Does mirror finish = flat?

[DerwenArtos12]

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi
IMO you can get the HSF as flat as flat can be but if the IHS is not just as flat it is a waste of time.

so he should measure the convexity of the IHS and match the heatsink to it?

Lapping is meant to join two mating surfaces. So getting both surfaces as close to the same flatness would yield the best outcome. If both surfaces are not flat and you lap only one you are only half way there. If one surface was convex the other would need to be concave to the same tolerance. For the mating surfaces of the HSF and IHS there should be some degree of roughness or unevenness to allow for the TC. If two surfaces are too flat they can be made to stick together.

By TC do you mean TIM? and what's wrong with lapping both surfaces to a pure flatness and smoothness. Theoretically if they were both perfectly flat and perfectly smooth no TIM would even be needed as it's sole purpose is to fill the gaps that would otherwise be filled with causing insulation between the two surfaces.

BTW my previous post was pure sarcasm. Lighten up a little, if you're not having fun you're wasting time, right?

I understood the sarcasm. I am completely lightened up explaining that was fun lol. Yes you are correct about not needing the TIM if the surfaces were completely flat. I just don't know how well it would transfer the heat without it. It might work better I do not know.

"damn it Jim I'm a machinist not a mechanical engineer"

I spent some time in the early 80's designing lasers for the USDOD so I'm fairly familiar with heat transfer and with creating convex and concave surfaces. With some of the higher power yag lasers we were building we had to dissipate upwards of 1000W of heat from the body of the projector and the lenses were machined in house(some by me) with tolerances in the range of 1/100th of a thousandth of an inch across an inch and a half lens. with anywhere from 3-7 lenses per laser depending on it's desired range. We knocked out 6 city blocks in tempe one night cutting a vault in half.

I spent most of my machinist career machining golf putters.

interesting. I figured they were all CNC machined, atleast for the last decade. Before that I guess it would have had to be atleast somewhat manual. Just not the kind of thing most people think about regularly. Very few people have a concecpt of what goes into making every day things, it can be pretty surprising.

 

[NinjaJedi]

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi

Originally posted by: DerwenArtos12

Originally posted by: NinjaJedi
IMO you can get the HSF as flat as flat can be but if the IHS is not just as flat it is a waste of time.

so he should measure the convexity of the IHS and match the heatsink to it?

Lapping is meant to join two mating surfaces. So getting both surfaces as close to the same flatness would yield the best outcome. If both surfaces are not flat and you lap only one you are only half way there. If one surface was convex the other would need to be concave to the same tolerance. For the mating surfaces of the HSF and IHS there should be some degree of roughness or unevenness to allow for the TC. If two surfaces are too flat they can be made to stick together.

By TC do you mean TIM? and what's wrong with lapping both surfaces to a pure flatness and smoothness. Theoretically if they were both perfectly flat and perfectly smooth no TIM would even be needed as it's sole purpose is to fill the gaps that would otherwise be filled with causing insulation between the two surfaces.

BTW my previous post was pure sarcasm. Lighten up a little, if you're not having fun you're wasting time, right?

I understood the sarcasm. I am completely lightened up explaining that was fun lol. Yes you are correct about not needing the TIM if the surfaces were completely flat. I just don't know how well it would transfer the heat without it. It might work better I do not know.

"damn it Jim I'm a machinist not a mechanical engineer"

I spent some time in the early 80's designing lasers for the USDOD so I'm fairly familiar with heat transfer and with creating convex and concave surfaces. With some of the higher power yag lasers we were building we had to dissipate upwards of 1000W of heat from the body of the projector and the lenses were machined in house(some by me) with tolerances in the range of 1/100th of a thousandth of an inch across an inch and a half lens. with anywhere from 3-7 lenses per laser depending on it's desired range. We knocked out 6 city blocks in tempe one night cutting a vault in half.

I spent most of my machinist career machining golf putters.

interesting. I figured they were all CNC machined, atleast for the last decade. Before that I guess it would have had to be atleast somewhat manual. Just not the kind of thing most people think about regularly. Very few people have a concecpt of what goes into making every day things, it can be pretty surprising.

They are run on CNC mills. Making jaws to hold them through the different stages was most of the manual machining. Typicly there are between 6 and 10 steps depending on the model. That is not including inserts and weights. Also prototypes were done a little manualy.