Topic: Engine and side cover polishing issue..

[Xander^]

I don’t understand, lately during my cb750 build im getting the worst luck seems like..

Im trying to polish my cam cover and side covers and ive read alot of posts online and pretty much every youtube video anddddd im not getting results i think i should be getting.

This sprocket cover i used a cordless drill with the 120grit wheel and then hand sanded with 150,600,800,1000,1500 sandpaper .. and then polished it with black, brown, and white compound using the cordless drill first... and then i tried to grt a better shine with a small electric dremel which spins at 13,000 to 15,000 rpm.. dhine was pretty good but the deep scratches stayed!!!! (Angry face)



So trying to correct the scratches, when i moved to the cam cover i did not use the 120 grit.. instead i started with a wire brush wheel on an electric grinder.. and then followed with 600,800,1000,1500 sanding. I polished with brown and white compound.. the cam cover photo shows only half the engine polished.. but this still left behind some odd scratches and dots on the cam ...

What am i doing wrong?

[Bootsey]

Are they actually scratches or is left over polishing compound? Can you feel the scratches with a fingernail?
If not, maybe try washing it with warm soapy water and wiping off with alcohol.

If there is scratches that weren't there to begin with, maybe it's due to contact from a steel piece of your drill/ drill attachment.

Sent from my Lenovo TB3-710F using Tapatalk

[Xander^]

Are they actually scratches or is left over polishing compound? Can you feel the scratches with a fingernail?
If not, maybe try washing it with warm soapy water and wiping off with alcohol.

If there is scratches that weren't there to begin with, maybe it's due to contact from a steel piece of your drill/ drill attachment.

Sent from my Lenovo TB3-710F using Tapatalk

Yeah theyre scratches.. they showed up as soon as i used the 120 grit pad on the cordless drill.. i thought they would go away as i increase the grit sanding... maybe i have to use a more powerful electric drill? High RPMs with the 120grit pad might create more scratches that would come together better and evenly scratch everything lol? Im so rattled by this

[Don R]

 Unless your parts are deeply pitted don't use 120 grit or steel wire wheels, I'd start with 400. If you don't scratch it then you don't need to sand the scratches out. When you are using compound you need to generate heat to melt the compound.  I've had some luck with scotchbrite wheels and pads on the corrosion.

[Xander^]

Unless your parts are deeply pitted don't use 120 grit or steel wire wheels, I'd start with 400. If you don't scratch it then you don't need to sand the scratches out. When you are using compound you need to generate heat to melt the compound.  I've had some luck with scotchbrite wheels and pads on the corrosion.

I see.. so what should i do with those marks and spots on my cam cover?

[Jerry Rxman Griffin aka MuthaF'er]

You may be chasing your tail on those self-inflicted "scratches". You have a LOT of work ahead of you. You're going to have to get most of those out with sand paper before beginning the polishing. Pretty exrtensive and deep. Me, I'd replace or paint but it can be done.

[seanbarney41]

Don't use any power abrasives except buffing wheel.  I have found that the tinyest wrong move results in scratches and gouges that are very difficult and time consuming to sand out. 

To fix your parts you will have to go back to the grit that left the scratches and completely sand them out by hand, then gradually go finer making sure to remove all the scratches from the prior grit.

Polishing aluminum is slow, tedious work.

[DurangoCB]

I agree with sean.  Do everything by hand except for the polishing.  And do all the sanding wet.  With water, not WD40 IMO.

I'd go back to 150 grit until you see those deep scratches go away.  Then to something like 320-400, then 1500. 

Then use power to polish to a shine using something like Blue Magic or Mother's Mag & Aluminum Polish.  I use a 4" cotton wheel on a corded drill, which seems to work better than the 6" wheel on my bench polisher. 

[pjlogue]

I would not use 120 grit.  It will leave deep scratches.  220 or 320 and work your way up wet sanding.  Rule of thumb is to double your grit # with each successive sanding.  Going from 220 to 600 and you will be there for a long time trying to get the 220 scratches out.  Scotch bright pads are a good tool for getting in tighter spaces.  When you get down to polishing, make sure you use clean rags for each successive polish.  keep your work area clean so you don't introduce prior grit into the fine polish.

-P.

[Xander^]

I Was able to use a scotch brite wheel on my drill that clean up the scratches really well! This is what the piece looks like now... in the picture below i used the same scotch brite pad wheel on the side covers of the motor, this is a way better starting point for my hand wet sanding to begin!

Also, i think im having trouble polishing itself.. i cant seem to get any compound on my wheel, the fibers from the wheel start ripping off (fresh wheel) when I press against the stick of compound.. i melted the end of the stick with a torch to get some on the wheel but thhis cant be a long term solution lol..

[Yamahawk]

You may be overdoing the compound... it doesn't take a lot on the wheel. and you may be trying to get too much on there. Try lightly applying the compound to a spinning wheel. and then use the wheel to buff your piece.
Charlie

[millla03]

https://www.caswellplating.com/buffs/images/Buffbook.pdf

Check this guide out. It helped me when I first started polishing aluminum, and provides a good overview of what you're actually doing in the polishing process. Basically making finer and finer scratches until the part reflects light in a uniform pattern. I follow their advice in loading the wheels with compound. Frequent buff "raking" and light application, rather than really laying the compound on heavy.

The scratches pictured are deep. I'm sorry, but Jerry is right - you have a very long road ahead to get those parts back to a good state. You're shooting for a smooth, completely uniform finish with each grit before stepping up to the next finer grit. It just takes a while, even if you're starting with parts that have the normal factory finish. Something like the valve cover would take me 5-6 hours start to end.

I use this buffer https://www.menards.com/main/tools-hardware/power-tools-accessories/grinders/performax-reg-6-benchtop-buffer/2411450/p-1444452320557-c-9075.htm?tid=245097396220868495&ipos=1 Not as good as commercial, but has enough power to get the near-mirror level of finish I'm shooting for with my "daily driver" bikes, and it'll still send parts flying if you're not careful. You learn what angles to approach the buffer with real quick!

Consider removing the covers from the engine. You're going to have a heck of a time trying to sand and polish the cam or side covers installed.

Good luck!

[Mr. Mike]

For me, those (drill motor) HF buffing wheels are no where near the caliber of tool you need to polish your aluminum. I tried that HF stuff, and quickly saw that coin size compression washer getting way to close to the metal as the little buffing wheel wore out rather quickly, or, more than likely it was me laying into it a tad too hard. More pressure has to be applied than what that drill motor stuff can produce. Take the tips from Sean and Jerry, it takes more effort (removing the parts), but the end results will be worth it. But...you’ve now got and extra work load ahead of you...bummer. Hope it turns out good enough for you.

[przjohn]

You can’t “Wish” the parts polished. As has been stated this is tedious, time consuming work. Take your drill and wire wheels and put them away, they will do you no good. There is no Silver Bullet or Mechanic in a Can for this job. This is manual labor, get a good pair of mechanics gloves and settle in for a lot of sanding. You appear to be moving up through finer sand papers without obviously completing the process with the coarser papers. If you have properly worked your way to 1500 wet that cover should be looking pretty good and will polish up nicely. It also sounds like you are using a drill and a Dremel. These tools don’t work well for polishing the types of parts you are trying to polish. A bench mounted polishing wheel is the way to go.

[DurangoCB]

It must depend heavily on the original condition of the part.  I polished a fork lower the other night in 60 minutes.  Wet sanding by hand (10 min per grade) and then polishing with a drill and cotton wheel and chrome polish for 20 minutes. 

I'm sure the results aren't perfect, but they're decent.  There's a photo in my project thread. 

[shads]

Here's my technique for polishing posted in another thread.

[vince102]

Try less RPM with the dremil and maybe the drill, take more time but less speed, I tried polishing some small scratches from a seat in the house with a dermil and got the same looking marks, looked like the high speed of the dermil burns the surface.