Crack on V bedway.
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    Default Crack on V bedway.

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    Hello guys! I recently bought a new lathe it's about 650 kgs. Total length of work from Chuck to the end is 1 meter. While getting out from the wooden crate it fell down only on one side across the Chuck but it is functioning good. I had a test cut on mild steel across a 120 mm length I had a 0.01mm deviation. Today I spotted a rough edge on the top of the bedway and a little bit closer to the chuck the crack that you can see in the picture. I'm not gonna operate the lathe for the next 4 months due to studies but I would like your opinion regarding the crack.How bad is it? Will it propagate? How I could stop it and perhaps fix it? Thank you all in advance!

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    Hard to specify a repair without seeing how the rest of the bed casting is designed. Is this a brand new lathe with new castings or a rebuilt one? I'd be concerned about any kind of crack growing with the way bed castings twist and move. You may find that the lathe cuts well today, but a year from now when the bed moves, possibly due to the new castings still relaxing, the crack is more prominent and the lathe won't cut true.

    I think the trick will be to determine exactly where and how far the crack goes. The best way I know to "stop" the crack will be to drill a small hole at the end of the crack. I'd take more cuts and see if you're getting a consistent error in the same spot or when making the same kind of cut.

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    Its a brand new lathe. The crack is visible on the shiny part that you can see. I need to remove the paint below to check further. The crack started from down because this is the way the force from the fall applied. Yes I am aware of that trick but it will be pretty tricky to make a hole on the bedway given I don't have a lot of space.

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    The crack might or might not have anything to do with the fall and could have been there since the beginning.

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    Quote Originally Posted by Conrad Hoffman View Post
    The crack might or might not have anything to do with the fall and could have been there since the beginning.
    Agree with this, that seems to be an odd place for a crack to start unless the lathe fell in such a way that it contacted that section of the bed, such as falling on an anvil horn (or similar unlikely circumstance).

    Perhaps it's a flaw from the original casting, or a gouge from something (carriage edge?) from the fall rather than a crack. If the area is otherwise stable just stoning it flush may be the best choice.

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    Quote Originally Posted by Conrad Hoffman View Post
    The crack might or might not have anything to do with the fall and could have been there since the beginning.
    Definetely though I cant be sure now because the lathe took a fall from approximately 40 cm only on one side and the carriage was around there on that moment. The lathe is placed on a bench and actually the bench took the hit from the floor transferring the impact to the bed.

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    Quote Originally Posted by Milland View Post
    Agree with this, that seems to be an odd place for a crack to start unless the lathe fell in such a way that it contacted that section of the bed, such as falling on an anvil horn (or similar unlikely circumstance).

    Perhaps it's a flaw from the original casting, or a gouge from something (carriage edge?) from the fall rather than a crack. If the area is otherwise stable just stoning it flush may be the best choice.
    Can you give me a hand regarding what you mean as stoning? The area looks really stable and the crack is not complete, its only only half way through starting from the point my finger is until about the middle before the V starts.It has a lot of material around for the crack to propagate. I dont know how deep it might be aswell.

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    Looks to me that the visible crack runs vertically from finger then runs a short distance diagonally. To me it looks like what I have seen in plate and rolled steel sections. In welding we call it cold lap. The molten metal meets other metal that is not completely molten so it laps against it leaving a small line.
    A fracture crack would be more ninety degrees to the axis of the structure. I may be blowing smoke up my own arse but it needs a close look with a cheap die penetrant.... even kerosene wash with a chalk dusting after.

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    Quote Originally Posted by hobbyman View Post
    Looks to me that the visible crack runs vertically from finger then runs a short distance diagonally. To me it looks like what I have seen in plate and rolled steel sections. In welding we call it cold lap. The molten metal meets other metal that is not completely molten so it laps against it leaving a small line.
    A fracture crack would be more ninety degrees to the axis of the structure. I may be blowing smoke up my own arse but it needs a close look with a cheap die penetrant.... even kerosene wash with a chalk dusting after.
    Well you got it right it is running diagonally. So you think I should go after the warranty?

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    Quote Originally Posted by Christosns View Post
    Well you got it right it is running diagonally. So you think I should go after the warranty?
    It might be worth a try, repair only if that doesnt work out. A month or two of frustration waiting to work through a warranty process will still be better than years of disappointment. Good luck Charles.

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    Quote Originally Posted by Christosns View Post
    Well you got it right it is running diagonally. So you think I should go after the warranty?
    Given it appears to have several OTHER cracks?

    Get in there with a UV dye crack test kit. See if my bionic 20/15's are lying to me.

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    Quote Originally Posted by thermite View Post
    Given it appears to have several OTHER cracks?

    Get in there with a UV dye crack test kit. See if my bionic 20/15's are lying to me.
    Or, could that be a casting defect that was welded up before grinding. It almost looks like a patch on the that face of the way that's a slightly different color.

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    Looked like casting defect or welded casting defect to my eye also.

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    If I had bought that machine, I would insist that it be replaced. A crack in the bed is a permanent non-repairable defect. Because of the location, the shape, and the appearance, I don't think that this crack has anything to do with the machine being dropped. It looks like a casting failure.

    My two cents worth: ask to have the bed or the machine replaced.

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    I am going to close this thread here, I think that the original poster has all the advice he needs for now. Once he decides what to do or if he will try to repair it then he can start a new post. Thanks to all who offered advice.

    Charles


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