Welding inside 90' corners ms tubing

[Paul-n]

Hi all

Well I am bike building again after a 3 year break so the welding is dire !
I am having some trouble welding a inside 90' corner on some 1.5" x 1.5" sq tubing 1/16th thickness [ 36mm x 36mm x 1.5mm ]

I am happy with one of the flat plate sides and the other is a little lumpy but I will just skim off the high spots.

However I am having problems with the inside angles , I think I need the Tungsten out more and maybe 10-15 more amps ?

I did the inside corners first as there were clamps/steel over the flat joints using a 3mm Tungsten.
I can't tell the amps used but did use the same setting for all 4 joints , it is a DC inverter from RTech.

The first weld is the last picture [ shame it is out of focus ] and I may have turned it up a little to do the second inside corner , I had a great deal of difficulty getting a weld pool I could see.

Any criticism that will improve any of the welds is welcome , but please no comments about ms tubing is not suitable for bicycles etc.

regards Paul

 

[chunkolini]

Mild steel tubing is great for bikes, my mates and I have never had a frame fail, and we only ever used a Mig welder.
I might be wary of welding and then rewelding over the top as the heat might not do the tubes any favours.

 

[justmental]

are you using a foot pedal and do you have a gas lense and what size cup.
i use on that size a material a 1.6 tungsten with a gas lense and a 5 cup at 60amps max on the foot pedal so will more than likely drop to 40amps once heat gets into the metal.

 

[wheresmejumper]

arc length is too long id say on the fillets.dont add filler until you have a pool in the very corner

 

[Paul-n]

Hi all

No foot pedal , no gas lense.

Cup size 6 with a 3mm Tungsten.

I think I will make up a couple of scrap bits and have a practice.

Unfortunately the RTech only shows the amps when welding and so I can only go by what the knob is pointing to and the result of the weld.

These joints will have a corner brace about 4" long and 1" wide in 3mm ms added when they are finished.

Yikes another 8 , 90' joints

Paul

 

[brianblock]

for a start i would say your Tungsten is too big and your cup too small
your arc is too long
possibly your also moving too quick and before the weld pool has properly formed

 

[wyn]

What sort of size filler wire are you using?
You can get a lot of grief just trying to melt the wire if it's too big for the sort of amps you are using.

The last two pics look like the filler is just sitting on top.

 

[Paul-n]

Hi all

Thanks for your advice.

Yes I think they are just sitting on the top as though there is not enough heat ?

Wire is correct for TIG and 1.5mm

regards Paul

 

[Paul.]

You will probably get on better with a smaller filler rod and feed it quicker, bigger rods need more heat to melt them, so you either need more amps or move slower, I generally use 1mm filler for this scale of work, and a 1.6 tungsten ground to a nice sharp point, all the information you need is covered in the tutorial, fillets are covered here {clickme}
This is a joint I made earlier today, on 40 x 40 x 1.5 box section, around 60 amps on the butt and about 75 on the fillet, and probably a bit higher than most diy'ers would use, I know its stainless but the technique is exactly the same, no need to aim for large fillets, if the throat thickness of the weld is equal to the metal thickness with no undercut then it will be ok.

 

[Paul-n]

Hi all

Gone back to basics , it seems I have forgot more than I knew !

measured my filler it is 1.5mm change cup from No 6 to no 5 , I will get some 1mm rods as advised.

So 1.6mm tungsten machine set to 45amps and a straight practice bead on 1.5mm box section off cut.

Started with blowing a hole , so speed up for A & B looking at the penetration I though the current was to much ?

Turned current down for C & D thought welds look better and thought rear looked better as well ?

So I had 2 pieces of same 1.5" x 1.5" x1.5mm but not at a right angle this time, I tacked the inner [ side 4 ] & outer [ side 2 ] angles first as the distortion would matter less in this direction and initially it was clamped across the flat faces.

I then welded them up , I touched at least once but other than that not to shabby ?

I then tackled the 2 sides , one was probably a good enough fit to weld without filler but added some filler the mess on the left hand side of 3 is where I had cut into that face by accident when cutting the part out and a hole developed whilst welding.

There is quite some stress on this part of the trike , it joins the front to the rear ] and I intend to add a 1" wide x 1" x 1" plate both sides on the flat faces [ side 1 & 3] as a doubler and maybe a short gusset across the faces of the inner angle [ side 4 ]

As you can see I had some problems also at the corners ? not sure now what went on at some of them.

Comments ?

regards Paul

ps TIG Paul your work is a thing of beauty

 

[howardm]

You will probably get on better with a smaller filler rod and feed it quicker, bigger rods need more heat to melt them, so you either need more amps or move slower, I generally use 1mm filler for this scale of work, and a 1.6 tungsten ground to a nice sharp point, all the information you need is covered in the tutorial, fillets are covered here {clickme}
This is a joint I made earlier today, on 40 x 40 x 1.5 box section, around 60 amps on the butt and about 75 on the fillet, and probably a bit higher than most diy'ers would use, I know its stainless but the technique is exactly the same, no need to aim for large fillets, if the throat thickness of the weld is equal to the metal thickness with no undercut then it will be ok.

Scuse my ignorance.
Was this done as a simple butt joint.?
No gap, no prep grinding.?
I am about to do some box section mitres, I take it you would use this same technique for mitres.?

thx
Howard

 

[Paul-n]

Hi all

been practising , cheated really as I folded the corner instead of having 2 pieces that needed tacking together , sorry

however I do feel that I have made some improvement since my last efforts ?

Gas lens in post , unable to find any 1mm rods locally may have to get them from Ebay as they seem as cheap as any where else I have looked.

Paul