Should I lap my heatsink?

[GalvanizedYankee]

Refuse to scrawny. I'm just responding to treatment from the Lego builders, children of the corn. Wrong is wrong when talking about cutting, welding, lapping, or tool use in general.

Stick around and really help some ppl before getting on my case, you member w/o a profile


...Galvanized

 

[Praxis1452]

ok galvanized. What EXACTLY is the best way to lap a heatsink? I'm just wondering...

 

[GalvanizedYankee]

Study the PDF on the left http://www.easypckits.com/
Every paragraph is important. I disagree with him on several points.
Use full sheets of wet or dry. Used 3/8" Plate glass or sometimes cultured marble
can be found that is near dead flat. Check any lapping surface with a machinest rule first,
before buying it. There is no need to go beyond 800 grit. 1200 grit will grab a flat surface
like super glue. A well worn sheet of 600 or 800 will do nicely. Do not buy/use cheap
China brand wet or dry. Use a Sharpie to mark the base with big X's to give an indication
of where material is being removed. A very damp towel folded in two will hold the lapping
surface steady on a kitchen counter top. Start with 320 grit and light pressure. Move to
400 grit before the surface is flat. Then move to 600 grit just as flatness is being
achieved.
NOTE: In the PDF he tells lappers to chamfer the edges and use figures of 8.
Not back & forth like in Howard's link.

Google, checking flatness and read.


...Galvanized

 

[VinDSL]

Originally posted by: scrawnypaleguy
Galvanized, how old are you? Grow up, man...

Galvanized is okay Scrawny! He's knows a LOT about sandpaper and stuff!

He's just mad about something...

 

[skooma]

Originally posted by: VinDSL

Originally posted by: scrawnypaleguy
Galvanized, how old are you? Grow up, man...

Galvanized is okay Scrawny! He's knows a LOT about sandpaper and stuff!

He's just mad about something...

Naw, I don't think he's mad about anytihng, he just doesn't suffer fools well.

More people here should realize that "its better to say nothing and appear a fool than speak and remove all doubt" (or however that goes).

Galv, Zep, jonnyG, Zap etc are great to deal with. Know why? They don't give simple answers. If you want to learn, then do your homework. They point you in the right direction.

 

[Injury]

Originally posted by: GalvanizedYankee

Originally posted by: Injury

Originally posted by: VinDSL

Originally posted by: Zepper
You don't want a "mirror finish" on a heatsink...

Heh! Yes, I do...

The more 'mirror-like' the surface, the less the imperfections. Less pits and scratches mean better heat transfer with less thermal compound. It's a win-win-win situation, IMHO!

... I see your point, but I don't believe that lapping heatsinks to a mirror finish really benefits. If it did, why wouldn't all of the companies that strive to have the best heatsinks lap theirs to begin with?

Originally posted by: scrawnypaleguy
I heard you weren't supposed to change directions while lapping. Aren't you just supposed to go one way the whole time?

This is mostly true. Whenever you are sanding anything, you are really just replacing the tiny ridges with smaller ridges. If you change directions, you hold the potential to put deeper ridges in spots as you cross over the old ones.

I say "mostly" because it's safe to change directions AFTER you've finished going in one direction. The main point is that you don't want to just plop it down and try to go as fast as you can moving it any which way.

Controlled strokes in one direction will show much better results than doing it any other way. When you change grits, do the same pattern, but the opposite direction. (IE, start north to south, change grits and do south to north.)

Be certain you aren't pressing really hard, either. You want to let the sand paper do the work. Press hard and you can leave gashes in the thing. You have to understand that most heatsinks have copper bases, and copper is a VERY maleable element, so it will respond harshly to excessive pressure.

You have NO idea what you are talking about

...Galvanized

I have to polish metal samples at work to a mirror shine to view them under a microscope. Are you aware of what the ridges left by abrasive materials looks like when you view it under a microscope? Using same direction strokes, it will polish to a mirror finish. Using swirls or multi-directional strokes will leave it cloudy, and really just makes a mess of things.

So I'll agree that heatsinks may be different, but I do know how to polish metals. You're welcome to point out the things in my post that you don't agree with, but simply telling someone that they don't know what they are talking about (When you apparently don't know who you are talking about) really doesn't prove your point.

Thanks.

 

[GalvanizedYankee]

Injury,

My brother is a metallurgical engineer, I have seen the process of mounting metal specimens in plastic, then polishing them on abrasive diamond dust wheels. I have seen a spectrograph in operation. I have been in the same room with an electron microscope. I have seen a 600 ton steam press forging Naval gun barrels out of hot ingots.

The reason one does not lap by going back & forth is because the hands natural tendency is to make a sphere. Did you read the PDF from easypckits?? It's explained there. The piece must be rotated every so often during figures of 8. Polishing is not to be done as the agents used will clog the pores and this is where we want TIM to migrate. A reflective surface can be had with a well used sheet of 800 grit.

NOTE: Always check surface flatness before lapping, as not all sinks need it.


...Galvanized

 

[Howard]

Yikes, metal porosity...

 

[scrawnypaleguy]

Originally posted by: Howard
Yikes, metal e-penis

fixed.

 

[VinDSL]

Okay, today was the day... OMG!!! I hate this Scythe Mine 3 [pronounced ME-nay] mount system!

Anyway, keeping in mind this isn't a scientific dissertation or a product review -- the satin finish produced, after bedding-in the Scythe MX-1 thermal paste through several heat/cool cycles, 40C (give or take), according to PCWizard. That is, ever time I looked at the temp, during many hours of 'normal' operation, it was always 39.6~40.1C -- days, nights, and weekends...

I just cleaned up the sink, 'polished' it with Simichrome, applied new MX-1, and slapped it back together. So, we'll see what happens...

LoL! BTW, I found a good ancillary usage for this MX-1 thermal paste!

I don't know about your computer, but installing a HSF in this monster is easiest if you remove the vid card and RAM. MX-1 is rather 'thick' and I always have a problem getting the chassis screw back into my ATI 9800 Pro mount. The hole doesn't line up exactly with the slot in the card, and I have to mess around with it, aligning the slot with the hole by pushing the edge down with a screwdriver. Invariably, the screw falls out, every time I put it in the hole. This time, I used MX-1 to adhere the screw to the screwdriver head. Worked like a charm!

So, here's to swimming with bow-legged women!

 

[VinDSL]

WoW! This is encouraging!

Up n' running for an hour, and it's stabilized at 36.5C. Something must be wrong!

I'm gonna go run Quake 4 for a while, even though I don't feel like it. That'll warm it up!

 

[Howard]

I get the idea you're trying to rub that in my face.

 

[scrawnypaleguy]

Good to know that my temps are at least better someone's.

 

[VinDSL]

Originally posted by: Howard
I get the idea you're trying to rub that in my face.

Heh! I've got a strange sense of humor, or so 'they' say. I thought it was a cute saying (put it in my profile too), but yeah, I'm pulling your leg. I'll stop, if you want...

Actually, I did a little checking, and the Sycthe Mine 3 is named after Mine City, Yamaguchi Prefecture, Japan [pronounced ME-nay]. I *guess* they have some sort of racecar circuit there, or they did. Mazda bought a couple of the tracks and does a lot of car testing in Mine City... kinda like their Daytona, or whatever.

Anyway, I ran Quake 4 for a half-hour, then someone IM'ed me, so I had to break it off (was losing anyway) -- 38C when I finished, so this thing is rocking'!

I'll give it a couple of days. It should get better though, from my experience...

 

[VinDSL]

Originally posted by: scrawnypaleguy
Good to know that my temps are at least better someone's.

I'm in Arizona, and it's hotter than Haides here -- probably 80F+ in this room, so don't read too much into those numbers -- back down to 37C already!

 

[Injury]

Originally posted by: GalvanizedYankee
Injury,

My brother is a metallurgical engineer, I have seen the process of mounting metal specimens in plastic, then polishing them on abrasive diamond dust wheels. I have seen a spectrograph in operation. I have been in the same room with an electron microscope. I have seen a 600 ton steam press forging Naval gun barrels out of hot ingots.

The reason one does not lap by going back & forth is because the hands natural tendency is to make a sphere. Did you read the PDF from easypckits?? It's explained there. The piece must be rotated every so often during figures of 8. Polishing is not to be done as the agents used will clog the pores and this is where we want TIM to migrate. A reflective surface can be had with a well used sheet of 800 grit.

NOTE: Always check surface flatness before lapping, as not all sinks need it.


...Galvanized

My dad is a metalurgical engineer. I work where I do because of him. My job requires that I mount metal samples in plastic and polish them. I use a spectrograph every night. I haven't been in the same room with an electron microscope, but that really has nothing to do with lapping heatsinks.

I do not use any chemicals to polish my samples. I start out on a grinder that is probably about 60 grit, then move to a buffer with 120, 240, 400, then 600 grit paper. Then I shine it up with non-abrasive felt cloth and a tiny bit of alcohol.

I most commonly do this to check the nodularity of iron samples to ensure that the magnesium that was added was fully mixed into the molten iron before parts were poured. The place I work at primarily makes iron castings, but I do have to check other metals from time to time as we do pour special parts for customers, some of which are copper-based.

Not trying to turn this into a pissing contest. I trust your opinion as it sounds like you've applied this knowledge to heatsinks more than I have, but it's no fair to tell me I have no idea what I'm talking about when I do stuff like this on a regular basis.

 

[VinDSL]

Day Two: Well, this thing is hovering around 35C now -- down from 36.5!

Scythe MX-1 thermal compound is kinda weird -- thick and dry (like dried-up tooth paste) -- and takes around 200 hours to burn-in, according to Scythe (and I believe it). During that time, temps will usually drop 2~3C from start-up.

I don't know if it's like AS5, requiring cooling cycles, but I've been turning off my computer when I'm asleep, just to play it safe. I suspect all I'm doing is prolonging the burn-in period though. I ran it for several days, with the satin finish, and it was still tacky when I disassembled the HSF -- no where near burned in.

Heh! MX-1 is industrial-strength stuff!!!

I suspect I'm going to end up around 34C, when all is said and done -- considerably better than the satin finish, in this impromptu and unscientific test...