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22nd Feb 2019, 09:44 PM #1Golden Member
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Welding long aluminium planks together - boat building
A common way of making punt boats for commercial work is to utilise aluminium planks similar to scaffold/painter's planks. To do this, the planks (about 230mm wide each) are butted side by side and welded along the top and bottom edge to form the basis for the bottom, sides, etc. Maybe 8 planks for the bottom of the boat, 2 or 3 for the each of the sides, etc. See the attached pic.
My question is, what sort of rig is used to do the initial long welds when putting together the big flat sets of the planks? A boat I've got at the moment has at least 150m of weld just on the main plank joins and it is a relatively short boat at 5.5m. I've heard mention of some sort of conveyor belt system? Anybody know?
thanks
Mick
Picture1.jpg
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22nd Feb 2019, 10:05 PM #2Most Valued Member
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You could modify a Quicky Cutter to do that, instead of a cutting head, mount a MIG welding torch to it. Hardest part might/would be getting the track in enough lengths to weld together.
That would be the cheapest way out that I know of.
KrynTo grow old is mandatory, growing up is optional.
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23rd Feb 2019, 12:25 AM #3China
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Ok what am I missing why could you not just run long welds with mig
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23rd Feb 2019, 08:43 AM #4Golden Member
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Yeah maybe, I was thinking of some sort of roller system with a cordless drill drive.
Probably could - just curious if anyone has done/seen it done otherwise. There'd be a risk of warping the planks, so I would've thought quite a bit of tacking and flipping, backstep welding etc would be required. The long welds on the boats I've seen seem to be continuous. That was what got me thinking about a roller system, with a set of top rollers effectively clamping the planks flat as the planks are fed through.
Cheers
Mick
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23rd Feb 2019, 11:12 AM #5Diamond Member
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Used to do this sort of thing on a weekly basis, with a motorised quicky type arrangement, although this one ran on batterys. Mostly doing 10 metre long welds at a time.
You don't necessary need a specific track, you could use a bit of flat bar that the edge of the wheel runs against and have the job slightly angled.
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23rd Feb 2019, 09:21 PM #6Most Valued Member
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Mick the big guys use a pulse mig to do the long runs so as not to over heat the alloy and a industrial machine with a good duty cycle so they don't need to stop they also use a push pull gun i reckon u could use any mig with a spool gun with a decent duty cycle i had a ESAB 150amp mig it welded beautiful but it was a trolley machine i now have a unimig i have been welding six mm alloy with it i reckon since your only welding thin material it would run all day that is a interesting boat i really like it! I'm currently rebuilding a 5.7 meter half cabin glass boat, building a alloy pod for it and possibly a new cabin heres my Noah's Ark going from this to this
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24th Feb 2019, 09:16 AM #7Golden Member
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24th Feb 2019, 09:53 AM #8Diamond Member
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Warping/Distortion is always an issue when it comes to welding. You need braces/props/strong backs etc and even then some straightening may be required afterwards.
Just started at the beginning and went to the end, starting and stopping wasn't really an option as they wanted to minimise this due to appearance issues, mill finish/polished product.
No photos sorry and this was not a boat either.
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24th Feb 2019, 04:58 PM #9Most Valued Member
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Boat builders weld a full continuous seam from one end to the other so there wont be any leaks!
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25th Feb 2019, 08:22 PM #10Most Valued Member
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Mick it's hard to see how the planks are put together i tried looking on ebay if your talking about welding one thin wall t the next maybe try run some thick flat bar up the inside of the wall to be welded to suck some of the heat away
here is how the big guns do it, they use the push pull gun a lot because spool guns only carry the small spool, you could get away with welding the thin material stop and starts might be the only way just go back over the stop and starts with a tig
https://www.youtube.com/results?sear...luminium+boats
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26th Feb 2019, 05:56 PM #11Golden Member
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The planks are just butted together and welded. Here's a pic showing the plank section dimensions. Just welded together at the red dots. It's easy enough to do with Mig (I have a pulse mig). My question is not really about the weld process - more about whether there is a easy way to achieve the automatic feed and clamping/rollers - i.e. if anyone has actually done it before.
planks.jpg
Don't worry about the google searches - I can do that. I haven't been able to find anything specific to what I'm asking.
Cheers
Mick
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26th Feb 2019, 07:31 PM #12Most Valued Member
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As it's welded both sides, I'd tack them together on opposite sides. Stand the pieces upright in a jig or tack welded to keep thm upright, then with 2 quicky cut machines (one on each side) start welding both at the same time.
It's the only way i can think of to minimise the distortion, because the heat is being transfered equaly along the joins.
Otherwise, there is a place in Perth I think it is, that build luxury yachts, (more like ships if you ask me) try contacting them to find out how they do it.
I think BobL has a relative that works there, you could send him a PM to find out.
KrynTo grow old is mandatory, growing up is optional.
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27th Feb 2019, 08:13 AM #13Golden Member
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Thanks Kryn, yes it would make sense to do both sides at once, but I think that would get too awkward on the wide floor panel (8 or 9 planks wide 2.4m), maybe could get most done if doing in pairs/triples first. I have a few leads on guys who do this specific work so will try them.
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27th Feb 2019, 06:39 PM #14Most Valued Member
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I thought the whole idea of doing tacks is to stop distorsion and twisting just put a tack every 50mm than run full length beads but i am no welder
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27th Feb 2019, 10:14 PM #15Most Valued Member
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Gazza, the idea of doing tacks every so often, is a good one, but where neatness counts, or a leakproof weld is required, it can sometimes be a problem. Where the tack is and you weld over it, if the weld is a bit on the cold side to prevent too much heat distortion, you may not get a good coverage of weld. You could grind them back, but then risk the tacks breaking.
Tacks 50mm apart is OK for sheet stuff, but for what Mick intends to do probably every 400-500mm would suffice, as the strength is in the thickness of the planks, approx 40 - 50mm thick at a guess.
KrynTo grow old is mandatory, growing up is optional.
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