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Old 11th Feb 2021, 1:45 am   #1
AmateurRepairer
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Default How to clean up a filthy chassis?

I’ve used dremel wirebrush and I’ve used WD40 etc... still terrible. Do I need to strip fully for shotblasting?
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Old 11th Feb 2021, 10:06 am   #2
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Default Re: How to clean up a filthy chassis?

What finish do you intend to have , paint, galvanized ,whatever you will need to strip it totally. at a glance it doesn't look to bad no rust , a good de grease and a coat of etching primer ,before top coat. or even powder coating is nice. just out of interest what is the chassis from, Mick.
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Old 11th Feb 2021, 10:51 am   #3
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Default Re: How to clean up a filthy chassis?

I did a total trip down of an Ekco A77 and used an electric file to strip the rust off. The on that I used was a cheap Aldi Workzone one and gets into most nooks and crannies which a disc sander can't do. There are many on the market - this is one example, but perhaps hardly worth buying for just a one-off job:

https://www.amazon.co.uk/Silverstorm...30624871&psc=1

When I'd cleaned the chassis up, I applied Jenolite rust remover gel, which you leave for 15 mins and wipe off (no need to rinse). To prime the chassis I used Autotek Acid Etch primer which adheres really well to galvanised steel, zinc coated steel, aluminium GRP and most plastics. I also use it on Bakelite and plastic radio cabinets when I've repaired and rebuilt them when smashed or cracked.

It's high build so fills any small blemishes, and comes in 500mL rattle cans. EG:

https://www.ebay.co.uk/itm/AUTOTEK-P....c101196.m2219

To finish the chassis, I used Halford's own brand Ford Dove Grey car aerosol which is an excellent match for many chassis.

https://www.halfords.com/motoring/pa...ml-452896.html

Some pics attached.

Pic 1: Top of chassis half cleaned up.
Pic 2: After removing rust and applying Jenolite.
Pic 3: Primed with Autotek acid etch primer.
Pic 4: Halford's Ford Dove Grey gloss applied.
Pic 5: Rear view of top of chassis partly assembled.

Still not finished - there was also a second chassis for the power supply.

A stalled 'Success Story' waiting till I get a 'round tuit'!

https://www.vintage-radio.net/forum/...d.php?t=134720

Hope that helps.
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Last edited by David G4EBT; 11th Feb 2021 at 10:59 am.
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Old 11th Feb 2021, 12:20 pm   #4
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Default Re: How to clean up a filthy chassis?

If you don't have sander, like David suggested, a wire cup brush on a full size mains drill, or better still on an angle grinder, might be a big improvement over the Dremil.

I too raid Halford's car sprays display to match all kinds of colours, particularly greys and silvers.

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Old 11th Feb 2021, 12:28 pm   #5
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Default Re: How to clean up a filthy chassis?

Agreed, you need something more beefy than a Dremel. I use a cup brush on my 4 1/2" angle grinder. It rapidly removes even deeply pitted rust and leave it shiny.
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Old 11th Feb 2021, 2:25 pm   #6
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Default Re: How to clean up a filthy chassis?

All the suggestions so far seconded.


One excellent way to blast through gunk is to stick the whole thing on a dishwasher cycle, perhaps two. Sometimes the jets are more powerful one way than the other so flip it between washes.


Dishwasher detergent is pretty powerful stuff and in combination with the hot water, will remove a surprising amount of muck!
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Old 11th Feb 2021, 2:53 pm   #7
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Default Re: How to clean up a filthy chassis?

Re: dishwasher, drop an extra tablet in the working area, this stops the inside going a bit grey (they recover, but for domestic harmony!). Paints like Hammerite are designed to go onto rust (not loose) directly if the finish is acceptable for you. Light blue hammer finish was used in all sorts of "period" stuff, (no one will know).
 
Old 11th Feb 2021, 3:51 pm   #8
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Default Re: How to clean up a filthy chassis?

Ah the chassis is from my Marconi cr100 I’m rewiring.

I ideally want it to have a bare metal finish. But I may have it galvanised.
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Old 11th Feb 2021, 4:17 pm   #9
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Default Re: How to clean up a filthy chassis?

It may well be the case that if you take it to a galvaniser, he may prefer (insist?) on taking on the job of cleaning it (e.g. grit blasting, perhaps followed by some kind of wash) so he knows that the whole job has been done to his standards.

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Old 11th Feb 2021, 5:55 pm   #10
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Default Re: How to clean up a filthy chassis?

A galvaniser will invariably do a 'pickle' of parts before they go anywhere near the zinc.

I've generally found that with a bad steel chassis, chemical cleaning is better than trying to do it mechanically. Strip off all the parts and dunk the chassis in a washing-up-bowl filled with a strong caustic-soda solution then put it somewhere safe and forget about it for a week. Any existing paint will be removed, along with rust and surface-corrosion.

One other issue with galvanising is that the zinc is notoriously bad for subsequent paint-adhesion!
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Old 11th Feb 2021, 6:25 pm   #11
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Default Re: How to clean up a filthy chassis?

I guess much depends on how much work we wish to do ourselves on a DIY basis or how much we wish to expend on professional services such as bead blasting, galvanizing, powder coating etc, especially if the equipment isn't of great value.

One DIY rust removal technique I've mentioned before, which seems to have much to commend it but I haven't personally tried, is that of electrolysis, using a 12V battery charger and an easy to set up tank with a sacrificial steel anode such as rebar, using washing soda and water, or distilled malt vinegar, salt and water as an electrolyte . EG:

https://www.bing.com/videos/search?q...DE&FORM=VDRVRV

https://www.bing.com/videos/search?q...7&&FORM=VDRVRV

Lots of other youTube videos with impressive examples.
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Old 11th Feb 2021, 7:14 pm   #12
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Default Re: How to clean up a filthy chassis?

I do a lot of car work and I use a product called EVAPO RUST it it appears to work very well on galvanised and nickel plated Chassis. I’m sure it will work great on a CR100 heavy weight chassis. It’s a lot better than those gel products I have used in the past. It does remove all the rust but will leave the surface pitted. It’s also effortless just leave it to soak for a few hours.

I have also used the electrolysis method that also works well where the object is to large and requires too much chemical to de-rust normally but it’s a dirty method and it doesn’t work as well as the EvapoRust. But it’s cheaper. I wouldn’t use it for your little chassis
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Old 12th Feb 2021, 3:14 am   #13
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Default Re: How to clean up a filthy chassis?

I've tried electrolysis for rust removal; never had the great success that the Youtube vids report.

Never tried Evapo Rust, but the SDS says it is a fully bio-degradable chelating agent (~16wt% in water), so it's a sibling of citric acid, EDTA etc.

I've never got close up to a CR100, so I'm not sure what the chassis looked like when they were made and what's the best way to deal with one which is need of serious restoration. I suspect that they weren't galvanised to begin with, more likely tin-plated steel, not required to last very long . I think my HRO chassis is tin-plate with a layer of paint on top

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Old 12th Feb 2021, 9:55 am   #14
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Default Re: How to clean up a filthy chassis?

An American machinist with a youtube channel, "ABOM79", uses evaporust quite a lot and he's impressed with it. He comes over as a chap with honest opinions. You might have to trawl through a lot of footage of lathe work to find the evaporust bits, though. He's using it on steel and cast iron and the results look good.

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Old 12th Feb 2021, 10:15 am   #15
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Default Re: How to clean up a filthy chassis?

Evaporust works well, but having taken the surface back to bare metal it must then be primed / painted in the normal manner.
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