Seeking Help in buying and building a CNC table


  • Member

    Hi there, I am hoping to attempt the purchase and building of a small (hopefully larger than 8.5 x 11 inches), that houses a lightly powered laser. I have a win7 desktop to operate it, and hope to be able to utilize vector (dxf, ai, cdr) files to do my cutting.
    I hope to buy equipment that is familiar to Makerspacers so as to access their experience without causing unnecessary problems. I am hoping someone will point me to a website that will sell me a kit, hopefully someone can vouch for a supplier online.
    I know Makerspace has a very high quality laser cutter already, but it is way more powerful than I require. I hope to build this unit myself, but would love a few pointers, some advice on avoiding pitfalls and some backup when I just don’t understand (it happens).


  • Member

    @cam
    http://makeblock.com/xy-plotter-robot-kit

    Here is a kit that I had sourced before I wrote this entry. You will notice that lower on the page they sell the XY plotter bundled with a laser module that works with the system.


  • Member

    @cam
    http://www.canadarobotix.com/

    I have experience buying products from these guys in Ontario, but they don’t have a kit for what I am trying to accomplish.


  • Member

    @cam
    http://www.aliexpress.com/item/Newcomer-large-area-laser-engraving-machine-mw-2500-DIY-laser-printer-recorder-IC-brand-size-size/32669685368.html?spm=2114.40010208.4.115.PP2YKQ

    not sure this link will work, but this seems like a sketchy purchase. It’s basically what I am hoping to acquire/build.


  • Member



  • You probably want to build it in an enclosure to protect yourself and others from stray reflections.

    I’m actually very interested in acquiring a low-wattage laser diode and driver for building a mini laser cutter not much different than the draw-bot that we can take to events. There was a battery powered setup at mini makerfaire like that where they ran it inside a box with a webcam that was pretty slick.


  • Member

    @pierre
    Yes, safety is a concern. I was thinking that a light plywood box would suffice. I will be cutting 3mm foam which is also a concern, so the device would need to work outside to avoid poisoning as well.



  • Here’s the relevant MSDS for burning styrofoam:

    http://www.glasscellisofab.com/sheets/polystyrene/msds/styrofoam_msds.pdf

    If you know the gasses that you are likely to be exposed to, it makes it easier to figure out the precautions to make it safe.

    My current research indicates that people burning foam to line toolboxes are using EPA or XPE foam. I’m currently looking for reasonable sources of laser-safe foam.


  • Member

    @pierre
    I just read that the foam I hope to cut is the number 1 cause of laser fires. So that sucks. So I guess I will need an adjustable laser power in order to control this hazard. The machine (wires) will need protection until the settings are perfected.
    Thanks for that link, I have yet to get it to load, but excited to read about the poisons I am exposing myself to. It’s similar to knowing the time before you do the crime. I am excited to hear that there might be laser safe foam, I am prepared to make adjustments to avoid toxic processes.



  • If we were not willing to take some form of risk, we’d never get anything done… But I feel it is necessary to quantify the risks as best as I’m able, and take what precautions I can to mitigate them. Certainly given a choice between two materials to burn, where one of them produces more toxic gasses, it starts to seem obvious. If I decide to burn something that produces extremely toxic gasses in spite of the risks, I just need to figure out what sort of filtration will capture and neutralize the gasses. I’m not comfortable with externalizing the risks by blowing the poison onto my neighbors, so capture, filtration, chemical breakdown are my choices.

    Regarding power adjustment and fire safety, I am pretty sure you can PWM a laser diode to get power adjustment. You want to do this anyway, since you’ll get better cuts using just enough power to cleanly cut the material, instead of blasting through, reflecting off your honeycomb and messing up the back face of your part. Laser will likely live much longer running at less than maximum power too.

    These guys: http://toolfoam.com/ sell some foam that purports to be laser safe… I’m looking for cheaper more local sources now… but I could be in for a group buy if other people want to order something online.


  • Member

    @pierre
    I have uploaded a backdrop image in my profile that depicts the product that I currently cut by hand out of foam. The material is rigid to a fault, as I have had to reinforce the tail section with light wood so that the fuselage doesn’t sheer apart. Otherwise I like the rigidity of this foam. I have noticed very different consistencies of foam being sold at the hobby shop. All of a sudden the foam seemed like a paper, and was very brittle. Nobody knew what I was talking about when I asked around. I am guessing it is a positive change, environmental concerns changing policy.



  • The tool box foam is squishy and flexible. Not good for your needs.

    Have you considered CNC hot-wire cutting? Or even lasering out two copies of a plywood template and then hot-wire cutting a stack of foam sandwiched between two pieces of plywood? I bet it would be fast and cheap to do.

    Hot wire melts the foam but does not burn it if you have your feeds and power dialed in… So it produces much different levels of gasses. I’m betting that a $20 hot wire setup will be an order of magnitude faster at cutting out your parts than a $200 diode laser in single part quantities… If you cut 10 at a time, productivity skyrockets.


  • Member

    @pierre
    yes, I do wonder about using a hot wire. The laser cutter that is available could do a nice template out of any wood. It would be awesome, but the ultimate product requires registration pins (eyelets) for accurate shape creation. So if I can figure that problem out I would be using much cheaper tech, hotwire, which suits me just fine. Thanks for this conversation.


  • Design Lab

    @cam I have a hand-held hotwire wand at the space, if that helps. 4" and 6" throat.


  • Member

    @Vaughn
    Thanks Vaughn, I will take you up on that when I do tests.


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