Lapping heatsink - Which surface?

Noto · 9 Aug 2007 at 09:36

Hi all,

I have read a few guides that advise the use of a piece of glass or mirror. I cannot get hold of those atm but what i do have is a laptop screen from a broken laptop (the screen has a hairline fracture on one corner) Would this be just as flat as a piece of glass or mirror?

thx in advance

noto

DaveMac · 9 Aug 2007 at 09:48

The mirror/glass is to ensure that the surface is flat and won't flex when light pressure is applied.

Unless the screen has has a glass front I'd use a kitchen worktop as next best alternative, check that it is flat by testing with a straight edge.

simonnance · 9 Aug 2007 at 09:49

i have a glass chopping board i use, glass is good as unlike metal or plastic it is very brittle, no flexing or bending under stress (though try not to break it).

If all else fails, try using a flat worktop in a kitchen or workshop, or anything totaly flat with a good amount of thickness to it.

you laptop screen prob isnt the best bet as the pressure you will put on it to get enough friction to lap will damage it further, and due to the thin nature of lappy screens probably deform the surface quite badly.

w3bbo · 9 Aug 2007 at 10:16

Glass out of a picture frame or a mirror.

Noto · 10 Aug 2007 at 12:58

how about the base of a pasta bake dish? ^^

also a quick question, do i want to soak the wet n dry paper or just poor some of the solution on top?

welshboyo · 10 Aug 2007 at 13:21

Noto said:
how about the base of a pasta bake dish? ^^

also a quick question, do i want to soak the wet n dry paper or just poor some of the solution on top?

Highly doubt that dish will be "flat"

Just put some water on top of the sandpaper

helmutcheese · 10 Aug 2007 at 14:13

They really REC thick glass ideally 4-6mm or marble to be sure its flat.

fornowagain · 10 Aug 2007 at 14:23

simonnance said:
i have a glass chopping board i use, glass is good as unlike metal or plastic it is very brittle, no flexing or bending under stress (though try not to break it).

Mirror glass or window glass is best, its comes from a float process and is very flat. Molded glass, usually with textures like chopping boards could be miles out. And thin glass will bend, use ideally 4-5mm thick and supported. There's flat and there's flat, proper flat is a granite or cast iron metrology surface. Most HSF will have at least a milled surface, better ones are done on a surface grinder. Watch out you don't just make it worse.