howto produce crisp folds without etch line?

[michael080]

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

 

[Scale7JB]

One of these..!



JB.

 

[Scale7JB]

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.

 

[simond]

JB,

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

TIA
Simon

 

[mickoo]

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.

 

[simond]

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

 

[michael080]

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

 

[Scale7JB]

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

We aim to please

JB.