Stainless Steel Chassis Polishing

[wrenchone]

I just received one of the Triode Electronics stainless pre-punched ST-70 clone chassis. The amp that will fill this chassis will be the subject of another thread, as the only common elements between the design I'm contemplating and the classic ST-70 will be the output transformers. Anyway, I got the chassis from Triode today, and it still has the plastic protective skin over most of it, but even with that protection, the chassis looks like it will need a good buffing up after I finish any extra mechanical subterfuges I have in mind in order to be at its austere best. Any suggestions for appropriate buffing compounds/techniques? I'd like to aim for a matte finish that will tolerate a bit of knocking about.

[rsumperl]

Good morning,
Not to change the subject, but how was the quality on that chassis? I have considered many times purchasing from them, however when I send an email or leave a voicemail with a question, it goes unanswered.

Thanks

[auplater]

sand blast or use a green scotch brite, depending on whether you want a matte random scratch pattern or flat dull finish.

[kevinahcc20]

For a matte finish sand or bead blasting would do the trick...if you want a brushed finish I would use wet-dry silicon carbide paper starting at maybe 150 grit (depends on the size of scratches you are trying to remove) and working up. If all surfaces are flat it works well to place the paper on a flat surface (a 12" x 12" marble or granite tile works well) to obtain flat consistent surfaces. A typical brushed finish would stop at 400 to 600 grit & as you go higher it transistions to more of a a smooth finish. With SS I would wetsand as this takes away the sanding debris and paper lasts longer.

[Buckapound]

I've, here's my thoughts: done a lot of stainless steel finishing for hobby projects, here's my thoughts:

- Easiest finish is the kind of swirly art finished achieved by using various grits of abrasive disk on a rotary device like a die grinder. 3M makes some 3" diameter ones that are fairly widely available (hardware stores, auto supply shops) and that you can use on a drill or die grinder. However, it's an artsy, random finish you rarely find on fine audio equipment. Looks cool, though, IMO.

- Really even, smooth finishes are very difficult to obtain with home tools or with sheets of abrasives alone. For satiny finishes, your best bet is a type of flap wheel, with sheets of abrasive interleaved with thin pads of scotchbrite material. Go slow and if you're very careful, you can get a reasonably professional look.

- For polishing, use a stiff cotton buff and a compound specially formulated for stainless. Prepare to get yourself dirty.

- If you have access to a drill press, you might look into engine turning. You can use the same 3M disks I mention above, but you put the item in place, pull the drill head down and let the sanding sick make a round swirl, then lift, accurately move a specific distance, then repeat. You will need to make some simple indexing fixture to make sure the swirls are evenly spaced. It's a really cool look that if you can pull it off, will amaze and astound.

Good luck.

--Buckapound

[Conrad Hoffman]

I'd never bead blast something that wasn't going to be painted as it picks up fingerprints and dirt like crazy. If you wanted it very shiny you could find somebody to electropolish it. For a matte finish The Scotchbrite is the way to go. To make the job easier and get an even finish, fasten a couple sheets of Scotchbrite to the workbench using Velcro, double stick tape or maybe even spray adhesive. Move the whole chassis over that under moderate pressure so you get even strokes parallel to the edges. The Scotchbrite will get somewhat torn up by the corners of the chassis, but is still usable for a long time. The green is quite aggressive and will make quick work of it. You may want to finish with grey for a smoother appearance.

[wrenchone]

rsumperl -

The chassis looks like it's good quality, with rounded corners and clean punch-outs. It's punched in back for three 5-way binding posts/channel, an IEC connector, a fuse holder ,and one other square punch-out. I may enlarge that one for an on/off rocker switch if I can't fit one of my stock switches. The front panel has two holes for RCA connectors. The chassis came with the plastic protective coating largely intact. The base material looks ok, though dull. The main reason I want to polish/finish is that the rounded corners are a bit shiny.

I think I'm going to try and get a good matte finish on the chassis (why pay a premium for SS just to paint it?) and paint the transformers metallic cast-iron grey. Stainless hardware, of course. The driver board will get a polycarbonate shield to keep inquiring fingers more or less at bay.

[Buckapound]

Check the spray paint aisle. There are some interesting hammertone and other sort of old-school paints available that are similar to the ones used in equipment many decades ago.

--Buckapound

[wrenchone]

I am very familiar with the spray paint aisle, both at the hardware store and at the local auto parts house. What I want is a deep metal flake cast iron grey that is available as an engine enamel or as touch-up paint, depending on the exact shade of grey I want. Greys are finnicky, and I'l want a colder tone of grey to go properly with the stainless. The touch-up paint is a more neutral tone, so it's likely the one I'll use.

[kevinahcc20]

Perhaps a matte finish on the stainless with clearcoat overspray to avoid the smudging?