Kirkham Skunk Works Sneak Peak :)

[ItBites]

David,

I thought you were the Engineer... Musta been Tom?

If you're not gonna re-heat treat, two things:

1. Your strength, especilly yield strength will be low in the center of the billet. Period. Further, your hardness will be down as well. These may not be any issue if you have put the thickness in the right places. Any aluminum billet above a T-4 condition and thicker than 6" suffers from property degradation in the center. Billets 12" thick can be real bad in the center, but depends on your source a little bit.

2. Your block will warp when you unclamp it from the CNC bed, even taking small amounts of material per pass (unless you unbolt it to allow relief between passes). You can mitigate some of this by unbolting from the CNC bed after each or a couple of passes and re-truing you datum (or even shimming your datum). To properly do this you need to index off of other important features (bore centerlines, crank centerline, and cam centerline...) and measure the block again in the 'free' state. Determine the average of how things moved and adjust your datum accordingly. I have done this, but it is very tedious to do right, and at the end, you still have, at best, an average of tolerances and dimensions.


Not knocking what you're doing (trust me, I am not, I see that you guys do some very cool stuff). Just hoping to share some advice from someone who has been there and also interested in learning, if y'all have found a way to do what you're attempting, without dimensional walk. I could use that mojo!