Today I started dimpling and countersinking.

First of all I tested my bench grinder with the scotchbrite wheel to deburr the borders of the aluminum angle. this went really well. I was a bit scared of this aggressive wheel but with a little 'feeling, things go well.

By starting today's job, I realised I already made a stupid mistake yesterday. I drilled the AD3's also witr a #30 drill. Which means... the hole is too large. In a regular project you would use the larger size rivet in this case but it is and remains ... stupid.

So what I did is drill the #40 holes between the others on the overlap. As this is a training project, I wanted to do the AD3 rivets as well so the result will be that I will finally do some additional AD4's. It's a good practice in the end.

As I was a little unhappy of this, I made a second mistake, you can see it in the next picture. The #40 drill wondered off of its initial position and left a dented scratch.

The next picture I dimpled with 1/8 dimple dies the top skins and the top and bottom skin on the overlap. For the rest, the dimpling went really good. I practiced with the manual squeezer and with the C-Frame.
The dimples really fit nicely together when dimpled on both sides.

In the picture you see the 3/32 dimples and the larger 1/8 dimples.

On the top side, there is a aluminum angle with a thickness of about .06 which is too thick to dimple. In this case, I had to use the countersink cage bit 100° - 1/8.

Here is a closeup of the countersunk holes

The final picture of the day shows the assembly after dimpling and countersinking, ready to be  rivetted.

Lessons learned: 

- Read the f*cking plans !... not once, not twice, at least 5 times to make sure you saw all the little arrows, numbers, dimensions and size.

- Always center punch when drilling a new -non prepunched- hole to avoid the walking away of the drill.