Dave's Guide to Lapping

[cadaveca]

Everybody's tried it almost @ one point.
I spend a great deal of time doing it each day.
So, i'll re-lap a 'sink and take you with me....

[cadaveca]

the victim will be a volcano 9.......
here's a pic of the sink after i pulled it...notice the reflection.
thermal paste and scorches included
sorry for the quality, but i am not rich.

[cadaveca]

for the faq i'm only going to use these 2 papers, as the sink had already been lapped.
both are of the wet/dry variety.
for metal sanding, it is always best to use just water as a lubricant, and to float away the particles already sanded off
i'll first wet down my kitchen table to provide "traction" between the paper and the table.
the paper get flopped on top and moved around until it starts to stick to the table.
i'll then wet the paper with about a tablespoon of water.
i'll disassemble the 'sink and start lapping.
starting @ one corner of the paper, i'll move the 'sink in circles around the outside of the paper, moving it in tiny circles whilst doing so.
think of "karate kid"....
wax on... wax off...
the "waxing off" is doing the same thing, but in the OPPOSITE direction.
as you sand away the surface you'll notice the paper start to look slightly copper coloured..this is ok..don't clean off your paper just yet. check your sink every once in a while and see how you are progressing....usually you'll seee some flat spots start to appear in the corners.

[Daniel ~]

Another front page Big C.!

http://www.aoaforums.com/

Also will copy to our FAQ section!

[cadaveca]

lol not quite done yet ..but ok!lol

while your sanding, the paper will take on a dark copper color...and that's ok.. but once you start to see shiny patches, take cloth and wipe the paper down. you should remove all of the excess copper and continue...don't forget to re-lubricate your paper!
sone people like to use dishsoap for extra "slide"..this is detrimental to lapping, as the soap will coat the surface of the paper and the 'sink, causing u to be sanding more soap than 'sink.

[cadaveca]

btw....it's ca dave ca for...canadian dave in canada..... cadaveca

[Daniel ~]

Hmm... I "Thought" (if one can call it that) The FAQ would update as you posted here, not so!

So I've removed it until you've completed your Mission.
Please PM me and I'll re-FAQ it. ":O}

[cadaveca]

so now, after i've moved to the 1500, sanded alot in circles, i still have scuffs.
to get the mirror finish on the last paper, sand in ONE DIRECTION ONLY
ie. up/down....not in circles anymore.

of course, as you are getting there with your lowest grit paper, all of the old machine marks from the factory lapping should be gone. DO NOT MOVE TO A HIGHER GRIT WITH MACHINING MARKS STILL PRESENT..YOU WILL RUIN YOUR LAPPING JOB!

[cadaveca]

here's the finished product..done in the time it took to write this ( of course the sink was lapped before, so i did not have the usualy 4 hour time-span spent removing the original machining marks

[cadaveca]

of you look closely @ the picture, you can tell that i had gone in circles, by looking @ the aluminum of the sink surrounding the copper.
here you can see were i did the lapping...notice the small bowl of water and no cloth..because the sink was previously lapped, i did not have to clean the paper, and you never should have to once it is properly lapped.

[cadaveca]

so it took me 1.5 hours to get a finish that i was satisfied with, even though it was previously lapped...so you should be able to tell how long it takes me to lap a fresh Tt sink.....usually 10-12 hours. although this may seem like alot of time for a couple of degrees, those of you who overclock to the extreme understand why i do it...besides, it helps my business when i show my customers how faulty the manufacturing process is, by renewing thier confidence in what i am capable of doing.

so....spend some time...lap your 'sink....make it shine like i have this one, and you'll get the benfits i did..higher clocks!

[danrok]

How important is the work surface? Does a table top always work just fine, assuming it's in good shape?

[cadaveca]

as long as it's smooth.. obviously i posted the pic of my table for a reason.. you can use a peice of glass, and most seem to prefer that, but i took a laser level to my table and a mirror....the table was flater.

[Gizmo]

Couldn't have been much of a difference, although that table looks to have a smooth formica top, so I could believe it is smoother.

[cadaveca]

formica...uh..i dunno what that is for sure even....
but yes it is nice and smooth...but there is a slight texture to it. not that it's enough to affect lapping, but it does allow for the paper to stick to the table with water, and the water won't interfere.

[Flarkit]

Hi Dave

Thanks for the guide!

How much pressure is required for lapping? I tried as far as possible to push the heatsink back and forth using 2 fingers, so that it's own weight was providing the downward pressure. This isn't easy though!

[cadaveca]

Originally Posted by Flarkit

Hi Dave

Thanks for the guide!

How much pressure is required for lapping? I tried as far as possible to push the heatsink back and forth using 2 fingers, so that it's own weight was providing the downward pressure. This isn't easy though!

ask and you shall receive!


the pressure is as much as you want to give....i use a fair amt...atleast 10-15 lbs i figure.
just dragging the 'sink will have you lapping until your toemail's grow up to your nose....
i just try to push the sink THROUGH the table...and i stand, so my arm is about a 45 from my body...mostly i bend at the waist.
push too hard.. and you'll never get that mirror finish perfect....so with that in mind, your best of to give light pressure, like you describe, at the end to polish it up.

[KrayZeeZ]

is that 400 grit you used as the first paper, than 1500 as the final? And when you said only 1 direction for the 1500 grit "up/down" did you mean in an up then down motion or either up or down?

[cadaveca]

i only used the 2 grits for the thread.. i normally use 400 then 600 then 1200 then 1500 and then sometimes 2000....
the difference is that when you are trying to get rid of the machine marks, you should be going in small circles....like waxing a car...and then in the reverse.
when doing your final "shine", circles will work, but you'll get a brighter, smoother finish if you go in straight lines.....up the paper and back down...on the same path (back and forth).

[BobRoss]

This is my first lapping job and I got it as smooth as I can with the 600 last night. I went out qand got some 2200 and 4000 today at lunch. They had no 1500? Anyway will I need to do the processor also? I can't imagine that it is anywhere near as flat and smooth as the synch is now?