I just melted a hole through the bottom rails of the chassis

I was trying to fully weld the join between two tubes and suddenly (as they say on insurance claims) a melty hole appeared.
Pictures here

Obviously I need some more practise (and perhaps to lower the juice a bit) but.. what should I do with it now? the bottom rails are tacked up and a few of the welds are fully done (only 6 or so). I think my options are:

1) cut out the whole tube, tidy the ends, cut and fit a new tube
2) cut out a section of the tube, tidy ends, cut and fit a new bit (this doesn't seem like a good idea)
3) try and fill the hole with the welder (easy option, but not sure how strong this would be)

I think I should go for option 1 but thought I'd ask for opinions of those less blatantly rubbish at welding than myself.

cheers.

Dont panic, it happens, either the juice was too high or you didn't move quick enough. All you need to do is weld the hole up by using very short bursts of the trigger, same as tacking, once the hole is filled, grind any excess metal off, and then run a bead of weld over the top.
Al.



]Originally posted by blueshift
I just melted a hole through the bottom rails of the chassis

I was trying to fully weld the join between two tubes and suddenly (as they say on insurance claims) a melty hole appeared.
Pictures here

Obviously I need some more practise (and perhaps to lower the juice a bit) but.. what should I do with it now? the bottom rails are tacked up and a few of the welds are fully done (only 6 or so). I think my options are:

1) cut out the whole tube, tidy the ends, cut and fit a new tube
2) cut out a section of the tube, tidy ends, cut and fit a new bit (this doesn't seem like a good idea)
3) try and fill the hole with the welder (easy option, but not sure how strong this would be)

I think I should go for option 1 but thought I'd ask for opinions of those less blatantly rubbish at welding than myself.

cheers.

Blueshift,
I'd just go for option 3 to be honest as I don't think that strength should be an issue as long as you weld it properly and don't just try to fill the hole with little disconnected balls of spatter. I'm sure someone like Mark Allanson will tell you the correct technique but I would just weld from 3 or 4 points of the compass until the hole was small enough to fill completely. This last weld usually requires a very slight circular motion but I usually find that it finishes off nicely.

Only thing to watch for is excessive heat which could cause distortion. For this reason you may wish to wait until the chassis is fully triangulated before coming back to this later.

I don't know if it's just me but I've had to make a good few compromises during my build so far and wouldn't think twice about plugging a hole with weld. Having said that I do still (vaguely) remember my first few days of chassis building and you do tend to seek perfection don't you...not a bad way to start I guess!

Cheers,
Craig.

I am a perfectionist, maybe to an uhealthy degree :/

I will go for plugging it up with weld. I've practised on another bit of metal.. sod's law, when I was TRYING to blow a hole through a tube, could I? ended up with a 2cm wide glowing pool of metal with a big blob on the back almost touching the other side of the tube.. but it didn't make a hole. bah.

bah! once more.

option 3

it maybe the 1st hole you made, by the time you finish it wont be the last...

Easy, use the same settings that you used to 'create' the hole. Zip along the leading edge and back again. Let it fully cool before you grind back

[Edited on 9/7/04 by Mark Allanson]

Mark,
Why let it fully cool before grinding?

By the way Blueshift, the welding looks very good to me and your tube cuts are neat. If you are blowing holes in the metal then penetration is not in doubt so that's one less thing to worry about...

Cheers,
Craig.

[Edited on 9/7/2004 by craig1410]

Letting it cool gives the weld a chance to christalise properly before you add more heat from the grinder. It reduces the chance of more distortion.

cheers craig

I made a load of paper templates in solidworks to wrap around tubes to give me accurate cutting/filing guides. they seem to work quite well.

Could release them as a PDF if there's interest..

[Edited on 9/7/04 by blueshift]

Practise your filling technique on it. It looks like you'll be putting an upright on top of it anyway so don't panic. It's always easier to blow the edge of a tube away, try moving a bit faster but don't drift away from the work with the torch.
http://www.millerwelds.com/education/tech_articles/articles8.php

Blueshift,

your PDF will be of much help to me, I'm very well known to be a bit daft when it comes to measuring, cutting and filing.

Reminder to myself to get an abrasive cut off machine.

right you are cassidy, but beware that my designs are all for a +4" chassis..

um, that is.. I'll work on making a PDF out of them next week (at work )

[Edited on 10/7/04 by blueshift]

Booboo fixed. Cheers everyone.

Thanx, much appreciated. Do'nt know why but I'm leaning towards the +4 chassis myself.

You can fit a bigger engine and bigger seats in a +4. apparently you can fit a rover v8 in a book chassis, but we didn't feel like making lift purposefully difficult for ourselves.

is to take a foot or so of wire and fold a bit of the end so it will just cover the hole, then hit it with the welder and melt it over the hole.

Done it with a stick welder an embarasing number of times.

quote:

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Originally posted by The Shootist
is to take a foot or so of wire and fold a bit of the end so it will just cover the hole, then hit it with the welder and melt it over the hole.

Done it with a stick welder an embarasing number of times.

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