Making this joint?

[adri123]

Hi.

I have to make this weld in the picture. The material is 30mm box stainless.

How would you go about it with TIG? I'm wanting to end up with a nice clean joint. Can it be done in one pass or would you clamp it to the table and then flip over?

Also, what gear/abrasives will I need to tidy up such a weld after so as to lave a nice tidy finish? I've seen some Youtube vids about it but there seems to be lots of recommendations to spend loads of money as far as I can tell...

Any thoughts appreciated.

Adri

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[Freshfabrications]

Hello adri,

If it's 304 stainless with a dull polish and it's not load baring then use 308 filler rod.

For decorative stainless, ie architectural/glass as oposed to structural, I would always tack. Then do the flat faces (but welds) with filler to penitrate. Then do the outside corner with no filler, just run it in nice, smooth and shiny. Try to avoid inside corners if you can as stainless can pull like a bitch. If any thing run inside with no filler.

Aprox 25-30 amps DC- for about 1.5-2mm material. But go at a pace that allows the weld to penetrate, remember you will grind off any EXTERNAL reinforcement.

Again this is all for NON-STRUCTURAL!!!

You will need to use aprox 60 grit and only touch the filler deposit on the flat faces and leave about 0.5-1mm of material then swap down to finer grit 80. Be super carefully and let it cool a lot so you don't warp it and dig in with the grinding by mistake. Take your time.

Once it's almost perfectly flat go to 120 grit. And use the edge tip of the disc to polish in the welded area leaving grain lines in line with the dull polish. Then do the same with a none woven abrasive disc equivalent to 120 grit in the same way.

Try not to grind an area any bigger than the width (30mm) of the material ether side of the weld.

To apply the dull polish to the 45° corner you will need the Kit from Metabo as a minimum.

http://www.waspsupplies.com/metabo-se12-115-stainless-steel-burnishing-machine-375-p.asp

Use a thin metal shim at 45° across the inner and outer corners, brush from the shim onto the metal, not the other way!

Use the grits and none woven abrasoves as recommended in the video on the roller drum to blend into the pre existing grain.
Pay close attention to stain straight and even pressure on the metal, again allowing it to cool as necicary.

The outside corner can be grained in too with a light touch with the graining machine.

Most of all......PRACTICE FIRST ON SOME SCRAP.....God knows my first attempts were OK but far from perfect.

More tips.

Wrap delicate dull polish areas in heavy cling film to avoid scratches.

Be careful of the heat near any protective plastic or it will get messy.

If you can use a peice of ply with carpet tacked on without melting or burning it then do as it will allow you to not scratch the rest of the job up too much.

Watch out for clamping marks on the stainless too. Metal chips are your arch rival.

Watch how your disk distorts as your grinding the high spots off the weld as it can flex and touch down where your NOT grinding too.

Buy good quality abrasives, Stainless is brutal on cheap abrasives.

Practice again.

 

[Rrunnach]

I would mitre joint, clamp in corner jig, weld/fuse, outside corner. Remove from clamp. Offset under 90 degree, on side faces, weld from inside corner, to outside. Do same other side. Finally do fillet weld, if fillet weld is required?

Dress, as above.

 

[Paul.]

Various methods of finishing mitred corners, no fancy kit or expensive polishers are needed unless you have a mountain of it to do,
I did a how to here, http://www.mig-welding.co.uk/forum/threads/finishing-a-mitred-joint.27837/#post-304411
All you need is some basic abrasives and a drill

 

[adri123]

Many thanks for the advice. I'm just about to make up a welding table with some 316 stainless I have bought pretty cheap and then attempts at welding will ensue!!!

Woohoo! Looking forward to it. Been working with wood exclusively for the past 8 years so this is quite a fun prospect.

Cheers

Adri

 

[slim_boy_fat]

^^ Remember the progress updates.

 

[Richard.]

Yeah I must say there are some nice tips there @Freshfabrications but really not essential to get a nice grained finish on a mitre joint. I don't do nearly enough to warrant an adjustable speed polisher and never see the need to use any more than 1 grade of flap disc to flush off the weld. After that I'm with Paul, flap wheel in a battery drill and some thin mask
plates cut at 45 clamped. Then just dressed with scotch brite and elbo grease. A mirror polish I would say then it's a different ball game and money to spent but I can achieve a pretty much perfect grained finish with simple tools and abrasives and lots of care.

 

[Rrunnach]

Many thanks for the advice. I'm just about to make up a welding table with some 316 stainless I have bought pretty cheap and then attempts at welding will ensue!!!

Woohoo! Looking forward to it. Been working with wood exclusively for the past 8 years so this is quite a fun prospect.

Cheers

Adri

Make up table top in L shape, square each L after fully welding, then bring them together to complete square or rectangle. This is the best way to produce frames, IMO.