lowgman
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 posted on 27/3/06 at 07:26 PM |
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beginner welding question...
Hi everyone,
I finally decided to build a locost recently and just started to cut and weld up my book sized chassis. I have a few questions about welding up the
chassis.
I've done some welding a few years ago, just exhaust piping with a mig welder. This would be the first time I would be doing such a large
welding project.
I picked up a Miller Challenger 172 MIG welder, which works great, but I have a few questions:
1. I did quite a few practice welds on scrap box section for a few days before beginning on the frame. I came up to the conclusion that upping the
power level and slowing down the wire helped penetration, as did the swith to a thinner wire. However, I managed to blow a few holes on the chassis
bottom rails. One of them was rather large (maybe 5-6mm). What would be the largest hole I can fill with a mig weld?
2. After my last welding session, I went to shut off my welder and noticed that the gas gauge showed the tank was empty! I have no idea how long
I've been welding without gas, but I did notice that there was a tiny bit more splatter than usual (I thought I was just getting sloppy
 ) Should I be worried and cut those welds out and lay on a new bead? Other than the splatter, the base weld (for a lack of a better term) looks just
as good as the first few welds where I knew the gas was on.
3. There was also a slight warpage to the chassis after I was done with the welding. I would say that the front end has about 1mm of warpage (enough
to slide 2-3 sheets of copy paper under the front) Should I be concerned about this?
4. For the T joints and L joints in the frame rails. Should I be laying down more than one bead?
I will try to post up some pics later on this week.
Thanks in advance!
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JoelP
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| posted on 27/3/06 at 07:32 PM |
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the weld would probably be visibly porus (damned spelling...!) if there was no gas at all. A mm of warpage is better than most id guess, i had more
like 10mm on my first one (fortunately scrapped now!). You can fill very large holes if required, but its not great. You end up with a hot blob in the
end, which might weaken the overall weld. I wouldnt worry myself, as im sure that practice will make it a rare thing.
As for point 4, i dont get ya
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kb58
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| posted on 27/3/06 at 07:42 PM |
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My guess is the tank wasn't *really* empty yet. I ran out of gas completely one time TIG welding and brother, you'll know it when it
happens. Smoke, sparks, and welds that look like a sponge are all symptoms of no gas.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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lowgman
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| posted on 27/3/06 at 07:44 PM |
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quote:
Originally posted by JoelP
As for point 4, i dont get ya
Thanks JoelP!
Sorry, my welding terms aren't up to par yet 
THis is what i meant:
Should I "layer" the welds on these type of joints?
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welderman
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| posted on 27/3/06 at 08:12 PM |
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A single fillet weld should you mate, your not welding thick stuff so should be ok. Just don't grind the welds flush to make them look good.
Thank's, Joe
I don't stalk people
http://www.locostbuilders.co.uk/forum/23/viewthread.php?tid=172301
Back on with the Fisher Fury R1
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antonyg
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| posted on 27/3/06 at 08:48 PM |
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Hi, if you want some info on welding try asking these guys on this site, full of experienced welders
http://www.ukwelder.com/
Antony
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