Need help lapping a Ninja Scythe

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Just4Ever

Member
May 10, 2006
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I just got a brand new Ninja Scythe Plus and, like many others, the copper base is horrible.

I bought 400, 600, 800, 1200, and 1500 grit sandpaper and I want to lap the base but I am having trouble keeping the base flat when sanding. I have a large piece of glass that I have my soaked sandpaper on and I can't seem to move the heatsink without it catching alot and making these awful jittering bump movements.

What am I not doing right?

Please help.
 
Z

Zepper

Elite Member
May 1, 2001
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Ignore this and skip to my following post - this was an incomplete duplicate...


.bh.
 
Z

Zepper

Elite Member
May 1, 2001
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You don't need to put much pressure at all on the interface between the sandpaper and the HS - the weight of the HS itself may be too much - copper is a very soft and sticky material which is hard to work. Aluminum is much easier to work and it is all I have done personally. You might want to start with the 600 and use a couple of extra sheets at that grit 'til you start to get a flat on it - that shouldn't be quite so sticky as the 400 grit. Or you could try cutting oil or sharpening stone oil instead of water on the paper - that should reduce the stickyness a bit.

And use light strokes in a random pattern for the best results. Too much pressure in the early stages and you will get gouges that are hard to get rid of.

Perhaps G-Y will chime in. He has lots of metalworking experience. I think I'm on the right path with my advice, but if he says otherwise, go with his.

.bh.
 
J

Just4Ever

Member
May 10, 2006
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I'll work on the 600 grit then as I have two sheets of that.

It seems to be that I'm only sanding the outside of the copper base and not the middle which I would think is very bad. I'll use less pressure and see if that helps.

About how long should I spend sanding on each piece of sandpaper?

Thanks guys.
 
J

Just4Ever

Member
May 10, 2006
132
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This is got to be one of the most frustrating things I have ever done!!!

I can't get the stupid sand paper to stick to the glass. Any ideas on what to do?
To make matters even worse, the sandpaper keeps rolling up on me after I get it wet.

Also, is there someway I should attach the glass to something because that will move around as well?
 
Z

Zepper

Elite Member
May 1, 2001
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You could get some of that non-slip rubbery stuff that is used for shelf and drawer liner, jar lid grippers. etc. and use a piece of that to keep the glass in place. I generally used my free hand to keep the sandpaper in place - not that hard with Al heat sinks. You use the coarsest grit to get 'er flat, then you go up to the finer to knock out the last little bit and remove the sanding marks from the coarse paper. You don't wan't a mirror finish, you want flat - not the same thing at all.

You'll need to know how to test for flat as you go along. I use a machinist's straight edge and some of the cheap, white heatsink compound to test for flat. There are other ways that don't require any special tools - there are links in other threads here on lapping.

You don't want to remove any more material than absolutely necessary to achieve the goal.

.bh.
 
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GalvanizedYankee

Diamond Member
Oct 27, 2003
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The Ninja is quite tall and will be hard to lap by moving the sink. I'd lay it on it's side, on a damp towel and use a very flat wet sanding block. The sink would be turned ninty degrees every so often. DO NOT go beyond a well used sheet of 800 grit, it's a waste of time. You do NOT need a shine.

http://www.easypckits.com/ The PDF on the left is decent...STUDY IT... He will tell you to do figures of eight and to break back all sharp 90's....DO IT.

Now VinDSL will be along to suggest plexiglass, then MadScientest will have to chime in with misinformation, contesting everything...Betcha! :p


...Galvanized
 
J

Just4Ever

Member
May 10, 2006
132
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I know, I have heard the wars that get going on this subject.

The lapping is going much better now. I think that I was just getting impatient before.
My only problem seems to be that the middle is not sanding even like the rest of the base. And by middle I mean quite a sizeable portion (about the size of a quarter).
Does anyone have any ideas on what I'm doing wrong or any suggestions on how to correct it?
 
B

Bluefront

Golden Member
Apr 20, 2002
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Well it could be that the center of the Ninja base has a low spot......but just how did you determine the base was not flat? What you describe, that the edges of the heatsink are being sanded, and not the middle......is an indication that you are lapping incorrectly. Tape each piece of sandpaper to the glass, and use the weight of the heatsink to do the cutting.

I cannot imagine starting with a courser grit than #800........and use cutting oil, not water.
 
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GalvanizedYankee

Diamond Member
Oct 27, 2003
6,986
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Bluefront, I've lapped 6 heat sinks for CPUs and dozens of smaller anodided sinks.

The anodized sinks I start out with 320. The CPU sinks I start out with 400. Very warm
soapy water is used to float away debris/swarf. They is NEVER a need to go beyond a well
used sheet of 800.

When over hauling diesel injectors, a few drops of oil is used on those lapping blocks :D

OP, I bet you never read the PDF or broke the dead 90 edges of the HS base. :p


...Galvanized
 
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Bluefront

Golden Member
Apr 20, 2002
1,466
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Yeah....me too GY. I've seen three Ninjas, and none were bad enough to use a coarse grit. The cutting oil acts similsr to water in the lapping process, but I think it's easier on the sandpaper, with less tendency to scratch the heatsink. We're not trying for a mirror finish, but the coarse grades(less than 800) are un-necessary except for the worst cases.....certainly not a Ninja.
 
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GalvanizedYankee

Diamond Member
Oct 27, 2003
6,986
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I bought an SI-128. The base was 0.004" concave :D

I use a Starrett, pink granite lapping block next to the kitchen sink. It's 10x14x2", works like a champ.


...Galvanized
 
J

Just4Ever

Member
May 10, 2006
132
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I read the PDF but not until after I had done the damage.

On another topic, is it ok to use Arctic Silver 5 as a GPU thermal compound. I have a Zalman VF900-Cu and I want to put it on my eVGA 7900GT. The Zalman has its own but I was curious if the AS5 would be better?
 
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GalvanizedYankee

Diamond Member
Oct 27, 2003
6,986
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You might get 1.5C better performance with the AS-5.

Zalman, CoolerMaster Premium, ThermalRight and Ceramique are all good stuff.


...Galvanized
 
J

jws2346

Member
Sep 22, 2006
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Originally posted by: Just4Ever
I read the PDF but not until after I had done the damage.

On another topic, is it ok to use Arctic Silver 5 as a GPU thermal compound. I have a Zalman VF900-Cu and I want to put it on my eVGA 7900GT. The Zalman has its own but I was curious if the AS5 would be better?
Click to expand...

I have lapped a few HSF's and only one cpu heat spreader. (PD 805) I have also lapped a few northbridge heat sinks. (fans or not) I use Zallmans compound (ZM-STGI) on the northbridges, it's thinner and has a brush. I use AS5 on all my cpu HSF's. I've never had any problem with cpu temps after applying AS5 like they say to. The machines I have now are all lapped: AMD Athlon64 X2 4200+, AMD Athlon64 3000+, Pentium D 805 (mini space heater) and an old skt 2.60 GHz, 800 fsb, P4.

Edit: Most of the time you only get a 2c or 3c drop in temp. It all depends on the flatness of your HSF to start with. I've read where someone got a 10c drop, but his HSF was mucho' bado'. ;)
 
VinDSL

VinDSL

Diamond Member
Apr 11, 2006
4,869
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www.lenon.com
Originally posted by: GalvanizedYankee
Now VinDSL will be along to suggest plexiglass... contesting everything...Betcha! :p
Click to expand...
LoL! GY, you cad! (redacted -- see below)

First of all, show & tell... 3060MHz Intel Pentium 4 w/Scythe Mine 3 as I type...

Secondly, yes, a full sheet of wet n' dry sand paper (wet) on a big piece of Plexiglas -- finished off with Happich SemiChrome Polish, to a mirror gloss.

Third, clean-up everything with 100% mineral spirits (paint thinner).

Fourth, Scythe MX-1 grease.

There -- that wasn't bad, was it? :)

*edit*

Oops! I just realized... This thread is months old!

If you'll pardon the pun, GY doesn't reflect on lapping HSFs any more.

My bad! Didn't mean to get anything started... Sorry!
 
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