stripped

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When tapping a thread one screws the tap in 3/4 of a revolution and then backs off at least 1/3 of a revolution to cut off the swarf that the tap has cut from the hole.

This is important to make sure the tap does not bind and cut oversize, it also helps prevent ragged threads.

The recomended lubricant for aluminium is methyolated spirit, and please bear in mind WD40 is not designed for cutting purposes, water does a better job.

Yeah, gotta use lube on it.
We had special aluminum cutting lube in the shop but have used Varsol or paint thinner when it wasn't available.
WD40 is mainly kerosene I believe. It will work. Also used various waxes when we didn't want the chips to fall.

Important to:
1) use the right size drill
2) drill straight
3) drill to the right depth
4) countersink the edge of the hole for a clean lead in of the tap and threads.
5) use a taper or starting tap to start the threads. If you have to, a plug tap will work,but poorly.
5) lube the tap
6) twist the tap backwards every 1/2 tun to break the chip
7) clean the chips out of the tap flutes frequently and completely when you are done

A 7mm bolt is an oddity. While this will work, and is done as an expedient, I suggest helicoils.
I follow all the above rules for tapping the helicoil, being very careful on depth.
I usually clean the tapped helicoil hole and use unremovable locktite on the coil when I insert it.
Let it cure before putting a bolt in it!

Keep in mind, it was over tightening the bolts that likely cased them to strip in the first place.

Steve