Aluminium spot welding for the Homebuilder?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,051
Location
Australian
Nice find! He says it won't work with the 110V version - but I'll give mine a try soon.
I note the aluminium he is using is 1mm, 0.040" or more thick, so 110V might do our regular thicknesses of 0.4 and 0.5 mm 0.016" and 0.020"?

You might have to juggle sheetmetal thickness as well, maybe half that of the aluminium as a starting point?

Please let us know how you go, thanks.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,830
Location
US
Looks good--and fast. I wonder if there's some steel left behind where the plates stick? It would probably only be a cosmetic issue later on, if it's an issue at all.
Why does it work? The Al conducts too well on its own to generate much heat, but the steel plates get hot enough to locally melt the aluminum?
Anyway, as nice as it looks, I can't use it. I've never built anything that I didn't need to disassemble at least 3 times before I was done. Unwelding is hard.;)
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,051
Location
Australian
Why does it work? The Al conducts too well on its own to generate much heat, but the steel plates get hot enough to locally melt the aluminum?
I figure that's the trick. It might be that the brass tips weld themselves to the aluminium also, but not to steel.



Anyway, as nice as it looks, I can't use it. I've never built anything that I didn't need to disassemble at least 3 times before I was done. Unwelding is hard.;)
True, but I CNC laser cut everything, the fit is usually perfect each time.

It would still be only applicable here and there, some areas owners would want riveted to be able to repair later, and other places you simply wouldn't get the spot welder into.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,830
Location
US
I figure that's the trick. It might be that the brass tips weld themselves to the aluminium also, but not to steel..
So maybe this could be made even handier by modifying the spot welder for aluminum. Put a small steel disc (size? Sacrificial? Use a dime?) on a swivel foot at the contact points so no separate steel plates need to be positioned, clamped, moved, etc. With the leverage of the spot welder handle it should break free easily and be ready for the next "stitch."
 
Last edited:

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,830
Location
US

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
12,813
Location
Memphis, TN
He builds car bodies. Structural aluminum will act differently than the 1xxx,3xxx,5xxx stuff he uses. Maybe for 6061 but you will need a bigger welder to do anything thicker than he is using.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,830
Location
US
- It would be interesting to make design changes to allow maximum use of this bonding method. A plane designed specifically for it might go together pretty fast. For example, if panels are joined with an interior 90 degree flange rather than a lap seam, the flange can be quickly stitched with spot welds > and < the flange forms an integral longeron/stiffener.
- There's got to be a practical way ( high tech or low tech) to get around the reach/throat limits of a handheld spot welder.
 
Last edited:

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,830
Location
US
110 vac works on the thin sizes normally used on skins up to .040. Chinese used this method all over on the CJ 6

did some on tail rotor blades for small kit helicopters [trailing edges .025] no issues
How does it look? Dimpling/wrinkling at each spot? Discoloration? Thanks.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,051
Location
Australian
110 vac works on the thin sizes normally used on skins up to .040. Chinese used this method all over on the CJ 6
Interesting, I know where some of those CJ 6s are, will have to go have a look when I can.

I think I have a picture of me sitting in one even, have to have a look later ..
 

D Hillberg

Well-Known Member
Joined
Nov 23, 2010
Messages
1,262
Location
very low low low earth orbit
A slight dimpling is seen at the weld spot 5/16 die - easily covered in primer - lots of little stringers

While your looing inside look at the twisted tube swages on the flight control cables

the door frames on the MD 500 is spot welded too
 

cluttonfred

Well-Known Member
HBA Supporter
Joined
Feb 13, 2010
Messages
7,284
Location
World traveler
Very cool and far less intimidating for the first-time builder than other types of welding or even drilling and installing traditional or pulled rivets. If it could be made to work with a 110v spot welder on thin aluminum and the two pieces of steel developed into a handier tool (perhaps little nose pieces to attach to a VIse-Grip C-clamp?) then this would be very, very appealing.
 

dog

Well-Known Member
Joined
Dec 29, 2019
Messages
294
thin wall steel tube to fit over the electrodes,with a larger nut to fit over the tube, welded on off course,
and thin wall disks welded to the bottoms of the tubes.
Slip on electrodes,spot weld,turn tubes with wrench to break bond(weld?l between steel and aluminum)
repeat.
 

cluttonfred

Well-Known Member
HBA Supporter
Joined
Feb 13, 2010
Messages
7,284
Location
World traveler
As Vigilant1 suggested, if the technique turns out to be suitable in terms of strength and consistency, the aircraft could be designed to suit the limitations of a typical handheld spot welding rig (the $160 Harbor Freight 110v unit has 6" tongs). That would preclude, for example, welding the skins on a stressed-skin wing, but not making a built-up aluminum wing for fabric covering.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,092
Location
Port Townsend WA
Might want to tear that spot weld completely apart and inspect for penetration. And what is the alloy?
 

Mad MAC

Well-Known Member
Joined
Dec 9, 2004
Messages
609
Location
Hamilton New Zealand
It should be noted that with spot welded alclad sheet products welds with an hour glass cross section due to the higher melting temp of the pure aluminum. Also spot welds can have low repeatable properties due to some of the current traveling though the previously spot weld.
 
2
Top