Brushing stainless steel

[GrahamGKD]

Hi,
I'm knocking up some brackets using 316l flat bar. The bar is supplied with fine mill scale and a slightly pitted surface. I have bought several different sizes for the job and the surface is not really consistent between them (i.e. some of the bars have a more pronounced patterned surface than others). What is the best/quickest/cheapest way to make it presentable please?

On a smaller item using the same material I sanded it by hand using wet and dry paper with water - this worked pretty well but is a bit labour intensive for larger quantities.

Cheers,
Graham.

 

[Shox Dr]

Either shotblast them or use a 60grit flapwheel ones ones with scotchbrite between the emery

 

[GrahamGKD]

Either shotblast them or use a 60grit flapwheel ones ones with scotchbrite between the emery

Thanks for that - I don't have shotblasting kit but I can use a flapwheel. I presume we talking an 'edge' type flapwheel which goes in the angle grinder as opposed to the normal disk type? It's just that the disk type will leave circular marks won't it? I have one of those polishing wheels which Weldequip sells - I need something like that only more abrasive. Any suggestions where to source the kind you suggest please?
Graham.

 

[Sam]

I find hitting it with a fibre disc first to get rid of the mill scale then the flap wheel the ones with the scotchbrite in between the flaps (j&l industrial sell them) gives a smoother more uniform finish "with a bit of practice that is". You could also use a linisher if you have one by drawing a cut lenght down over the front cylinder/roller but if the bar has been sheared it will have an edge and will have to be taken down using a fibre disc. I found the flap discs cause a bevel and are hell of an expense. p.s. it is labour intensive no getting away from that one.

If you are going to do a lot of polishing it would be worth getting yourself one of these a Polly-PTX polishing thingy expensive but if you are doing a lot of stainless a time saver and far superior finish you can get attachments for doing tube as well.

 

[GrahamGKD]

I find hitting it with a fibre disc first to get rid of the mill scale then the flap wheel the ones with the scotchbrite in between the flaps (j&l industrial sell them)

Thanks for that Sam - are these the flap wheels http://www.mscjlindustrial.co.uk/SBP-03770L/SEARCH:KEYWORD/product.html#

Is there a version for an angle grinder (I had to drill down to the additional product information to find mention of scotchbrite on these ones). If not, would I be OK with a power drill or would I need to get hold of a die grinder (or maybe these won't tolerate the speed of a die grinder)?
Graham.

 

[Sam]

There is a version for the grinder but I used the ones you linked in a pistol drill for years. Someone posted a link to free sample discs with the scotchbrite flap disc to suit a grinder I sent away for a sample but have not used it yet only discovered the disc again when I was looking for something else.

 

[Sam]

Just had a look in their book could not find them myself almost certain it was j&l I bought them from many years ago another grey moment, also use Zirconia (blue) discs they do not glaze up as easily as a normal fibre disc.

 

[Paul.]

I made myself a small bench polisher, see the thread here, used with 40 grit and 60 grit flapwheels you can make a very quick job of graining hot rolled stainless bars, you can also use a power drill mounted in a bench clamp, I did that for years, but the sideways force on the drill soon knocks the bearings out. for small items you can even bright polish, like the brackets in my album, here, and flat bar cleaned up here, I also use the 115mm scotchbrite flap discs for the grinder that Sam referred to, they are called surface conditioning disks, a typical example is here

 

[Sam]

I like that bench polisher! Did you try the sample disc if that is the same one have not had the application to use it on recently.

 

[Paul.]

I like that bench polisher! Did you try the sample disc if that is the same one have not had the application to use it on recently.

No didn't bother sending for a sample, they've been around for years, I couldn't even say what make I'm using at the moment just whatever my supplier sends me!, they are all pretty much the same unlike other abrasives.
They are colour coded for grade, Brown is coarse, blue, medium, and red fine.
the fine ones are great for taking the colour out of a spot weld or the reverse of a tack etc, I find a standard grinder is too fast for serious work with them they melt glaze over and leave a deposit on the surface, I use a 7" variable speed polisher, works a treat

 

[GrahamGKD]

Thank you all - some good ideas to go on there. At the moment I'm not sure how much of this I will be doing so I don't think I'll make any special tooling just yet. I'll try one of those flap disks. Thanks Again.
Cheers,
Graham.

 

[GrahamGKD]

Update....

I have been doing a bit more work with stainless so I bought one of these (allows the speed to be turned down for flap wheels):

http://www.makita-direct.co.uk/acatalog/Makita_GD0800_High_Speed_Die_Grinder.html

and these (various sizes and grades):

http://www.abtec4abrasives.com/60mm-2-38-diameter-x-30mm-1-14-width-x-6mm-14-spindle-abrasive-cloth-impregnation-1459-p.asp

That all seems to work quite well for the time being without investing too much.

Graham.