Rubbing compound?

[CharlesHF]

I haven't ordered a waterblock yet, but I know that it'll probably need to be lapped, and I'm prepared. I have plenty of 3M Imperial wet/dry sandpaper from working on my case today. (got one side done--a nice reflective black!)

The process called for using rubbing compound after doing the final sanding of the paint. Supposedly, it's supposed to take up where 1500 grit leaves off, and bring it up to a 5000 grit. That's my first question-is that true? I did notice that my case panel got much shinier after putting it on.
My second question is: is putting rubbing compound on a waterblock after going up through the grits going to help? Or, would it somehow, someway, hinder performance?
Thanks,
Charles

[UserName]

well there is a debate that lapping much over 600 grit is any good.

But what's not in debate is using compounds. the rubbing compound will embed itself in the metal surface and hinder heat flow.

Dont want to use anything but water really. the metal bits will fold back into the base and fill in the little holes themselves. some thin AS3 or whatever is good to use, but it gets in there and water don't and i'd rather have metal in the holes than AS3 as it's 300+ times better at heat transfer.

[Gravity Man]

Rubbing Compound will not give you the perfectly flat surface you are looking for when lapping a waterblock/heatsink. With sandpaper, you can tape it down to a piece of glass, and because of its uniformity, you get a good, flat surface. With rubbing compound, however, there is no way to ensure a perfectly flat surface.

In other words DON'T USE RUBBING COMPOUND.

[CharlesHF]

Ok, thanks.

[DodgeViper]

You can use a product called SimiChrome, its a cleaner and will leave your lapped H/S looking like a miror. You will need to follow the SimiChrome with Acetone to remove any SimiChrome thats left on the surface.

Follow this thread that I responded in another forum.

http://www.amdmb.com/vb/showthread.php?s=&threadid=98032

[Gravity Man]

Good link, although I disagree on lapping a heatsink past about 600-800 grit. Also, that rubbing compund still doesn't address the problems pointed out my previous post.

[DodgeViper]

I will have to agree with you. In no way should someone use a rubbing compound. SimiChrome is a cleaner and NOT a rubbing compound. I have provide a snap shot of my current temps. For air-cooling these are really good temps, 24c or 75f is my ambient case/room temps within my computer room. Below is a link to SimiChrome.

http://www.competitionchemicals.com/simichro.html

http://teamajo.com/BMX_LINKS/FIREWALL/Current_Temps.jpg

[Ridenow]

One thing that is frequently tried with some success by overclockers on a budget is Crest toothpaste. Toothpaste contains very fine abraisives. How it is used to get flat, not just smooth, I do not know.

[Colin]

SimiChrome is good stuff exept it will leave a residue in the HS where the thremal grease should be. Stick with wet/dry paper.

[Patchmaster]

While it may look very cool, the object here is not to turn your heatsink or water block into a mirror. You just want to get it flat and smooth so it will conduct as much heat as possible. As some of the others have said, rubbing compound will just gum up the works and largely defeat the heat conduction objective. I'd avoid the SimiChrome too. "After polishing, Simichrome leaves a thin protective coating to help prevent tarnishing. " I'm willing to bet that thin protective coating is not going to help heat conduction.

When I lapped my CPUs (old Celerons) and heatsinks I used a succession of grits from 200 to 1500. The benefit of the 1500 is probably debatable, but I'd say there is definite benefit to going beyond 600. I certainly don't think it can do any harm.

[DodgeViper]

Does anybody finish reading the paragraphs before they begin to write their own? My very first post I wrote, You will need to follow the SimiChrome with Acetone to remove any SimiChrome thats left on the surface. As for looks who is going to see the bottom of my H/S? The very reason that my H/S looks the way it does is for heat transfer only.

[Patchmaster]

Does anybody finish reading the paragraphs before they begin to write their own? My very first post I wrote, You will need to follow the SimiChrome with Acetone to remove any SimiChrome thats left on the surface. The acetone wash will certainly help, but the reality is that whatever the SimiChrome leaves behind will end up embedded in the microscopic surface imperfections and there's no way wiping the surface with acetone is going to remove it. If you're going to go to the trouble of lapping the heatsink, it only makes sense to do it in a way that will maximize thermal transfer. This means no fingerprints and no substances that will leave any kind of residue.
As for looks who is going to see the bottom of my H/S? The very reason that my H/S looks the way it does is for heat transfer only.It seems to be rather common around here for people to get caught up in the activity of the moment and lose sight of the overall objective. I've seen several people post pictures of their highly polished heatsinks reflecting some object in the foreground of the photo. The same kind of thing happens with temperatures in general. People whose computers are running just fine read about lower temperatures and suddenly start cutting up their cases and adding fans by the dozen. While there's certainly nothing wrong with adding more ventilation if you need it (or even if you just want to play around with it), it's probably pointless for most people who aren't already having a problem. My comment about turning a heatsink into a mirror wasn't meant to be pejorative. I was just trying to keep things from getting carried away.