Copper flathead screws and nuts

[JPT]

A slotted head screw can be made with common tooling that many of us have.

If required, slotted is OK.

 

[whitmore]

I need a small batch of copper 145 phillips flat head machine screws with nuts.

Material:
copper 145

Phillips flat head machine screw sizes:
4-40 x 1/2"
6-32 x 1/2"

I need a minimum of 10 each.

If push comes to shove, you can get copper rivets in approximately the right size
<https://www.mcmaster.com/rivets/material~copper/> (note, alloy 110, not 145)
and cold-work the Philips indentation then maybe with a little bit of honing, a
die can cut the threads (copper is kinda... grabby, you'd want to have a zero rake
edge, like for brass).

 

[JPT]

If push comes to shove, you can get copper rivets in approximately the right size
<https://www.mcmaster.com/rivets/material~copper/> (note, alloy 110, not 145)
and cold-work the Philips indentation then maybe with a little bit of honing, a
die can cut the threads (copper is kinda... grabby, you'd want to have a zero rake
edge, like for brass).

Thanks for the suggestion.

I have been down this path...




The mechanical connection I need to match for the head is a countersunk, flat head machine screw, so the rivet, while viable for demonstrating some aspects of the goal, remains problematic on the head end.

 

[brino]

One more idea.......

Could you use copper plated "off the shelf" hardware?

But I don't know if it could be done directly or if it would require nickel then copper plate.....

-brino

 

[JPT]

One more idea.......

Could you use copper plated "off the shelf" hardware?

But I don't know if it could be done directly or if it would require nickel then copper plate.....

-brino

Thanks for the suggestion.

Unfortunately, no.

This is a test of conductive fasteners and the plating would be inadequate for the required amperage.

 

[matthewsx]

Okay, we have some pictures now

Can we see the rest of the "test" or is it secret?

If conductivity is the key what about some kind of conductive coating?

John

 

[JPT]

Okay, we have some pictures now

If there's one thing I've got a lot of, it's photos...

These days, I often use them as memory aids.

is it secret?

No, not at all.

I'm planning to post the entire test over on Endless Sphere when complete.

If conductivity is the key what about some kind of conductive coating?

Thanks for the suggestion.

A conductive plating or coating will be inadequate to carry the amperage in this application.

I need a sizable conductive fastener that won't create high electrical resistance under heavy amperage load - thereby creating a lot of waste heat and voltage drop.

 

[JPT]

For those who are curious about the conductivity of various metals, here's a list sorted by IACS, which is 100% for copper.







source: http://eddy-current.com/conductivity-of-metals-sorted-by-resistivity/

 

[JimDawson]

Just to put what you are requesting into perspective, I was looking for something else, and I ran across this screw in my sample drawer.

The picture below is a metric equivalent of roughly a 6-32 x 1/4'' special screw that I made 20 pieces of for a customer. Material is aluminum, 6061-T6. A bit easier to machine than copper, but C145 is pretty free machining.

These were $45.00 each. These were done on a manual lathe for the turning and threading, and a CNC mill for the head. But in this case a rather odd shaped head (that I am purposely not showing), thus the required use of the CNC mill. A screwdriver slot would not require a CNC mill, but the setup time would be about the same, minus the CAM work required for the CNC.

A screwdriver slot would only take about a minute in either a CNC or manual machine. A hex socket could be milled into the head with a tiny endmill in a CNC machine, but most likely would take about 15 - 20 minutes for that operation, tiny end mills don't like to be fed fast, they tend to break. A Philips slot could be done the same way on a CNC mill, and would take about the same amount of time.

Your copper screws with a slot head would be about the same amount of work/time as required by the aluminum screw in the picture.

A hex nut could be done in a manual mill with a rotary table or a hex collet block. Or could be done on a CNC mill. The setup time for either is about the same. The actual machining time is a few minutes, it would require 3 or 4 manual tool changes. Then some lathe work.

Sorry for the out of focus.

 

[JPT]

Jim,

Thanks for the example.

Greatly appreciated.

Agreed on all counts for the similarities of the jobs.


I don't currently have a lathe or mill, so can't take on the turning aspects of this myself.

I can cobble together the nut out of c145 bar stock with a hacksaw, drill press, file, and a tap.

Yes, cringe worthy and definitely crude but will be effective enough for the test.


If I can find somebody here to turn a sample #4 and #6, that would be great.

A slot head is fine for the test but it needs to be a countersunk flat head.