Topic: sandblasting engine side covers

[Chris Liston]

I just picked up some spare engine side covers,  sprocket and clutch.  I was going to have a friend glass bead the old chrome off of them and then hand polish them.  I know some of you have done this.  Do you recommend glass beading or another media?

thanks

[theunrulychef]

Sprocket cover should be aluminum so this will work great.  The clutch cover (outer) is chromed steel which will rust without any protection unless it's an aftermarket finned one, which should be aluminum.  Any bare steel will rust quickly if it's not painted or chromed.

Glass beads will put a small ammount of texture in otherwise polished metal. Start off at 400 grit in one direction (until perfectly smooth), then step up 600, 800, 1000, 1500, 2000 alternating (perpendicular) directions with each step until no traces of the previous grit are evident.  After 2000, polish with Mothers & it should shine like chrome.

I've seen you guys' site.  When I get my cafe finished, I'm gonna have to take a trip over to the bowling alley to see your bikes.  Looks like a cool place - they seem to book alot of good shows.

Good luck,
Jay in Philly

[Steve F]

Are you sure these covers really chromed?  If so, you'll be at the sandblaster for two weeks   Chrome is really hard stuff.  Glass bead isn't very agressive and probably won't do anything to chrome.  You'll need to switch to aluminum oxide at the very minimum to remove chrome.  Like was said before, glass bead will work fine on bare aluminum, and will leave a "texture" that isn't easy to hand polish out.

[Chris Liston]

Well,  Its definetely chrome and both covers are aluminum; tested that with a magnet.  The sprocket cover is pretty much all done except for the edges as that seems to be the strongest chrome plate.  The clutch cover will probably take alittle more time.  We're using 80grit glass bead.  I may get some walnut shell tomorrow to tackle the really tough chrome.  But they look great at the moment on the parts the chrome comes off.  Some parts just literally peal off which is pretty neat to see.

[theunrulychef]

I didn't realize that you're working on a 550 - 750 has the steel covers for clutch & points covers.  The chrome must be coming off quicker because it's aluminum underneath.  If you have access to a soft wire wheel (make sure it won't bugger the aluminum by trying a test piece), that is also a good quick way to smooth out the texture a little before sanding.  I haven't had any troubles hand sanding off the texture for some of my parts, but I honestly have no idea of the grit of glass I have in my blaster, so it could be putting less pits in. 

Walnut shells, I believe, are a finer grit than glass in general.  In fact, people use walnut shell & corncob to actually polish metals & rocks in vibratory tumblers (I'm planning on trying to build one in the future for small parts).  That may be a good intermediate step to help smooth out the metal if you have some available, although I don't know if it would be worth the while to switch the blaster media for 2 parts.

If you're anything like me, you're going to get addicted to polishing everything that's made of aluminum on the bike.  Once you do your first peice & it comes out beautiful, you'll be hooked. 

-Jay in Philly