Migging stainless

[knoba]

I'm building myself a decent, all-rounder, metalwork bench out of stainless steel (approx.: L2.4m x W0.6m x H1.0m). Before I brazenly purchase a TIG can anyone tell me how well my MIG will do the job? Or give me any indication on the best setup to see how good it can get.

All the S/S is 1.4301. The main framework is 50mm x 50mm x 2mm square hollow section. I have some 6mm x 50mm x 50mm S/S equal angle, which also needs welding, to reinforce the top edges, and some 2mm sheet for the surface worktop. I want to weld in S/S bolt sleeves to reinforce the square hollow sections and also weld in S/S captivated nuts too. I want to do a "really nice" job of it.

The MIG is a Murex Tradesmig 210. I was told 308L filler wire (cited by Parker steel) and Pureshield gas (cited by BOC).

Assumptions remaining;
Wire thickness and filler type?
welding techniques?
Shielding gas?
Will tungsten carbide burrs, HSS Drill bits, 1mm Norton cutting discs & fibre discs handle/contaminate the S/S?
Special liner/rollers for the MIG?
All the other things I don't know, because... I don't know; I don't know them

Any input gratefully received...

 

[fingers99]

I think you'll be fine. Take it the material is 304?

Do a few practice peices first and you might want to tee off a purge line to the tube like the TIGistas do.

Must have cost you an arm and a leg, but at least it won't go rusty!

Pics of the completed project, please!

 

[knoba]

Thanks fingers99,

The Stainless steel 1.4301 is designated 304 (X5CRNI18-10). Aalco recommends 308 filler and not the usual 308L.

I have some S/S aerial brackets to knock together for my old man first (as a taster) and I can't do him a bad job can I!

The gas tee is a good idea . It'll have to be done outside so I might enclose it in a clear plastic Gazebo with positioned vents. Thanks for that fingers99! It is going to cost, but, the job's for me and I hate to see good work go to waste through rust - If living in the UK isn't bad enough I live right on the coast too.

I'm playing about with it in CAD at the moment and researching it like I should. I like to get everything in before I start a job, as god knows there's enough issues that always crop up during. I'm still waiting for two vices (4 to 6 weeks) before I can finalise the design and optimise the bracings and strengthen the main stress points.

Here's a rough front view from CAD, it's the best I can do for the mo;

 

[Hitch]

Wire, 308L. 0.8 would be my choice.

Gas, Stainsheild Universal id say if your on BOC.

Contamination minimal, not worth worrying about.

Discs, most cope with it well, although you can get specific ones for SS work.

Liner, same as normal will be fine.


Once youve done a bit of mild steel work on it, it will start getting rust spots anyway.

 

[Justme]

Once youve done a bit of mild steel work on it, it will start getting rust spots anyway.

That was my first thought too. Especialy welding & grinding.

Justme

 

[knoba]

Thanks for the info Hitch! - Have you tried the Stainshield range yourself? I can soon change supplier if another is better. Some of the other S/S posts recommended Argonshield Light -2.5% Co2.

Justme - Will the S/S be tea resistant? I can get through 20 - 30 cups a day!

I figured I could deal with any blemishes that arise on the surface. It would be a rub though; finding out a few years later that the back legs have disappeared completely. I'd like to use stainless more in future projects and figured the bench would cut down on contamination when jigging, welding etc.

I read an interesting article on the web about some unpolished ferritic S/S rusting easily - the upshot was finishing with 240 SiC improved its resistance to an acceptable level. So I'm assuming a going over with a sander once in a while will cure its measles?

I would have liked the bench to be more receptive to magnets, but, alas, there's no guarantees unless I change the S/S grade to a non-austenitic grade. www.bssa.org.uk has some wonderful info on S/S, but there's no better voice than real experience!

 

[Hitch]

Sometimes, depending on how bad the spots are,attacking it with things like sanders can spread it a bit.

Been using allsorts of gases wires recently, did some 304ss yesterday using coogar5. (Pretty similar to argosheild light)



Thinking about it, your using light section 304ss anyway, use the argosheild and save a few sqids. Probably have some of that anyway?

 

[fingers99]

It should polish up OK. And the tea, too!

304 is what folk use on yachts and stuff (if they're too poor to afford carbon), so it should last for many years.

AFAIK, it's not magnetic, but you may actually find this an advantage.

 

[Hitch]

304 isnt yacht stuff. Thats 316 generally.

 

[fingers99]

304 isnt yacht stuff. Thats 316 generally.

Ah, yes. Just found AZoM. Clearly 316 is better in chloride environments.

 

[knoba]

I've been putting together a list of recommendations for the job, all from various sources, including some old posts of yours Hitch; (only the best make it onto the list )

* Use anti-splatter spray- lightly - may dissipate in areas of high heat.
* Use plenty of tack welds and clamps to keep distortion to a minimum.
* Use a spray arc technique.
* Torch +, Earth -
* Use a purge line.
* Use a welding tent outside.
* Use scrap of S/S under earth clamp to avoid contamination.
* Clean all faces with S/S wire brushes.
* finish with 240 SiC
* Stainshield, Pureshield, Coogar5 or Argonshield Light
* 0.8mm wire; 308L, 308LsI

1.4301 (304) is a cheap (relatively) and readily available S/S, but polishing should help its resistance to rust greatly according to B.A.S.S. It just has to be of a fine enough grade to allow the S/S to heal properly. That being said Aluminum Oxide abrasives can contribute to corrosion (and don't last long) compared to Silicon Carbide which is neutral. * It would be great to have this info verified.

The magnet thing is very complicated; the main areas may not be, but the welds and any stressed parts may well be according to B.A.S.S. But you are talking about something else fingers99 - an advantage! Tell me more...

I had no idea Stainless steel was so complicated.

 

[fingers99]

The advantage -- I was just thinking that with fiddly little jobs, sometimes it'd help to use the magnet to hold the work together and not have the possible interference of a magnetic table. I guess you could also stick a magnet underneath the table if necessary.

I think you'd probably do polishing with silicon carbide anyway -- wet or dry is available in much finer grades than aluminium oxide papers.

 

[Jed]

It should polish up OK. And the tea, too!

304 is what folk use on yachts and stuff (if they're too poor to afford carbon), so it should last for many years.

AFAIK, it's not magnetic, but you may actually find this an advantage.

some stainless becomes magnetic when worked cold yeah? i think.

 

[Justme]

Justme - Will the S/S be tea resistant? I can get through 20 - 30 cups a day!

Going on my ss tea pot NO


Justme

 

[matt1978]

Thanks for the info Hitch! - Have you tried the Stainshield range yourself? I can soon change supplier if another is better. Some of the other S/S posts recommended Argonshield Light -2.5% Co2.

Stainshield gases contain Helium, (Stainshield Light, Heavy and Universal) the 2.5% Co2 97.5% Ar mixes are called Specshield. In my opinion, to make a really good job, I would use Stainshield, if you are using 0.8mm wire on Standard mig. The 2.5% Co2 mixes are mainly used if you are using Pulsed mig, as you can still get very nice colour appearance, with a relatively cheap gas.

 

[knoba]

DROOL...

matt1978 - What setup; (welder, wire, gas etc.) made that beautiful weld?

Fingers99 - I guess its a case of the devil and the deep blue sea ...again! I'm just trying to make as many advantages as possible so I won't be left thinking after the job "ohhh I should have done it this way!" I don't mind a slow planning stage. It really allows me to build a good picture of the job in my mind before I go to work on it.

Here's a link to the permanence of stainless steel;
http://www.bssa.org.uk/faq.php?id=24

and the importance of "surface finish";
http://www.bssa.org.uk/cms/File/surfacefinishbssaVer2.pdf

 

[matt1978]

Hi Knoba,

I welded that with a 'Pulsed' mig, so its quite easy to get nice looking results, it was 1.0mm 316Lsi Wire with 97.5% Ar 2.5% Co2.......... you may be able to get a nice colour on the welds you do with Standard mig, if you use the more expensive Helium enriched gas, such as Stainshield etc.

 

[skippy]

304 does tend to rust slightly in costal areas although tends to be more of a rusty blemish than proper rust if you want to go the hole hog 316 would be my chioce but it is much harder to cut and machine than 304 and much more costly, if cutting the stainless lots of coolant if using a hacksaw or bandsaw and high quality blades cheap ones will just melt when drilling stainless sharp drills with much more flater angle is better a new drill normaly has a angle of around 118 degrees you would be best with around 100 degrees and the rake angle (the releif angle that slopes away from the cutting edge) should be around 5-10 degrees as if it is more the cutting edge will break down very quickly also use roocal cutting grease is best hope this helps jon

ps i use to be a cnc miller and used stainless most days