contact lapping

[Nikea Tiber]

Since my search delivered no useful results, I've got a question for those of you perusing the mech section.
If you have lapped (hand or otherwise) the contacts on your mech, did you run a resistance test before and after?
My copper cb clone finally arrived and I lapped all the contacts when I had it apart for its second cleaning. Since my fluke dmm is broken since I loaned it out I didn't get to test out its resistance/vdrop before and after. It certainly feels like it hits a lot harder, but I can't discount the placebo effect.
Anyone else's experience? Has lapping your electrical contacts made a difference at all?

 

[Johntodd]

I've often wondered why there isn't a whole "lapping community" on this forum.

As an old computer guy, I know exactly how effective lapping can be for conductivity. I still lap my CPU/heatsink interface by hand. Makes thermal xfer much better, keeping things cooler.

Lapping contacts on a mech (or otherwise) mod would increase conductivity.

Nikea, you may have started a whole new thing with this thread.

C'mon everyone, join in!
-Johntodd

 

[Nikea Tiber]

Those are the exact reasons I lapped all the contacts. I used to do the same thing for my CPU heatsinks 15 years ago when consumer manufacturing quality wasn't quite so high. Since my clone was milled in China, I figure there could be a bit to gain. I just wish I had an operational dmm to quantify it.

 

[duc916]

Copper threading is tough to keep clean, so most of your losses are in there anyway. All the better mechs have silver plating,which you can't lap. Lapping is good for making a throwaway mech a little more usable.

 

[Mike 586]

Copper threading is tough to keep clean, so most of your losses are in there anyway. All the better mechs have silver plating,which you can't lap. Lapping is good for making a throwaway mech a little more usable.

For threads just one of the high temp anti-seize lubes out there loaded with copper flake for threads on copper. There are also silver flake versions. They're conductive, don't run and most are designed to withstand stupid high temperatures without running or breaking down.

I've often wondered if things like Arctic Silver were just repackaged anti-seize compound...

..oh yeah. I know a lot of guys use noalox, but that stuff is designed specifically for aluminum conductors and aluminum rigid conduits to cut into the oxide layer and prevent it from re-forming. I wouldn't use the stuff on straight copper, brass or SS.

 

[duc916]

Makes more sense to me to use an anti-oxidant like Ox-Gard. In my Infinite SMPL clone, subohming around 0.35 ohm daily, I used the same coat of Ox-Gard in its (brass) switch for about 6 months with no noticeable drop in voltage. I only cleaned/relubed it because I felt like it. When I wiped it clean, I saw no oxidation whatsoever, as intended. Seizing has never been a problem because it rarely gets warmer than my hand.

 

[Eric Auer]

I call BS. Lapping will not make any difference.

Anyone that has a general understanding of conductivity would get it.

Eric

 

[Eric Auer]

And, the computer geeks that lap their heat sinks to gain 0.03 degrees can have it.

To each their own.

Eric

 

[Johntodd]

Eric; this is just an exploration of an idea, man.

Lapping basically polishes the contacts. Polished = more flat surface contact area. That means more space for electricity to flow, in the case of a mech mod, so less drop and more power transfer occurs.

But will it be worth the effort?

Well, that's what this thread is about. No doubt it will make a difference. But is it enough to justify the work?

-Johntodd

 

[Eric Auer]

You really think a polished flat surface would be better than an unpolished flat surface??

And if you could measure it, I bet you would not be able to tell the difference while vaping.


Eric

 

[Johntodd]

Absolutely. It is proven to conduct heat/electricity better. That's why high-performance computers built by geeks are done that way.

Keep in mind, we're not just talking "polishing to make it shiny". We're talking about polishing down to the microscopic level. Uber-polishing, if you will. When polished to that degree, the two surfaces mate much better. Unpolished-or-less-polished surfaces have microscopic gaps between them. Gaps = less contact, so less conductivity.

But the question still remains: Is it worth it on a mech mod?
-Johntodd

 

[Bad Ninja]

Absolutely. It is proven to conduct heat/electricity better. That's why high-performance computers built by geeks are done that way.

Keep in mind, we're not just talking "polishing to make it shiny". We're talking about polishing down to the microscopic level. Uber-polishing, if you will. When polished to that degree, the two surfaces mate much better. Unpolished-or-less-polished surfaces have microscopic gaps between them. Gaps = less contact, so less conductivity.

But the question still remains: Is it worth it on a mech mod?
-Johntodd

Polished as in "clean" contacts are one thing.
But actual lapping?
You gonna lap the battery ends too?

Waste of time.
You will not gain any noticeable increase.



And NoAlOx has graphite not grit.
It doesn't "cut" anything.

 

[Johntodd]

Yes, the battery ends would have to be lapped. That kills it for me, right there.

Nikea, you still here?

 

[Nikea Tiber]

I was fighting traffic up until about ten minutes ago (I work nights).
Overall, the gains are going to quite minimal... hundredths of an ohm at best. In my opinion this is only significant when compared to the (already hopefully low) amount of voltage drop the mod has by design.
I was hoping that maybe someone that has a working digital multimeter of reputable manufacture (as dmms are definitely not all created equal) had the same idea and tested the resistance/vdrop before and after contact lapping so I could get some actual idea of results (if any) people were getting.
In the end, the voltage you might gain to the coil is going to come up to maybe 5 watts at best on a coil build only suitable for parallel batteries or a high drain 26650.
I don't want to seem like I'm making a 180 here because I didn't expect any massive increases to begin with. Vaping is an activity we engage in because we find it pleasurable. If I can get a little more pleasure out of something I own, it is worth it me. I just want to get some numbers, I got unlucky when my friend managed to blow my fluke a few weeks ago. Its fuses didn't even help it

 

[Bad Ninja]

I was fighting traffic up until about ten minutes ago (I work nights).
Overall, the gains are going to quite minimal... hundredths of an ohm at best. In my opinion this is only significant when compared to the (already hopefully low) amount of voltage drop the mod has by design.
I was hoping that maybe someone that has a working digital multimeter of reputable manufacture (as dmms are definitely not all created equal) had the same idea and tested the resistance/vdrop before and after contact lapping so I could get some actual idea of results (if any) people were getting.
In the end, the voltage you might gain to the coil is going to come up to maybe 5 watts at best on a coil build only suitable for parallel batteries or a high drain 26650.
I don't want to seem like I'm making a 180 here because I didn't expect any massive increases to begin with. Vaping is an activity we engage in because we find it pleasurable. If I can get a little more pleasure out of something I own, it is worth it me. I just want to get some numbers, I got unlucky when my friend managed to blow my fluke a few weeks ago. Its fuses didn't even help it

You would lose any tiny gain after one draw.

You would need to lap the battery ends as well as contacts and precision cut the threads.

Not worth the microscopic gains.

 

[DaveSignal]

I don't think the lapping would work even if you lapped the batteries too. The switch isn't clamped down like a heatsink. There are detectable variations in the way you depress the button with your finger every time. I think you ensure more contact with a clean but slightly less than perfectly smooth surface.

As far as the contacts, they definitely work better when cleaned / polished. Sometimes, I will actually use a file on them to quickly remove any hard to get grime and to make the surface microscopically rougher (the opposite of lapping). It hits hard like this.

 

[JKuro]

Lapping is a process of mating two surfaces together. It cannot be done on a contact, as the clearances are too great. The actual contact patch between the contact and body is very small on most switches, and the greater the clearance, the smaller the contact patch. Polishing or cleaning helps just for the sake of removing any oxidation on the surfaces.
Excessive polishing will only make the surface uneven and further reduce surface contact.