satin finish rims (scotch brite)

[cumagutsa]

Well yep another newby question,
I have bead blasted my rims, triples and carb, with a very very fine glass bead but now want a slightly shinier satin finish.
I was just thinking of throwing them at a wire wheel, however that came out pretty average so had to sand and re blast.

Will a finer wire wheel be the go as the one I used was a pretty a corse wire.

I was thinking one of those fancy soft brass wire wheels then some scotch brite mite be the go.


cheers in advance..

[Rookie#1]

Have you tried giving them a thorough rub with "Autosol"?

[Nathan S]

Wet blast?
Scotch-brite pad?

[hagon_84]

You can get different grades of scotch pads I generally use the grey stuff medium for prepping panels for paint, if you use it with a grit free prep and blend paste or something like jif u should end up with a good satin finish, see your local smash repairs and buy a cople of metres from one of them cheaper to buy it in a roll but you won't need that much 

AL.

[rocketfrog]

I have just refinished a set of rims, the method I used was:

Remove anodising using Sodium Hydroxide (28% w/w) and scothbrite, clear water rinse and neutralise with Acetic Acid (10% w/w).
Sodium hydroxide is a fancy name for Draino or Caustic Soda and Acetic Acid is a churched up term for vinegar. Suit up and get some fresh air moving when you do this as the fumes from these products can quite literally take your breath away and the Caustic leaves nasty chemical burns on skin, splash it in your eyes and there is permanent damage. Common sense and careful handling are the key. Mix up about a cup full and work in small areas swabbing the Sodium Hydrixide on with a sponge or rag, work it in with some scotchy and re apply until the aluminium starts to darken. Rinse and move onto the next spot and repeat.

Crack test, various methods are suitable (liquid penetrant and eddy current), but a good visual check will suffice after/as the surface is stripped using the above method.

Watch closely when you rinse the Sodium Hydroxide (you might need to lightly scrub the rim with fine scotchy as you rinse to remove the smut which is a dark grey deposit left from the chemical reaction) and observe for cracks at this stage.

Cracks often appear as dark lines on the clean surface. This is the result of the Sodium hydroxide continuing to react with the aluminium where the rinse water is difficult to penetrate. It is for this reason that a thorough rinse and neutralise is necessary as Caustic Soda/Sodium Hydroxide is highly reactive with Aluminium.

File and dry (coarse) sand the tyre lever burrs and deep scratches and corrosion.

Dry bead blast the tyre bead seat and nipple recesses to remove corrosion (some sanding and blending required using a small rotary burr).

Ream or polish out corroded spoke holes and valve/rimlock holes.

I use a reamer or a slotted thin piece of metal tube (driven by battery drill) used as a mandrel to hold a small piece of scotchbrite.
 
Use your imagination here, think of a dowel be it wood, steel, aluminium plastic etc with a hacksaw slot (or a filed out slot for the scothbrite) to form a fork in the end that you can slide in a small piece of abrasive paper or crocus cloth and what have you. Drive this with your drill and now you have a really effective tool for cleaning bores and inaccesible little areas, cheap and simple.

Wet sand 120 down to 600 or keep going to 1200 for a polished result.

Grey scotchbrite to achieve a factory brushed effect. Grey is ultrafine, red is medium and green is coarse. Use this as a guide only as different brands (3M, Norton) use diferent colours to denote the grit (equivalent grit).

Anodise the rim.

Dont kid yourself, all this takes a long time and you will still have used rims (likely fatigued) at the end of the day. The end result is satisfying and I have basically tried this method to recover an obsolete OEM rim for a restoration project. Would I go through this for a racer - No, not when I can buy new rims in the same profile as stock from most any online bike store at very reasonable rates.

[cumagutsa]

thanks for the replies fellas,

looks like im going to be in the shed for a few more nights

cheers

[firko]

Thanks for that Rocketfrog, very helpful..............We all know that Molasses is brilliant for removing rust and scale from tanks and other parts but, as many of us have learned the hard way, it can be brutal on metal if left un checked. My question is....Would soaking parts Molasses be another way of removing anodizing? 

[rocketfrog]

It wont cost you much in $$ for materials and even the cost of re anodising is $50 plus postage if you require, so for well under $100 you can get a rim to look just like new again.

It does mean you will be burning the midnight oil for a while to do the prep, if you are going down this road and you intend to use silicon carbide wet and dry, rinse and dry the rim before you finish for the night. Saves dealing with fresh corrosion on your polished surface when you do get back to it.

Anodising is great for environmental protection and aesthetics, just remember that the prepared finish you give to the anodiser is the finish that you will be left with. In other words, if it has scratches when you send it, it will have the same scratches when the anodising process is completed. Spend the time perfecting the finish and you will get stunning results.

[rocketfrog]

I dont know about mollasses for anodising, yes for stripping steel but for Aluminium?

The actual anodised finish stripping using the Caustic method is quite quick, never leave the aluminium soaking in the caustic solution unattended - there will be nothing left when you get back!

Strip the old anodising before you start work polishing the rim to make life easier. The anodised finish is surprisingly hard, just try sanding the old anodised rim in a damaged area before you strip it to the substrate to test this point. Try sanding with the same grit paper now with the anodising stripped and see how much softer the base Aluminium is - amazing.

No surprises I guess when you consider that the Anodising process is basically inducing a crust of aluminium oxide onto the part surface, and aluminium oxide is an abrasive in it own right.

Firko, if you have a mollasses tank set up maybe try a scrap rim to test your theory. A side by side comparison of the stripped against the anodised should be apparent to the eye. Always interested in an experiment if there is a cheaper, safer or more effective way to reach the same result. 

[firko]

Firko, if you have a mollasses tank set up maybe try a scrap rim to test your theory. A side by side comparison of the stripped against the anodised should be apparent to the eye. Always interested in an experiment if there is a cheaper, safer or more effective way to reach the same result. 

I'll make a start today.....I have to mix up a batch to descale an old AT1 tank anyway. 

I've nearly always used Anodizers and Electroplaters Pty Ltd at Mortdale for my anodizing and in the times I've needed a rim or case just stripped without re anodizing they've done it for comparatively little money.

Anodizers & Electroplaters Pty Ltd
55 Barry Ave, Mortdale NSW 2223
Phone 
(02) 9533 2333

[GMC]

I wouldn't be hitting alloy with wire wheels, I consider them too savage.
Maybe if you can reduce the speed but I personally still wouldn't use them.
Plus you should only use stainless steel wire brush as mild steel wire can leave traces of steel behind that will show traces of rust in the future.

Scotch brite wheels are fairly common these days, Hardwares have small ones you can fit in your drill and they will leave a better finish than wire wheels. Use these to get the grain running the right way and to get the marks out then finish by hand with a scotch brite pad

[rocketfrog]

"I've nearly always used Anodizers and Electroplaters Pty Ltd at Mortdale for my anodizing and in the times I've needed a rim or case just stripped without re anodizing they've done it for comparatively little money."

I have heard good things about this company at Mortdale, I have used A grade Anodising at Ormeau (QLD) with good results as well. The Anodising process is a pre clean using Sodium Hydroxide - clear water rinse - desmut and neutralise in Nitric Acid - Rinse - and finally, Anodise in Sulphuric acid (typically) - colour as required and seal to finish. Removing anodising would be simply stopping after the initial preclean and neutralise stage I should think.

You can Anodise small parts at home with a few basic chemicals as mentioned, some plastic tubs, a battery charger, aluminium or titanium welding rods to hang your job and insulated wire with alligator clips to make the connections between the charger and the anodes. For cathodes, use some 6061 sheet. Sulphuric Acid can be substituted with Phosphoric Acid if you desire.

The main issue you run into is cooling, the Acid heats during the process and must be kept at approx 27-28 degrees C. Anodising Shops have heat exchangers to regulate the bath temp.

I have successfully Anodised small parts in the garage with info I have learnt from the net (Ahhh, how did we ever get by - my local library was never this good).

Colouring is easily achieved using just about any sort of dye you like, printers ink or food colouring will work!

Most of us will just take the parts along to the Pros, but if you have time and the inclination, it is not rocket science.

As a matter of fact, A grade Anodising started as a backyard business using a battery charger and a fish tank. Still family owned and operated but with bigger fishtanks!

[Mick D]

What a contribution to the world of old dirt bikes.
You are a deadset Champ Rocketfrog

[Big Bird]

Thanks gents, very informative. 

Just a quick question if ordering new rims.  Where would be a good place to order rims that are drilled appropriately for drum brake / vmx bikes.  I recently ordered new Excel rims for my RM125T.  The front was pre-drilled for what must be a modern bike, so the holes were drilled at a too-perpendicular angle to the rim ( I figure to aim towards the smaller PCD of the spoke holes on a small disc brake hub).  So once laced up, all my spokes are in bending at the nipple.
The rear wasn't drilled, so that cost me $30 from memory for the shop to do it to the appropriate angles.
In effect, one rim that needs rework, and the other with an unexpected cost appended...
Does anyone market appropriately drilled rims for VMXers at reasonable cost?     

[Rookie#1]

Thanks gents, very informative. 

Just a quick question if ordering new rims.  Where would be a good place to order rims that are drilled appropriately for drum brake / vmx bikes.  I recently ordered new Excel rims for my RM125T.  The front was pre-drilled for what must be a modern bike, so the holes were drilled at a too-perpendicular angle to the rim ( I figure to aim towards the smaller PCD of the spoke holes on a small disc brake hub).  So once laced up, all my spokes are in bending at the nipple.
The rear wasn't drilled, so that cost me $30 from memory for the shop to do it to the appropriate angles.
In effect, one rim that needs rework, and the other with an unexpected cost appended...
Does anyone market appropriately drilled rims for VMXers at reasonable cost?   

Hers's ya man! http://www.lightfootwheels.com, also John Titman Racing (JTR) are very experienced and renowned for being first class wheel builders.