Quick Lapping Question

[grunjee]

First off, I did a search and skimmed/read through several threads about lapping, including Maximus Nickus's and Hoot's just to name a few, so go easy please :)

I didn't see the answer to my question though. I'm a complete n00b to lapping and tried it for the first time this evening on a (POS) Coolermaster Heatsink (chosen because if I screw it up, no loss). I want to do my Maze2 tonight also.

So I bought some 600 grit and had at it for about 20-25 minutes. Seemed to be getting smoother. Washed it off, cleaned it, rubbed it with my fingers, seemed a lot better.

But I noticed I could still see some lines. Some of them are from the sandpaper, but some appear to be the machine lines. Now, I'm not going for a mirror finish, just a flat one. I (gently) scraped my fingernail several times across the bottom of the HS, and could not feel any of the lines I see.

So, did I do it good enough? Or do I need to remove more of the HS bottom, until I can't even see the lines anymore?

Thanks in advance. :)

[cack01]

I would go for a bit finer grade for a finished product. I usually use three grits. 400, 600, and then up to 1500. I feel 600 is a little too ruff, try 1500 or around that area 1200 will do and I think the lines you see will go away; and even if you don't care about it you might start to see a mirror finish.

[grunjee]

Originally posted by cack01
I would go for a bit finer grade for a finished product. I usually use three grits. 400, 600, and then up to 1500. I feel 600 is a little too ruff, try 1500 or around that area 1200 will do and I think the lines you see will go away; and even if you don't care about it you might start to see a mirror finish.


Thanks for your reply... I really do appreciate it... but I can guarantee you, a bunch of guys are going to come in here and say, 'You don't need any higher that 600 [possibly 800]' :D

[See, I did do a search] :D

[Yodums]

Originally posted by grunjee



Thanks for your reply... I really do appreciate it... but I can guarantee you, a bunch of guys are going to come in here and say, 'You don't need any higher that 600 [possibly 800]' :D

[See, I did do a search] :D

You should start from 200 and move up. I think there is no difference, people just reported they saw better results from 600 than higher grits. I'm thinking your start was a little bad (Make sure your lapping on glass), and that the other aren't being sanded down because it's still uneven. Start at 200, then go 400, and then 600, your choice if you want to go higher but those are the basics. Do not move to a higher grit until it is completely flat on the 200 grit. Hold it on the base and not the fins or it will create a concave base. I really like Hoots method, it works great.

[cack01]

Originally posted by grunjee



Thanks for your reply... I really do appreciate it... but I can guarantee you, a bunch of guys are going to come in here and say, 'You don't need any higher that 600 [possibly 800]' :D

[See, I did do a search] :D

I can understand what you mean, i was just thinking that if those machine are small enough for your nail not to feel them then it might be possible to get them out with a finer grit. But you are 100% right on the 600 being the finest you need. I never see any temp difference between anything after 400.

[grunjee]

Ok, thanks for the replies... I just want to make sure though... because no one explicitly said it ----> so I DO want to get rid of the lines (ie, so I can't see them), right?

I was doing it on glass... I thought I was doing it right... who knows... but I went out and got some 200 and 400 grit, so I'll start over with the 200 and see if it helps.

[Yodums]

Originally posted by grunjee
Ok, thanks for the replies... I just want to make sure though... because no one explicitly said it ----> so I DO want to get rid of the lines (ie, so I can't see them), right?

I was doing it on glass... I thought I was doing it right... who knows... but I went out and got some 200 and 400 grit, so I'll start over with the 200 and see if it helps.

Yea, if possible try to find 3M wet/dry sandpaper because it's the best brand. The quality of the sandpaper does matter because I remember lapping with a bad quality sandpaper seemed to add some weird patterning to my heatsink!

Just remember, start off slow and with pressure and then move it without pressure and fast since at the start you want to get it flat and the pressure does that. At the end you want no scratches so ya the fast and no pressure just takes off the extra scratches.

If you have questions about anything, don't hesitate and post it because you don't want to lap it twice.

[CrystalMethod]

Yeah, if you can actually see the lines, then there's a groove there. I'm not saying that you will get a significant desrease in temps. Just that being able to see the machine marks is an indication that the surface isn't completely flat. As for grit of the sandpaper, I wouldn't go past 800. There's nothing to be gained from going any further, unless you're willing to lap you're CPU as well, and have the equipment to make sure that the two surfaces mate perfectly.

[grunjee]

Well, I don't know what my problem is :(

I put in about 10 minutes with the 200, and the same with the 400... again, it feels flatter/smoother, but I can still see all kinds of lines (sandpaper only - not machine).

One problem I'm having is that when I'm lapping, the block seems to 'skip' around a lot. Like for an instant it loses contact with the sandpaper... like it hits a speed bump or something. I've tried applying varying amounts of pressure, water (w/soap), etc. and can't seem to control it.

This may or may not be the cause of my problems, but I think the stuff (sandpaper) I got might be cheap. I got it at a local hardware store and it's called 'Gator Grit'.

[hellrazrblade]

i lapped my hcc001 2 days ago. it dropped my temps 7f so i obviously did something right :D anyway, i started with 400, went until i couldnt see a difference after lapping for a few minutes (the marks were all from the paper). It was probably 15 minutes and alot of copper flakes later that i was satisfied (this heatpipe has a really poor finish). i moved on to 600 until the same thing happened. then i went on to 1000 grit auto paper. i got a good FLAT surface that had okay reflective properties. i'm going to go get some 1500 tomorrow and make it a mirror.
i think the reason people are getting "better" results with low grit paper like 600 or so is because they didnt gradually increase the grit, but went after the heatsink with the high grit immediately. this would accomplish very little because the paper is only contacting a few areas and is removing only tiny bits. also, cleaning the paper off during lapping is VERY important. i learned that two days ago. one big flake can really scratch things up.
anyway, sorry about the long post, but i thought this info might help someone. :)

EDIT: grunjee, i had problems with skipping around too. i was using 3m paper, so i guess its good stuff. i found that changing the amount of water on the paper changed how much it skipped. so i messed with it a little and found the 'skip free point'. which for me was either with zero water and the paper taped down very well, or with standing water on top of the paper.

and yes, get rid of the lines, if for nothing else but pride and .5F hehe

[grunjee]

hellrazrblade --

Thanks for your comments, I appreciate them.

I was contemplating lapping without water, but everyone here seems to say to do it with water, so I didn't try... but tomorrow I think I will.

As for cleaning the paper, I've been cleaning it like after a minute or less of lapping. There's all kinds of buildup and I've been wondering if this is normal or a sign of the cheap stuff...??

[hellrazrblade]

i had buildup even with cleaning it in water every minute or so. mine turned out fine, so yours should too. i think that the stuff that you aren't able to remove from the paper is embedded deep enough in the paper that it will not touch the heatsink. that would mean that it wont hurt anything. (but of course thats just my opinion) ;)

[grunjee]

What I mean, is, I'll lap for 30-60 seconds... then I see all this buildup -- dirt-like stuff all over the paper. I'm pretty sure it's the sand just grinding down, coming off.

Well the bottom line is, after 5-10 minutes of sanding on a sheet, all the sand is gone, and my heatsink looks no better (it looks worse in fact).

Is this normal? -- that even good sandpaper wears down this quickly???

Also, I went to Home Depot this afternoon and they didn't have any 3M. :( They had some other stuff which I picked up, but haven't tried it yet. It looks a lot like the other stuff though. :(

[Iron Hawk]

I recomend using wet/dry sand paper. I usualy wetsand my hetsinks, and I get my sandpaper from an auto store, they usualy have up to 3000grit, but i never bother lapping past 800 grit, usualy only to 600grit.

[CrystalMethod]

Originally posted by grunjee
Well, I don't know what my problem is :(

I put in about 10 minutes with the 200, and the same with the 400... again, it feels flatter/smoother, but I can still see all kinds of lines (sandpaper only - not machine).

One problem I'm having is that when I'm lapping, the block seems to 'skip' around a lot. Like for an instant it loses contact with the sandpaper... like it hits a speed bump or something. I've tried applying varying amounts of pressure, water (w/soap), etc. and can't seem to control it.

This may or may not be the cause of my problems, but I think the stuff (sandpaper) I got might be cheap. I got it at a local hardware store and it's called 'Gator Grit'.

Actually the skipping around like you describe is an indication that the surface is becoming increasingly flat. It's a little hard to explain. The two surfaces are becoming flat enough that they will, with the aid of water, stick together. You definately don't want it to be skipping around, but at that point it may be already flat enough. When I get to this point (I usually do this outside), I run water on the sand paper as I'm lapping, with a hose.

[grunjee]

So I take it that if it starts skipping, I need to use more water...?

[madcow235]

don't mean to intrude on your thread but i hear rubbing compound used to get rid of scratches worke on about everything. anyone ever tried it on a sink it brings the scratches to that of 5000 grit sandpaper. IMO that would be very nice very very very nice :D

[Voodoo_fx]

hrm, I lapped up to 600, should i lap my waterblock with a higher grit?

[cackle]

What's the whole thing about doing it on glass?

[grunjee]

Glass is uber-flat, and that's how you want your heatsink, so it's a choice material to lap on.

Update... I tried the stuff I bought at Home Depot tonight... and it seems to be better than the crap I had last night... but I am still having difficulties. I can't seem to get rid of the marks... although tonight they seem much smaller and finer. Again, I worked up from 200 to 400 to 600.

[ezeKieL987]

yea so can u expalin the whoe glass thing in a little more detail...like do i use it to measure how flat the bottom is?...imma newb to this whole lapping thing and am just learning...i want to do this cause ive seen people post there temps dropping 6-7 degrees celcius...also, i just rub across the bottom of the heat sink with the paper using my hands right??? i just want to get this all down...and if one of u more experienced people have some time...id like to talk to someone more in detail about this....like through a pm or something...i have been into overclocking some, now this stuff interests the heck outta me...and i just want to learn, learn, learn!! and have the fastest possible....i got the overclocking bug BAD!!! just look at my bank account activity..tells it all! :eek:

[Emericana]

for me i start at 600 if the base is flat

i go 600-800-1000-1500

i do each for 30 mins usually around 1hr on 600 tho.

if the base is a little concave i start at 400

if it is killer concave (coolermaster heatsinks) i start at 200

[hellrazrblade]

my heatpipe was really convex, so i started with 400, then 600, then 1000, i still cant really get a good reflection out of it unless i get at a really low angle to the surface... but thats a different subject. The little marks arent going to go away, theyll just keep getting smaller as the grit gets higher.

[grunjee]

I got another question for you lapping experts.

How do you secure the sandpaper to the mirror?... I had a hard time keeping it from slipping/sliding around. I tried tape, tried just wrapping the sandpaper completely around a smaller mirror, etc. and I couldn't seem to keep it under control enough.

Wait... ANOTHER question.... how long can you lap on a typical sheet?... I had a hard time telling whether all the sand was gone on a sheet or if there was still some left.

[hellrazrblade]

if its a new sheet of paper, it should definately last through like 3+ lappings, so dont worry about that. just keep it cleaned out. i used regular scotch tape on the corners and sides.

uh... what happened to my sig? ... it was green and had my truck's specs...

[grunjee]

Originally posted by hellrazrblade
if its a new sheet of paper, it should definately last through like 3+ lappings, so dont worry about that. just keep it cleaned out. i used regular scotch tape on the corners and sides.

uh... what happened to my sig? ... it was green and had my truck's specs...


Ok well, supposedly you're supposed to use quite a bit of force, at least at first right? That was my problem... I used force, the thing would slide around like crazy.

I guess I don't see how scotch tape could withstand that much force... it certainly didn't for me. I must be doing something wrong.

[#13]

You might try duct tape -- it's pretty much the mother of all tapes, and should resist the water (at least until you're done lapping). As far as the paper goes, if it starts losing sand, you're probably pressing too hard. Let the sandpaper do the cutting, and you'll notice everything is easier to control -- use your effort controling the hs, instead of pressing down. And be patient. The scratches could be from the "sandless" paper, because the sand left on the paper will keep cutting, while the sandless areas (obviously) won't. Good luck to you, and keep the questions coming -- as another noob, it's nice to have people iron things like these out a little for you before you try it yourself...

[hellrazrblade]

yeah, you really dont need to (and probably shouldnt) be pushing down on the heatsink any more than it takes to keep the heatsink level. the paper probably wont 'grab' as bad if you make sure there isnt standing water on the paper, damp is good, just not standing water (unless you have it completely covered in standing water, then it will slide just fine)

edit: and yes it is nice to have people iron it out for you first, i would know because i hadnt done or known about any of this junk until a month ago, now i have an unlocked xp, a lapped heatpipe w/ fandapter and a 120mm blowhole in the side of my case. hehe, quick learner i guess

[grunjee]

Hmmm well thanks for the info. That was probably much of my problem -- applying too much pressure. At times I was almost exhausted, I applied so much pressure.

The reason I *did* that though was because someone said it was necessary (to apply a lot of pressure).

Think I'll grab some duct tape the next time I'm out... and give this lapping stuff another try.

[JFettig]

use some dish soap as lubricant, i had a MIRROR shine at ALL angles once using 600 grit sand paper, then i saw a waterspot that i couldnt rub off so i figured id sand it out.. never saw that mirror again:(

but lapping a heatsink shouldnt take hours and hours, i take about 30minits to 45minits on a new waterblock that i just make.. and i get awesome results... unless theres a deep scratch in it

[Yodums]

Yea you skip the heatsink because uneven pressure is applied to different areas of the heatsink and may create a concave base. Like maskedgeek, I used Hoot's method and used a few drops of dish degergent w/ a container of water as lubricant and hold the heatsink down by the base. Holding down by the fins will create a concave base.

[grunjee]

Originally posted by Yodums
Yea you skip the heatsink because uneven pressure is applied to different areas of the heatsink and may create a concave base. Like maskedgeek, I used Hoot's method and used a few drops of dish degergent w/ a container of water as lubricant and hold the heatsink down by the base. Holding down by the fins will create a concave base.

This is also confusing to me... how do you hold it by the base? I'm guessing the 'base' does not mean the bottom, correct? Because that way you'd be lapping your fingers along with the HS :D

I'm guessing it means on the two sides of the HS that are 'solid' as opposed to the two sides where the fins are visible...?

[grunjee]

Ok, update.

I found some duct tape out in the garage and went to work. I just gone done lapping for about 20 minutes with 600 grit.



Someone said in one of the lapping threads I read that it's not possible to achieve a mirror finish on an Alu HS. After my lapping job tonight, I am able to see myself in it perfectly... I could, and just might, use the thing as a travel mirror someday. However, there are still several 'circle marks' or 'scratches' on the base of the HS. I can't feel any of them so I don't know that they'd hurt performance too much but I'm still wondering how I can get what appears to be a mirror finish with lots of visible circles.

[hellrazrblade]

wow, sounds like an excellent job. what was your final grit#? and did you use detergent? just curious cuz i might finish my HS some day.

[grunjee]

Originally posted by hellrazrblade
wow, sounds like an excellent job. what was your final grit#? and did you use detergent? just curious cuz i might finish my HS some day.

Well thanks for the compliment but I'm not so sure it's an excellent job, seeing as how I can still see lines... but hopefully Yodums or someone else who's had experience can clear this up for me. :)

My final grit was 600 (would like to try 800, maybe someday I will). And I did use water with dish soap.

[hellrazrblade]

good to know, i guess that i just didnt go long enough with the 1000 or something, i bet the soap helps too. i doubt the little lines are hurting anything because mine looked pretty rough even though i couldnt feel anything with my fingernail. then again, copper is alot softer, so it probably behaves differently.

oh, how can you get a concave base? isnt that impossible with a flat surface? you could end up with a convex base by rounding off the edges. but a flat surface has no way to come into contact exclusively with the middle of the heatsink bottom. please correct me if i'm wrong because i must have a really bad mental image of this. i'll draw up a picture... just a sec

[hellrazrblade]

here: forgive my paint skilz, but is that what you're saying will happen if i dont hold it by the base?

[cack01]

I think you can get a concave up look if when you lap you put too much pressure on the sides of the sink, or you don't apply even pressure to all four sides.

[hellrazrblade]

may be, but i really can't figure out how, because the middle can only be rubbed if the edges are rubbed, meaning that it can't be rubbed more than the edges, meaning it can't go concave because... well you just saw the logic i think... maybe... or maybe lack of school is rotting my brain.... ok, we'll forget i said that ;)

[Yodums]

Holding by the base, hm is at the bottom, where the fins aren't. If you hold by the fins you'll bend them and grab them and will cause a concave base. Aluminum is hard to shine, copper you'll see it within the first grit.

[DodgeViper]

1. Use a piece of flat glass as your work surface (it must be very flat, and supported well)

2. Use waterproof sandpaper (sometimes called wet or dry)

3. Use lots of water (several cc at a time, the water flushes the metal particles away, keeps the sandpaper clog free, and makes it stick to the glass)

4. Depending on how flat and smooth your heatsink is, expect to spend 30 minutes or more at this work (I do it on a glass coffee table top in front of the television - you don't even have to watch the work [of course, if the show is bad enough, you can watch the work, and finish faster])

5. Use a relatively light pressure on the workpiece and move it in a circlular motion across the sandpaper; try to keep an even downward force on the workpiece and avoid digging in the edges or corners. Rotate the heatsink 90 degrees approximately (NOT exactly) every dozen or so strokes.

6. If your heat sink is relatively flat and smooth, then 400 grit is a good place to start. If after ten minutes of work you do not see much progress (there are many pits larger than the surface roughness left by the 400 grit sandpaper), drop to a lower number grit (320) or (260).

7. Using finer grit sandpaper will help improve heat transfer: 1500 is certainly fine enough, but since you need to get such fine grades at an automobile parts store (it is used for finishing automobile paintwork), you might as well get a sheet each of 600, 800, 1000, 1500, and 2000. The more coarse grits are easy to find at a paint or hardware store 40, 60, 80, 120, 180, 220, 280, 320, 400, 600. (Grit # 40 will take the portrait off a franc coin in a minute or so; the average heatsink with faint circular milling marks can probably be started at 320.)

8. The work can be completed in less time if you step up through each grade, removing all the pits left by the previous grade before moving to the next finer grit.

9. Each time you change to a finer grit, VERY carefully wash the work surface, your hands, the heatsink, and the sandpaper. Any larger grit left when you start with a finer grade will leave visible scratches.

10. The waterproof (or wet/dry) sandpaper will last a long time. After you are through with the work, wash the sandpaper and let it dry. You can reuse it many times as long as it is not torn.

11. As an example of how fine 2000 grit is, you could use it on Mercedes paintwork and almost not notice an effect other than the missing wax polish.

12. Do not use too much pressure when sanding the heatsink; you want a flat as well as a smooth surface, and too much pressure can cause one edge or corner to be ground down more quickly (that is one reason for occasionally rotating the heatsink a random amount.) Too much pressure may also cause a corner to tear the sandpaper. If you do not tear the sandpaper, one sheet of each grade should last through ten or more heatsinks.

[Yodums]

Awsome tips Dodge Viper however I go in circles. I start off with slow circles, big ones, and lots of pressure, as I get to the end it gets faster and less pressure since you are using a finer grit and you don't want to scratch it.

[grunjee]

DodgeViper you are the man! Thanks so much for your post, that's exactly the kind of detailed info I've been wanting to see.

Much appreciated... I almost want to say we should make a sticky out of your post.

[DodgeViper]

This is the rewards of lapping with finer grit paper. Yodums I will correct want I mentioned above. You should lap using a circlular motion.

[Yodums]

Originally posted by DodgeViper
This is the rewards of lapping with finer grit paper. Yodums I will correct want I mentioned above. You should lap using a circlular motion.

Ditto also the quality of the sand paper matters. I picked up some brands I didn't know, they put more scratches than before on the heatsink, hmmm... I would recommend 3M Sandpaper.

Is that an Alpha PAL8045?

[grunjee]

D-V

One word... WOW. Nice work.

[hellrazrblade]

i found that figure 8's work better than circles, but thats really pretty minor. and as for the concave base, there is no way that you are going to bend that 1/4" + plate of copper with your bare hands... and bending the fins has nothing to do with the base... if anything, bending the fins in would cause the outside edges of the base plate to bend upward, making a conVEX surface unless theres a law of physics in play here that i havent heard of.

a rough and exaggerated example

[DodgeViper]

Yes that is a Alpha 8045. I am now water cooling though.