What do you use to get a glass smooth lapping result?

[Judaeus Apella]

I've been using worn out sanding sponge till now, but it only goes so far, and very slightly rounds the edge if you're not careful... not to mention it takes too long to do it this way. What do you guys recommend?

My dremel XPR came with two "425 Emery-Impregnated Polishing Wheels", and it polishes small things made of metal to a very shiny gloss, but unfortunately it spins in a circle, meaning that it leaves rotational marks which doesn't look good. Its even worse if I use the thin edge, making little lines. :( Maybe a larger version of something like this?

Edit:
Oh yeah, I forgot to mention I tried the polishing compound that came with the same dremel kit, but it doesn't seem to work that great. I seem to recall seeing that stuff on a jewler's supply website before. Is the stuff that came with my dremel the wrong kind... or do I just need something of better quality? Also, how thick of scratches can that type of stuff remove.. or do you have to sand with super fine paper first?

[Sanborn]

I have yet to lap anything but I was under the impression you could just use very fine sandpaper w/ a little (tiny) dish soap.

[Judaeus Apella]

Yeah, but that still leaves fine scratches. I think polishing compound is supposed to be used... but the stuff that came with my dremel, didn't remove the fine scratches, or "grain", left behind by the fine sandpaper. It make it shiny and smooth, but now the surface is made up of tiny little speckles and it didn't remove the scratches from the sandpaper. I can still see a prominent grain, and scratches that now look worse. lol Maybe the sandpaper I used was too course... the number was missing but it felt fine to me. Maybe I'll buy a new sheet, and start over. :)

[ozzimark]

if you're going for best temps (which you should be ;)) don't worry about the "mirror shine", lap on a relatively thick and flat pane of glass with running water.. go up to around 1000 grit sandpaper. 2000 can be used for the extra mile, but i haven't noticed any difference in thermal performance from 1000 to 2000.

[Judaeus Apella]

Where do you buy this? I don't think I've ever seen 1000 or 2000 grit...

[vaio]

Auto repair shop should have a wide range of grits to choose from :)
*weird knowing that as I don't drive :D *

[ozzimark]

Where do you buy this? I don't think I've ever seen 1000 or 2000 grit...
a sears down the road about 5 miles from my house has it :D

[[cTx]Philosophy]

I tried lapping my 90c from 200 with dish and little water all way to 2k and it still didnt give the results I wanted, so I gave up, but have lately been wanting to retest my approach, think I might just have to check back into lapping camp..

[Revv23]

according to cathar's very in depth testing, best temps are at a 600grit finish, he was saying that a 2000 grit finish with a polish is about equal temps wise to a 230grit finish iirc.

[Judaeus Apella]

What about 3000 grit? 5000?

[Demo]

I'll stick with cathar's idea also with the 600Grit finish

[古強者死神]

Your overdoing it if you go over 1000, even 600 is probably fine.

Its not like your puting this thing directly on your cooling unit your still using thermal compound and with things like AS5 it makes the diffrence in finish pretty much null. Even in a super best case scenario you get a whole 1c diffrence. What are the chances that will effect your OC be even 10mhz?

I say there are better things to spend your time on, laping is for the people that buy very cheap prodcuts that come with obvious flaws in its surface.

[heydo6]

walmart has 2000 in auto department . i never heard of anything finer than 2000 but someone probly makes it .

[Revv23]

walmart has 2000 in auto department . i never heard of anything finer than 2000 but someone probly makes it .


finer then 2000 you have to go to rubbing compounds usually...

anyways, like i said, over 600 hurts ore then helps.

[Judaeus Apella]

10,000! http://www.xtremesystems.org/forums/images/smilies/biggrin.gif

[HaxR3]

iirc 6k is printer paper :D

EDIT=(SP)

[GAM]

Some results for you from my recent lapping-see avatar and...:
Pics 1&2 @240grit, used 400grit as soon as all copper visible surface. 3 @ 1000-1200grit. I didn't use any fluid (all dry), although I should have to reduce sandpaper clogging.

I set out, 3 - 4 1/3 sheets of various grit sandpaper on a 6mm thick pane of mirrored glass and stuck them down at either end with duct tape. The mirror is placed on a hard flat surface.

The important things are to keep everything FLAT, use even flat-motions, use each grade starting from 240,(320,360),400,600. I went to 1200 with these and I skipped 320 & 360. I shouldn't have though because it just means you spend much longer on 400.
http://www.gam.net.au/pcmods/images/3333.jpghttp://www.gam.net.au/pcmods/images/3336.jpghttp://www.gam.net.au/pcmods/images/3341.jpg
http://www.gam.net.au/pcmods/images/3338.jpg
The final polish was done after lapping the TTBT as well. It's not as good because I didn't spend as much time on each grit and the paper was clogging. However, lapping the cpu again on the clogging 1200grit served to provide more of a polished effect.
http://www.gam.net.au/pcmods/images/3487.jpg

I hadn't heard that before about 600grit being optimal. Good to know.

My recent TTBT install guide: See thread http://www.xtremesystems.org/forums/showthread.php?t=114323 and URL to guide http://www.gam.net.au/dq6-ttbt/index.htm

Cheers

[syne_24]

i could never get that perfect mirror shine with just sandpaper. So I cheated; used some brasso :D

Just make sure you wipe it clean and use some artic silver cleaner to remove any residue left.

[[XC] moddolicous]

I'll save you guys the trouble. Here's cathar's post:


Well in the hunt for the best die-baseplate thermal "connection" with my waterblock research, I've found the "best" method that I've been able to achieve, and it falls in line with what's accepted and been tried elsewhere. However, me knowing me, I don't believe stuff until I try it for myself.

Basically I've lapped bases with:

150 grit
220 grit
320 grit
600 grit
800 grit
1000 grit
1200 grit
1500 grit
brasso + strong cloth
toothpaste + cloth
fine-cut cleanser
jeweller's rouge

All in incremental steps, to varying degrees of finish from rough, to a copper finish you can shave in.

So what's worked out the best?

Go to Bunnings. Grab a small board of 12mm thick MDF (Medium Density Fibreboard). It's flat as glass and a whole lot cheaper. Should cost about $5. Pick up 1 sheet each 150grit, 320grit, and 600 grit wet'n'dry sandpaper (black colored).

Take your heatsink, and lightly scribble over the base with a black permanent marker. Color the whole base in if you want.

Stick your 150 grit paper onto the MDF.

Take your heatsink/waterblock and scrub lengthways (if the block has a longer length in one direction - otherwise just pick). Move the block up and down the sandpaper while pushing down firmly. Do not move in a circular motion, just straight up and down. You'll need 3 hands. One to hold the block, and two to hold the edges of the sandpaper down so it doesn't "grab" and fold and rip. If nature didn't supply you with 3 hands, sitting on the floor and using a foot works just as well. Keep scrubbing until you can't see ANY of the ink/black. I periodically look at the base to see how it's going, this is how I can tell if a block is initially convex, concave, or whatever. This can take anything from 1 minute to 30 minutes (or more) depending on how flat the base is to start with.

Once the ink is gone, use the 320grit and scrub cross-ways. This time keep doing it until all the cross-lines left by the 150 grit sand-paper are ground away. Just move the block straight up an down - no round motion. This should take about 3-5 minutes.

Then use the 600 grit sandpaper and moving straight up and down lengthways sand the base until the 320-grit cross-ways lines are gone (another 3-5 minutes).

Finally follow up with a circular grind of the base on the 600-grit sandpaper for about 30 seconds. Wipe clean. This should leave the base with a dull reflective surface.

You're done!

Like I said, I've tried anything from 150-grit up to a mirror polish, but the dull 600-grit finish works out the best. Surprisingly, a 220-grit finish, and a mirror finish give about the same results (at least for me), while the dull 600-grit finish gave me about 0.5C better than either of those two for a ~100W CPU load.

I know that the above has been said here before a few times, so consider this as a re-affirmation of the procedure.

[[XC] DragonOrta]

I knew you were going to pop in here with that quote, modd. I found Cathar's original post a while ago and bookmarked it, but have since reformatted the HDD.