# Laminates with Metal Cores



## Lacumo (Aug 18, 2013)

I've also read about and seen pictures of fork and frame failures in board cut and even laminated frames, and they honestly scare me. I've got my OSHA-approved safety glasses and proper shooting glasses from a local gun dealer, but still -- the possibility of broken frame/fork pieces being flung back into my face by the pull of a drawn band set is something I'd like to avoid if possible.

I've also seen images of a lot of laminate SS frames with a metal core layer (usually sheet Al, which usually looks like 1/4" sheet stock).

My question is this -- Is 1/4" Al sheet stock the right stuff to use for a laminate SS frame core layer? Could I get away and do a satisfactory job with a cut-out piece of a baking tray? The baking tray sheeting is nowhere near 1/4" thick, but I think it's likely steel and not Al.


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## squirrel squasher (May 17, 2013)

http://kookaburrakatties.blogspot.com.au/p/streng.html

Make a split frame


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## AnTrAxX (Jul 18, 2012)

You will have a very hard time drilling or cutting a baking tray.

Aluminum is used often, but i think for starting just crossing the grains or a layer of muliplex as core will do the job.

If it "has" to be metal i bet you will find a company that sells all sorts of metal to bigger companys.

Normally they can give you "scrap" parts very inexpensive. 5mm of Aluminum is easy to work with, you can drill it, file it and cut it with a saw.

Since there is no grain in metal i often found it easier to work with compared to some hard-woods.

You could also try one of my cores i offer and just begin with adding some scales.

Best of luck


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## BCLuxor (Aug 24, 2010)

hmmm seems appropriate I guess...

One of my frames "failed" not long ago. I have been away all week itching for more testing .. Wombat covered the process of laminating wood for strength even going to the extreme of hammer hitting different laminates. Before I left and while trying to establish how the frame failed I took some photos of just how strong a glue line can be.. I rested a 1.26 Tonne Ford Focus directly down a glue line from some of the Sapele stock that was in question. The following photos show how the two 10mm laminated Sapele sheets with alternating grain faired...













No problems...

Illustrating that glue can be very very strong... The weakness in laminated frames comes "**I believe**" from the design. The weak point in my ZF frame for example would be compression on the fork tips which during normal usage should be no issue.





alternating the grain on the sheet compensates to a certain amount for any one directional weakness..

The following shows compression failure (I Had to squeeze HARD to break the tip)





Even with a frame so badly broken no "flyers" come from the board although you would not want to shoot a frame this damaged! The following show some 1745 tubes drawn out around the broken tip! 15?lb? ( if I remember) draw weight...







To be honest safety dictates that you check your frame REGULAR before and while shooting if any laminate checking occurs or splitting in the joins you should stop shooting immediately.

The only violent breakages on laminates I have had experience with where large pieces sheer off or break away from the bond are when significant fork hits have occurred.

The lamination of wood therefore is fairly safe in my *opinion* with careful craft and regular testing of stock etc you can get away with some daring designs safely without the need for metal cores. For example even with a metal core if a fork hit occurs then the impacted scale/face with still sheer away from the aluminium core perhaps returning towards the shooter.. The fact that there was aluminium in the centre would not prevent failure in this instance. Aluminium core however would stop wood checking and splinting becoming dangerous because the whole of the frame is anchored to a core.

Edit for example the image in the topic would be prevented by an Alu core ... Yet even with wood the user has to shoot the frame before such failure occurs http://slingshotforum.com/topic/26273-never-put-a-slingshot-on-top-of-your-trap/


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## toolmantf99 (Feb 16, 2012)

I have been using 1/8" aluminum lately. I feel safe with that thickness. But if you don't have the right tools, it can be a pain to work with. I would start with a plywood (doesn't look as nice, but much easier to shape). I don't know about using a baking sheet though.


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