DIY Bus Bars

[carstendenmark]

Also called "thread forming taps".

Use pure cutting oil, not water based lub.
Use a drilling machine, with the bus bar fixed in a vice.
Uncertain result by hand cutting, sorry.
Pre-drilling according to manufacturer of the tap.
No need for power up the drilling machine, just use a wrench to turn the spindle, while gently guiding the tap into the material.

For washers, preferrably use same material as the bus bar. A guy with a lathe can make them for you. Standard size washers tends to be too thin.

SS 316 is good for fastening bolts, as galvanic difference to the copper is not high.

Please use a torque wrench, when you have googled the limits of your thread in the bus bar. Overtighten, and you are in bad luck !
Alternatively, you can make a test piece with a few threads to determine the torque.

Another way could be to make a through hole in the bar, and use a nut on the "back" side. That takes that you can access the back of the bar in case of changes, of course, but saves you the trouble of an (unsafe) thread cutting.
Third way could be to insert Heli-Coils, which will hold the bolt much better than a "raw" material thread. Expensive, though.

Lugs are a kind of religion - but here's a link :
https://www.ecmweb.com/content/artic...uld-you-decide

[coopec43]

Originally Posted by stormalong

I wouldn't use these unless a fuse or circuit breaker is immediately adjacent to the lug. ABYC says within 8 inches of the battery. I think that is overkill but your insurance company may disagree.

Are you referring to an ANL (something like 200A)?

[RaymondR]

Another way could be to make a through hole in the bar, and use a nut on the "back" side. That takes that you can access the back of the bar in case of changes, of course, but saves you the trouble of an (unsafe) thread cutting.
Third way could be to insert Heli-Coils, which will hold the bolt much better than a "raw" material thread. Expensive, though.

Tap the holes, countersink the back side and use brass countersink bolts. Gives a greater contact area in the countersink and putting terminals onto the bolt and putting on a nut is a lot easier than locating the terminal whilst trying to start a screw. Also no risk of pulling out the thread in the bar.

[Spot]

Originally Posted by stormalong

I made a jig to drill all the holes on a drill press equally spaced.


The problem tapping copper is that it is so soft that it is easy to seize the tap in the hole. Care must be taken to back out the tap frequently and clear the chips. Small taps are brittle. I made two of those buss bars because I broke two taps off in the first one. I was much more careful on the second one. I saved the ruined one so if someday I need a shorter one I could use it.

PS. Hand tapping.

Originally Posted by carstendenmark

Also called "thread forming taps".

Use pure cutting oil, not water based lub.
Use a drilling machine, with the bus bar fixed in a vice.
Uncertain result by hand cutting, sorry.
Pre-drilling according to manufacturer of the tap.
No need for power up the drilling machine, just use a wrench to turn the spindle, while gently guiding the tap into the material.

For washers, preferrably use same material as the bus bar. A guy with a lathe can make them for you. Standard size washers tends to be too thin.

SS 316 is good for fastening bolts, as galvanic difference to the copper is not high.

Please use a torque wrench, when you have googled the limits of your thread in the bus bar. Overtighten, and you are in bad luck !
Alternatively, you can make a test piece with a few threads to determine the torque.

Another way could be to make a through hole in the bar, and use a nut on the "back" side. That takes that you can access the back of the bar in case of changes, of course, but saves you the trouble of an (unsafe) thread cutting.
Third way could be to insert Heli-Coils, which will hold the bolt much better than a "raw" material thread. Expensive, though.

Lugs are a kind of religion - but here's a link :
https://www.ecmweb.com/content/artic...uld-you-decide

Thanks for the tips!

[carstendenmark]

Hi, Raymond
Could you "quote" your first 5 lines, please ?

The special bolt type and extra work you suggest is not of any help, when the lug face is the main contact to the bar. Which is the case in almost every connection.

If you do cut the "difficult" thread (to avoid nuts) then just use an ordinary SS 316 bolt screwed in from the back side, secured with Loctite, and fix the lug on this, at the front side.

As you know, soft material threads requires a VERY soft hand when tightening a bolt. Once overtightened, the thread becomes a repair job.
The "hole" solution is safer.

Hey, mate - are we too far out (technically) for the common DIY'er now ? ;-)

[mitiempo]

Originally Posted by coopec43

Are you referring to an ANL (something like 200A)?

Use MRBF fuses.

[stormalong]

Originally Posted by coopec43

Are you referring to an ANL (something like 200A)?

The physical form of the fuse is irrelevant. The fuse or circuit breaker rating is what counts. It should be based on the amperage carrying capacity of the wire and expected load, up the next point where there is overload protection.

For example, the most current draw you would have is 100 amps for a windlass plus 10 amps for electronics and lighting. I would choose a 150 amp circuit breaker as long as the wire could easily carry that load. I prefer circuit breakers. If you use a fuse carry spares. If you had a problem that popped the fuse you might go through a few of them while troubleshooting.

I have never had a problem with that size of load but it could happen and you would not want to get stuck somewhere without power.

There is a common issue with my windlass that if I hit the opposite direction button while the windlass is still moving it will pop the 140 amp circuit breaker. That means a trip back to the engine space for a reset. If it were a fuse a would have gone through dozens over the years.

[stormalong]

Originally Posted by carstendenmark

Hi, Raymond
Could you "quote" your first 5 lines, please ?

The special bolt type and extra work you suggest is not of any help, when the lug face is the main contact to the bar. Which is the case in almost every connection.

If you do cut the "difficult" thread (to avoid nuts) then just use an ordinary SS 316 bolt screwed in from the back side, secured with Loctite, and fix the lug on this, at the front side.

As you know, soft material threads requires a VERY soft hand when tightening a bolt. Once overtightened, the thread becomes a repair job.
The "hole" solution is safer.

Hey, mate - are we too far out (technically) for the common DIY'er now ? ;-)

When making a buss bar for a lot of small wire connections (12 gauge and smaller) nuts on the backside are impractical unless they are brass and soldered in place. IMO threading the bar is the only practical solution. A quick google search tells me that a #8 screw is about 5/32" diameter. At that size taps are pretty easy to break and caution is needed.

For large wires bolts make a lot of sense.

Electrolysis would not be an issue unless the wiring is wet and then you have other problems.

[noelex 77]

Originally Posted by stormalong

The physical form of the fuse is irrelevant.

The interrupt current should be considered.

[carstendenmark]

Then you make your bar by cutting the threads with a forming tap, with 316 SS boltsfrom the back side ;-)

[Frankly]

For the larger lugs, as the threaded hole in the BB is just to hold the bolt/ stud in place until the lug and nut are installed, oversize the hole to make tapping a little easier. You can also use silicone bronze bolts and solder the backside.

For the smaller gauge just buy something commercial.


Frankly

[CassidyNZ]

Originally Posted by carstendenmark

Then you make your bar by cutting the threads with a forming tap, with 316 SS boltsfrom the back side ;-)

It seems that you have missed earlier posts in which it is made reasonably clear the SS is a very poor conductor of electricity. So using a copper bus bar and then connecting to it using SS bolts/screws seems counter-intuitive. Some posts even report a dramatic loss of conductivity by just using SS washers. But then again, you may have some counter-intelligence that indicates that SS is OK as a conductor? If so, please share as that would save me some money and a lot of effort.

If I change my apparently poor-performing SS bus bars to copper (and following what I learned on this thread I might), I’ll drill and tap the copper, insert brass studs and silver-solder them in from the back. Easy permanent fixture.

[Shaneesprit]

I am afraid it’s copper or silver!
At the voltage used on a boat. Aluminium is really only for higher voltages, sometimes you see Copper that is tinned for protection.
Just buy copper you won’t be saving much

[nfbr]

Originally Posted by Shaneesprit

I am afraid it’s copper or silver!
At the voltage used on a boat. Aluminium is really only for higher voltages, sometimes you see Copper that is tinned for protection.
Just buy copper you won’t be saving much

It's resistance. Every metal has resistance. Every wire. It's why the marine wire tables are length tables, not just diameter.

So for aluminium, if it's 1.6x the cross section area of copper, then it's the same resistance.
We can debate / argue surface / corrosion. I would say "make good joints"

So if you want to use aluminium, make it bigger and voltage loss is same.

Copper is 3x heavier than aluminium, so aircraft are moving to aluminium wire as at 1.6x thicker you get same conductivity, but still lighter. (A380)

This is the mistake people make with titanium strength. It's stronger than steel by weight, but not by size.

If you want ideal system, then cool the wires to <1 degree Kelvin like a MRI machine and go superconducting

[mitiempo]

Originally Posted by CassidyNZ

It seems that you have missed earlier posts in which it is made reasonably clear the SS is a very poor conductor of electricity. So using a copper bus bar and then connecting to it using SS bolts/screws seems counter-intuitive. Some posts even report a dramatic loss of conductivity by just using SS washers. But then again, you may have some counter-intelligence that indicates that SS is OK as a conductor? If so, please share as that would save me some money and a lot of effort.

If I change my apparently poor-performing SS bus bars to copper (and following what I learned on this thread I might), I’ll drill and tap the copper, insert brass studs and silver-solder them in from the back. Easy permanent fixture.

There is nothing wrong with stainless bolts as the current doesn't pass through the bolt. The current is between the lug and the copper bar.

Same with Blue Seas bus bars - all their studs are stainless but not current carrying so it makes no difference.