cutter, single axis stationary wire moving foam type and have successfully used stepper motors from old/junk xerox machines. the motors were 12v 1.8 step unipolar ones (with six wires), i used two of such motors to move foam block on the x axis while the wire rides over the ply template attached to the sides of the foam block. Sir initially i used the belt and pulley mechanism salvaged from some DMP printers but there was some slop in the system so i shifted to threaded rod-nut system which is quit slop free.
sir now i am interested in building a four axis cnc foam cutter (X-Y axis on both ends) and need your help in interfacing the system with the computer.    

[rajarshi]

u can have my design and mount the laser (after removing the router)
cost would be Rs 40000 and mach 3 software