Hello everyone,

Me and my friend need to do a lot of precision textile (fabric) cutting for one proof of concept project, and I decided to build a CNC laser cutter to help us out with that. If that other project goes well, the machine will remain part of it.

I have no previous experience with CNC machines or lasers, however I do understand how their work and I have some experience building stuff, working with dangerous electricity, etc.

The requirements for this cutting machine are very simple and somehow abstract:

  • Need to keep as cheap as possible, with possibility to upgrade later to a more sophisticated/powerful machine if it turns out to be useful. And to be "sell-able", if it doesn't.
  • Needs to be able to cut textile (typical denim fabric being the thickest one) and keep as little browning of the edges as possible.
  • Need to be able to cut acrylic glass and be precise and fast enough to work as an engraver.
  • Minimum required precision for cutting textile is 0,5mm, but I am not sure how precise it needs to be for engraving.
  • Cutting speed is also an open question. I have seen specs of a similar commercial machine state max cutting speed 40cm/s which seems OK for me. Engraving, I suppose, need to be faster.
  • Working surface size should be about 2x3 meters.
  • The whole machine must be dismantleable to flat pieces for easier transportation.

At this moment, here are my considerations (which may be false):

  • Start with 60W non-branded CO2 laser tube, but design everything to be able to upgrade to 80-100W RECI tube.
  • The laser tube will be fixed on the moving gantry to shorten the maximum travel distance of laser beam and keep its effective power more consistent between the closest and the farthest point on the table (from tube's end). Also that should ease up the adjustment of mirrors, since tube will be much closer to the cutting head.
  • The gantry will be moving on 20mm open type linear bearings, and cutting head will be moving on makerslide.

I started by designing a base for the machine. Due to the fact that I have no previous welding experience, I designed it to be adjustable at critical points to compensate for potential welding accuracy failures. The whole base will be made from steel. Here it is:

Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-01-jpg Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-02-jpg Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-03-jpg Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-04-jpg Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-05-jpg

  • Blue beams will carry the bearing slides and need to be as straight as possible. For this reason I plan to fix them with bolts instead of welding, as welding might cause some unwanted deformations. It will be 60x60x2 steel.
  • Red supports will have adjustable stands to be able to perfectly level the whole base. The bottom beam will be 60x60x2 steel and the vertical ones will be 60x30x2 steel.
  • Green stabilizers will be 60x60x2 steel.

One linear bearing slide will be fixed to 50x30x2 aluminum profile which, in turn, will be fixed to a blue beam. The other slide will be fixed to 50x30x2 aluminum profile, and that profile will be "floating" freely on the other blue beam. There will be a screw-and-bolt based "mechanism" to adjust the position of each end of it (on the horizontal surface), to make sure that both slides are perfectly parallel to each other and the gantry moves freely. These adjustments should compensate minor building errors, etc.

Newbie making 2x3 meters laser cutter/engraver. Build log + questions-base-06-jpg

The yellow beams are meant to support the working surface (table), whatever it will be. They are fixed to green stabilizers with adjustable screws, so that they can be adjusted to be perfectly parallel to each other vertically and parallel to gantry's direction of movement. It will be 60x30x2 steel.
I am currently designing the gantry mechanism and will update this post when finished. So far, the other "headache" questions are:

  1. Gantry motor. In general I'd rather be on the safe side and choose ones with more power, but I've read it somewhere that overpowered motors causes some problems. If I knew the desired acceleration/deceleration of the gantry, I suppose I could calculate the required force, and then work it down as a torque requirement for the motor. But I don't know what acceleration is considered normal for my scenario. Also, I don't know how to estimate max speed of gantry. The full gantry setup will weigh ~10kgBut I have no idea how much influence the friction will have.
  2. Laser head motor. I'll be using standard makerslide and their carriage, so somebody should already have done it (I guess I'll google that one out).
  3. Should I put the laser power supply on the gantry, to keep the high voltage line as short as possible? Or maybe it doesn't make sense, ant I should keep it stationary somewhere on the base? If so, should I run the high voltage lines separately (e.g. on the other side of the main slides) from other control lines and water coolant lines?
  4. For each axis: should I use timing belt or something else? If timing belt, then which configuration is better?Newbie making 2x3 meters laser cutter/engraver. Build log + questions-motion_a-png Newbie making 2x3 meters laser cutter/engraver. Build log + questions-motion_b-png I guess version B is easier to implement, but adds even more weight to the movable gantry. Should I use one motor (synchronized to both sides) for moving gantry, or one per each side?
  5. Working surface/cutting table. I suppose the top should be some kind of honeycomb or similar structured metallic (laser-proof) surface with as little top surface as possible not to have laser reflections from it on the fabric being cut. Under it there should be a "sealed" box with laser-proofed surface and wholes to suck the air and fumes out of it. At this moment I have no idea how to make the surface part of it, as we don't have local suppliers, and shipping such huge thing from overseas would be a financial overkill.

The chiller, electronics and software do not raise any questions to me yet, everything seems quiet straightforward. We found a CNC parts supplier in a neighbor country and plan to go there for some shopping next week. Unfortunately I don't have the privileged of trial and error, or ordering parts one at a time. I plan to buy linear bearings, slides, motors and drivers, belt and pulleys

I will do my best to update this log when I will have progress. And I will be more than happy to hear from you any suggestions, critics, etc. Everything I've written down is solely me inexperienced opinion.

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