This is a very fun project if you have a lot of time and love to build everything rather than just going to the store and buying it. This guide will show you how to build a CO2 laser cutter with a cutting bed size of 38X17X10. It costs about 1200-1500 to make at the time of writing.
Video of the system cutting cardboard: http://www.youtube.com/watch?v=4fwhJxxNYtI
I apologize in advance, this is my first instructable and I am not the best writer.
First thing to know about building a laser cutter is that this is an extremely time consuming, dangerous, and difficult process.
You should not work alone. If you hurt yourself, you need someone around to call for help. This is a very real concern.
Things to know when working with lasers:
* Death: Voltages as high as 50000 volts with currents up to 100 ma. This can instantly kill you.
* Blindness: The laser used here can destroy your vision before your brain can recognize there is a problem.
* Fire: The laser used here can set objects on fire without your knowledge through a reflection of the beam.
Whenever the laser system is powered:
* Eye protection should be worn by you and everyone else
* Doors and windows should be closed
* Insure adequate distance between you and high voltage terminals
The laser used here emits infrared light which is invisible to the human eye. Considering that this light cannot be seen, it is difficult to tell where the beam is being directed. Polycarbonate absorbs infrared light very well. I recommend you head over to home depot and purchase several pairs of clear polycarbonate safely glasses. Do not fire the laser irresponsibly.
Now that we got through all the safety stuff, I have one disclaimer: I highly do not recommend that you do not build a laser cutter. Cheap Chinese laser cutters can be purchased on eBay for less than 1000 dollars with similar accuracy. I understand that most Chinese laser cutters do not function properly upon delivery, but with minor repairs they can be made to function as well as the laser I am about to describe, with far far less work and with a similar amount of financial investment.
About CO2 lasers
The type of laser most common used in laser cutting is a CO2 laser. CO2 lasers work by exciting CO2 (along with other gasses) inside a tube at 12000-24000 volts. When the gas is excited it creates infrared light which is reflected back and forth between a full reflective and partial reflective mirror. When enough infrared light exists to exceed the reflectivity of the partially reflective mirror, the infrared light exits the laser tube through the partial reflective mirror. The infrared light emitted from the tube is directed at other full reflective mirrors to get the light to the surface you would like to cut. Once the light is at the right location, the light needs to be focused to a point using a focusing optic. At the focal point of this object, is the object you would like to cut.
Making a CO2 laser
At the beginning of this project, I was interested in making a laser tube from scratch, but I discovered the lasers that could be made at home would not be very reliable, while being expensive to operate. I managed to find a sealed 40 watt laser tube with a power supply for $300 shipped from someone on eBay. Some say this is cheating. oh well.
* hack saw
* blow dryer/heat gun
* drill press
* table saw
* scroll saw
* propane torch
* palm sander
* soldering iron
* screw drivers
* allen wrenches
* wire cutter/stripper with 6/32 and 8/32 bolt cutter built in
* #6 acrylic drill bit
* #8 regular drill bit
* 1/2 acrylic drill bit
* 1/2 regular drill bit
* 6/32 tap
* 8/32 tap
* 1/2 npt pipe tap
* Laser tube and power supply $300-$600
* Plywood $150
* Aluminum $40
* Hobby CNC Pro $90
* Solenoid $20
* Blower $93
* Roller blade bearings $12
* Sliding door bearings $34
* Linear bearings $83
* Belts and pulleys $91
* Optics $60
* Hose $10
* Solid rod $12
* Threaded rod $20
* Polycarbonate $50
* Acrylic $20
* Hinges $20
* Assorted parts $100
Build of materials
* 2 sheets of 52 3/8 X 16 ½ X ¾ plywood for front and back. Home Depot.
* 2 sheets of 27 ½ X 16 ½ X ¾ plywood for sides. Home Depot.
* 2 sheets of 52 3/8 X 26 X ¾ plywood for bottom and CNC table. Home Depot.
* 1 sheet of 30 ½ X 9 ½ X ¾ plywood for front access door. Home Depot.
* 2 sheets of 26 X 2 ½ X ¾ plywood for main access door guide. Home Depot.
* 1 sheet of 48 X 29 X 3/16 polycarbonate (maybe acrylic?) for top cover. Freeman Plastics.
* 2 cabinet door hinges. Rockler Woodworking and Hardware.
* Drywall screws. Home Depot.
* 1 piece 4 inch 200 CFM duct fan. EBay: Tjernlund M4.
* 1 piece 4 inch 25 feet flexible dryer duct. Home Depot.
Motion table (X and Y):
* 1 piece 50 X 2 X 2 aluminum angle iron. Home Depot.
* 2 pieces 22 7/8 X 2 X 2 aluminum angle iron. Home Depot.
* 1 large stepper motor. Scrap HP LaserJet II.
* 1 small stepper motor. Scrap Epson FX-880 dot matrix printer.
* 4 piece cash register linear bearings. EBay: FBW2560.
* 9 pieces 3/16 nylon/steel sliding door ball bearings. Any well stocked local hardware store in the slide out drawers.
* 2 pieces 6 feet X 3/16 inch solid steel rod. Local hardware store. Home Depot only has this in 3 foot lengths.
* 2 pieces 3 feet X #8 threaded rod. Home Depot.
* 1 long belt. Stockdrive / sdp-si.com: A 6R 3-450037.
* 2 short belts. Stockdrive / sdp-si.com: A 6R 3-225037.
* 4 pulleys. Stockdrive / sdp-si.com: A 6Z 3M12DF09505.
* 1 any model of Hobby CNC. hobbycnc.com.
* 1 power supply for Hobby CNC. Needs to be able to provide about 5 amps at 18 - 24 volts. Old inkjet printer.
* 2 optical limit switches. Hp LaserJet II / old printer.
* 1 solder bread board. Radio Shack.
* 5 small NPN transistors (2N3904). RadioShack.
* 1 large NPN transistor (TIP122). RadioShack.
* 5 1/4 watt 1 k resistors. RadioShack.
* 2 switches for door indicators. RadioShack.
* 1 medium power diode (1n4007). RadioShack.
* 3 pieces 5/16 fender washers. Home Depot.
Floating Table (Z):
* 1 sheet of 44 X 22 X ¾ plywood for lasing table. Home Depot.
* 8 pieces 5/16 ball bearings. Sports store. Ask for roller blade bearings.
* 4 1 foot pieces of 5/16 threaded rods. Home Depot.
* 12 feet Ball type light fixture/fan pull chain. Home Depot.
* 8 pieces 5/16 fender washers. Home Depot.
* 3/16 acrylic sheet
* Aluminum foil. Grocery Store.
Mirrors and Optics:
* 1 old hard disk that you don’t care about. Junk bin.
* 2 pieces 2 X 2 X 2 aluminum angle iron. Home Depot.
* 1 piece 5/16 fender washer. Home Depot.
* 4 pieces 1 inch #8 ALUMINUM thumb screws. Local hardware store.
* 4 pieces 1 inch medium strength springs. Local hardware store.
* Powerful magnet. Old hard disk or junk bin.
* Rubber cement. Home depot
* 1 piece 20mm 55mm focal point ZnSe lens. EBay.
* 3/16 acrylic sheet
1 piece 40 watt or greater Chinese laser tube. EBay.
1 piece 40 watt or greater Chinese laser power supply. EBay.
3 feet high voltage wire. Possibly came with power supply. CRT tv or monitor.
4 spade terminals. Home Depot.
1 Aquarium Water pump 1200 GPH. Pet co.
20 feet 1/2 inch OD vinyl hose. Home Depot.
1 piece 3 X 3/16 hard aquarium air line. Pet co.
1 piece ½ inch 90 degree male thread to polyethylene fitting. Home depot in the plumbing section in little white bags.
2 Clic pipe clamps of the correct diameter to fit around laser tube. I am not listing a size because laser tube diameter
varies from supplier. Plumbing supply house.
2 Carriage bolts. Local hardware store.
1 solenoid which can handle 10 PSI of air pressure.
* A lot of 5/16 #10 #8 #6 nuts, bolts, lock washers, washers, and other assorted hardware. There is just too much to individually list.
* Computer with a parallel port built on to the motherboard, Windows XP SP2, Pentium 3 1.0 ghz or better 2 GB ram or better.
* Solustan Linkmotion Virtual CO2 laser controller software.
Get started by taking an 8 foot piece of 2 inch aluminum angle iron and use a chop saw or hack saw cut it down to 50 inches. Cut off a 1 inch segment on one side of the end of the angle iron. Make the same cut on the other end of the other angle iron. This will leave you with 1 face of the angle iron 48 inches long and the other face 50 inches long. These cuts will allow the belts to pass on the left and right. Mark the inside of the 50 inch face at 25 inches (center) with a permanent marker.
Take the remainder of the 8 foot piece of angle iron and cut it down to 2 pieces of 22 7/8 inches. Find the center of both of these pieces. With a permanent marker, mark an inside face of both of these pieces at 11 7/16 (center).
Take a linear bearing track assembly and remove the blocking cap on one side. Remove 1 linear bearing. There should now be 2 linear bearings on the linear bearing track. Replace the blocking cap. Repeat this for another linear bearing track assembly.
Place a modified linear bearing track on a 22 7/8 piece. Line the center mounting hole up with the 11 7/16 mark you made on the 22 7/8 aluminum angle iron. Insure the linear bearing can slide the whole length of the track with 1/16th of clearance from the aluminum angle iron in all locations. The linear bearing assembly must be straight on the aluminum angle iron. Mark all mounting holes on linear bearing on to aluminum angle iron with a permanent marker. Remove linear bearing assembly and drill out mounting holes with properly sized drill bit using a power drill or drill press. Repeat for other 22 7/8 piece.
Take the two remaining linear bearing track assemblies and remove blocking caps from both. Remove all linear bearings from one of the tracks and remove 1 from the other track. There should now be 2 linear bearings on one of the tracks, and none on the other. Do not reinstall blocking cap.
Place both linear bearing tracks on the inside of the long face of the 50 inch piece of aluminum angle iron. Insure both non blocked off sides of the linear bearing tracks are touching face to face with absolutely no gap between them. Line up both tracks so the faces meet at the mark you drew on the aluminum angle iron. Insure you can slide the linear bearings from track to track with very little resistance. Insure there is 1/16th of an inch clearance between the linear bearing blocks and the wall of the aluminum angle iron in all locations on both tracks. The tracks must be perfectly straight on the angle iron, or the laser cutter will not make straight cuts. Mark all mounting holes from linear bearing tracks on to aluminum angle iron. Drill out all mounting hole with a properly sized drill bit.
Cover large and small stepper motors with masking tape except for mounting face. Insure to cover any holes that would allow anything to get into the stepper motor even on the mounting face. Insure bearings are adequately protected. Spray the mounting face with black spray paint. Immediately push a piece of white printer paper on to the mounting face of the motor. This will punch a hole in the paper and now the spray paint from the motor will have transferred on to the paper giving you a mounting template. Clean off spray paint with isopropyl alcohol applied to a sheet of paper towel. Do not pour alcohol on motors as it will strip the oil out of the bearings. Do not disassemble stepper motors for any reason. The alignment of the motors is defined at the factory and is difficult if not impossible to restore at home.
Insure newly created templates are dry.
Take the 50 inch piece of aluminum angle iron and rotate it so the 50 inch face is flat on the work bench while the 48 inch face is perpendicular to the work bench. Tape the small motor template on to the outside face of the top left of angle iron using packing or scotch tape. Drill out all mounting holes and a hole for the power take off rod. Mount the small motor (possibly using the screws which were used to previously mount the motor in its previous application) Mount pulley on stepper motor. Take the long belt and put it around the motor pulley. Take another pulley and pull the belt tight using the pulley that is in your hand. Using your eyes, make the belt as straight as you can relative to the aluminum angle iron. Mark the location of the center pulley in your hand on the aluminum angle iron using a greatly extended graphite clicky pencil down the boar of the pulley. Remove the belt and the pulley in your hand. Measure the height of your mark relative to the height of the pulley installed on the motor. Correct your mark as necessary. Move the mark 1/16th of an inch further away from the motor pulley. Drill a 3/16th inch hole on the mark. Slip a #10 bolt which has a large smooth section near the head through uninstalled pulley. Install a nut on to the bolt and screw nut down until it is about 1/32nd from the pulley. Reinstall belt and pull belt tight with the pulley which now has the bolt through it. Push the bolt through the newly drilled hole in the aluminum angle iron. The belt should be very tight and it should be slightly difficult to install the bolt. Install a lock washer on the bolt and a nut. Tighten the nut insuring not to tighten nut on the other side of the aluminum angle iron as this will lock up the pulley.
Place both unblocked linear bearing tracks on the inside of the 50 inch face. Slip #8 bolts through all drilled out holes. Fit with #8 lock washers and nuts on the back face. Do not tighten. Align tracks to insure 1/16th of an inch clearance between linear bearing blocks and aluminum angle iron in all locations. Make sure track is completely straight. Tighten bolts. Bearing blocks should slide easily with almost no friction between tracks.
Take a 22 7/8 piece of angle iron and place it with mounting holes down on work bench. Tape the large motor template to the outside top left of the aluminum angle iron. Drill out mounting holes and a hole for the power take off rod. Mount the large motor (possibly using the screws which were used to previously mount the motor in its previous application). Mount pulley on stepper motor. Take the long belt and put it around the motor pulley. Take another pulley and pull the belt tight using the pulley that is in your hand. Using your eyes, make the belt as straight as you can relative to the aluminum angle iron. Mark the location of the center pulley in your hand on the aluminum angle iron using a greatly extended graphite clicky pencil down the boar of the pulley. Remove the belt and the pulley in your hand. Measure the height of your mark relative to the height of the pulley installed on the motor. Correct your mark as necessary. Drill a ½ inch hole on the mark.
Place linear bearing track on to inside mounting whole face of 22 7/8 piece of aluminum angle iron with motor installed. Slip #8 bolts through every other mounting hole leaving half of the holes unoccupied. Align track to insure 1/16th of an inch clearance between linear bearing blocks and aluminum angle iron in all locations. Make sure track is completely straight. Tighten bolts. Repeat for other 22 7/8 piece.
Flip 50 inch aluminum angle iron upside down so mounting nuts for the tracks are now facing the ceiling. Install aluminum angle iron in a vice. Mark the center of both ends of the aluminum angle iron. Take 2 uninstalled linear bearings and place both linear bearings face down on the end of one side of the 50 inch aluminum angle iron. Center the two edges of the linear bearing on the centering line you drew. The bearing blocks should be oriented so the short sides are touching. Flush up the edges of the bearing block with the edge of aluminum angle iron. This should create a T shape. The bearing blocks should be perpendicular to the length of the aluminum angle iron. While holding the bearing blocks against the aluminum angle iron, mark the 4 screw holes (2 per bearing block) on the aluminum angle iron. Remove the bearing blocks. Drill out the marks with the proper size drill bit. Repeat for the other side of the 50 inch aluminum angle iron.
Screw the 50 inch aluminum angle iron on to the bearing blocks on to both 22 7/8 pieces of aluminum angle iron. Use both linear bearing blocks on both sides. The linear bearings have a lot of slop when used alone. Using 2 seems to clear up most tolerance issues. Both the large and small stepper motors should be on your left side.
You should now have a very large sliding contraption.
Cut all pieces of wood to size listed in build of materials. Take one of the sheets of plywood 52 3/8 X 26 X ¾ and cut a hole in it 41 X 17 ½. Let’s call the longest side closest to you the front. The edges of the hole are located 4 ¼ from the front and 4 ½ from the right. I made this hole by placing the sheet of plywood on a table saw with the blade down. I started the table saw with the sheet above the lowered blade and raised the blade to the maximum high, cutting through the sheet of wood. Keep in mind that the saw will want to throw the wood when you pull the wood backwards through the saw. Also keep in mind that a table saw blade is a circle and therefore the bottom part of the cut will always be wider than the top so do not finish the cuts with the table saw. Finish them with a hand saw or a scroll saw and sand smooth with a palm sander.
Place the large sliding contraption on the piece of plywood with the newly created hole. The motors should be all on the left. The 22 7/8 aluminum angle iron should not sit flat as it has nuts on the bottom. Align the right 22 7/8 aluminum angle iron with the right bottom edge. Push hard on both 22 7/8 tracks to create dents in the wood with the nuts. Remove large sliding contraption. Drill out all dents in wood with a drill bit wider than nuts used to hold linear bearing tracks. Place sliding contraption back on wood. Insure right aluminum angle iron is square and flush with right edge and bottom edge of plywood. Put screws through all unoccupied holes in right side angle iron. Insure that left angel iron side is parallel to right side angle iron. This needs to be perfect or the 50 inch aluminum angle iron will not slide freely. Screw down left side angle iron.
From now on this assembly of aluminum angle iron, linear bearings, belts and plywood will be called the XY table
Take the 44 X 22 X ¾ sheet of plywood and mark the center of sides on all sides. Draw a cross on the plywood. Find the center of the hole in the XY table. Mark center on all sides of the hole. Place the smaller piece of plywood underneath the XY table. Line the marks from the bottom piece of wood to the top piece of wood. Put 2 drywall screws through the top piece of wood in to the bottom piece of wood in any location to fix the two pieces of wood together. Place the other unmodified 52 3/8 X 26 X ¾ sheet of plywood underneath both of these sheets. Line the bottom sheet up with the top sheet. This needs to be perfect. Screw drywall screws through the middle sheet into the bottom sheet. All sheets of wood should now be sandwiched together and locked together with no play in any direction. If there is play, put more drywall screws in the moving piece of wood. Measure 10 inches from the left to right from the bottom left corner from the big hole. From this point measure 2 inches down. Draw a dot. Now from the bottom right, measure from the right 10 inches. From this point measure 2 inches down. Draw a dot. Do the same for the top except measure up instead of down. You should now have 4 marks on the top sheet of wood. Drill through the marks through all 3 sheets of wood with a 3/16 drill bit. When you drill this, you must drill perfectly perpendicular to the top surface meaning the drill must go straight down with no angle in any direction except straight through the wood. If you do this wrong, the floating table will not go up and down. Remove all drywall screws and separate all 3 sheets of wood. As you separate the pieces of wood, mark the relations of the wood to each other. This doesn’t have to be precise. You just need to know which pieces went in what direction and what side is up on each one.
Use a drill bit which is the same size as the diameter of the threaded inserts and drill all the 3/16 inch holes in the middle sheet to this size. Hammer in 4 threaded inserts into newly widened holes
Take 5/16 bearings and find a wood hole saw which matches closely to the outside diameter of the 5/16 bearings. On the top piece of wood drill half way through the wood in the existing 3/16 inch holes. It is very important that you do not drill all the way though the wood as the wood will be used to hold the bearings. Use a flat head screwdriver to peel out the wood that the hole saw cut through. Drill out the center of the remaining 3/16 hole to a size wider than 5/16 nuts. Do this to all holes on the top and bottom sheets.
Take a 52 3/8 X 16 ½ X ¾ sheet of plywood and cut a 26 ½ X 7 ½ hole. This hole is centered on the long axis and 2 inches from the edge on the short axis. Use the method described above used for cutting the XY table. This sheet is now considered the front side of the laser enclosure. The unmodified sheet will be considered the back
Attach the bottom sheet of wood to front, back and right sides using dry wall screws. The bottom sheet goes between the sides. The bottom sheet does not go below the sides. You should now have a box with no left side or top. Do a good job and keep everything square and flush.
Take a 12 inch 5/16 threaded rod and thread on a nut about 1 inch. Put a 5/16 bearing on the side you just threaded on. Thread on another nut, trapping the bearing between the nuts. The bottom nut should have the bottom of the threaded rod flush with the nut. Tighten both nuts well. Repeat this for the other 3 threaded rods.
Thread the rods in to the bottom (the side that you hammered the inserts into) of the wood with the threaded inserts installed 4 inches. Take this whole assembly, flip it over so the bearings are facing the floor and place it on top of the bottom piece of wood in the same orientation as when you drilled the holes through all the sheets. Line up the bearings so they fall into the widened holes. You now have a floating table which can be raised and lowered by spinning the threaded rods. All threaded rods should spin freely
Put the XY table on top of the floating table remembering to keep all the orientations the same as when you drilled the holes through all the sheets of wood. Adjust the threaded rods to adjust the height of the XY table so the XY table is 4 ¾ inches from the top of all sides. Make sure that this is perfect on all sides. Do not hesitate to measure this many times. Place an aluminum yard stick or any other guaranteed long straight item across the XY table. Insure that the table is flat in all directions. If the XY table is warped, install 2 screws perpendicular to the bend in the XY table through the sides of the enclosure. Use the threaded rods to warp the XY table straight. The XY table must be straight, or you will not be able to align the beam in all locations to the laser head. Once you get the table straight, install many drywall screws from the outside of the enclosure into the XY table. Back the floating table down by spinning the threaded rods.
Remove the right side. The structure will be a little unstable now so be careful. Measure the location of the ½ hole in the left side aluminum angle iron with the large stepper motor mounted on it. Drill an identical hole on the right side aluminum angle iron. Take the 6 foot 3/16 solid rod and slip it through the hole half way through the enclosure. On the rod, slip on a bearing, pulley, 3 more bearings, pulley and another bearing. All pulleys set screws should face in to the table and all bearings are the white nylon type with a 3/16 inside diameter. Slip both short belts over the rod and push the solid rod through the hole on the other side of the XY table. Slip the belt on the left over both the motor. Take the pulley off the large stepper motor. Put it in a vise and drill a 3/32 inch hole completely through the sprocket part of the pulley 1/8th of an inch from the edge of the pulley. Use a 6/32 tap and tap both sides of the pulley. Reinstall the pulley on the stepper motor. Put the left belt on the front and back pulley. It should be very loose. Measure the position of the pulley on the large stepper motor relative to the enclosure. Mirror that measurement to the opposing aluminum angle iron. Drill another ½ inch hole in that location. From this hole, take the other 6 foot 3/16 solid rod and push it part way through the enclosure. Slip the right side belt, a bearing, the remaining pulley, and 2 the two remaining 3/16 nylon steel bearings. Push the rod all the way into the end of the pulley on the large stepper motor. Install 2 short 6/32 Allen wrench set screws in the pulley. Install the belt on the right side pulleys. The belt should be very loose.
Cut 6 pieces of #8 threaded rod to 5 inches and 2 pieces to 11 inches. Thread a nut 3 turns down both sides of each new short rod. Take a 1/2 inch hex socket used for driving hex bolts and nuts and mount it in a vise. While holding both nuts on a threaded rod, heat the rod to cherry red using your favorite propane/map gas torch. When the rod reaches temperature, center the rod visually behind the socket and pull towards you to make a loop in the rod. Immediately dip the rod in a bucket of water to cool it and temper it. Dry the rod and clean any metal flakes off of it. Each loop will hold 1 bearing to the enclosure.
Each pulley has 2 bearings immediately surrounding it with no gap between the bearing and the pulley. Each solid rod has 1 bearing in the center of the rod for stability. The front center threaded rod goes through the front wall. The rear center bearing goes through the XY table. It cannot go through the rear wall as the laser tube will be installed there. The outermost bearings are flushed up with the aluminum angle iron. Slip the threaded rod loops over each bearing and mark their position on the enclosure wall. Remove the loops and drill the holes in the enclosure. Slip the loops back over the bearings and through the wall. Install washers and steel/nylon locking nuts on the ends of each loop. Adjust the front solid rod so that ¼ inch of rod protrudes from the left side aluminum angle iron. Tighten all set screws on all pulleys. Tighten each loop until the belts are taught. Cut all solid rods to flush with the aluminum angle iron on the right. Install the left and right side. In my case the large stepper motor was too large to fit in the case. Cut a hole for the stepper motor on the left side if it doesn’t fit.
Pull out your favorite old garbage hard disk. Remove the cover and remove the platters. Place the platters on a very clean and soft surface to protect them from being scratched. Cover all platters entirely with masking tape. Clamp a platter to a drill press table with a piece of wood sandwiched between the table and the platter. Take the centering drill bit out of an 1 ½ inch hole saw and install in a drill press. Slowly cut the platters making sure not to press to hard which might distort the platters as you cut them. Defiantly take your time here. It’s worth it. Cut out at least 3 mirrors. I got 4 out of a single platter. Take the tape of one side of each mirror and look at a straight edge through the mirror. Look for any abnormalities in the image of straight edge. If you see anything even slightly wrong, throw the mirror away. Put new masking tape back on to the surface of the mirror to prevent it from being damaged. Keep in mind these mirrors are not quite as good at reflecting inferred light as real mirrors purchased for this purpose, but these mirrors are really free. I’m guessing they transmit 95% of the light because they do not get hot in operation.
Cut a piece of 2 inch aluminum angle iron 2 inches long. Take a fender washer slightly wider than the newly cut mirrors and center it on an outside face of the newly cut angle iron. Trace the edge of the washer on to the angle iron. Draw a cross centered through the newly traced circle. At every intersection of the circle and the cross, drill a 1/8 inch hole inside the traced circle. Tap each hole with an 8/32 tap. Thread an aluminum thumb screw with a spring on it in to each hole. Remove the tape off one side of one mirror and use rubber cement to glue the mirror to the fender washer. Stick a powerful magnet on the back of the angle iron and put the washer/mirror combo on the front. The magnet will hold the washer/mirror combo in place. Drill 2 small holes in the base of the new mirror mount. You can adjust the mirror with the thumb screws.
Take a piece of aluminum angle iron at least 3 inches long. Cut one side at 45 degrees. I cut this on a chop saw but you could potentially do this with a hack saw. Once this cut is made, measure the face that faces your body and make a mark at 3 inches. Cut on this mark parallel to the previous cut. Take another mirror, remove the masking tape and glue it to the outside of the angle iron.
Print out the included dxf file on a piece of blank paper and cut out the laser head and assorted pieces using a pair of scissors. Tape the pieces of paper to a piece of 3/16 piece of acrylic. Using a scroll saw, cut out the pieces. Drill the holes out with a drill press using acrylic drill bits. Regular drill bits will crack acrylic. The smaller of the two large holes needs to be tapped with a ½ pipe tap and a ½ inch 90 degree polyethylene adapter needs to be threaded in. The 4 holes surrounding the largest hole need to be tapped with a 6/32 tap. The hypotenuses of both triangles need to be drilled and tapped with 2 holes per triangle ¼ inch from each corner. The bottom of each triangle ¼ inch from each 90 degree needs to be drilled and tapped. Use a 6/32 tap. Attach the piece of plastic with 4 small holes to the hypotenuse of the triangles using 4 6/32 screws. Glue another mirror to the inside face of this piece. The holes on the bottom of this now created mirror mount can be affixed to the laser head platform through the slot in the head platform. If you were not able to cut out the slot in the laser head platform, don’t worry, you can substitute this slot with many screw holes. The mirror can be adjusted by the screws on the bottom. The lens is held in place by the square with the big circle in it surrounded by 4 smaller holes. Flip the laser head platform over and place the ZnSe lens with the shiny side facing up (or when attached to the XY table, face down). Put the lens holder over the lens and affix 4 6/32 screws. Tighten them down sequentially and carefully with moderate pressure to insure you don’t crack the lens. Don’t ever touch the lens with your bare hands. It is extremely toxic. Install laser head on both linear bearing blocks on the 50 inch aluminum angle iron. Note that this head is designed to be cut out by the laser cutter, you can cut out a better one when you actually get the laser functioning.
Install both clics lightly on the laser tube and slide them to reasonable position on the tube. Place the laser tube in the back of the enclosure and center it in the enclosure. Move the laser tube as far as possible from the back while maintaining at least a 3/16 inch gap between the laser tube and the center rod bearing. Insure the laser is parallel with the back of the enclosure. Outline the base of the clics with a pencil. Remove the clics from the laser tube and place the tube in a safe location. Line the clics back up with the outlines and mark the hole in the bottom of the clic on to the XY table with a greatly extended clicky pencil. Remove clics from the XY table and drill out marks with a ½ inch drill bit. Insert carriage bolts with the proper diameter through clics. Install clics back on the laser tube. Rotate the clics so the right water connection faces the ceiling. Place the laser tube on XY table with the carriage bolts penetrating the XY table. The output of the laser should face the left of the enclosure. Measure the height of the center of the laser head mirror relative to the XY table (not the floating table). Measure the height of the center of the laser tube output. If the output of the laser tube is lower than the center of the mirror, add fender washers underneath the clics. If the output of the laser tube is higher than the tube, remove the clics from the tube and sand them down with a palm sander and coarse grit sand paper. When the proper height of the tube is achieved, place a fender washer, a lock washer and a nut on to each carriage bolt underneath the XY table. Do not tighten. Straighten laser tube with back wall insuring it is parallel. Tighten nuts on carriage bolts.
Drill holes from back of enclosure to allow penetration of the laser tube high voltage wire, laser tube ground, large stepper motor, small stepper motor, X limit switch, Y limit switch, 3 door switches, air supply hose and two water hoses. If the laser tube manages to get disconnected from either the ground or high voltage wire or manages to leak out all of the gas contained, the high voltage wire will arc to ground in some location. To protect yourself when this happens, and it will happen at some point because eventually laser tubes loose there gas charge, keep these wires at least 6 inches away from other wires, hoses, pieces of metal or anything else conductive. Keep tube ground and high voltage wires close together. Have both of these wires penetrate the enclosure in the same hole, and wrap them in aluminum foil where they penetrate the enclosure to prevent fire if arcing occurs at this point. Considering the water passageways are close to the high voltage terminals in the tube, keep water lines isolated from other electrical connections including the high voltage wire.
Feed high voltage and ground wire in to the enclosure through the same hole. Solder on spade terminals on to both wires. Be sure to use plenty of solder on the high voltage spade terminal to reduce corona discharge and risk of arcing. Squeeze both terminals slightly with a pair of pliers to decrease the spade terminal loop diameter. Wrap both terminals with plenty of electrical tape, excluding the front of the connector. Note that every wrap of electrical tape is rated at 600 volts. Push connectors on the laser tube electrical connections. The connectors should be fairly snug. If not, disconnect and squeeze the spade connecter again with a pair of pliers. Do not solder to the tube. Not only does it make it difficult to replace the tube, you risk fracturing the tube as the glass on the tube will expand unevenly as you heat it with the iron. Attach high voltage and ground wires to the power supply. Connect a button to a 10 foot wire and connect this to the laser power supply control terminals. Each laser power supply is different so refer to your laser power supply manual on how to do this. You will use this button as your hand firing button.
Connect the water lines to the laser tube. Connect the water line which connects to the output of the tube to the pump. Fill a 5 gallon bucket with water. Place both the pump and the unconnected water line in the bucket. Plug in the pump.
Put on safety glasses.
Place a small piece of plywood in front of the laser tube with an edge flush with the back wall of the enclosure. Insure you are not pressing the fire button. Plug in the laser power supply. Press the fire button briefly. The wood should instantly burst into flames. Do not move the piece of wood. Center the mirror mount with mirror with thumb screws directly behind the block of wood at approximately 45 degrees. If the mirror mount is too short, cut a small piece of wood and place it underneath the mount. Using dry wall screws, fix the mirror to the table. You will probably have to move this mirror many times to get alignment correct and you can fix the mirror’s orientation with thumb screws so do not put much effort of initial placement of the mount.
Using a large wood clamp, clamp the other mirror mount to the front of the linear bearing block on the left.
Move the block of wood that you just shot with the laser to in front of the mirror mount with thumb screws. Keep the block fairly close to prevent stray beams. Fire the laser briefly. Adjust mirror with thumb screw to get the beam to fire approximately to the other mirror. Push the 50 inch aluminum angle iron all the way to the front of the enclosure. Put the block at the end of the linear bearing closest to the large stepper motor. Fire the laser briefly. Move the beam block to the front of the linear bearing and fire the laser briefly. Adjust the mirror to get the beam to strike the same spot. Perform the same procedure on the other axis until you can get the beam to the laser head. Because the Y axis mirror is fixed up and down, you may have to bend the angle iron to get the beam in the laser head. You also may have to trim the mirror mount with a saw to get it in the correct location. Once you get the Y axis mirror in approximately the correct location, remove the clamp and place an uninstalled bearing block upside down on the mirror mount and mark the screw holes. Remove the mirror mount, drill the holes and install the mirror on the Y axis bearing block.
Take 3 fender washers and drill 1 small hole ¼ inch from the edge of the washer. Remove 1 screw from each linear bearing assembly. Install a screw through the hole of a washer you just drilled. Install washer/screw assembly back on the bearing block in such a way that it clamps the belt to between the washer and the bearing block.
Solder together your Hobby CNC. Do not install the Z axis stepper motor driver as the Z axis is actuated by hand in this laser cutter. Connect Hobby CNC to stepper motors as instructed by the manual. Set the Hobby CNC for 4 micro steps per full step. If you extracted the large stepper motor from an HP LaserJet II, find 2 optical limit switches inside the printer and remove them from their PCBs. If you did not disassemble an HP LaserJet II, you will have to locate optical limit switches to have XY homing capability. This is not a necessity but it is very useful at times.
Solder the optical limit switches to pieces of solder bread board. Follow the included schematics and construct the limit switch circuits. Connect the limit switches to the Hobby CNC. If you are using the 4 axis Hobby CNC, loop a wire around the left side of resistor R13 on the PCB and solder it in place. This wire can be used as your 5 volt source for the limit switches.
Follow the included schematic to construct the laser driver. Connect the laser driver to pin 14 on Hobby CNC. Connect the laser in line with your hand trigger.
Follow the included schematic to construct the solenoid controller. Connect the controller to pin 16 on Hobby CNC. If you are using a 24 volt solenoid, you can use the 24 volt fan output on Hobby CNC as your power source for the solenoid. Attach the solenoid to a convenient location. Take a piece of 3/16 hard aquarium tubing and cut it to 3 inches. Heat it with a blow dryer on high. Bend a 45 degree arc in the tubing 1 inch from one end. You may have to restrict the airflow through the blow dryer slightly to get the airflow hot enough to bend the tube. Let the airline cool. Jam the piece of airline in to the bottom of the polyethylene to threaded adapter mounted on the laser head. It should fit snugly. If it does not, wrap some electrical tape around the tubing and try again. Rotate the airline so it is facing approximately where the beam would cut material. Attach vinyl hose to the other side of the adapter. Connect the vinyl hose to the solenoid. Attach the air supply to the solenoid.
Drill a 4 inch hole in the rear of the enclosure with a hole saw. Attach 4 inch blower to enclosure. Attach the 4 inch dryer hose to the back of the blower. Vent this hose outside the building. My laser is in a concrete building with no penetrations to the outside anywhere near the laser except for a door with a mail slot. I decided to take a register adapter used for a duct in a wall and I cut it to fit the mail slot. In my case, my blower had a lip on the suction side. I drilled 4 holes in this lip, placed the lip into the newly drilled hole and affixed 4 screws to the enclosure through the lip. I then sealed any gaps with silicone.
Connect Hobby CNC to your computer using a straight through parallel port cable. Install Solustan’s Linkmotion software. Install Corel Draw or similar.
Install both 26 X 2 ½ X ¾ pieces of plywood on the top left and right edges of the enclosure. Take a hand router and use a rabbet router bit to rabbet in a small edge all the way around the top of the enclosure. This edge will provide a sealing lip for the polycarbonate cover to set into. Measure the dimensions of the top of enclosure lip. Cut the piece of polycarbonate to this size. Set the piece of polycarbonate on top of the enclosure. It should not fit because of the rounded edge that the router created. Mark the sections of polycarbonate that overhang the edge of the lip of the enclosure. Remove the polycarbonate and cut off the overhangs with a scroll saw or hack saw. Sand the edges of the edges of the cut with a palm sander with medium grit sand paper. Sand all edges of the polycarbonate to prevent paper cuts. You may have to realign the beam after using the router as the intense vibrations from the router may have shifted the mirrors. Clean up all wood chips and plastic fragments.
Install the hinges on the enclosure. Peel the protective covers off the polycarbonate and place it on top of the enclosure. Mark the locations for screw holes from the hinges on the polycarbonate. Attach polycarbonate to hinges. Attach something creative to the polycarbonate to act as a handle to lift the polycarbonate door.
Cover the floating table with tin foil. Place a piece of 3/16 acrylic on the floating table. Measure the distance between the laser head and floating table. If you purchased a lens with a 2.5 inch focal length, set the distance between the laser head and the 3/16 sheet of acrylic using the threaded rods to 2.5 inches. Make sure the floating table is level with the XY table.
Put on safety glasses.
Power on blower, forced air supply, Hobby CNC, water pump and laser power supply. Cut out all parts in the included file with Corel Draw or similar. Power down everything.
Rebuild the laser head with the new parts following the instructions above. Spin one of the threaded rods on the floating table so the bearing comes out of its holder. Unthread one of the nuts and remove the ball bearing. Spin the remaining nut up an additional inch. Put a 5/16 fender washer a just cut out plastic gear, another fender washer, a nut, the ball bearing and a final nut. The final nut should be flush with the bottom of the threaded rod. Spin down all other nuts to lock the bearing and the plastic gear in place. Tighten well. Spin the threaded rod so it levels the floating table back out. Repeat for the other 3 threaded rods.
Take the electrical light switch pull chain and wrap it around all 4 plastic gears. Pull the chain very tight. Make sure that the chain is seated in the cogs of the gear. Mark the point where the end of the chain meets the middle of the chain. Remove the chain and cut it 1 ball earlier, giving you 1 ball of slack in the chain. Take a straight edge razor blade and find the seam in the last ball in the chain. Press firmly on the seam to slip the razor in to the ball. This is a very difficult process and it will take many attempts but it is defiantly possible. You may want to wear gloves because there is a possibility you may cut yourself. Slip another razor blade next to the first blade to widen the gap in the ball. Pull the two razors apart to open the ball. Crush the last ball of the other side of the chain with a pair of pliers. Find the link in the crushed ball. Discard the crushed ball and place the link into the other side of the chain at the split ball. Close the split ball with pliers. You should now have one complete endless chain.
Spin the threaded rods of the floating table so the floating is at half height. Lift the floating table so the ball bearings come out of the bottom sheet of wood. Slip the ball chain around each threaded rod. Realign the floating table bearings so the bearings fall back into the holes. Spin the threaded rods to level the table relative to the XY table. Put the ball chain on all 4 gears. This may be a little difficult with the top fender washer in the way. Feel free to undo one of the top nuts on the threaded rod to allow unrestricted access to the plastic gear. If the chain has slack in it, take a sliding door bearing and place it between the two left threaded rods. Pull the bearing against the chain to tighten the chain. Take a drywall screw and screw it through the bearing.
Place a nut on the top of the threaded rod and spin it down about ¾ of an inch. Place a ball bearing on top of the nut. Spin down another nut to lock the bearing in place. Tighten both nuts. Repeat for the other threaded rods. You can now pull the ball chain left and right to raise and lower the table.
Find a clever way to attach the access door to the front of the enclosure. I used 2 handles with bolts on them threaded into threaded insert adapters.
If you made it here and followed my instructions, you should now have a fully functional laser cutter. Congratulations.
This is a very fun project if you have a lot of time and love to build everything rather than just going to the store and buying it. This guide will show you how to build a CO2 laser cutter with a cutting bed size of 38X17X10. It costs about 1200-1500 to make at the time of writing.