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  1. #1
    Join Date
    Mar 2003
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    6855

    New 24 x 48 laser project log

    OK I have started to design my new laser, so far this is what I'm going with-

    1) 5/8" feather shafting mounted on end supports

    2) cutting area of 24" x 48"

    3) nema 23 frame stepper motors

    4) belt driven X and Y

    5) simplicity linear bearing with my own billow blocks

    6) 20w RF co2 laser w/ 80 volt power supply

  2. #2
    Join Date
    Nov 2003
    Posts
    634
    Paul, I'm not the expert on this, but I think that there are a few more things you need for a working system.

    1. The Z axis must float over the material. Its very important the the laser beam is focused exactly at the right point. Its kind of like holding a magnifying lense over a piece of paper. You have to move it up and down to get the proper pin point of light to burn the paper. Your 5/8" rails will sag. The material will warp and bow. You have to make up the difference with the Z axis.

    Maybe someone else can chime in with some real life experience. You must not be cutting much with only a 20 watt laser. Balsa wood?

    2. You will need some kind of baffle to sit your parts on. Honeycomb plastic should work well.

    3. A fume extraction under the table would be helpful so you don't smoke up the place.

    Good luck and keep us informed

    Trent

  3. #3
    Join Date
    Mar 2003
    Posts
    6855
    Quote Originally Posted by buscht
    Paul, I'm not the expert on this, but I think that there are a few more things you need for a working system.

    1. The Z axis must float over the material. Its very important the the laser beam is focused exactly at the right point. Its kind of like holding a magnifying lense over a piece of paper. You have to move it up and down to get the proper pin point of light to burn the paper. Your 5/8" rails will sag. The material will warp and bow. You have to make up the difference with the Z axis.
    1) I think 5/8" would be more than enough, the carnage that will be holding the lens should be less than 5lbs, so the amount of sag will be less than +/-.001 ? I do need to play with some numbers.


    Maybe someone else can chime in with some real life experience. You must not be cutting much with only a 20 watt laser. Balsa wood?

    2. You will need some kind of baffle to sit your parts on. Honeycomb plastic should work well.
    3. A fume extraction under the table would be helpful so you don't smoke up the place.
    1)with 20w I will be cutting balsa, ply, foam as well as engraving, and vinyl cutting.

    2,3) I plan on using alum honeycomb material with a pan on the bottom for vacume and to terminate the laser beam.


    BTW here is the laser I bought- http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MEDW:IT

  4. #4
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    Mar 2003
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    6855
    Does anyone have some experience with feather shafts and bearings?

  5. #5
    Join Date
    Aug 2004
    Posts
    2849
    Regarding the sag....I put those numbers on the other thread....so with a 5/8 inch end supported rail the deflection at the center with 10 lbs is 0.100 inches....the 0.001 is the straightness of the Thomson shafting per 12 inch length.

  6. #6
    Join Date
    Mar 2003
    Posts
    6855
    Quote Originally Posted by ViperTX
    Regarding the sag....I put those numbers on the other thread....so with a 5/8 inch end supported rail the deflection at the center with 10 lbs is 0.100 inches....the 0.001 is the straightness of the Thomson shafting per 12 inch length.
    That's a solid shaft right? .100 should be acceptable I would think, I could always add a support in the middle?

  7. #7
    Join Date
    May 2003
    Posts
    550
    The 5/8" Feather shafting is the Pacific bearing CC10 stuff? Then I've used it on a sliding table for my table saw which isn't very relevant. Surplus stuff but its works well for that.

    Note it's 6061-T6 so has a modulus of 10,000kpsi. 48" of 5/8" feather shafting with ends simply supported with a central 5lb load will deflect 0.1538". Fixed ends drop that to 0.0385"

    24" shaft will deflect 0.0192 and 0.0048 respectively.

    If you use the Pacific End support blocks I'd suggest you'd be more towards the fixed end figure.

    nice buy on the laser !

    Andrew

  8. #8
    Join Date
    Mar 2003
    Posts
    35538
    Next time I decide to dig out my bearing catalog and do some deflection calculations, I'll just wait 20 minutes for you guys to do it.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  9. #9
    Join Date
    May 2003
    Posts
    550
    Ah, I cheated -- I still had the spreadsheet from when I was working out the tablesaw.... Used the same 5/8" stuff...

    Only problem with it was cutting it to length by hand. The coating is RC70 which is harder than SS or drill rod.. Took a bit of effort to get the hacksaw started without it skating all over the place...

    besides, you have to keep the moderator happy!

  10. #10
    Join Date
    Mar 2003
    Posts
    6855
    Well after much designing I have started over, I found a cheap more accurate way of getting this thing moving. I won't go into it yet, but I have ordered some material for testing, but I think I really found a great solution to using thk or linear bearings.

  11. #11
    Join Date
    Sep 2003
    Posts
    1469
    Oh come on give us a hint.

    Is it cheaper?

    Stronger?

    More precision?

    Lasts longer?

    Or all of the above????

  12. #12
    Join Date
    Mar 2003
    Posts
    6855
    Here is a first look at my design.........
    Attached Thumbnails Attached Thumbnails LASER.bmp  

  13. #13
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    Mar 2003
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    6855
    The design is done and now I just have to prototype the whole thing. So far it looks like the machine will cost about 1,000.00 not bad. This design could easily be used for a small dremal router.
    Attached Thumbnails Attached Thumbnails laser-2.JPG  

  14. #14
    Join Date
    Mar 2003
    Posts
    6855
    I have decided on a new material from 80/20, that will be much easier to work with and a little cheaper. The design is going to allow for minimal machining. I will post the progress with pics as I start to assemble the machine.

  15. #15
    Join Date
    May 2003
    Posts
    550
    New material?

  16. #16
    Join Date
    Mar 2003
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    6855
    80/20 sells this extrusion that is a 1.5 x 1.5 tube with a leg 1/8" thk. I'll post a pic or it, I have a sample. It's cheap to at .44 a inch.

  17. #17
    Join Date
    Mar 2003
    Posts
    6855
    Got one set of mirrors and should have my laser today. I'm still waiting on a track and wheels to see if they will work well enough for my leaner drive system. The design and drawings are done and as long as I keep the components I plan on using, I can go right to producing the frame. I'll post some pics on the progress when I make some

  18. #18
    Join Date
    Jan 2005
    Posts
    11
    paul, i'm in the process of bidding on the same type of laser system. how much and where are you getting your optics? also any info on the 84v power supply would be appreciated as well. price? i already have a cnc platform to place this on so it should go fairly smoothly i hope. thanks, toby....

  19. #19
    Join Date
    Mar 2003
    Posts
    6855
    Quote Originally Posted by tobytorkn
    paul, i'm in the process of bidding on the same type of laser system. how much and where are you getting your optics? also any info on the 84v power supply would be appreciated as well. price? i already have a cnc platform to place this on so it should go fairly smoothly i hope. thanks, toby....

    I got the mirrors on ebay, the lens I bought from the ebay seller of that laser. You need 3/4" to 1 1/2" focal length. For the power supply, I have a transformer that will work, you only need about 8amps and 80-84 volts. If you are cutting foam make sure your will ventilated the fumes that will come off are cancer causing. Another thing is that that laser is not high powered it's only about 7 watts and can only run 70-80% duty cycle, which means it may not run for more than a few mins with-out over heating, once it over heats it can be destroyed. Once I get mine running, I'm going to sell it and get a full 20w laser tube, I already have a power supply for it.

  20. #20
    Join Date
    Jan 2005
    Posts
    11
    have you found any cost effective 20w lasers yet? if so, where? i'm looking at cutting mostly 1/16" & 3/32" balsa and also maybe depron. i hear you about the fumes, not good. thanks for the help! great site! toby silhavy
    www.silhavyaerosports.net

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