The ceramic media particulates are small enough to get through the smaller openings. The RC swing arm is a prime example of an item that has its drawbacks when tumble media polishing. One can plug all the threaded holes with screws but the others are next to impossible to seal off. Anything inserted in a hole has to be secure enough that it does not fall out while being tumbled. Any foreign item tumbling in the media can ruin what it being polished and plus you have to find the loose object so it doesn't ruin the next item(s) being done.
So, if you are pretty familiar with every orifice on the SP2 swing arm, it is very challenging.
The guys at the shop that do the polishing put in a fair amount of effort to remove as much of the media as possible as do i myself, s I know how much work it takes to try and shake them out. After doing quite a few of these I've just accepted the fact that some media may just as well take up permanent residence inside as they are not really going to hurt anything in the long run.
I'll have to check with the shop that does this process and see if they have a station set-up with larger size media maybe but I'm pretty sure they are a certain size for a reason.
Smaller media size particulate for a finer finish.
But I understand doing things to the greatest detail also and having some media floating around inside can be bothersome for some perfectionists...
Not a rant, just telling yall how I approach/accept it.
I totally understand that buddy, that's why I never complained to you about the rattling noise the swinger was doing when I took it out of it's packaging.
I have done a lot of sandblasting myself to know that the sanding/tumble/whatever agent is used, eventually is gonna be literally everywhere in the part if that has enclosed spaces on it.
I have thought about leaving it rattling a bit as I have removed the majority of those tiny balls out of it but since it'll take sometime to resolve the staining issue, it wouldn't hurt me to shake it for a couple of hours every day to get some more of them out as well.
Who knows.....maybe I'll manage to take them all out eventually.
Went through a different kind of hassle awhile back when I tried using a different powder shop to do the black powder that I do them in. Went there just merely because they were down the block from my work and it was more convenient to go there and they had the correct matching color I needed.
Up until then I was familiar with the other shop, I had done business with a number of years, and their process to prep parts/surfaces for powder.
This other shop had a phosphate chemical rinse they do on all parts they do before entering the spray booth or something with just became a huge problem when doing the swing arms because the cleaning agent would get trapped inside the swing arms and get absorbed by the expanding foam that is inside them. This would make them weep/leak out as they cured in the oven and then ruin the surface finish in the areas the liquid would leak out. I fought them tooth and nail on the whole thing and they had to do them three times. The third time around i got charged extra for cleaning labor. Never went back there since because of the hassle and all the trips I had to make there.
All this is just to illustrate the struggles/endeavors that I've gone through to make sure these work when re-finishing them.
I figured that much myself cause I know from previous experiments I've done that aluminium is a bitch to paint in such a way it can withstand small road gravel chips and dust hitting it while riding for more than a few months without the coating start pealing off and shows marks and scuffs on it.
Before I ship it to you, I tried to sand the scuffs it had with some water sand paper and I found out that Honda has it painted from the factory. A very thin and durable silver coat that is definitely NOT powder coating. Looks more like autoshop professional painting but it has been treated in a way that it won't come off even with sand paper.
Most likely oven baked treatment.
I went to my storage and found an NC29 CBR400RR Gull Arm and an MC21 NSR250 Gull Arm swingarms I have and sanded them with sandpaper on a random spot and it turns out they are NOT spray painted like the SP2 swingarm was.
That means that Honda didn't use to spray paint their swingarms on models prior of 2000.
And those swingarms don't stain with water no matter what kind of water is that or what temp it is heated on.
I concluded that they must have used some kind of chemical treatment on the aluminium surface so that it remain neutral and not react to nature's elements it might come across during riding.
That's why I tend to believe that since I don't have it powder coated, the next best thing I should be looking on, is some kind of chemical agent that will neutralize the swingarm's surface.
And all the above wouldn't have happened if it weren't of those tiny balls stuck in the swingarm......