So my boss thinks because I'm a welder that I can weld anything and assigns me a little stainless steel job I'll be welding up very soon. So I measure it up and order some 304 grade SHS, flat bar and angle.
The SHS is nice and shiny and I can cut that in the cold saw on the slow speed setting right?
But the flat bar and angle has a crappy dull finish - how do I polish it up to match the SHS?
If I manage to scratch up the SHS since i don't work in a proper workshop with wood top benches, the best way to remove those?
The welds, do people still use pickling paste or a mechanical means of cleaning only?
Share your preferred methods and tools you use so I can go on a spending spree with the company credit card before i get into it...
You are asking a lot of qestions there. 1st. pickling pastes are still used and there are lots of types. 2nd. make covers for your benches with craft wood or mdf. cheap and save a heap of trouble. 3rd The "matt" finished ss can be polished but its an art, and one guy i know of who does it "guards" his secrets. Have a look on you tube. I know the "pfherd 'combi click' system" offers a complete system of wheels and compounds for polishing.
If the angle & flat bar are hot rolled as I assume which is common here you are in for alot of work to get any sort of finish - you really need to order in stainless in a finish suitable for the completed product & do the minimum clean up after welding - otherwise you could spend longer polishing than making the thing ! - only real answer to mottled / rough hot roll stainless is to flat it with a linisher - then go through grades of compound starting with " Satin " greasless gritted compound on a heavy spiral stitched mop or " Steel cut or Carbrax " on sizal - then once imperfections are smoothed out polish with " Hyfin " on softer open leaf mop - best compromise if the product can have " brushed " finish order the SHS in that form which is the most common & cheaper which allows all clean up to be done with a fine grade Scotchbrite wheel - this is what I do on larger stainless structures like gantry frames - obviously boat handrails etc are always wanted polished - my preferred method of after weld cleaning is 25 > 30 volts AC applied as an electrolytic action using a home made glass fiber pad about 2" wide with dilute phosphoric acid - then rinse with water - works well & no nasty " Alien " blood acid stuff !
I'll go for a brushed finish, it's only a stand for some electrical equipment, why it's got to be out of stainless I don't know. I only need to finish the outside surfaces of the angle and the flat bar will be cut into small 25mm tabs so I think it's doable.
Youtube helped a bit, I like the look of a burmishing machine but it annoys me that it wouldn't get into the inside corners of the SHS. Would I get more use out of a "straight grinder"? Do they make 50mm wide wheels of different diameter to suit (50 x 50 SHS is used)?
Local shops probably won't have what I need so just need to know what I want before placing orders...
It's a frame where most of it is visible, all welds will be ground and blended apart from the fillet welds. For the next frame I'll be sure to use material with the same finish but for now ill use what I got.
Just still wondering if a straight grinder will do in place of a burmishing machine/linear polisher to achieve the final brushed finish as well as being able to get into all the corners on this and future jobs. Or will the angle grinder get it close enough to do the rest by hand....
A frame for what ? Describe what you're making.
If its a filter frame to filter elephant shit, it's one thing. If it's a display rack for a bakery or jewelry store it's another.
Well whatever the frame is for the OP is needing help blending / finishing it to a uniform brush finish - my advice would be Scotchbrite wheels - available in many grades including fine silcon carbide which is my preferred mop for this - I use 6 of 8" mops 6leave wide mostly on a 7" sander / polisher ( looks like angle grinder but slower & lighter ) using a tapered splindle adapter often sold to convert bench grinders to polishers.
I have a piece of 1/8" thick stainless about 2" tall by 1-3/4" wide ( approx ) welded to the end of a 8" piece of 1/4" rod - the power cable is attached to the rod - I then take a 4" long piece of fiber glass exhaust wrapping tape - fold it over the flat & retain it with an "O" ring - I filed two small indents in the stainless to keep the "O" ring in place - it's important that the tape completely envelopes the metal - ( in effect it looks like a long handled scraper ) - the power source seems to ideally be between 25 > 30 volts - I have used a largish 24vlot battery charger - going a little higher does'nt hurt too much - but can leave a white residue on some material - I have also used a very old 140amp " buzz box " that had a notoriously low OCV of around 42 volts - if you Google "Tig mop" you will find something similar & a demo video - it looks good except for the 2.5k price tag ! - & I was'nt paying that ! -
Would the requirement be met with media-blasting? This is the lowest investment of time and material, though it may take some experimentation to achieve the most even look. There's a recent media I've seen that is essentially bits of abrasive-impregnated sponge, like shredded scotch-brite, that makes a very even finish, though I don't recall what it's called. Saw a demo, but it wasn't aggressive enough to be efficient on extremely large surfaces, so we opted against.
It will sit in a mobile building filled with data racks and other expensive stuff I know nothing about, that building is dumped out in the middle of nowhere next to a tall ass tower and powered by a generator. Just gotta look good for the big wigs that will run there eyes over it.
Sounds like a sir sander/polisher is the go. I had the impression for a good finish you'd need to polish/brush in just one direction as opposed to a spinning disc.
Yes you need to be careful with direction - & there are metallic tapes that can be stuck on at corners etc to protect the finish from cross brushing - when you have a Scotch-brite wheel on the polisher you only use the outer .edge ( so its like using a cutting disc on a grinder ) - I have a modified front handle & have turned the rear handle / switch through 90 degrees to make this easier - I enclose a link for a site where I buy most of my polishing supplies - the " Scotch-brite is listed under " non woven products - as it's a trade name.
I might be to late to this thread but here are a few products that I use for finishing SS. The Norton wheels are just two of their line up and will say they work very well. They are a little expensive but they last quite a while, as long as you stay away from edges and sharp objects. The flap wheel/scotch brite wheel, I use on a die grinder or drill and gives the brushed look you may want. There are a lot of options for finishing SS. One warning I would give on the orbital is it will be hard/harder to get that consistent finish with out some practice and slowly moving from course to fine. It does work but I would try it on a scrap piece until you get the hand of it.
-Jonathan
Attachments
Norton Rapid Finish 2SF.JPG (167.69 KiB) Viewed 676 times
Norton Rapid Finish Med.JPG (157.73 KiB) Viewed 676 times
