- Thread starter Jonathan Webb
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Jonathan Webb
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Not sure what you mean? Is it not doable to grind a weld flush? Especially as it it is in a valley between the two parts with a backing piece welded behind?
Jonathan Webb
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Not sure where I put the invoice for the steel. Pretty sure it's mild steel - don't know why I would have asked for carbon steel and I recall the decision was hot or cold rolled and had a conflab with the steel people about which would suit my purpose better and went with their recommendation as I'm not conversant with the ins & outs of steels.
Jonathan Webb
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Not sure what you're saying. What is LOF Thanks
Are you saying that the weld hasn't cracked, but that the filler hasn't fused adequately on one side of the join 'valley'?
eLuSiVeMiTe
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Lack of fusion.
Crank her up.
Crank her up.
Basically looking at the pic and reading the posts on the thread it certainly looks like you are only laying the weld bead on the surface with very little penitration then when you grinding back you are seeing the weld root that looks a little wavy were you have a little penitration up the amps and see how it goes you should be able to see if the weld has got in to the joint from behind that's if you can see the back of the weld
zeppelin builder
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open the gap to 3 to 4 mm turn sculpture on its side and weld uphill at around 45 degrees make sure you are burning into the backing and biting into the sides say 75 to 85 amp
if your laying a bead on a 1mm gap with low current you will gett little or no pen
your ending up with a very thin layer after you ground it and its gauranteed to crack with expansion /contraction
the more times you weld it the more distortion will appear too
if your laying a bead on a 1mm gap with low current you will gett little or no pen
your ending up with a very thin layer after you ground it and its gauranteed to crack with expansion /contraction
the more times you weld it the more distortion will appear too
Yes thats what it is
LOF = Lack of Fusion
Kent
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What you have found is very very common. Backer or no backer is not relivent to what is occurrinf Imo
If you imagine the joint itself does not contain that much space for the weld to actually occupy and will not be perfect in alignment and geometry .
In theory you grind two flats cutting the bead back flush and leaving a point (theory also being perfect geometry between the two and enough space for the weld to occupy) the reality is far different though than that theory
Then you hit the peak of those two grinds and the thing will generally go to hell in a handcart. Cracks appear because in places you are actually going to thin.
The real cure is thicker parent metal (obviously downsides to that ) or fold. Failing both just put a bead in that's nice and don't hit it with the grinder.
Jonathan Webb
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Thanks, that's a lot clearer.
Leaving a bead isn't an option, so I may have to beef up the thickness somehow.
Arclikeharrypotter
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no need to beef it up imo 2mm gap between plates and bang a decent run in. I think it’s a skill problem rather than design/material. No offence intended
Kent
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Well firstly its 3mm sheet so 1. I should not want 2/3 material thickness as a gap !
Very wrong to assume its a welding skill issue - it's a grinding and fabricating issue.
Heck the guys doing it with stick to boot ! 3mm sheet with a 2mm gap over a fair length !
Arclikeharrypotter
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He’s using a back strip,hence my recommendation for a 2mm gap’ plenty of room to tie into all 3 materials. I’m assuming he wants a seamless appearance so he has to grind the weld back flush, but due to lack of penetration he’s grinding through all his weld.
Kent
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Your correct about hinges grinding through the weld of course
Remember it's 3mm sheet! 2.5mm 6013
Jonathan Webb
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Some of this is over my head a bit.
Can readily believe that it is a skill issue (as well as construction possibly) as my welding has been dreadful. It has improved with the new welder, but I've not done that much with it yet.
I can try & replicate this on some scrap that I can cut into to look at penetration/fusion. May help me, if i get to see what it looks like in the weld zone
Forecast is not good for the rest of this week, so probably no progress for a few days but if I get a chance I will.
I appreciate all your input, this is a bit of a worry as I'm well overdue on delivery...
Can readily believe that it is a skill issue (as well as construction possibly) as my welding has been dreadful. It has improved with the new welder, but I've not done that much with it yet.
I can try & replicate this on some scrap that I can cut into to look at penetration/fusion. May help me, if i get to see what it looks like in the weld zone
Forecast is not good for the rest of this week, so probably no progress for a few days but if I get a chance I will.
I appreciate all your input, this is a bit of a worry as I'm well overdue on delivery...
Jonathan Webb
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I've just watched a video on ceramic backing and not sure what its for/how it helps? If you've only got access to one side, you can't do the tape thing.
And how is it better than welding a piece to the two sections (before assembly)?
Cheers.
