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Old 04-30-2021, 03:19 PM
crystallographic crystallographic is offline
MetalShaper of the Month October '14 , April '16, July 2020, Jan 2023
 
Join Date: Dec 2010
Location: Western Sierra Nevadas, Badger Hill, CA
Posts: 4,388
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Quote:
Originally Posted by Ducatichica View Post
Kent thank you for the #4 tip I received the other day.
I used it a bit and it gave me a good sense of high heat low volume.
I went an switched back to the number three and I think my tacking turned out rather well. I could hear the clicking in my brain
https://www.allmetalshaping.com/atta...1&d=1619645799
https://www.allmetalshaping.com/atta...1&d=1619645799

Attachment 59773

Attachment 59774

Attachment 59775

Hi Paloma,
Your work is looking smoother and more confidence is showing.
Glad you got the #4 tip. Big soft flame is helpful.


Re: Tacking:
There are two basic - and very different - situations that require two different tacking approaches.
One - the parts are jigged, clamped, fixed together and the edges fit perfectly. For this you can tack with either no filler or with filler. Production parts are done this way, one after the next.



Two - The panels are simply held in space and you have to hold one against the other and tack them any way you can. This is how we put car bodies together, large sculptures, large airplane cowling parts, etc. Sometimes I will weld a little blob or nugget onto one edge, every two inches or so. Then I flux these and hold the panels together and fuse where they touch....Boom, tacked.

Drawback is that any movement in the held panel at all right after tacking and the weld cracks.

Weld must be held still for 15 seconds, until it has solidified enough for strength.
Many times just 5 or 6 tacks will hold well enough to get a skip weld (short welds that are only 1-2 inches long) or three on there to really hold well. Then from there it is much easier to pull the edges into alignment and tack on ahead as you progress along the long seam.
On larger panels it is hard to get perfect fits, so working the seam with hammer and dolly as your weld progresses can help a lot.
(On big jobs the welds can sometimes be 6 - 8 - 10 feet long.)



Example of a "big job" follows:
(some welds are 5 -6 -7ft long ... 3003, .050" thick)
GT40 door tacked _Geo.jpg
P1170372 c GT40 rear deck fit for tacking.jpg
P1170266 rkw welds tacked panel GT40.jpg
If you look closely you can see the tacks are about 1.5in apart - standard distance on long welds.

P1170386c GT40 rear deck welded.jpg
P1170395 GT40 rear deck weld partly planished c.jpg
P1170397c planishing welds on rear deck, GT40.jpg
GT40 rear clip welded and planished.jpg
P1170255 c GT40 wheel arch weld.jpg
P1110509 cGT40 body finished bare aluminum, ready for chassis mounting.jpg
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Kent

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"All it takes is a little practical experience to blow the he!! out of a perfectly good theory." --- Lloyd Rosenquist, charter member AWS, 1919.
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