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IndustryArena Forum > MetalWorking Machines > EMCO CNC Machines > EMCO Lathe > Emco compact 5 X-axis tolerance
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  1. #1
    Join Date
    Aug 2011
    Posts
    2

    Emco compact 5 X-axis tolerance

    Hi guys!

    My first post over here

    A few years ago I bought a Emco Compact 5, and rebuild it with edingcnc, sadly health issues came in between but now I finally got it running I spend a long time on getting the settings for the backlash right, when I measure with the dial gauge everything runs withing 0,01mm which made me very happy But..... when I turn a test part then the tolerances are too much off for what I need, for example I turned a testpart with various diameters/chamfers/fillets and it came out like this:

    Green = diameter as drawn
    Red = diameter as machined

    Attachment 391780

    I hope you guys can advice me a little on this I don't have much experience with a cnc lathe yet, I assume it's still some kind of backlash somewhere that adds up all the time resulting in a bigger diameter than it should be?

  2. #2
    Join Date
    Sep 2009
    Posts
    26

    Re: Emco compact 5 X-axis tolerance

    Hi,Mitch!
    It's a little bit tricky to get precise results on the C5 CNC....!
    First,check if your tool is exact in centre high.
    My most important tip is,that you should machine all relevant diameters with the same cutting depth on the last cut,may 0,1 or 0,2 mm and you should place your tool always from "+" to "-" direction to reach the end diameter.
    That means,you should start by X +51.00 ; Z +2.00 and go to X +50.00 ; Z +1.00 to finish the diameter 50 mm.
    If you're starting from a smaller diam,may from X +20.00 ; Z -10.00,you should go to X +51.00 ; Z -10.00 First and from there to X +50.00 ; Z -9.00 before you go to X +50.00 ; Z -20.00.
    So,you'll get always the same load from the same direction (!) on your tool and on your spindle and your scales should be much more accurate.
    Sometimes,you should just make a test part,check the actual diameters and change the diameters in the program,if something is not accurate.
    BTW +/- 0.02 to 0.03 mm in diam. is not really bad for the C5 mechanical strukture.
    Greetings from Germany!
    Martin

  3. #3
    Join Date
    Aug 2011
    Posts
    2

    Re: Emco compact 5 X-axis tolerance

    Quote Originally Posted by kaktus-martin View Post
    Hi,Mitch!
    It's a little bit tricky to get precise results on the C5 CNC....!
    First,check if your tool is exact in centre high.
    My most important tip is,that you should machine all relevant diameters with the same cutting depth on the last cut,may 0,1 or 0,2 mm and you should place your tool always from "+" to "-" direction to reach the end diameter.
    That means,you should start by X +51.00 ; Z +2.00 and go to X +50.00 ; Z +1.00 to finish the diameter 50 mm.
    If you're starting from a smaller diam,may from X +20.00 ; Z -10.00,you should go to X +51.00 ; Z -10.00 First and from there to X +50.00 ; Z -9.00 before you go to X +50.00 ; Z -20.00.
    So,you'll get always the same load from the same direction (!) on your tool and on your spindle and your scales should be much more accurate.
    Sometimes,you should just make a test part,check the actual diameters and change the diameters in the program,if something is not accurate.
    BTW +/- 0.02 to 0.03 mm in diam. is not really bad for the C5 mechanical strukture.
    Greetings from Germany!
    Martin
    Thanks for the detailed info Martin! I was so focused on the backlash that I kinda forgot about the tool height, I checked that and it was too high. Now it's in the center and I run the program again and it already came out much better it's now 3,01mm, 5,35mm 8,70mm and the biggest diameter has now the biggest gap 15,03mm which is 0,07 smaller than it should be.

    I'll definitely keep playing with this It's actually a conventional compact 5 which I converted to cnc myself, it does have some parts of the cnc version though

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