Thread: ANODISING ALUMINIUM ROUTER PLATE

As far as preparing it for anodising, you don't need to do anything, assuming it's in good condition.

If there are big unsightly scratches, you might like to sand/polish them out.

The anodising process goes something like:
Solvent bath --> Chemical etch or brighten --> Anodise --> Seal

There are threads here on how to DIY anodise if you'd like to know more about the process, or see here - http://astro.neutral.org/anodise.shtml

> I have just bought an alloy (seems quite hard) router plate in 6mm aluminium.
> If I get it anodised is it going to soften the plate at all?

On the contrary. Anodising makes the surface of Aluminium much harder and more scratch resistant. That said, any defect in the surface will be harder too and may scratch your workpiece.

> The reason I ask that some years ago I had a Bow sprit powder coated and it softened
> it causing the forestay to sag (Yachting terms for the non nautically minded) Not good for racing.

Powder coating is a process whereby material is built up onto a surface. Think of painting a surface. Anodizing oxydizes the surface. Think more of something like etching into the surface. Typically the anodized coat penetrates 50% into the surface, and another 50% builds up onto the surface. Typical build-up would be about 0.05mm.

> Next question How do I have to prepare said plate before getting it anodised

Any imperfection in the surface to be anodised, will be exaggerated after anodizing. The darker the color you choose, the more will imperfections be highlighted. Easiest is to choose no color at all = natural Aluminium silverish color.

I am not a woodworking expert, but I think a router plate should be smooth and "slippery". This is certainly not what you will get by anodizing brushed aluminium, quite on the contrary it would feel like sandpaper. You want a very fine and smooth sufrace finish before anodizing it. Also there are different types of anodizing. You want the "hard anodizing" which is done in a cooled bath. This penetrates much deeper into the metal making it more wear resistant. It also makes for a more "glossy" surface. Hard anodizing is much more difficult to DIY.

At the end of the day, if you do not do your own anodizing and do not know someone to do it for you, and have high expectations regarding usability of your part, you may be better off to buy that router base ready made, or leave your plate just polished and uncoated.

Yachtie, as CBA said, polish it up and then search for Aluminium Anodisers and get it professionally done. I send a lot of stuff to Brisbane and have it done, well worth the effort.
rgds,
Crocy.

Powder coating involves heating the object up to fuse the powder together. Anodising is a cold process so should not change the temper of the material.
Like most surface treaments, anodising reflects the finish of the substrate underneath. Rough substrate = rough finish. Anodizing also relies on the surface being clean so polish up with things like wet and dry rather than chemical polishes that may leave waxy or greasy residues. Different grades of Al will anodise differently, so if you know the grade the anodising place should be able to give an indication of how well it is likely to come up.

Michael

Hi yachtie,

Anodising is the bastard child of a perfectly natural event usually called corrosion.

Aluminium is a pretty reactive metal and will readily corrode in contact with moisture to form aluminium oxide. That layer of oxide can then act as a barrier to the further contact of the aluminium and moisture. In that way it prevents further corrosion, or at least slows the process down considerably. Anodising is the controlled forming of a layer of corrosion on your router plate with the aim of preventing further corrosion!

The layer of fresh oxide will absorb dye. It is then hardened. I have read that this is achieved by immersing the anodised object in boiling water or similar. The relatively low temperatures involved won't alter the temper of the alloy and thus there should be no changes to the plates strength.

Care and feeding of your router plate...

The surface finish of the plate will be tougher than the underlying alloy. Any threads cut into the plate should be get a clean out and a bit of grease before you screw in any bolts. What can happen is that the friction of screwing in the the bolt can start to abrade the oxide film. The abraded oxide forms into a little ball trapped between the threads and slowly builds in size, chewing out the alloy, rolling it up, until it gets big enough to permanently lock the thread A process appropriately called "galling"

Titanium can be anodised as well as it forms a surface oxide. It won't accept one particular dye (purple?)

Stainless gets it's corrosion resistance from the formation of a Chromium oxide on the surface.

All three metals are subject to galling of threads. The recommended preventative measures are to keep the threaded parts cool before use, keep the threads clean and use some lubrication on the threads. You can clean any excess lubricant off the top of your router plate before use.

Cheers

The Beryl Bloke

Thanks all you wise and informed metal workers. I am going to pro shop in Adelaide and now have some idea on what to do.
What a wealth of information these forums contain Thanks again
John

The remianing question in my mind is "why do you want to anodise it in the first place?" Seems an odd finish for a woodworking tool....

Joe,
There are 3 reasons to anodise this plate
The main one being that sometimes routing on bare alloy leaves black mark on wood,
secondly I can match the plate to my Incra system and it looks better.
and Thirdly because I obviously have too much time on my hands to think about such an idea.
John

I finally got round tuit. Looks heaps better than bare alloy $30.00.
Thanks again for all the help a great forum
john

John I can't help with the anodising, but I do some powder coating and am curious about your comments on PC. Did you speak with the powder coater after the fact? The baking temperatures of powders are typically around 200 C, which is not hot in metal speak. I'm surprised that aluminium would change dimension at that temperature and would be grateful for any more information you could provide on that particular case.

Sorry for the OT diversion, but it sounds like your initial question is resolved.

Originally Posted by Pete F

John I can't help with the anodising, but I do some powder coating and am curious about your comments on PC. Did you speak with the powder coater after the fact? The baking temperatures of powders are typically around 200 C, which is not hot in metal speak. I'm surprised that aluminium would change dimension at that temperature and would be grateful for any more information you could provide on that particular case.

Sorry for the OT diversion, but it sounds like your initial question is resolved.

Pete,
This was in the early nineties, and a lot of water has gone under the bridge since then. I had a 20ft deep keel trailersailer, the bowsprit I made out of a tapered section of OK dingy mast about 1400mm long and 80mm diameter welded to 50mm section base near one end worked fine in strong winds for one season. It carried an asymmetrical spinnaker 200sq ft. Had bright idea - powder cote. Next sail it bent sideways some 20* !!!!!. There were no stays for sideways support. could be the reason?
Made a wooden one which worked till I sold boat.
Must admit not good at metalwork.

sorry don't have any photos.
John

Ok thanks John. That's interesting. I would guess the mast section was of a section and alloy that was hardened either in forming or by design. I wouldn't previously have thought the powder coating temperatures would be high enough to anneal the aluminium, but now I'm not so sure. It's definitely possible it could have been affected and annealed (ie softened) by the heat used in powder coating. I'm certainly pleased you raised that point, as it's something I wouldn't have previously considered. I'm sure the Google-jockeys will launch to work, declare their instant expertise in the subject, and set us straight, so I await with baited breath for that revelation.

In the application you asked about here, any annealing wouldn't affect it at all, and I wouldn't let your previous experience put you off the process. Given you say you don't know much about metal working, I think the rule of thumb would be to if the application is designed to be under stress then it may be a good idea to apply caution in regard PC, otherwise I'd go for it. I do think anodising was a better finish for your application anyway.

Thanks again for the info

anealing can happen at fairly low temperatures in metal terms.

It is common for wood turners to put old files in SWMBO's home over turned up flat out to take the edge off the temper to they are not a brittle hazard......and steel working temps are way higher than aluminum.

I've seen aluminium get very soft in reflectors in halogen light fittings.

the other pronlem that may be the case is that items in an oven may get considerably hotter than the air temperature as the past the radiant eliments.

cheers