Back Step Welding

Newbie questions here....what is "backstepping" your weld Or a "weld backstep" Also, why is it needed for steel hulls.....sorry for this, I know it is prob point 1 I should already know.

Cheers
Matt

 

easy, backstep, you run say in Mig, as long as comfortable, , then you chip back and then you run to where you started, in ALLOY the length does not matter but in steel dont run too far you must remember to keep welding even on both sides of the hull,

 

backstepping, minimises distortion. in steel you can pre peen plate edges, which then , when you weld shrinks the plate back to somewhere near where it was peening means, placing a dolly under the plate and hammering along the edge

 

fore and aft joints are called seams, , vertical plate joins we call butts

 

some more welding tips; http://www.steelboatbuilder.com/hull9.html

Below is a rough sketch showing the welding sequence in back stepped welding. The reason is that as you weld, the molten steel cooling down shrinks and when you weld in one direction only, the shrink will be directional as well, and pull the joint into a curve. To prevent this, you run welds in the opposite direction spaced in between to cancel this out.

Just take care that you weld port and starboard at the same time. I actually seen a hull welded by an amateur, that is banana shaped lengthwise. He welded one side complete before tackling the other side:!:

 

sorry you are wrong your sequence is skip welding, the top is backstep and bottom is skip

 

good link

there ya go plowman take a gink at this

 

http://www.twi.co.uk/j32k/protected/band_3/jk36.html

 

Lazyjack, backstepped welding is actually a misnomer for welding steel hulls correctly.
After having done my stint of 11 years building steel hulls, from 7.5 to 20 meters LOA, with the thickest hull plating only 4mm thick, and believe me, I produced extremely fair hulls, the method I shown above in the hand drawn sketch is the best way to go.
The trick is not only to backstep , but also reversing direction of weld by doing so as I described above.

You know my friend, there are so many persons out there trying to make a buck by producing books etc on how to do this and to do that....all nicely illustrated, BUT, how many of them have actually done practically what they preach:?:

 

Oh BTW Lazeyjack, did I mention I am a qualified boilermaker for at least 29 years:?: and have seen and tried most there is to steel and welding in general

 

no but I have a few years on you, you may call it something different, it matters not. lets just say we are both rght DEal?

 

if you look at my galelry, I made everything there, I got nothing from a book at all, (not the keel)

 

You're right!

Hey Senior Members, Actually you're both sorta right. Illustration "b" shows a skip welding sequence and backstepping technique. Does anybody know what the symbols are for this on a print?..regards, rusty

 

well ectuelly!! I,m not sure there is one, its sort of a given that joining seams, you backstep the key is not to butt em up hard, leave a gap stick a bit of wirre in the gap helps to stop it closing follow that advice on that page, abt tacking, peen the edges, try not over prep, that is just make the prep big enough for penetration, big wide, or extra passes to fill it up reallyy do stuff the job OR change to alluminium, it gets rid of the heat quick, does not shrink like steel
When I switched from Steel to Alloy I was amazed how forgiving alloy is
Steel dirty heavy rusty and if you use the good stuff like Corten, then it becomes hard to form, but super strong
A lot of MS is so poor now, that it does not even have the tensile of high ten alloy, you press it, its soggy crap

 

Nice Boats

Lazyjack, I really enjoyed your gallery, that's some pretty impressive work. I suppose that's how you get to be a senior member. I believe you got the answer right about the welding symbol, I'm not sure if there is one either, regards, rusty