curved file for clip on sunglasses?

[ali27]

Hi guys. I have a question for you guys. I have started working
for an optician. One of my tasks is to occasionaly file a clip-on sunglasses
in the same shape as the glasses of the client.

My boss only has a straight file, but I was thinking a file with a slight curve
might be much better to get the final correct shape. I have been searching the net
for an appropriate file, but haven't found antything really suitable. Hope
you guys can help.

Thank you.

Regards,

Ali

 

[AndyT]

Hmm, I assume it's not wood that you are filing!
I'm guessing it must be acrylic. You might find a riffler with a curved shape, but these are mostly for wood or stone and might be too coarse. One other idea would be to shape some suitable pieces of wood and then stick various grades of abrasive paper to them.

However, in my experience of filing things, a flat file is best for filing a convex curved shape.

 

[CHJ]

Have a search round for Jewelers or watchmakers Files, and try 'draw filing' . Example of smaller ones.

 

[AndyT]

One more thought about filing curves. This would be so much easier to show than it is to describe, but I'll have a go.

I think (as you asked for a curved file) you must be working along the edge of the lens with a narrow file. It's much easier to turn round 90 degrees and use a big flat file. Imagine that you have a 2p coin and you want to file it down so it's the same shape as a 20p. The way many people would approach this is to file along the narrow edge of the coin, tilting the far end of the file and lifting its handle as they complete the stroke.

Instead, put the coin in a vice so the face side is towards you. Use a long, broad file. Start the cut with the file level end to end and also level side to side. As you push forwards, rotate your wrist but keep the file horizontal end to end. Aim to complete the required amount of twist as you get to the end of the stroke, so the file ends up tangential to the new curve.
I think you will find this much easier to control.

(It's also the best way to round off sharp corners on brackets and suchlike - you know that if you twist the file 90 degrees (from horizontal to vertical) as you make the forward stroke, you will make a quarter circle shape where the sharp corner was. Much easier than rocking the file end to end.

 

[Cheshirechappie]

Try googling 'riffler files'.

If all else fails, Cousins UK stock good quality swiss ones by Vallorbe - www.cousinsuk.com . Not cheap, though.