Quickest method for finishing mild steel

[Maplehead]

Hi All
This is directed to the pros here.
How do I finish 1/16” sheet metal steel for a scratch free mirror finish for nickel plating?
Is this just all about handing sanding from 80 grit to 5,550,000 grit, and 3 million hours?
I’ve tried the Scotch-Brite Roloc discs but they only go up to 320 grit and they leave a lot of swirl scratches.
I’ve tried the radial bristle discs but they don’t produce an even finish. Metal always looks wavy.
I tried wet/dry sand paper up to 2500 grit on a sheet sander but that took hours.
How do you pros do it in a timely manner?
All help and advice is greatly appreciated.

 

[GeneT45]

You've got a tough row to hoe there. The 'teeth' in your design are going to eat up any of the various Scotch-Brite style pads. I'd suggest tumbling. Barring that, the 3M X-tract discs are excellent, but I don't have enough experience to say that they won't also be eaten up by the abundance of edges in you piece (and you don't mention how well those edges need to be preserved...). A surface grinder comes to mind if you're trying to finish the flats while maintaining the 'comb'.

GsT

 

[Maplehead]

You've got a tough row to hoe there. The 'teeth' in your design are going to eat up any of the various Scotch-Brite style pads. I'd suggest tumbling. Barring that, the 3M X-tract discs are excellent, but I don't have enough experience to say that they won't also be eaten up by the abundance of edges in you piece (and you don't mention how well those edges need to be preserved...). A surface grinder comes to mind if you're trying to finish the flats while maintaining the 'comb'.

GsT

Ideally all the edges will end up being smooth. The “comb” needs to be there. I don’t want it misshaped if that’s what you were implying.

 

[Karl_T]

finish with glass beads on sandblaster. Get it close conventionally.

 

[jbobb1]

Might be a long shot, but could you possibly use a coarse, medium, fine lapping compound on a piece of glass? Then polish it with something. If you can hold it easily that is.

 

[tq60]

There are places that have machines that do this.

They lap between moving disks with assorted compounds.

Likely chemical options as well.

Your long ours or a few bucks.

Most platers have knowledge of such services.

Sent from my SM-G781V using Tapatalk

 

[erikmannie]

How smooth does it have to be for nickel coating? My guess is 400-600 grit.

This link has some good info:

A step-by-step guide to surface preparation for electroplating.

Step-by-step guidance on how to prepare surfaces for electroplating with pen, brush and tank electroplating. Advice with cleaning and polishing.

www.goldn.co.uk

See also:

Polishing metal for electroplating

An overview of machine and hand polishing metal for electroplating.

www.goldn.co.uk

and

Hand polishing and cleaning metal for electroplating

A quick reference table for hand polishing and cleaning metal for electroplating.

www.goldn.co.uk

 

[Flyinfool]

First choice would be to take it somewhere local that has a machine to do this.
The plater may have a good source or even be able to provide the service.

If you need to do it yourself then I would use a DA sander with progressively finer grit paper to around 2000, then switch to a buffing wheel with progressivly finer grit untill you have the level of mirror finish you are after. Nickel plating will not hide anything all scratches will show thru perfectly duplicated. You may need to do a final polish on the nickle.

 

[erikmannie]

This guy sanded a bumper from 80 through 400 grit and proceeds from there:

Bumper Prep | Build Tips | Jeff Lilly Restorations

Learn our techniques on expert bumper preparation at Jeff Lilly Restorations. Click here to view detailed build tips to complete your bumper prep to perfection.

jefflilly.com

Remember to be careful as you sand around those combs. An orbital or DA sander may result in an uneven finish on the corners of the combs.

 

[C-Bag]

I had never done any polishing but wanted to put a mirror finish on a body hammer and on my English Wheel and its anvils. I found a kit for my MultiTool that had progressively fine belts then a special woven polishing belt with different grades of rouge. the pic of the hammers is before and after. Like has been mentioned dealing with those fingers you’d have to make sure you never put the towards rotation, only away.