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3000x1500 CNC

Discussion in 'CNC Mills/Routers' started by Said, Apr 25, 2014.

  1. Said

    Said Well-Known
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    Said published a new build:

    Read more about this build...
     
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  2. Tweakie

    Tweakie OpenBuilds Team
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    Great looking build @Said I look forward to following your progress. :thumbsup:

    Just one point I think that using all Delrin wheels would be a lot kinder to the V-Slot than using steel wheels. ;)

    Just a thought.

    Tweakie.
     
  3. Said

    Said Well-Known
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    @Tweakie
    Thank you for your comment but I made the choice of steel wheel because I thought the Delrin wheels would deform with the weight of the gantry.
     
  4. bhalkett

    bhalkett Journeyman
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  5. Said

    Said Well-Known
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    @bhalkett
    Thank you for the info I will look at all tonight
     
  6. JustinTime

    JustinTime Master
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    What will be easier, and less expensive, to replace? The delrin wheels or the V-rail? Also, if you use the solid wheels, rather than the slotted wheels, they will withstand quiet a weight. You are using enough of them to distribute the weight.
     
  7. Said

    Said Well-Known
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    @JustinTime
    Indeed, by posing the problem in this sense the choice is quickly made. The delrin wheels are better
     
  8. Florian Bauereisen

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    Hi,
    wish i would have the space for such a big cnc.:)
    Here is a thought: you have spend quite an effort to stabilise the x- axis but ( this is just my personal feeling) totally neglected the side Plates of your y. Your gantry and spindle will accellerate and stop apruptly and so your gantry will "sway"/ swing from side to side.
    That is if you want to cut fast - and you will - for using such a big machine you do not want to go slow- the big cutting jobs you do with the machine will use a lot time anyway.
    On you belts: A 6mm belt feels awfully small for the sice and weight of your cnc.
    the one i am currently designing (1,0x0,5m cutting area) uses 15mm wide ones as i feel 9mm slightly to small.

    6mm belts will work initially for sure but will it over time? The stretch under load will be more for 6mm than for 15 thats for sure.

    About motors: your side plates are big enough so you could easylie belt reduce your motors if needet. If you figure this in before hacking away it boils down to a few more holes to drill. Easy conversion if you need to.
    Just a couple of thoughts.

    Good luck

    flo
     
  9. Said

    Said Well-Known
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    @Florian Bauereisen
    For the belt I knew I'd have surely problem. by I do not understand your last sentence on the motor that I could reduce
     
  10. JustinTime

    JustinTime Master
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    I think flo used a computer translator to translate from German. I think he meant to gear it down with pulleys.
     
  11. n0kjf

    n0kjf Well-Known
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    If you are concerned about the mass of the Z axis, use gas shocks to help the stepper. Our Z weighs about 55 pounds (25kg). The stepper had a lot of work to do to move it up and would sometimes miss steps. Several times the Z would crash into the table. Also, keep your accelerations at a reasonable level, with a massive bridge, that can cause a few missed steps as well. Our bridge weighs a whopping 250 pounds (113kg). Big steppers and a significant gear reduction helps with precision.

    And one last suggestion, you should think about adding mass to the table. Our frame is 3"x3"x.25" steel angles and a 12" channel brace on each side. The top is 4 layers of 3/4" MDF (Medium Density Fiberboard), plus one 1/2" spoil board. Very heavy and it helps steady the table during the sudden starts and stops of the cutter.

    600 pounds (275kg) of steel in the table, 500 pounds (227kg) of MDF makes the table very rigid.
     

    Attached Files:

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  12. Said

    Said Well-Known
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    thank you justin, now I understand better what it meant florian
     
  13. Said

    Said Well-Known
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    @n0kjf
    thank you for the ideas, hit the gas cylinder is excelent, had to think.
    And the chassis it is clear that I must find a solution for stability, if you will allow me I inspire many of your chassis if it is really well designed.
     
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  14. Florian Bauereisen

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    Nope,
    my english is just that bad -LOL
    But yes, gearing down using pulleys was what i meant.

    greets

    flo
     
  15. Jeferson SImoes

    Jeferson SImoes Well-Known
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    I would be the first to post, if it had not closed the browser tab unintentionally. It's hard for me to write in English, so I left to write another day. But today I saw that the forum saved the draft, then follows what I had typed.

    ------

    I want to know more about the belt too. First I made a machine using leadscrew for all axis. But was very hard to get the two Y leadscrew perfect parallel. Now I'm using a GT2 2mm belt, the only one I found to receive fast here in Brazil. It's only a prototype, then, the final version that I intend to sell will use the 3mm belt setup with nema 23, that is all avaiable in here part store. The Openbuilds suport already answer me about belt VS leadscrew, and I thik that will be nice in small machines.

    In some research, I read about some belts that have stell cords instead of fiberglass cords. Anybody know about? It would nice if have this belts in 6mm, to fit inside the v-slot.

    I think you will have problem with the stell whells and aluminum extrusion. The whells will scratch (I don't know the right word in english for that) the aluminum.

    And I think probably will better made the v-slot of Z axis fixed at the X axis plate, and put the whells fixed on the Spindle plate. That will reduce the weight that the nuts have to suport. With the v-slot fixed to the spindle plate, the delrin nuts have to hold the whole v-slot + the motor. Made this two parts hold by the X axis, the delrin nuts (and the stepper) will have a relieved.

    I hope that you can see in this image. The two 2020 v-slot that I used to Z axis, is fixed at the X axis carriage.

    [​IMG]
     
  16. Mark Carew

    Mark Carew OpenBuilds Team
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  17. Owen Johnson

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    3000mm Y, (Z?) rails? Does that mean you plan on butting two 1500mm rails to reach 3000mm? How do you plan on joining them? Are you going to use any type of cross bracing to minimize shifting of the two rails? I'd also like something that could handle longer material, such as sheets of plywood. I'm wondering if it might be better to determine some way to index parts on the table and mill them in multiple steps rather than build a bigger machine. Meaning have the mill bore indexing holes through the waste portion of the material and the waste board. You can then use a dowel or steel rod to align the index holes for the next pass.
     

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