Tips for anodizing metal plate, screws and lockwashers

[ipetruk]

Hi,

I am about to get my Mainline kit. I was considering to anodize it black and there is a company in my city that does it.

I am a bit concerned with grounding. In particular the screws and lockwashers. Is it feasible to make their caps the same color as metal? Should I just buy black screws of the same diameter?

My concerns are:

1) If I anodize them, can screws still fit the lockwasher?

2) When it is used for grounding afaik I do not only need to clean the chassis on the inside, but I also need to clean the screw/lockwasher that holds it together, right? From the guide it is hard to tell which screws are important to have electric contact with the chassis, which ones don't. Only the one near the power socket is obvious.

Any tips appreciated.

Thanks,
Igor.

[Paul Birkeland]

You can't anodize our hardware since it isn't aluminum.

On the underside of the chassis, you can scrape the panel up a little bit where the earthing points are to ensure a more solid connection.

[ipetruk]

You can't anodize our hardware since it isn't aluminum.

"hardware" as screws, right? I can still anodize the chassis. Should I then just paint the screws black separately with some simple paint? Or should I buy already painted ones? With already painted I am again concerned with electric contact

On the underside of the chassis, you can scrape the panel up a little bit where the earthing points are to ensure a more solid connection.

In case of Mainline, what would the most important points (except near power cord)? For example I've had issues with Crack when one of the screws holding transformer has unscrewed, so I wonder if that is a subtle grounding point.

[Paul Birkeland]

You can paint the heads pretty easily or just buy black ones. 

Where the three lug strip mounts up by the attenuators, be sure you see low resistance between that middle lug and the earth lug on the IEC power entry module.  The same would go for the solder lugs by each tube socket.

[oguinn]

I bought black screws from Fastenal. I think they look great and you don't have to worry about paint scraping off.

[ipetruk]

You can't anodize our hardware since it isn't aluminum.

I have successfully received my kit. Excited to start.

Are tube mount holders (rings) and tube shields aluminum? I am looking at them and they look aluminum to me, but am not 100% sure. What about transformer top plates?

I think it could be a good idea to list all parts that are aluminum in the manual, as I've been told that trying to anodize non-aluminum parts by mistake leads to them dissolving :-|

In addition some anodizing companies I've contacted are asking about the series of aluminum, they say it impacts their tech process, so they need to know

Thanks,
Igor.

[Paul Birkeland]

The top plate aluminum is almost always 5052.

You can buy anodized shields, and I would definitely recommend doing that over paying someone else to attempt to anodize those for you.

The transformer cover is steel.

[ipetruk]

Ok, I will settle on anodizing chassis only. Any other parts can be just painted with automotive paint later.

Yes, indeed, on Ebay I see these, they may even click in. Or I can also paint shields form the kit

https://www.ebay.ie/itm/193111985392

Thank you.

[Paul Birkeland]

https://www.tubesandmore.com/products/tube-shield-9-pin-miniature-aluminum-multiple-colors

[ipetruk]

So the front side is kinda ruined because it was anodizied over the wavy pattern.

The question is, should I

• Go via monumental pain and TWO companies, as this one can only remove anodizer in a solvent and reanodize, but not polish it. Minimal charges for polishing may be steep
• Ask them to remove anodizer only and attempt DIY polishing.
• Give up and powder coat it as a part on the right. They say it requires no polising.
• Order another chassis from Bottlehead and polish and anodize it. I am in Republic of Ireland

[oguinn]

I'd just get it powder coated. You'll have a range of colors available and it seems to be the path of least resistance. I've powder coated every one of my chassis plates but one and I've been really happy with the finish and the durability.

[Paul Birkeland]

About ten years ago at a different job I was tasked with testing every anodizer in the Seattle area to determine if any could do a good, reliable, quality job.  None of them could; all of them ruined pretty much everything we sent them.

The anodizer you used should have run the panel through a grainer proir to anodizing.

I would definitely just get the panel powder coated.  You'll want to be careful to scrape off the anodizing and powder coating on the bottom side of the panel where much of the hardware mounts.

[Doc B.]

Before you decide on another go at it you might spend some time studying the type of finish texture you want and look at a lot of images of items with a similar finish. Powder coat comes in a large selection of finish textures as well, so the same advice holds even though the texture of the metal finish does not show like it does with anodizing.

I suggest either powder coat or hammered finish spray paint. Either one requires careful and thorough degreasing prep of the panel. With that care taken the results can be very repeatable. DIY polishing can be done but it is very messy and takes many hours to get really nice. It also requires very careful handling of the soft aluminum finish afterwards.

[2wo]

I don't know, just looking at the one picture, I think it's interesting. Have you tried setting the components in place and seeing how it looks? Maybe try a Matt clear coat or something

Just because it's not. What you were aiming for doesn't mean it might not grow on you. Give it a little time...John

[ipetruk]

Thank you all folks for all your advices!

My plans are derailed a bit with me getting COVID  . Two particularly hard days are over, I seem to recover well. However now I am only suppose to contact people only after Nov 19th, after full recovery.

I am leaning towards powder coating it. My hands are super itchy to solder so I am thinking of soldering 4 PCBs first. They don't seem to be dependent on anything. I can make them and put them away until my chassis is ready.

Have you tried setting the components in place and seeing how it looks? Maybe try a Matt clear coat or something

2wo, excellent idea. I will definitely try that, maybe it will change my mind.