Finished up the mechanical part of the cutter. The X/Y/Z table is done and everything is moving great. It went together really well other than a few small issues. Once I got the gantry on the y-axis rails, I noticed it started binding up about halfway up the rails. It took a lot of tweaking, loosening, tightening and prying but eventually I got everything nice and square. The gantry is smooth like butter. No problems installing the laser car on the gantry, it moves very smooth too. I also got the belts cut to length and attached on both sides of the Y axis and on the gantry arm. I think tomorrow I will hit the hardware store and buy some wood to cover the whole enclosure. I haven’t decided it I want to just go with cheap wood and paint it or go with some nice wood and stain/polish it. I think it could look amazing with a nice polished wood grain look. I don’t want to hook up the electronics or anything until I have a place to start mounting stuff. I plan on mounting the computer components on the side of the enclosure and the motor controller, stepper power supply and laser power supply to the bottom over on the left side. The back left piece will be for power, video, water and air inlets/outlets. I hope to get the table up and running under computer control by next weekend.
The project, not the actual laser cutter, but progress is once again being made. I live in Houston, TX and unfortunately, we only have two seasons; mild and ball-melting hot. We get mild from November to February or March and then ball-melting hot for the next seven or eight months. Since my garage is practically a functional furnace, I can’t do much work out there during the hot season. We’ve been enjoying some cooler weather the last couple weeks and I decided it’s time to start work on the cutter again.
When we left off, I had gotten the majority of the frame assembled and had collected most of the parts needed to complete the table. Due to some design changes, I had to order a few new frame pieces and other little bits and pieces. The first box of parts was either delivered to the wrong address or stolen off my porch. The first thing I did was put the lid together and mount it on the rest of the frame with a 36″ piano hinge. I still need to find a couple hydraulic pistons to keep it open but that won’t be necessary till near the end of the build. I replaced the two lower 20mm cross supports with 40mm pieces instead. This was necessary for better mounting of the z-axis lower brackets as you’ll see in the pictures later.
The next logical step was assembling the z-axis. The table is just a rectangle of aluminum frame. It has four brackets sitting on t-nuts that ride on 4 threaded rods. the rods are run through a bearing captured in a bracket at the top and the bottom of the frame and held in place with a nut on top and an XL pulley on the bottom. The assembly was actually a little challenging because everything has to be sort of pre-assembled together and put in place. I ended up mounting the top and bottom brackets on the frame and the table brackets on the table; all relatively loose to help with lining everything up. I laid the belt on the brackets since the four threaded rods needed to be inside and the belt isn’t open. I put a pulley on the bottom of each threaded rod and threaded a t-nut halfway down. I then put the table in the center of the frame, slid each rod up through the table bracket and into the top bracket on the frame until the bottom would slide into the bottom bracket. It was a bit sketchy with just the first corner and I was worried about bending or breaking something so I awkwardly held the table as a did the other three rods the same way. once opposing corners were done, it mostly supported itself and wasn’t that bad. once all four rods were in place I screwed a nut on top of each one, loosened the pulley and let the rod settle. Then it was just a matter of threading the belt around the pulleys and bearings, lining up each pair of brackets, getting them all in to position and tightening everything. I leveled the table and then tightened all the pulleys. All in all it turned out great and it has a nice smooth movement up and down when I pull the belt.
I did some basic test-fitting of the x/y axis as you can see, but I bought a new piece of extrusion for the gantry so I need to drill and tap it and transfer the rails over before I can assemble anything else. I’m happy with the progress I’ve made so far and I am starting to think about what I want to cover the frame with. I may just end up running it open for a bit, I haven’t decided. I hope to finish the whole table up in the next month so I can start working out the kinks with the computer and motor controllers and think about things like air assist, ventilation and cooling. I may even get the laser tube and power supply ordered before the end of the year, who knows. Progress should be much more rapid than it has been so expect more posts soon.
I love how smooth the movement is with the v-groove bearings and v-rails. It is really a beautiful thing. So beautiful in fact that I had to take a video of it. There is (almost) zero (happy?) slack on the movement, the sound you may hear when I switch directions is the mirror/lens assembly moving a bit since I haven’t tightened it down yet. I have all the rails and frames drilled, tapped and assembled. I’m working on the z-axis bearing pieces now and all the acrylic that needs to be drilled/tapped is done. Assembly is moving forward as fast as the heat permits, it’s been somewhere close to 5000ºF here in Houston lately and I haven’t setup the portable AC in the garage yet. I should really do that, maybe this weekend. Just need to cut a hole in the ceiling for the hot air exhaust. Here’s a video of the progress I’ve made on the laser so far.
So I’ve been slowly collecting hardware for the laser cutter and I think I’m just about done. I currently have a huge pile of little bags of various fasteners on my workbench. Nuts, bolts, washers, lock washers, cut washers, t-nuts, bearings, rails, threaded rods, etc. I have a few more bits and pieces coming over the weekend and next week, mostly for the lid and z-table, then I will be ready to begin assembly. I need to buy a #4-40 and #10-32 tap also. I’m a little nervous about drilling and taping the HDPE and acrylic since they each react very differently to drilling and can be very touchy if not done right. Hopefully I don’t have to get Bart to cut me any replacements.
My parallel cable came in today and I was all excited about playing around my motor controller and stepper motors but I accidentally bought a DB25M to DB25M when I needed a DB25M to DB25F. I ordered a DB25F to DB25F coupler from Amazon and it should be here Saturday. Amazon Prime is a wonderful thing. I built a computer that I plan on installing inside the laser enclosure but I’m not 100% sure everything will fit. My vision is to just plug a beefy power cable, monitor cable, mouse, keyboard, water and air hoses into the back of the box and start cutting. I’m going to order some nice toggle switches with those cool red toggle switch guards on them for the front to power up everything and a big red emergency stop button for… just in-case. Might also mount a 20×4 LCD I have on the front for some data display. I’m thinking it might be interesting to have a readout of water temp in the laser tube and some other stuff.
Well, the frame is done. I’m really happy how it came together and squared up once all the pieces were connected. It feels quite solid now.
I also did a test hole on a scrap piece of steel v-rail. I’ve never really worked with anything harder than aluminum but it was cake. Hole looks nice and it should be no problem drilling all the v-rails with the necessary holes. Used my drill press from Harbor Freight, a nice set of 130 degree split point cobalt drill bits. I have decided to use a 5/32″ drill bit for the v-rails and then a 7/64″ bit tapped to 6-32 for the aluminum frame. I could go with a bigger hole on the v-rail but hopefully there is no need.
Also, I got some new parts for the project. A couple lens holders, a mirror/lens assembly, a couple nice Keling stepper motors, a ColdfusionX 4-channel stepper controller and a 24V 8.5A stepper motor power supply. Also got my cut acrylic pieces from Pololu. Those guys are the best. They were incredibly fast, cheap and they called me three times to clear up little issues with the file before cutting. I highly recommend using them for any and all laser-cutting needs. They do a lot of other stuff as well, but I can’t vouch for that since I haven’t used it yet.