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WIRE GLUE, has anybody tried it?
- Thread starter darius8
- Start date
That's kind of my point - for lack of a definite shape, a given volume of a substance can have pretty much ANY resistance. Making such a number meaningless. I could take their measurement, double the x-sectional area, halve the length, maintaining the same volume, and suddenly I've cut the resistance to a quarter of their claim.
Which is why a more standard practice is to provide a substance's resistivity, based on the cross sectional area, and allow the user to determine the actual resistance based on the application.
I think you have to assume that 13 Ohm/cc means that a 1 cm cube has a resistance of 13 Ohms from one face to the opposite face. Otherwise it is meaningless. On that assumption it equates to a resistivity of 0.132 Ohm-m which is reasonable given that graphite is as high as 0.003 Ohm-m and the glue binder is an insulator which is going to raise the effective resistivity. Of course copper and aluminum and solder are all at least 6 orders of magnitude better conductors than this glue. If you are going to the trouble of using metal foil shielding do you really want to connect the seams with a material that is no better than conductive paint? This product is interesting and may have some uses but I don't think you want to use it in your bass. Just learn to solder.
Ken
Ken
did they mention how much the resistance changes over time? or is it constant (like solder). if they didnt test it, i would wonder. its true solder has some resistance, but if you are soldering properly the two parts will be mechanically connected and touching so the solder acts more like a protective coating keeping out oxidation rather than the actual electrical connection. ( unless you are using solder like glue, which i see alot) johnny a.
radio shack used to sell these little strips of solder you would wrap around the connection and heat with a match 
radio shack used to sell these little strips of solder you would wrap around the connection and heat with a match
I remember that stuff! Never tried it, but always thought it was a cool idea.
You're not kidding! And a typical solder joint contains much less than a cubic centimetre. More likely several hundred ohms or even k's of ohms in each joint.
OK I'll bite.. I just ordered it. I was thinking leaving some at work (I teach middle school) just in case and that way I don't have to worry about soldering there... I can leave all my solder stuff at home...
Yeah.
On the other hand, the wires will probably closer together than 1cm.
Still not a very good idea to use if for high power applications.
If nothing else, we've found the answer to the question...
"What's the best glue for Metal?"
(returns to soldering iron...
)
"What's the best glue for Metal?"
(returns to soldering iron...
)
- Aug 21, 2008
- 10,386
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- Disclosures
- Owner, SGD Music Products
Actually, as we discussed above, Ohms/cm^3 is a nonsensical unit of resistivity as the conclusions you draw from it illustrate. Ohms/cube would be a better unit and it is essentially what the glue makers are saying. But that is an odd unit. It seems natural to me but then I sometimes design integrated circuits for a living and in IC design the on chip resistors are always specified in Ohms/square which is the equivalent for thin film resistors where the film thickness is tightly controlled.
What the glue resistivity spec means is that if you have a cube of this stuff (doesn't matter how large or small the cube is!) you will measure ~13 Ohms across two opposite faces of the cube. As most wire connections have far less thickness than length or width a typical glue joint will have much less resistance than 13 Ohms but far more than a solder joint would.
Ken
Remember that the measurements you are referring to are also ohms per cube. You can't make a layer of resistive material (Or any material for that matter) in only two dimensions. You may have a material with a given resistance per square cm. That material must have a given thickness. The thickness isn't relevant to you because you design only two of the dimensions. Somebody had to work out how thick the material have to be to give the correct resistance from one end to the other.
I guess that is the same way they measure the resistance in that glue. If you make a cube 1x1x1cm between two sheets of metal, the resistance between the two metal sheets is 13ohms. Increase the length to two cm, but keeping the same cross section of the cube you will get 26 ohms.
When used as a glue the calculations will get much more complicated, though. You will then get lots of resistor networks both in series and parallel. Simplifies you could calculate the volume of the glue that sit between the cables while ignoring all the glue around the cables. All of the glue will aid in conducting currents, but some parts of the join will get higher loads than the other.
I think the ohm per square cm is the only useable way of giving the resistance of the glue. I will admit that it is very difficult to accurately calculate the resistance in a practical application, though. Then again, I don't think people that need accurate data for their conductive glue buys it from think geek.
Uh, yes, you are right. Doubling the size of the cube will halve the resistance so Ohms/cube is not a constant as Ohms/square is in a semiconductor process where the thickness is not allowed to be changed. My bad. But I think we still have to assume that when they say 13 Ohms/cc they must be talking about a cube that is 1 cm on a side. Otherwise we have no clue as to what the resistance might be.
Ken
Ken
This might useful for people who not-so comfortable with using a soldering iron and want to be able to change a pickup. Say like, twist two 22 awg (or smaller e.g. 22-30 gauge) wires together and put a dab of this glue to keep it from separating. Yes?
That's the way I interpreted it -- and that's pretty bad.
[distance between faces is still 10mm for all quantities below]
A 10mm x 10mm face-to-face is 13 ohms.
5mm x 10mm is 26 ohms.
5mm x 5mm is 52 ohms.
2.5mm x 2.5mm is 208 ohms.
1.25mm x 1.25mm is 832 ohms.
1mm x 1mm is 1300 ohms.
When you get down to the realistic amounts that you will be
applying, the resistance is quite high.
Tin/lead solder is about 0.000000165 ohm.m.
For a 1 cm cube, that would be
resistance =
resistivity * length / cross-sectional area =
0.000000165 ohm.m * 0.01m / (0.01m * 0.01m) =
0.0000165 ohms
That's a huge difference from the glue resistance of 13 ohms.
For a 1 cm cube, that would be
resistance =
resistivity * length / cross-sectional area =
0.000000165 ohm.m * 0.01m / (0.01m * 0.01m) =
0.0000165 ohms
That's a huge difference from the glue resistance of 13 ohms.
Yeah, but that is 1x1x10 mm, will you really try to connect two wires with a 10 mm long piece of glue? More likely you would twist the wires together and then cover them with glue. The wires are already touching so the glue mainly holds them together. The glue thickness is at most a few hundredths of a mm when you use the product in a sensible way.
The product takes a couple of hours to set up. If you were to sit down with a pile of stripped wires, some old pots, solder and an iron after two hours of practice you'd be quite good at soldering. The glue joints are never going to set up faster than 2 hours....
Ken
Well if you were twisting two wires together, then the glue wouldn't really even need to be conductive - you could use wood glue or epoxy and get roughly the same results.
But pickup wires don't go to other wires, one goes to the backside of a pot and one goes to the terminal on the pot. The glue *might* work for the terminal connection cause you could wrap the wire around and through the terminal, but then like I said above, wood glue would work there too since the electrical connection is being made mechanically - directly from wire to terminal, the glue is just there to keep it from coming apart. I wouldn't even try it for the connection to the backside of the pot, since you'd be depending on the glue to stick to the flat metal surface on the back of the pot. There's nothing to wrap the wire around, so you're 100% dependent on the glue's ability to hold on to that flat surface and also conduct the signal from wire to pot. Solder makes a rock solid bond to that flat surface.
I gotta go back to not seeing what the problem is with soldering. It's really easy and the bare minimum tools are really cheap. Your soldering iron will pay for itself the first time you use it on something real - like swapping pickups for example. Go to Radio Shack and buy a 15w pencil iron and a small roll of rosin core solder. You should be out the door for less than ten bucks. Search youtube for "how to solder" and watch a dozen videos or so until you have the general feel for it. Then take a few scrap pieces of wire and start soldering them together. I was doing this when I was ten years old. Don't let it intimidate you - you can do it too. Really. It's way easier than learning how to play bass and you did that - right?
If there's even a little bit of a chance that you wanna work on the wiring and electronics in your bass, you owe it to yourself to learn how to solder.
Then start making your own instrument cables. You can make 'em for a fraction of the cost and much higher quality than what you can buy at GC.
