howto produce crisp folds without etch line?

Discussion in 'Techniques' started by michl080, 11 November 2018.

  1. michl080

    michl080 Western Thunderer

    good evening.

    I guess the title says is all. I am happily building a MMP Class 08 kit and have been running into a problem with the cabin roof.
    I will have to remake that from a plain brass sheet, but it requires two crisp folds with a 130° angle and first trials resulted in a pretty ugly radius. I assume that the only proper way to do it is to prepare some kind of groove where the etch line would be. But I have no idea how to do that.
    How are you scratch builders solving that problem? Any input is highly appreciated.

    Michael
     
  2. Scale7JB

    Scale7JB Western Thunderer

    One of these..!

    image.jpeg

    JB.
     
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  3. Scale7JB

    Scale7JB Western Thunderer

    The Olfa cutter will give you a good groove, though you may find you need to open the angle of the groove out a bit with a triangular or square mini file.

    JB.
     
  4. simond

    simond Western Thunderer

    JB,

    Could you post a photograph of the cutting edge from the metal’s point of view?

    TIA
    Simon
     
  5. mickoo

    mickoo Western Thunderer

    I did a write up on skrawkers 7mm - US model dabblings post 313, this'll give you a good idea how they work mechanically and create the groove and some pitfalls. As JB notes, you may need to open the groove a bit more if it's thick material but up to say 10-15 thou you should get a nice tight bend just with the blade.
     
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  6. simond

    simond Western Thunderer

    Ta. Answers my question behind the request, and explains why my home made scrawkers sometimes don’t.

    Will have another go, but better informed next time :)
    Simon
     
  7. michl080

    michl080 Western Thunderer

    Wow!

    JB, thanks for directing me to this nice tool. Mick, thanks for the very informative link and Simon, thanks for asking what I asked myself. :)

    what a wonderful forum. (Especially in comparison with some others where rant takes over)

    Michael
     
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  8. Scale7JB

    Scale7JB Western Thunderer

    We aim to please :D

    JB.