Author Topic: material to make DMM probes with?  (Read 3261 times)

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Online coppercone2

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material to make DMM probes with?
« on: January 14, 2022, 04:29:06 am »
If I wanted to make my own DMM probes, what would be a good material for the shaft? Lets say you want something custom (i.e. pogo pins)

I thought about teflon and some kind of glass reinforced nylon.


What would be some good candidates? I don't have much knowledge 'robust' plastics. I thought teflon would be good since its high density so that means it will be pretty safe I think.
 

Offline floobydust

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Re: material to make DMM probes with?
« Reply #1 on: January 14, 2022, 06:58:29 pm »
Top quality Fluke or Pomona are using polypropylene core for strength and rigidity, with santoprene TPV rubber for grip.
Teflon I have always machined and never tried moulding it, seems to be compression required.

Russians make multimeter probes out of old pens, I tried it and meh it can work if you're not always rich.
 

Online coppercone2

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Re: material to make DMM probes with?
« Reply #2 on: January 14, 2022, 10:19:35 pm »
No, I want to make it out of the correct materials, you can do some weird things to it like make a bent probe or whatever.

A set of needle probes (literally sewing needles in pens with banana jacks is something I have some where though). If I were to do it again though, I would make a collet to hold the needle in. They feel janky as FUCK though.
« Last Edit: January 14, 2022, 10:24:55 pm by coppercone2 »
 

Offline bill_c

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Re: material to make DMM probes with?
« Reply #3 on: January 14, 2022, 11:46:59 pm »
Teflon is usually too soft, it will bend and stretch too much. Acetal might be better but it is also slippery plastic which would be hard to grip.  Have you looked into garolite or similar?
{example} https://www.mcmaster.com/garolite/
 

Online coppercone2

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Re: material to make DMM probes with?
« Reply #4 on: January 15, 2022, 12:13:14 am »
No, I know very little about plastics. thats the kind of stuff I am looking for
 

Offline rpiloverbd

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Re: material to make DMM probes with?
« Reply #5 on: February 14, 2022, 03:20:05 pm »
You can get some idea from here too:
 

Offline David Hess

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Re: material to make DMM probes with?
« Reply #6 on: February 16, 2022, 03:11:14 am »
Nylon has high leakage.

In the past some probe handles were Bakelite, but it is pretty brittle.
 

Offline fcb

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Re: material to make DMM probes with?
« Reply #7 on: February 17, 2022, 12:34:59 pm »
Tufnol (phenolic cotton laminated plastic or SRBF synthetic resin bonded fabric).

Some HV probes we use have tufnol bodies.

It's tough, durable and good for HV's
https://electron.plus Power Analysers, VI Signature Testers, Voltage References, Picoammeters, Curve Tracers.
 

Online coppercone2

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Re: material to make DMM probes with?
« Reply #8 on: February 17, 2022, 07:30:02 pm »
Well if you are making your own probes, I did find a easy way to make something good.

After you solder whatever tip you want to the wire, get a brass tube and crimp it over the wire using the type of crimp used for steel cable crimps on linemans pliers or cable cutting pliers. After 3 layers of heat shrink it makes a pretty stiff and nice probe for low voltage work. I crimp gently on top of the solder joint (not ideal), but if you want to make probes that are not junk fast.. it does do a good job, You can probobly fill it with glue after wards using a syringe too.


Keep in mind the brass tube will be energized so its just the heat shrink protecting you, so <48V only.. but its fast enough if you want something special for PCB hookup.
 

Online coppercone2

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Re: material to make DMM probes with?
« Reply #9 on: February 20, 2022, 05:55:24 am »
you know what might be a pretty good probe, a discharge one for high voltage capacitors. The idea would be to have a resistor at the tip of EACH PROBE, so there are two series resistors with the circuit to limit current on the 'shorting stick', I kind of don't like how the wire on one side of a capacitor is not current limited
 

Offline xavier60

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Re: material to make DMM probes with?
« Reply #10 on: February 20, 2022, 07:28:01 am »
For the actual probe tip, I use the 1.5mm steel shaft material that's used in small electric motors. It doesn't rust in normal use and holds a sharp point for months. The extra bit of resistance has not been a problem.
I have not be able to find for certain what sort of alloy it is, that's if there isn't more than one type of material.
« Last Edit: February 20, 2022, 07:43:37 am by xavier60 »
Hioki AS100D vom, HP 54645A dso, Fluke 87V dmm, AN8008 dmm, Agilent U8002A psu,  FY6600 function gen, New! Brymen BM857S-(With Battery)
 

Offline Calvin

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Re: material to make DMM probes with?
« Reply #11 on: February 20, 2022, 07:30:08 am »
Hi,

how about PE as insulator?
Cheap, very high surface- and volume resistance and lowish epsilon.

regards
Calvin
..... it builds character!
 

Online coppercone2

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Re: material to make DMM probes with?
« Reply #12 on: February 20, 2022, 09:47:00 pm »
Well it depends on resistance. I like really low resistance probes but for digital work, making a needle probe out of a stainless steel pin could be really good, since it does not matter how much resistance is in the probe when measuring a voltage signal. Really, you should have diff probes for voltage and for current/resistance I think, if you really want to optimize your measurements and keep burden voltage in check.

Dave Jones showed that gold plating really makes a huge difference. I thought about getting the less-toxic gold plate to try it out, but really I wanted to do things with pogo pins since they are gold plated, replaceable tip, good grip. But there are defiantly different things you can do. Let's just say I would need a lineup of designs to make before I bought expensive gold plate.
« Last Edit: February 20, 2022, 09:49:37 pm by coppercone2 »
 


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