Aileron practice kit question / clarification

[JetMech72]

I just finished drilling the skins and the trailing edge wedge, next comes the dimpling and countersinking. Here is where I am confused:

"(Dimpling the spar is a special case. It is 0.040" thick - a bit thick to dimple well and a bit thin to machine countersink safely. So, we combine methods by dimpling first, then enlarging the dimple with the hand deburring tool. This is done by eye and tested by dropping a rivet in the hole to determine fit.) Machine countersink the spar and trailing edge wedge with the microstop countersinking tool."

The first part says the spar is too thin to machine countersink safely, but the second part says to machine countersink the spar. Which is it?

[Jamie]

What they mean is that the spar material is too thin to simply countersink so that a rivet would sit flush...so they have you dimple it and then just "touch" it with the countersink enough to make a rivet sit flush.

[JetMech72]

Originally Posted by Jamie

What they mean is that the spar material is too thin to simply countersink so that a rivet would sit flush...so they have you dimple it and then just "touch" it with the countersink enough to make a rivet sit flush.

So I just dimple it and lightly use the countersink tool and bypass the hand deburring tool altogether?

[apkp777]

Debur then Dimple then machine countersink. You should always debur all holes before dimpling (IMO). That method is only used on thick material like the spars. By dimpling first you will avoid a "knife edge" that would be produced by machine countersinking only.

[JetMech72]

Gotcha.

Thanks!


BTW I do deburr all my holes