Thread: Motorcycle tank
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Old 12-08-2016, 06:59 PM
AllyBill AllyBill is offline
MetalShaper of the Month Feb 2019
 
Join Date: Dec 2014
Location: UK
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Hi Jeff,

I would firstly put a bit of pre-heat into the job with a propane torch. If in doubt, draw a line with a Sharpie next to where you intend to weld then heat it until the ink begins to fade then place your tacks. Use a nice soft filler rod so you dilute down in terms of tensile strength. If necessary you can always dilute back up again on your final pass. Spend a few extra seconds on each tack just pooling the filler through the thickness of the native material then be sure to allow it to harden under the flame. If you can, put a dolly behind it and give it a crack with a hammer while it's still hot. And try to keep all your tacks the same size so they all pull in the same way and don't fight one another as they contract.
As a general rule of thumb, the longer you spend pooling the tack the less chance it will fail when you work it but that's just down to the heat soak and the expansion so pre-heating and soft filler rods are your best options.

Will
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