CPU Lapping

[MrNintend0]

Hi all, it's been a LONG time since I've been to this forum, been real busy for a while. Anyways, I've got a question, I just made a pdf of Kayin's CPU lapping tutorial just in case I ever needed to refer back to it, but I have a question for you all who have lapped your proc: What is the best thing to use for "lapping glass"? I picked up a few small sheets of plexi, but I wanted to know if it was considered "flat" enough to be used as lapping glass...

Any feedback is appreciated.

Thanks

Mike

[mDust]

Hi all, it's been a LONG time since I've been to this forum, been real busy for a while. Anyways, I've got a question, I just made a pdf of Kayin's CPU lapping tutorial just in case I ever needed to refer back to it, but I have a question for you all who have lapped your proc: What is the best thing to use for "lapping glass"? I picked up a few small sheets of plexi, but I wanted to know if it was considered "flat" enough to be used as lapping glass...

Any feedback is appreciated.

Thanks

Mike

Cast acrylic should work just fine.
I don't understand why a perfectly smooth surface would be absolutely mission critical when the sandpaper isn't going to be perfect anyway. Plus, any slack in the paper...and I mean ANY...and the surface isn't going to be flat anyhow. I used a 'reasonably' flat surface to do mine and it turned out perfectly mirrored after 2000 grit and polishing compound. It dropped the temps of all 4 cores about 3-4*C. I'd say it worked just fine.

[MrNintend0]

Thank you mDust, that's all I wanted to hear

[Kayin]

The smoother the surface you start with, the better the end result.

[x88x]

The plexi is probably flat enough but my concern would be, is it stiff enough? If the surface you set it on isn't just as flat and the plexi flexes at all, it doesn't matter how flat the plexi is. Personally, I just used a reasonably flat kitchen counter for a while but recently I started using a Lexan casserole dish. It's just the right size to fit my sheets of sandpaper in the bottom, and it contains the soapy water too, which makes cleanup a lot easier.

[Konrad]

The boys at the shop generally consider window glass "true" enough for all but the most demanding tolerances. And they're machinists, their ideas of "perfectly flat" are quite particular.

[MrNintend0]

Alright, thanks guys. I thought it would work out, but I see what you mean by it may flex to much. I tried gluing two pieces together (at the sides, so I won't have any space between the two) and it didn't work out as well as I planned... I guess I can take them apart and use them for something else... Guess I'll be heading back to the store to get a small mirror or something...

[mDust]

Alright, thanks guys. I thought it would work out, but I see what you mean by it may flex to much. I tried gluing two pieces together (at the sides, so I won't have any space between the two) and it didn't work out as well as I planned... I guess I can take them apart and use them for something else... Guess I'll be heading back to the store to get a small mirror or something...

Just put the acrylic sheet on a table or something. The table prevents flexing and the acrylic provides a smooth surface.