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Drilling and tapping aluminum fuselage

Posted: Sat May 18, 2019 10:32 pm
by SaulOhio
I've learned that just because aluminum is relatively soft, that doesn't make it easy to drill and tap holes. In fact, its softness has its own hazards. I managed to break a tap.

What is happening is the soft aluminum shavings are getting stuck in the flutes of the tap, clogging it up. If the resistance suddenly increases, you need to reverse it, pull it out, and clean the tap. One time the aluminum shavings were stuck so hard I was wondering if they were welded in, and I had trouble removing them.

The same sometimes applies to just drilling the aluminum. If the shavings stop coming out, usually in a long spiral string, its probably because the aluminum is stuck to the bit.

You definitely need to go slow (despite it being called a "high speed tap") and make sure you aren't putting any lateral force on it.

I am making my own hydrofoil fuselage from a 1" x 1" bar. I cut the ends into a more streamlined shape with a cutting wheel, and did some additional shaping on a belt sander. I plan to continue shaping it, working on it now and then when I'm not riding it.
20190518_172815.jpg

Re: Drilling and tapping aluminum fuselage

Posted: Sun May 19, 2019 2:04 pm
by downunder
Thanks for that, never thought about that.

Which bolts u using? Isn't threaded alu too soft?

Re: Drilling and tapping aluminum fuselage

Posted: Sun May 19, 2019 11:28 pm
by max
downunder wrote:
Sun May 19, 2019 2:04 pm
Thanks for that, never thought about that.

Which bolts u using? Isn't threaded alu too soft?

When I first started foiling with homemade setup . . . drilled and tapped aluminium for use with 6mm SS bolts to hold wings with no issues.

Re: Drilling and tapping aluminum fuselage

Posted: Wed May 22, 2019 12:13 am
by SaulOhio
downunder wrote:
Sun May 19, 2019 2:04 pm
Thanks for that, never thought about that.

Which bolts u using? Isn't threaded alu too soft?
Mostly 1/4-20

Re: Drilling and tapping aluminum fuselage

Posted: Tue Jun 11, 2019 4:09 pm
by Bille
I drill and tap aluminum a Lot , with my sailboat ; i use
aluminum tapping fluid, to keep the aluminum from sticking
to the drill or tap.
https://www.google.com/search?q=aluminu ... e&ie=UTF-8

Also
i only do a few turns in, with the tap ; then un-screw the
tap so the shavings can fall away. Then add more tapping fluid.

YEA -- i've broken taps also :( ; not now, with the new method.

Bille

Re: Drilling and tapping aluminum fuselage

Posted: Tue Jun 11, 2019 4:59 pm
by Herman
I am old enough to know that lubrication can be a wonderful thing! If you are into tapping you might want to research thread inserts for repairs etc but don't turn down a session or chance to lubricate, it is only to relieve boredom.
Lubricate when you drill too, to be kind to your tools!

Re: Drilling and tapping aluminum fuselage

Posted: Tue Jun 11, 2019 5:27 pm
by Jyoder
Which kind of aluminum? 6061? Wondering if it’s worth it to pay extra for 7075 for extra strength.

Re: Drilling and tapping aluminum fuselage

Posted: Thu Jun 13, 2019 6:36 pm
by Bille
Jyoder wrote:
Tue Jun 11, 2019 5:27 pm
Which kind of aluminum? 6061? Wondering if it’s worth it to pay extra for 7075 for extra strength.
Both 6061-T6 , and 7075.

6061 -T6 is a bit more ductile than 7075 ; it will give a bit more
than 7075 , before it breaks. Also , if you do bend a rod made
from 6061 ; you can bend it back, but 7075 will almost always snap
because it becomes more brittle . Something about how the slip-planes
align themselves, between the molecular weight chains ?? Yea -- i didn't
understand that one either ; when the engineer told me ! :(

6061 T6 is Fine for anything that ain;t gonna fly , and weight isn't
a major concern.

Bille

Re: Drilling and tapping aluminum fuselage

Posted: Thu Jun 13, 2019 6:47 pm
by Herman
Hi Billie! Just trying to reawaken my brain. Can the 7075 be annealed, quenched and then allowed to age harden?

Re: Drilling and tapping aluminum fuselage

Posted: Thu Jun 13, 2019 6:58 pm
by grigorib
Dear friend of mine made this. (I will post post-anodized pics when he gets it back)
But yep. tap responsibly :)