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Plasma cutter - 608 on steel tube version

Discussion in 'Other Builds' started by openhardwarecoza, Apr 17, 2015.

  1. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    openhardwarecoza published a new build:

    Read more about this build...
     
  2. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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  3. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    To do list:

    Draw the Z Axis / Torch Height control
    Draw the front/rear belt mount points / endstop holder / etc plates

    Despite trying to limit machined parts the Carriage plates will need to be CNC/Laser/Plasma cut. No bending required though, these get welded into shape too. Saves one hassle

    I requested quotes from the steel supplier today, hoping to get it ordered and delivered early next week so Glen can start welding up the frame
     
  4. Tweakie

    Tweakie OpenBuilds Team
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    Sounds like a very interesting project indeed - I am looking forward to hearing more about this as you progress with the build. :thumbsup:

    Tweakie.
     
  5. GrayUK

    GrayUK Master
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    Don't forget the videos!! :thumbsup:

    Gray
     
  6. Mark Carew

    Mark Carew OpenBuilds Team
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  7. HeartMan

    HeartMan New
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    I am also building a CNC plasma cutter. I have the frame built from a purchased set of plans. The plans call for just V rails and V wheels for both sides of the gantry's Y Axis driven by racks and gears on the steppers . I'm told plasma cutters produce a significant amount of fine steel dust. I'm wondering if anyone has a comment about what type of open builds linear motion pieces would be best for this application. I'm worried about the dust gumming up the works.

    Thanks!
     
  8. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    I did do a lot of research on the topic of linear motion, and in particular against the dust.

    1. A water bath cuts down 80% of the dust at least
    2. HDT type belts, are apparently virtually immune against dust wear. According to several posts on cnczone.com forums :)

    @kram242, yeah I noticed those! Tooo nice. I really just need to figure out a logistics plan to get those 1.5m lengths here ): If I could I'd have made this whole thing out of 60x20 rails (plasma tooling is light enough)

    Here's what the design looks like now. Steel quote came back as $380 so ordered for delivery next week :)

    Table.PNG
     
  9. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    @kram242 anay chance we can up the limit of the Build picture to more than 50k? A bit of a pain to resize down that low sometimes :)
     
  10. HeartMan

    HeartMan New
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    Thanks for the information about belts. I guess my main concern is about what kind of bearings would be best for the X and Y axes to run on. As I mentioned, I'm worried about the bearing system getting clogged with the dust.
     
  11. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    ZZ rated bearings should be sufficiently sealed. Else use OpenBuilds V Slot with extreme wheels... Cheap enough if you do wear them out.
     
  12. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    Updated the Build page with building instructions!
     
  13. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    Received the set of carriage parts lasercut from gorgeous 3mm mild steel:
    20150423_090412.jpg
    And as soon as I got home, welded one up. Now, note I have only owned my first stick welder for approx 3 weeks at this point, and have only done one quick project table as practise. So the welds does look crap - sorry :) - a few years of practise ahead

    IMG-20150423-WA0002.jpeg
     
  14. HeartMan

    HeartMan New
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    First of all, your welding. If it is structurally sound, in this sort of environment who cares. Actually if you paint it or have it powder coated it will help hide what YOU don't like. If you are going to be doing much of this sort of welding in the future, consider getting a mig wire welder. It makes welding for us "hacks" much easier. Now a question if you don't mind. Who did the plasma cutting for you and how much did it cost?
     
  15. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    To answer your question first, the set of parts cost me $60 to get lasercut (but if you view my Freeburn2 build on here as well - according to the forums I get metal lasercut at half the price the rest of the world pays. One of the pro's of living in the 3rd world I guess)

    Regarding Mig. I picked up the literally cheapest machine I could find. $90 for a brand new 200A Inverter with 12month warranty from a clearance warehouse. The cheapest Mig they had was $340+-

    Now I do agree the investment would be good, but I have seen experienced stick welders do great jobs. I am just splashing more than beading (; though putting todays job next to the first weld I ever made (blow through mess) - I'd say give it 6 months (;

    However, anyone have anything good to say about flux core Mig? I cant really rent a argon bottle for $20/month considering how rarely I actually use it...
    If its OK, i might consider trading in the stick. That was the big turn off for me, having to get a large bottle...




     
  16. edward siegel

    edward siegel Journeyman
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    looks great from here ive been welding all my live as long as it holds who cares
    of course I have two migs and a tig welder
    what are you going to use for a plasma cutter im using a simadre d5o its black and so far its doing great the trick is to and a ground from the torch tip to the work
    I bought a 65 dollar machine torch of ebay it was the same brand as the hand held that came with my plasma
     
  17. HeartMan

    HeartMan New
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    Yeah, if you're not going to use it very often, argon can be a hassle. The strange thing about argon (at least in my location) is that it costs only a small percentage more to get a large bottle filled than one half its size. There is really nothing wrong with flux core wire welding. I find it infinitely easier than stick. Of course the only way to get good with any welding technique is practice, practice and more practice. But that also may be because I'm not the most coordinated guy around. The only downside is the flux forms slag that you have to chip and brush off. Another plus with many flux core wire machines is, that as delivered, they can only use flux core wire, but at a later time can have the extra goodies added for actual mig.
     
  18. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    I picked up a Tradeweld Cut 40H with HF start from a clearance warehouse locally for under $200. Bargain. 40A is fine for the 3-6mm material we intend cutting (mild steel mostly) and can always upgrade later, table is investment (;
    The HF start also means I should get away with some GCode trickery like go to 5mm above surface, dwell for a few ms to get the pilot arc going, then do a M3 to light up, lower to 3mm to pierce, and then start cutting... Going to use Sheetcam, so will use the Tangent lead in to make a clean start too. I intend having a capative touch probe to probe the height during the job too - more details on the electronics later.


    @HeartMan - exactyl - as long as its structural, I can sand and grind it smooth, if it needs be I can even put some body filler in any holes before sending it out to powder coating

    Promo video by Tradeweld


    Some handheld cutting with the Tradeweld Cut40H


    A pic of the machine, nothing fancy
    MIN_238237_EAA.jpg
     
  19. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    Got access to a mig welder and factory floor for today and tomorrow! Packing up my camera to make a timelapse - will see you all tonight!
     
  20. Tweakie

    Tweakie OpenBuilds Team
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    Good fortune with the build - I am looking forward to watching your video :thumbsup:

    Tweakie.
     
  21. HeartMan

    HeartMan New
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    OK, I'm looking for an opinion now. Given a choice which of the three drive systems would be best for a 4' X 4' plasma cutter?
    1. Acme screw or the like
    2. A drive belt with the stepper mounted at the ends of the rails
    3. The "traveling stepper" where the stepper is mounted on a trolley with the drive belt looping up over the gear on the motor.

    Also for each option, how much torque would the stepper motors need, particularly the two on the Y axes driving the gantry.
     
  22. stargeezer

    stargeezer Veteran
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    Acme screws are pretty much the standard here for use in environments that are dusty or dirty. The squared off teeth of the screw help to keep dirt from accumulating and help to insure that what does collect can fall off/out as the screw turns. Mounting a brush on the gantry to follow the screws as the head moves is cheap insurance against dirt. We have lots of commercial laser cutters and plasma cutters in the plant and none of them use belts. There are a couple with VERY well protected racks/gears, but the overwhelming majority use large acme screws.

    For your steppers, I'd use NEMA 23 270 in.oz. in the 2.4-3mh inductance range. I believe the lower the inductance, the more torque/speed you will have. If you elect to go with Acme screws, get "5 start" for better speed, if you can. For instance, a single start 1/2" 10TPI Acme screw must rotate 10 times to move your gantry 1". A 5 start Acme screw will move that same gantry 1/2" for each revolution. If you make the mistake of getting steppers with too high a inductance rating, you'll find that even a high torque stepper will stall out or run too slowly. Higher stepper operating voltage is a good thing too.
     
  23. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    First day didnt progress particularly fast... mig didnt show up for the day (arrived yesterday so on hand for next build session) so had to continue tig welding... also waited for 3 hours for a delivery of argon which was scheduled for 7AM (they delivery guys showed up at 10AM)...

    But did get the two sides done:

     
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  24. HeartMan

    HeartMan New
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    I appreciate your thoughts on the matter. Your statements about stepper motor inductance are right on the money. Even having been educated as an electrical engineer, the influence of inductance had never crossed my mind (what little is left of at my advancing age, hence my avatar). Here is a link to a succinct explanation of the issue.

    http://www.nmbtc.com/step-motors/engineering/torque-and-speed-relationship/

    One more question, if I may. Do the number of starts effect the need for backlash protection? Also I assume that for screws that are going to be in the 1000 to 1500 mm range, 1/2 inch diameter is probably a lower limit in size, true?
     
  25. Mark Carew

    Mark Carew OpenBuilds Team
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    This build is coming along very nicely, keep up the great work. :thumbsup:
     
  26. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    Bed installed.... First cut coming up!

    IMG-20150620-WA0001.jpg
     
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  27. Mark Carew

    Mark Carew OpenBuilds Team
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    @openhardwarecoza I have a question, how are you able to adjust the preload on the bearings to the rail?
    Keep up the good work, looking forward to your first cuts!
    EDIT: Nevermind I see the adjustment slots now :)
     
    #27 Mark Carew, Jun 23, 2015
    Last edited: Jun 26, 2015
  28. Atomist

    Atomist Journeyman
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    Any updates on this build? Would like to see it cut!
     
  29. openhardwarecoza

    Staff Member Moderator Resident Builder Builder

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    Soon! The TinyG based controller boards should arrive this coming week

    I designed my own PCB to sit atop an Arduino Due running Tiny G G2 firmware
     
  30. Raed Al Nuaimi

    Raed Al Nuaimi Well-Known
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    Nice build,

    Looking for the plasma torch assembly.
     

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