No idea about graphite plates, I imagine they will be expensive. I use stainless steel, a strip cut of an old sink drainer. This can be bent to suit the size of the job, the closer the better. There seems to be some worry about heavy metals but I can't see any great problems, there's probably more in road dust.

I use a bit of bent welding rod inside a plastic tube with holes cut in it (to prevent shorts), but the biggest thing I've de-rusted is only about 6 ounces.

Neil

Electrolyte soon gets dirty, depending on the amount of rust to start with, but settles clear if left overnight after switching off. The liquid can be poured off and reused, add water if needs be. I've just taken out a largish bit, about 7" x 5", after 2 days it's pretty good considering it was encrusted solid ( it is a wire fence tensioner grab ) A quick wash in water and dumped in some diesel should be working tomorrow. There is no sign of any thinning on the s/s.

Graphite could be had from a spark erosion company, they use it for sparking out steel moulds for injection moulding machines etc, they may have odd bits laying around!
If they don't have any to spare they could point you in the direction of a supplier, I do know one such company, will ask about sources atc next time I'm over there, but may not be for a couple of weeks yet!

If using stainless as an electrode in your electrolytic tank, keep shtum about it, the process 'could' in certain circumstances leave hex-chrome in the fluid, which is illegal to tip down drains and 'could' lead to a serious 'Whigging' by elf & safety if caught! (Please don't shoot me, I'm only the messenger, if you don't believe me, google it!

e.g: **LINK**

**LINK**
(This link includes methods for neutralising said hex-chrome)

John.

@ Tim – and sorry to the OP, not rying to hijack your post

Probably a really dumb question, but if the attack on the anode metal isn't that severe, why don't people use a tin drum as the container and this doubles as the anode – genuine question, not trying to be a smart ass

Cheers,

Paul

Use of metal container, for a one off job, is Ok but you must remember to insulate the part or suspend by insulator. I use an ex supermarket plastic tray with lots of holes in it.

Or how about a lump of coal ?

W.

( Sorry – I couldn’t resist it ! ).

Paul asks 'What about a tin drum as anode?' – my response is:

No problem with the theory, really, but in practice I think people with this sort of kit tend to leave it between uses with the electrolyte in the container. Tin (or tin-plated thin sheet steel for clarity) only has a very thin layer on tin, and my guess is that the steel would rust away. And use would only make this worse, as the anode is oxidising – ie promoting rust.

I'm not sure how good any adhesion of the Fe3O4 is, in engineering terms. So, I would be inclined to clean as much as I could off any bearing surfaces, etc. Another factor is that there is a risk of embrittlement* of any high-tensile steel, so an hour or two in a domestic oven should help. Especially for a wide two-bearing crank …

* this is because hydrogen tends to creep between the crystals of the steel, and this can continue if a tensile load is applied. Plated HT bolts will snap off when tightened or a few minutes later, if de-embrittlement is not done properly.

Cheers, Tim

Thanks guys, very informative. I have a couple of 25l drums made of thin steel/tin that the solvent for the parts washer came in. Plan now is to cut off top and bottom and drop into a plastic drum as the anode. Means the anode will suround the items to be cleaned.

Cheers.

Paul.

Just FYI you can get high quality graphite blocks from any EDM workshop or from a mouldmaker who uses EDM. They often have bins full of large chunks of worn out graphite electrodes. Usually these chunks can be bought very cheaply and sometimes they are free for the asking in shops local to me. Some are quite large, being used for automotive part moulds.

EDM shops often also have quantities of worn copper electrodes which can sometimes be bought reasonably depending on copper scrap prices.

Good luck, JD

Hi Phil

I don't see that you've anything to loose by giving it a go. Presumably you'd transfer the the horns to the new frames so drilling the rivets out would be part of that job anyway, so all you'd be risking is a bit of time, effort and fairly minimal cost rigging up the de-rusting bath. Got to be less effort than cutting new frames and less cost than laser cut ones. Definitely worth having a go in my opinion.

(edit added)

With the horns off, even less effort to give the rusty frames a soak in brick acid, over night would probably get all the rust off, it's worked wonders on a number of rusty spanners that I'd got lying around, shifts the black mill scale from hot rolled bar and plate as well.

Keith

Edited By Keith Long on 05/04/2014 14:55:41

For "Brick Cleaner" translate to Hydrochloric acid and I buy from these guys: APC Pure

Much cheaper to buy the strong stuff and dilute it, remember – Acid to Water – not the other way around.

graham.