View Full Version : fishmouth question

02-22-2011, 11:25 AM
I have a fishmouth I did ( my first ) that isnt real tight.
How much clearance can I get away with before I need to scrap the joint and redo the fishmouth?

02-22-2011, 12:41 PM
Hi there

That depends on the type of welding you are doing and thickness of metal to be welded..

Both stick and MIG have filler in abundance , TIG & Gas tend to use considerable less filler.[ a close fitting flat butt joint can be welded with these process's using NO filler at all ! ]

regards Paul

02-22-2011, 02:13 PM
I will be welding round 1.5" .063 ERW with a harbor freight buzz box using 1/16 6013 rod.
Its not horrible but there was a spot with a 1/8" gap they made me concerned.

02-22-2011, 06:42 PM
I would have said as a rule of thumb gap < 1/2 rod thickness , but then I am no welder and it is not mentioned here :-


Still we can keep chatting , I am sure a real welder will be along shortly !

Good luck


02-22-2011, 07:04 PM
using that rule it may be time for a do over!

02-23-2011, 10:34 AM
You can weld that... but you will want to weld a little. Stop, clean it up and let it cool and then weld some more. Basically you build a bridge over the gap.

It takes time but you don't lose the piece you have already cut for that part. I think that's why you want to keep your pieces long until you're ready to attach the next part on the other end.

It also takes patience to weld a little and let it cool and clean to weld the next part.

Good luck

02-23-2011, 11:17 AM
Thanks for the help stormbird and DoubleG!
I am going to try that welding strategy and hope it comes out as good as stormbird's T joint did.
I have the good luck of still having some room on the piece like you said just in case.
Either way I will try to post a pic of the results.
It's time I start feeding you zombies....