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Vic Thompson

18Mm Plastic Foresight Elements Wanted.

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As title, I'm on the scrounge for two or three gash 18mm Plastic Foresight Elements because I want to have a go at machining them to a non standard size for use with an Eagle Eye. I had a couple to start with, and now I've got none as my first efforts were ruinous, but I think that I've got the technique now, boring them to size rather than trying to drill them to size. Any hole size below say 3.5 mm or so will do as I'm going to bore them to around 5mm, final sizing being determined by trial and error.

Any offers of help appreciated.

 

Thanks, Vic Thompson.

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I do indeed, set one has some larger sizes up to 5mm. Make me an offer to include postage and I'll include the 2 odd ball ones for you to play around/destroy :-).

 

I'm assuming you have a lathe and I'm guessing you first experiments with drilling produced an out of round hole?

 

I've not had much success boring them either, the best results I got was by drilling undersized then using a countersink/pilot drill to get the chamfer.

 

Headstock/ tailstock alignment is critical too, anymore than 0.002-03" out and hole will be oval. Holding the piece square to the axis is important the best way I found was to adapt an old front sight tunnel.

 

 

Not trying to teach you to suck eggs you've probably got far more experience than I have. I'm just trying to relate my experience doing this.

 

I'm sure I read somewhere that there is a formula/rule of thumb to calculate size increase when using an eagle eye. Or am I thinking about sight radius increase??

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I've heard +0.6mm for a 1.3X lens, and +1mm for a 1.5X lens

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The one's that I've made so far by trial and error ended up being made with a centre drill (after I checked and re-set the Tailstock alignment). It works ok, but I can't get a very good degree of control over the hole size in that I can't make to size, it's small cuts and measure.

 

The step on the perspex disc locates the disc on the jaws of my lathe, it might not be 100% accurate, but it's quick.

 

Regarding purchases at the moment, I've just broken my shooting frames, so I need to sort out a new pair first before anything else. I've got three or more sight sets and I've changed to another one on a temporary basis.

 

Vic Thompson.

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