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  1. Quote Originally Posted by JAZZCNC View Post
    Could but then I'd have to kill you ALL.!! . . . And I actually do like some of you so I'm doing it to protect the innocent. . ..
    oh, which of us do you like then Jazz? :D

  2. #22
    Quote Originally Posted by irving2008 View Post
    Don't need BK both ends, just at drive end. BF is fine for other end.
    Hi Irving,

    I almost sure that you are right, but it will be my first built CNC (so I'm trying to do my best as I can)
    what I know about screw and ends?

    only one,
    fixed + fixed ends its much bater than fixed + floated
    (it will eliminates wipping and increas the speed ?)

    Thanks for input !

  3. Yes it does but:
    A. its much harder to set up right

    B. the speed increase factor isn't needed here - very roughly 2600rpm to 3900 rpm for a 16mm screw. Even with a 1605 screw the lower end is >10m/min, far more than you'll achieve in reality

    C. It needs more complex machining of the ballscrew end

    D. It costs more

    By your own admission this is your first build so KISS IMHO :D

  4. #24
    Quote Originally Posted by irving2008 View Post
    oh, which of us do you like then Jazz? :D
    Could tell you Irving but then I'd have to kill you all to protect my self. .

    Quote Originally Posted by Gytis View Post
    Hi Irving,

    I almost sure that you are right, but it will be my first built CNC (so I'm trying to do my best as I can)
    what I know about screw and ends?

    only one,
    fixed + fixed ends its much bater than fixed + floated
    (it will eliminates wipping and increas the speed ?)

    Thanks for input !
    Completely agree with Irving. Fine for industrial machines using servo's with high feed rates 25m/min+ and heavy loads but here the only difference you'll see is less cash in your wallet.!!
    With DIY building you'll gain more performance by concentrating on build quality and careful alignment of screws/motors and linear rails than using Industry standards.

    One thing wanted to point out which catches new builders out is to think carefully about bolt hole location and fastening of brackets etc.?
    Often the obvious place to fasten something is completely the wrong place which makes assembly a right pain in the arse.

    IE: You have the Y axis ball-nut bracket (thru slot) fastening from the front side of Z axis rear plate. Doing this means you have to remove front plate from Z axis to access those bolts or drill access holes in it.
    You need this bracket to have some adjustment to make alignment with Y axis ball-nut easy and doing this from front and thru a hole will be a pain so would be much easier if it bolted from the rear into tapped holes in the Z axis rear plate.
    It's simple things like this that make building and setup just that bit less painful.! . . . Unfortunately finding these things out often comes from building the first machine and at worst case scraping a few parts learning on first build.

  5. #25
    Quote Originally Posted by JAZZCNC View Post
    Could tell you Irving but then I'd have to kill you all to protect my self. .


    Fine for industrial machines using servo's with high feed rates 25m/min+ and heavy loads
    This will be my second CNC with these feed rates

    You need this bracket to have some adjustment to make alignment with Y axis ball-nut easy and doing this from front and thru a hole will be a pain so would be much easier if it bolted from the rear into tapped holes in the Z axis rear plate.
    You mean like this (see pics) , just drill a bigger hole in the bracket for adjustment ?

    Unfortunately finding these things out often comes from building the first machine and at worst case scraping a few parts learning on first build
    I understand this and I'm ready for this (to scrap few parts, especially with my tools)!

    Thank you guys
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  6. #26
    HI,

    this is my almost finished CNC machine model,
    bed is from the aluminum extrusions (heavy) 90 x 45 and 45 x 45, it will cost me about 800 eu + delivery?, only for the extrusions!
    overall dimensions (bed) is 1590 x 1250 x 590 mm.
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  7. #27
    Wow your really making that harder and more expensive than it needs to be.? Also has a flaw.?
    First I'd use Steel for the frame and save 600eu.!! . . but that's not what I mean here.?

    Orientate the side profiles on there edges and you'll gain strength and be able to do away with those aluminium braces and the 2 long middle profile, then Extend the 3 uprights to meet top rail.
    Put the ball screws on the outside and make drop brackets part of gantry sides, sides will be shorter than drop bracket, less material,weight,money. Easier to setup and adjust screws/motors has they are more accessible. Then you can line the inside walls doing away with the slot and stop crap hitting the screws completely.!! . . . . Your way has a BIG flaw in that it will allow chips into the sides, still hitting screw and eventually filling up the sealed cavity.
    You'll be constantly cleaning it out and believe me it won't take long to fill the void between middle profile and slot. Chips spray in a linear direction off the cutting tool and that Gap is in direct firing line so you'll be surprised just how much disappear thru it.!. . . . Kid you not Bet I could fill that gap with alu chips within 3weeks and that's allowing for sizeable percentage not hitting slot gap.!!!!

    One other thing.?. . . If those bed supports are 45x45 then I think you'll find there not strong enough at that length and allow bed to potentially bow in centre when cutting or plunging. My suggestion is to put 2 or 3 45x90 on there edge for main supports and make rest up with 4x45.

    Sorry to keep pulling at your designs but with experience these things just jump out at you and I'd feel shit if didn't mention them, then at later date you came back and said wished I'd done this or that which I'd spotted.!!
    Last edited by JAZZCNC; 26-07-2013 at 08:50 PM.

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  9. #28
    Hello,

    OK..., this is me second attempt to make a strong frame, but this time not so expensive.
    Frame from the steel box 60x40x4mm all round, steel will cost me about 180 (6 x 7.5m), it's a big savings compared to aluminum.
    just a little bit worried for the welding work, but I'll try and we'll see what happens

    Wish me good luck

    frame size 1600x1180x600 (x,y,z)
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  10. #29
    The way you've mounted the bed looks a little weak to me. The bed box section could rotate about the fixing 'rails', so the end fixity is poor, which means the bed itself will sag more when a weight is placed upon it. You could instead bolt the bed frame directly to the machine frame.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  11. #30
    Hi Gytis,

    Looking good just couple of things which will help, you may have seen me post it on other threads has I seem to be repeating my self quite a it now more folks are taking to steel.!!

    Make the top rail bolt onto plates, much easier for setting rails parallel and on same plane.

    The connection of bed to frame looks a little weak and could flex. I'd just bolt straight to frame with angle brackets. It will also be very heavy so I'd consider having some way to help assist with the lifting, IE Acme lead screw or Large pitch Threaded rod.

    Would make the sides separate bolt on sides and have the green frames separate structures, would also make the triangle braces on green ends longer so they support frame further down.
    Having separate sides will make assembly easier with flexibility to adjust any error out like getting square and vertical. Also will come apart for moving or if you sell it.

    Secret to good DIY is lots of adjustability.!!

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