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Rob,

I found that all the smaller holes in the stainless firewall could be made with the stainless backed by wood, lightly center punched and a pilot hole drilled with a 1/8 inch bullet point drill (won't wander, cheap, can be replaced easily when dulled) followed by a Greenlee step drill in your cordless hand drill.  There are two which are valuable - the 1/2 inch max and the 1 1/8 in max.  These are more expensive but will drill any material up to 1/8 inch thickness with a perfectly round hole and no chattering.  You can finish the hole by using the next step to remove (chamfer) any burrs and then do the same by back drilling or using an inexpensive de-burring tool.

For larger holes, use a compass to mark, stop by your local Radio Shack and pick up a couple of inexpensive hand nibbler tools (you will be able to wear them out), "nibble" out the larger hole and then (horrors) use a fine 1/2 round file to smooth out to the final dimension.

BTW, you can file-smooth the outer edge and then, to really finish it nicely, get a $12 double-roller hand "beveling" tool from Aircraft Spruce to put a 1/4 inch wide slight bend "bevel" around the outside.  The bevel will also reduce the tendency to "oil can" in open areas.  This tool is used to strengthen lightening holes in aluminum ribs.

Scott Krueger
LNC2 N92EX

LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.

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