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DIY busbar power distribution
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author DIY busbar power distribution
Zaibach
Hello fellow wigglers,

After a long time thinking about the power distribution in my rack I came to the point where I wanted to try making my own busboard power distribution. Right now there's two Doepfer busboards and… well, busboards made out of stripboard in my rack. No, I won't post a picture of them here, they are just „bad“ in every kind of way. This thread finally gave me the push I needed to finally get started:

https://www.muffwiggler.com/forum/viewtopic.php?t=102801&highlight=
also this one:
https://www.muffwiggler.com/forum/viewtopic.php?t=134925&highlight=

For this project I am indebted to Graham Hinton, who showed in the first linked thread a solution for the inferior (mis-engineered?) eurorack power distribution.

If you're playing with the thought of making your own busboards as well, let me tell you that it takes a lot of time. And I mean a lot. For example, for drilling and tapping the aluminum bars alone took at least about 18 hours, spread over several days. And then there's making the cables – stripping wires, crimping etc. If you don't like wiring, just don't do it.

If you want a complete, ready made busbar power solution then look here:
http://hinton-instruments.co.uk/paprod/psu/

Well, what do I need?
My rack I want to upgrade has 4x 180HP, and i want to power two rows from one set of bars. So first, some aluminum! eBay has a lot of vendors selling raw metal bars cut to the lenght you need. I got six 1m bars 20x10mm (AlMgSi0,5) from here:

http://www.ebay.de/itm/321518712952?_trksid=p2060353.m1438.l2649&var=5 10397749287&ssPageName=STRK%3AMEBIDX%3AIT

I decided to use M4 screws to attach the power cables to the bars and tap the threads by hand. That means, after drilling the required core hole with 3,3mm diameter I had to tend to every single hole with a T-wrench and bottoming tap, the intermediate and finally a taper tap to get the thread I need (this is a good start if you want to know the basics https://en.wikipedia.org/wiki/Tap_and_die). I know, i know, there are machine taps that create the thread in on go but I didn't want to get into that and made them by hand. I am patient that way. And hey, the busbars are 80cm long with 53 holes in total, three for mounting and the rest for attaching the cables, so it's just 300 threads to make.



Next, the connector housings that fit with dual-row 2,54mm spaced headers, as used by the eurorack format. You can find them with search terms like „pololu crimp connector housing“ or „dupont crimp connector housing 2x5“ or similar expressions.



I bought them here:
https://eckstein-shop.de/01-254mm-Crimp-Connector-Housing-2x5-Pin-5-Pa ck

Apparently they belong to the same connector family as the single ones used as patch cables for breadboards and arduino stuff. They also have the female crimp connectors that go with these housings, but a friendly vendor from china had 500 pieces for 2,39€, so I had them send 2000 crimp connectors my way.

http://www.ebay.de/itm/500Stuck-2-54mm-Stecker-Crimpkontakte-fur-Ardui no-22-28AWG-Dupont-Kabel-DIY-/262999292517?hash=item3d3bfaba65:g:j9IAA OSwlMFZI87t



Most important is the right crimping tool! The vendor from whom I got the housings from offered a crimping tool that looked suspiciously familiar to the one I got for crimping Molex KK-connectors (sorry, I can't find a picture rigt now). So I crimped a wire and the result was a firm connection that just looked like a crimped connector on pictures I found online. I am still not 100% sure whether it is the intended tool or not, but I will go with it for now (sorry for the amateur-ish approach on this one!).

These connectors take cable up to AWG22 size, so I needed that. Let's say I wanted to make 100 power connector cables, that's 10 single cables for one, and preferably in three different colors. So, two each for +12 and -12V, and six for 0V. Assuming a cable lenght of 20cm, that's 40m red, 40m blue, and 120m green. Again eBay was my saviour: Someone auctioned AWG22 wire and no one bid on it – exept me. So I got roughly two kilometres of wire for – 5€. Plus shipping, but who am I to complain?




Now I am at the point where I sit down and crimp a lot of cables. They don't look too bad, right?



I want to make about a hundred for starters, since I have a second rack I want to upgrade. Also, I am still undecided to buy a new power supply as well, since I am running right no a Doepfer psu and two Meanwell RT-65B.
Well, that's it for now. Sorry, no measurements regarding voltage drop along the bars as of yet. Questions, remarks and criticism welcome!
flab
I was thinking to do the same to my new cases, after reading the thread where hinton was explaining things, two things still keep me from not doing it, a) big backlog of really nice busbord pcbs at home and b) exposed power inside my case Dead Banana? but i guess it the correct way to do things. i think you keep your psu meanwell for other projects, and start this new case with a nice linear psu (for the recorded i use meanwell as well,linear,or whatever i have access )
indigoid
flab wrote:
b) exposed power inside my case Dead Banana?


You could address the "exposed power" bit by making a clear (acrylic?) shell to sit around each bus bar, with slots spaced along the top/bottom to poke the connectors through, and small holes spaced along the front to let you screw them down

Surely someone has made something like this already?

It would be a bit fiddly (probably even more irritating to work with than rails with sliding nuts!) but you'd get your nice bus bars and dramatically reduce the risk of accidentally shorting things on them

... one might add, though, that you should make sure your synth is fully powered off before messing about in there anyway razz
neil.johnson
Don't forget to use shakeproof washers to cut through the aluminium oxide layer and make a nice gas-right joint. Or you can use an electrical jointing compound that has zinc crystals for doing the same thing.

I think Graham uses a touch of CopaSlip on the threads to stop them binding after a couple of decades of sitting inside a cabinet.

Neil
Zaibach
flab wrote:
and b) exposed power inside my case Dead Banana? but i guess it the correct way to do things. i think you keep your psu meanwell for other projects, and start this new case with a nice linear psu (for the recorded i use meanwell as well,linear,or whatever i have access )


Yes, I have thought about that too. One idea was to use a long piece of shrink tube and pull it over the bars, but then I would have to cut holes in there, and there's the exposed ring crimp connector still looking at you.

indigoid wrote:
You could address the "exposed power" bit by making a clear (acrylic?) shell to sit around each bus bar, with slots spaced along the top/bottom to poke the connectors through, and small holes spaced along the front to let you screw them down


That's an idea. Since it's more hassle now to install a power connection cable (screw the power connector to the busbars now instead of just plugging one into the busboard like before) I just wanted to put in more cables than necessary and just leave unused power cables in the rack. So I could put an acrylic sheet with holes on top of the busbars, and pull the cables through - since I am planning to have more cables attached than needed I would basically never have to touch the busbars anymore.

neil.johnson wrote:
Don't forget to use shakeproof washers to cut through the aluminium oxide layer and make a nice gas-right joint. Or you can use an electrical jointing compound that has zinc crystals for doing the same thing.

I think Graham uses a touch of CopaSlip on the threads to stop them binding after a couple of decades of sitting inside a cabinet.

Neil


Thanks for the tip, I need to look into that. I haven't come across this stuff before, but I'll make sure I won't forget it.
nurbivore
Those look great! I too have long fantasized about Doing Power Right, but usually only get as far as reading about taps before losing steam.
peloazul
zaibach - could you talk about the crimp tool you used for those connectors? I've been using a Engineer PA-09 on a similar type of pin, and wasn't super satisfied with it. (Or I suck at crimping pins.)
Morphology
This is a lovely looking solution, and congratulations for taking the time to thread all those holes!!

Rather than have exposed power rails, you could always mount each rail inside slotted plastic conduit - that way you just list the lid and screw in a new connector rather than pre-connect all the connectors and have them hanging inside the rack?



Morph
revtor
And we're still stuck with the crappy euro power header standard...

love the busbars!
peloazul
Morphology wrote:

Rather than have exposed power rails, you could always mount each rail inside slotted plastic conduit


As a bonus, that would be an insulator between rail/rail and rail/case.
xonetacular
Graham's pricing for a custom set of bus bars and all cables is very reasonable. Probably not worth the small savings to DIY for something less polished when there are a lot of up front costs involved. Honestly I wouldn't be surprised if you ended up paying the same or more to DIY them. I am very happy with them and you can save yourself a lot of time and frustration just going that route and integrating it to the supply of your choosing.
Zaibach
nurbivore wrote:
Those look great! I too have long fantasized about Doing Power Right, but usually only get as far as reading about taps before losing steam.


Well, I have thought about just drilling holes and fix the connectors with screws and nuts. But then it would become almost impossible to install new cables once the bars are fixed inside the rack. So, threads are the way to go for me.

Zaibach
peloazul wrote:
zaibach - could you talk about the crimp tool you used for those connectors? I've been using a Engineer PA-09 on a similar type of pin, and wasn't super satisfied with it. (Or I suck at crimping pins.)


Yes, I have this one:

https://www.reichelt.de/Crimpzangen/CRIMPZANGE-PSK/3/index.html?ACTION =3&GROUPID=572&ARTICLE=6844&OFFSET=16&SID=93WWj-L6wQATMAAC-vQCY0e6cf67 5444c7aab3ac187372f8c234e&LANGUAGE=EN

It's just a generic crimp tool for 18€, but it does the job quite well, seeing that professional crimp tools can cost you 150€ upwards. You can even adjust the force required to crimp the connector with a wheel. I don't think you suck at crimping, it's just the tool you have. The page you linked to shows that you have to crimp the connector and the insulation separately - the tool I use does that simultaneously. Also maybe the lever action allows for tighter connections without using stressing your hand so much.

I had to learn to strip the wires to the right lenght and insert them into the contact just far enough that the insulation doesn't reach more than 3-4mm into the contact. Once you get the hang of it the result is very acceptable. And of course I took some of the better-looking ones for this picture thumbs up

Zaibach
Morphology wrote:
This is a lovely looking solution, and congratulations for taking the time to thread all those holes!!

Rather than have exposed power rails, you could always mount each rail inside slotted plastic conduit - that way you just list the lid and screw in a new connector rather than pre-connect all the connectors and have them hanging inside the rack?

Morph


Thanks! Now that's also a nice solution to the exposed power rails. As I said, I'm still undecided how to deal with that, but thanks for the idea!

xonetacular wrote:
Graham's pricing for a custom set of bus bars and all cables is very reasonable. Probably not worth the small savings to DIY for something less polished when there are a lot of up front costs involved. Honestly I wouldn't be surprised if you ended up paying the same or more to DIY them. I am very happy with them and you can save yourself a lot of time and frustration just going that route and integrating it to the supply of your choosing.


I haven't done the math but honestly, I don't think I save much, if anything money-wise. For this project I had to buy some stuff like a crimp tool for the ring cable lugs, other tools I had at hand. The "raw materials" (cable, connectors, the aluminum bars) didn't cost that much, but of course it accumulates. I don't do it to save money, it's because I can do it - and I'm having fun doing it. This week I sat down every evening to make some power cables - and I'm still not done. For a hobby you don't count the hours involved like when you're at work. And yes, of course my stuff doesn't have the quality like the products that Mr. Hinton offers professionally made - as long it works as intended I'm satisfied. You have to ask yourself whether it's worth the trouble or not. I like DIY very much, but haven't gone as far as to etch my own pcbs for example - buying everything needed for that with no guarantee that when I try it the result would be accetable or even usable - no thanks. Other people are into that. I don't know If I had started making my own busbars if I wouldn't have had so many tools already (like a drill press)... Anyhow, it sure is a big, time-consuming project, but I don't mind the time or money spent. And for now, that's just for my first rack... hihi
BananaPlug
revtor wrote:
And we're still stuck with the crappy euro power header standard...

love the busbars!


Yes and the ones in the pix are not even polarized. ZAP!

Well, maybe they are but just happened too all be turned away from that size.
xonetacular
Zaibach wrote:

I haven't done the math but honestly, I don't think I save much, if anything money-wise. For this project I had to buy some stuff like a crimp tool for the ring cable lugs, other tools I had at hand. The "raw materials" (cable, connectors, the aluminum bars) didn't cost that much, but of course it accumulates. I don't do it to save money, it's because I can do it - and I'm having fun doing it. This week I sat down every evening to make some power cables - and I'm still not done. For a hobby you don't count the hours involved like when you're at work. And yes, of course my stuff doesn't have the quality like the products that Mr. Hinton offers professionally made - as long it works as intended I'm satisfied. You have to ask yourself whether it's worth the trouble or not. I like DIY very much, but haven't gone as far as to etch my own pcbs for example - buying everything needed for that with no guarantee that when I try it the result would be accetable or even usable - no thanks. Other people are into that. I don't know If I had started making my own busbars if I wouldn't have had so many tools already (like a drill press)... Anyhow, it sure is a big, time-consuming project, but I don't mind the time or money spent. And for now, that's just for my first rack... hihi


Yeah rock on, I totally get it. That comment wasn't so much aimed at you but more putting it out there for other people who are considering bus bars to consider getting them from graham.
Graham Hinton
Zaibach wrote:
I had to tend to every single hole with a T-wrench and bottoming tap, the intermediate and finally a taper tap to get the thread I need


I hope that was a typing mistake. Taper tap should be first.
In every British tap set I have ever seen the only difference between between each tap is the amount of taper. You only need a bottoming tap for blind holes and if the straight part of the tap is longer than the material depth you only need one pass. However I have one German tap set (Ruko) and the three taps are different diameters, so the thread gets progressively larger, cutting less material each go. I don't know if that is usual in Germany?

Quote:
I know, i know, there are machine taps that create the thread in on go but I didn't want to get into that and made them by hand.


You can use machine taps by hand, they have the same square ends. There are special types for aluminium that are less likely to clog. Or you can use a forming tap.

Of course it's a lot less RSI inducing like this:



Quote:
Next, the connector housings that fit with dual-row 2,54mm spaced headers, as used by the eurorack format. You can find them with search terms like „pololu crimp connector housing“ or „dupont crimp connector housing 2x5“ or similar expressions.


Note that the triangle on the side indicates Pin 1, and pins 11, 21, etc. on larger versions, but this is the opposite side from pin1 on a ribbon cable connector which reverses odd/even pairs. It doesn't make any difference to a Euro power cable because the pins are used in pairs, but it may be an issue for other uses.
The contacts may be removed by lifting the plastic tabs in the sides very carefully with something like a scalpel blade. Don't bend them back.

Quote:

Most important is the right crimping tool! The vendor from whom I got the housings from offered a crimping tool that looked suspiciously familiar to the one I got for crimping Molex KK-connectors (sorry, I can't find a picture rigt now). So I crimped a wire and the result was a firm connection that just looked like a crimped connector on pictures I found online. I am still not 100% sure whether it is the intended tool or not, but I will go with it for now (sorry for the amateur-ish approach on this one!).


The proper tool has a slotted blade in the middle, the wires go through the slot and the edge of the insulation butts against the blade. This ensures that one set of tabs wraps around the wire and the other around the insulation. If the contact does not crimp down to the right size you will have problems inserting them in the housings.

If you can't afford the right tool the answer is not to use the wrong one, but search on eBay for the right one to come up at the right price. They always do.

neil.johnson wrote:
Don't forget to use shakeproof washers to cut through the aluminium oxide layer and make a nice gas-right joint. Or you can use an electrical jointing compound that has zinc crystals for doing the same thing.


I'm not sure that is correct. They are similar looking special hardened washers for penetrating paint finishes, but the use of shakeproof washers may be cargo cultism. Do you know they are gas tight long term?
Zinc jointing compound against the aluminium and a shakeproof washer above the ring, under the screw head. The screw should be tightened until the washer compresses and then no more.

Morphology wrote:
Rather than have exposed power rails, you could always mount each rail inside slotted plastic conduit


This is not necessary. Exposed to what? You have exposed power on both Euro header and KK busboards and on pcb components everywhere. Voltage regulators shut down fast when excessive current is drawn.

revtor wrote:
And we're still stuck with the crappy euro power header standard...


Only if you keep making modules with them on. Use a better connector and heavier gauge wire. It is actually cheaper too.
Zaibach
Graham Hinton wrote:

I hope that was a typing mistake. Taper tap should be first.
In every British tap set I have ever seen the only difference between between each tap is the amount of taper. You only need a bottoming tap for blind holes and if the straight part of the tap is longer than the material depth you only need one pass.


Yes, sorry! I am unfamiliar with english terminology, so I looked it up at wikipedia and hoped i used it right. Of course I used them in the right order when I cut my threads!

Quote:
However I have one German tap set (Ruko) and the three taps are different diameters, so the thread gets progressively larger, cutting less material each go. I don't know if that is usual in Germany?


That seems to be the case - at least the ones I have seen are like this. My textbook from profession school also shows no other kind for hand taps. Of course different kinds of machine taps are also mentioned there, but this chapter is not comprehensive in any way.

Quote:
You can use machine taps by hand, they have the same square ends. There are special types for aluminium that are less likely to clog. Or you can use a forming tap. Of course it's a lot less RSI inducing like this:


I figured the force required to use these by hand would be too big, so I refrained from doing so. When I make busbars for my second rack I will give it a go... Thanks for linking to a video that shows how it's done properly by machine! But, stupid question: Isn't the use of cutting oil highly recommended for this kind of process, cooling the bit and reducing wear and tear? At least I couldn't see that any is being used.

Quote:

The proper tool has a slotted blade in the middle, the wires go through the slot and the edge of the insulation butts against the blade. This ensures that one set of tabs wraps around the wire and the other around the insulation. If the contact does not crimp down to the right size you will have problems inserting them in the housings.


You mean like this (picture from my crimp tool)?


I have found in the meantime the intended tool for those connectors, they look very familiar, although I will get one of those for my next batch of power cables.
https://www.pololu.com/product/1928
Zaibach
BananaPlug wrote:
Yes and the ones in the pix are not even polarized. ZAP! Well, maybe they are but just happened too all be turned away from that size.


Indeed, they are not polarized. I have never used keyed headers in the past. And yes, I have plugged in power cable the wrong way in the past once or twice (no damage done, luckily). What did I do? I took a big fat red marker and drew a well visible line next to the -12V side - just pay attention when you plug in a power cable. Yes, keyed headers eliminate the chance of plugging in the power cable the wrong way completely. I am putting a lot of effort into upgrading my power distribution system right now, but I am sure as hell not going to desolder all the power headers on my 100+ diy synth modules and exchange them for keyed ones... too much effort for too little gain.
Graham Hinton
Zaibach wrote:

I figured the force required to use these by hand would be too big, so I refrained from doing so. When I make busbars for my second rack I will give it a go... Thanks for linking to a video that shows how it's done properly by machine!


Note that a forming tap is being used, the hole is just being reshaped--no waste. There is another video using a spiral flute tap which pulls the cut material up out of the hole like a drill flute. See this thread Euro Power Header Question - Why 2 rows? (sorry about the trolls).
The other advantage of machine taps is that they just go in and screw back out, eliminating all the backwards and forwards action of using hand taps that really does your wrist in.

Quote:

Isn't the use of cutting oil highly recommended for this kind of process, cooling the bit and reducing wear and tear? At least I couldn't see that any is being used.


There was a drop of cutting oil applied to each hole beforehand. If it were steel and/or a faster cutting speed then you would use "suds" which is an oil emulsion and a pump squirting it at the work, but that is messy and you need a collection tray. For aluminium you could use WD40 or even a drop of paraffin applied with a brush.

Quote:
You mean like this (picture from my crimp tool)?


Similar, but it is also parallel action, rather than pliers which close from one side and tend to bananafy small contacts.

neil.johnson
neil.johnson wrote:
Don't forget to use shakeproof washers to cut through the aluminium oxide layer and make a nice gas-right joint. Or you can use an electrical jointing compound that has zinc crystals for doing the same thing.

Graham Hinton wrote:
I'm not sure that is correct. They are similar looking special hardened washers for penetrating paint finishes, but the use of shakeproof washers may be cargo cultism. Do you know they are gas tight long term?

I suppose that depends on your definition of "long". For durable bonding tests here is an amusing report written for the US Navy (which, as those rather large ships can carry cargo, I guess you could say it's a cargo cult of sorts):
https://www.nsrp.org/wp-content/uploads/2015/10/Deliverable-2011-452-I mproved_Bonding_Grounding_Final_Report-Ingalls_Shipbuilding.pdf

Graham Hinton wrote:
Zinc jointing compound against the aluminium and a shakeproof washer above the ring, under the screw head. The screw should be tightened until the washer compresses and then no more.

That's one way to achieve the result, although the main function of the jointing compound is to minimise galvanic action -- the zinc crystals provide a conductive path and the grease seals the joint to stop any further corrosion.

Neil
Graham Hinton
neil.johnson wrote:

I suppose that depends on your definition of "long".


The lifetime of the system.

Quote:
For durable bonding tests here is an amusing report written for the US Navy


Not so amusing if you are one of the tax payers enabling it.
It does explain why I have never seen bonding washers in a range of sizes though, but it doesn't support your claim that shakeproof washers are a valid alternative.

Quote:
... the main function of the jointing compound is to minimise galvanic action -- the zinc crystals provide a conductive path ...l


Copaslip is to prevent galvanic action on the screw threads if an electrolyte is present, e.g, air near the sea or a swimming pool, the zinc crystals are to pierce the oxide layer that forms on aluminium. It is only one molecule thick and seals the surface so it does not increase over time.
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