Lapping problems

-Ad- · 5 Sep 2006 at 12:55

Hey

Spent about 4 hours lapping my x2 tuniq towers the other day and my results are... well crap. I started at 240 then worked up through 400, 600 , then a little finishing on 1000. But im nowhere near mirror shines and all that seems to have been done is just remove the machining grooves. But most importantly, whatever i have tried the lapping is not equal. The pic below shows the problems, with the red areas having a worse finish that the white area

Il try and get pics of the bases up later, but i presume that people will say that the bases are not flat, covex or concave (as the middle seems to need more lapping to get the flatnes so that the edges will be done)????

I used the guide in the link below, and lapped on a sheet of glass with a constant water flow:

http://www.overclockersclub.com/guides/heatsinklappingguide.php

Any ideas what i should do as im stumped ????????

Sir Random · 5 Sep 2006 at 13:10

1000 isn't fine enough for a really smooth finish, try 1200, 1500, and even 2000 to finish it off.

Don't worry about getting a mirror finish, as you need to use polish for that and that's counter-productive. The polish just fills tiny imperfections in the metal, which should be filled by the thermal paste for optimal cooling.

-Ad- · 5 Sep 2006 at 13:20

TA

I was just worried that the lapping isn't producing a smooth finish across either of the bases. I'm not looking at going over 1200 as the results i have seen, show that 600grit is the optimal with 2000 actually giving better results.

Im using the coolab liquid metal paste which looks like mercury and i doubt that i should worry too much about the eveness of the base. Ive just placed the cpu's on the base and it looks as though the good finish in the middle of the bases should cover the whole IHS.

I'm just a bit of a perfectionist

AFK_Matrix · 5 Sep 2006 at 13:43

Hi,

Um just a word of warning about that liquid metal, don't get it near aluminium if its the stuff I am thinking about. And be prepared to have your heatsink welded to your CPU :eek:

If you want more info look here:

http://www.xtremesystems.org/forums/showthread.php?t=111663

-Ad- · 5 Sep 2006 at 15:01

Ye cheers for that, ive seen that thread before and bought it anyway. These yanks are weaklings

Im going to use it as itl give a nice temp drop. It might be an ass to clean off, but i don't intend on switching cpu's every few hours like some of the XS guys. Once it's on with a good contact im gonna leave it on

Marci · 6 Sep 2006 at 11:37

See http://www.ocforums.com/showthread.php?t=329453&highlight=lapping+grid

-Ad- · 6 Sep 2006 at 15:25

Marci said:
See http://www.ocforums.com/showthread.php?t=329453&highlight=lapping+grid

Fantastic find. Cheers

I'm off to get my bases flat, plus one of them has got some weird dark brown colouration now :eek:

Marci · 6 Sep 2006 at 15:46

plus one of them has got some weird dark brown colouration now

Oxidisation - unavoidable really. Won't have any effect on performance whatsoever. All copper will do this, and there's no real way round it. Just ignore it. Half of the professionally produced blocks arrive with such staining anyways...

mrthingyx · 6 Sep 2006 at 16:48

Not sure on the 'accepted' wisdom for lapping, but it looks like you're getting a bevel in one of the corners of your HS. Now, not having played with A64 yet, I don't know if that corner is essential to the HS' efficiency, so forgive me in advance.

Make sure that, with each stage of lapping, you rotate your block 90 degrees. This means that you give each side equal pressure and prevent your lovely surface from bevelling.

But then, I have an automatic polisher/grinding wheel here at work.

-Ad- · 6 Sep 2006 at 19:04

Finished lapping then, and even went onto lapping the tops of the towers

The areas that havent lapped as well are still there, but won't be near where the IHS make contact. I went 240, 400, 800, and am stopping there as going further will prohhibit thermal transfer.

Il get some pics up tomorrow too.