Sharpening your own testleads - Page 1
Forum section: electronics / general

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: April 19, 2017, 09:09:06 am
content: So, I have some old multimeter leads with nice silicone/rubber cable, probes that are nice to hold, etc. However, their tips are quite dull. I was wondering if there is any good reason why I wouldn't just use a file to sharpen the tips up a bit. Keep in mind I'm only doing like 4 digit measurements on my handheld DMM (on that note, is there any reason on higher accuracy measurements why I wouldn't sharpen them? I wouldn't even use handheld probes to do high accuracy measurements...)

author: noidea
author_rank: Unknown
timestamp: April 19, 2017, 04:11:11 pm
content: I'm not into metrology but as I can never seem to find the perfect set of multimeter probes regularly do take to modifying and sharpening them myself.Sometimes you may be surprised what you findI sharpened the Keysight probes which came with my U1252B so that they were sharper and had a longer taper (no longer CAT II rated as there's more than 2mm exposed metal). It turns out they are chrome plated brass so whilst they are sharp they're also a little fragile now. The Multi Contact ones I modified at the same time were stainless.You'll know if they're stainless or not after a few strokes of the the file anyway.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 21, 2017, 10:19:20 pm
content: Quote from: TheUnnamedNewbie on April 19, 2017, 09:09:06 amMost test leads have a plating to prevent oxidation. By sharpening them, your tips will rapidly oxidize causing your readings to drift. This would either require cleaning the tips every time you want to use them or replating.

author: belasajgo
author_rank: Contributor
timestamp: April 22, 2017, 08:35:55 am
content: Quote from: PedroDaGr8 on April 21, 2017, 10:19:20 pmIn this case, how is it better to use the test leads (if replating is not possible)? Sharpened but without the plating, or unsharpened but with the original plating? Having to clean the tips each time you want to measure something is not that practical...

author: VintageNut
author_rank: Frequent Contributor
timestamp: April 22, 2017, 09:03:23 am
content: Why do you require sharp DMM probes?

author: noidea
author_rank: Unknown
timestamp: April 22, 2017, 09:07:06 am
content: Not really metrology but when the boards you work on are coated in Humiseal or some other conformal coating sharp probes make all the difference

author: SeanB
author_rank: Super Contributor
timestamp: April 22, 2017, 12:03:03 pm
content: So buy some probe leads with needle sharp tips then, they are available. They are designed to pierce those kind of conformal coatings with ease.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: April 22, 2017, 12:25:44 pm
content: Quote from: noidea on April 19, 2017, 04:11:11 pmI would not know a manufacturer using stainless steel for probe tips, as the electric conductivity is less than 1/10th that of brass and maybe less than 1/40th that of copper.Exposed copper alloys tend to fast oxidization (copper and zinc oxides are bad el. conductors), so plating is essential.If you want to go with a DIY approach instead of buying new probes – I can relate to that – take some very fine grit wet sanding paper, stick it on a flat surface and gently shape the tips to your liking.Afterwards, do some DIY electroplating with nickel

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: April 24, 2017, 05:36:31 am
content: Thanks for the replies all!I want to sharpen them because they seem to have been dropped or somthing, or maybe just used in situations where they had more abuse going on. They are quire dull, and the red lead has it's tip slightly dented such that the material sticks out slightly in one direction. It's fine for measuring mains and such, but make probing fine pitch PCBs a lot harder.I'm gonna give the DIY-nickel plating a try I think! Sounds like a fun challenge. Thanks for the suggestion!

author: slurry
author_rank: Regular Contributor
timestamp: April 24, 2017, 05:58:33 am
content: Fluke TL910 has some silly sharp steel tips, replaceable too and they also have rubbercaps to protect the tips.I use them often in my lab but they are somewhat delicate thus not made to be used in the farm or on the oilrig

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: April 24, 2017, 06:19:16 am
content: Quote from: slurry on April 24, 2017, 05:58:33 amThey are quite expensive tho. I'm not trying to say overpriced - I do not doubt good test leads are worth the price. However, as I have less than 50 euros a month to spend on my hobby electronics (as my other money goes to my uni and just feeding myself) I can't justify spending that much on leads (for now).

author: 2N3055
author_rank: Super Contributor
timestamp: April 24, 2017, 07:46:37 am
content: Quote from: frozenfrogz on April 22, 2017, 12:25:44 pmThere are quite a few with tips made from stainless steel, from Pomona, Fluke and such..I have few of them. Fluke modular ones are scary sharp and kinda heavy, if I drop them, they stick into my hardwood floor like an arrow...

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: April 24, 2017, 08:08:44 am
content: Quote from: 2N3055 on April 24, 2017, 07:46:37 amI stand corrected. As you pointed out, e.g. Fluke TP220 feature stainless steel tips. Is this for some specialty application? Maybe for corrosive industrial environments?I always thought stainless steel had quite bad properties for electrical probes, such as ten times the electrical resistivity of brass.

author: 2N3055
author_rank: Super Contributor
timestamp: April 24, 2017, 08:20:26 am
content: Quote from: frozenfrogz on April 24, 2017, 08:08:44 amWell, they are mechanically strong and stable. Sharp, so you can probe through conformal coatings, oxide layers and such..Resistance is not an issue. It is only a tip, 10 mm long and 2 mm in diameter. Even with steel, that's milliohms.. No problem for voltage (10Meg input resistance of meter), not a problem for current ( in series with measurement ). For 2W ohms, your probe wires will dominate the resistance (1 meter VS 10 mm ) regardless being copper. So you short them, null out the instrument and you're good to go..I don't use them much, except when called for, because they are dangerous for sensitive stuff. You can easily damage PCB and components with a minor slip. They feel more like a weapon than sensitive measurement accessory. But you presumed correctly, on a car, industrial environment and alike, they are great..Take care!!

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 25, 2017, 03:13:27 pm
content: This brings up the question, what's the best material for probe tips? Assuming cost is no object, you want them to stay sharp for a long while and not oxidize. Ideally they'd have low thermal emf to copper, but that might be a lot to ask. I'm thinking one of the hardenable stainless steels like 420, 430 or such. Tungsten? Pure tungsten welding electrodes are easily available. Other ideas?

author: 2N3055
author_rank: Super Contributor
timestamp: April 25, 2017, 04:50:21 pm
content: Quote from: Conrad Hoffman on April 25, 2017, 03:13:27 pmFluke probes I have have tips made from stainless that is just slightly ferromagnetic. That means some sort of austenitic stainless ( that would be 300 series in US ).I have had them for 20+ years, and i did touch up tips once. Only once. That makes them tough enough.I guess for maximum hardness, you could make tips from tungsten carbide... Sharpening and reshaping PCB drills and routing bits should be easy enough with diamond wheel grinder.But they would be prone to chipping and breaking if dropped on hard surface....For modular probes, with no cable attached, you just put them in a drill, and pull across sharpening stone or a abrasive paper on a glass at angle while rotating them.That takes care of tip if it was a bit deformed.. If it is a lot, you will need to reshape it.. All the same, more time...

author: eKretz
author_rank: Frequent Contributor
timestamp: June 06, 2017, 05:10:55 am
content: I re-tipped my Fluke TL probes with tungsten carbide tips. The original tips were cut flat on the end then I drilled down the center with a 0.040" drill and silver-soldered the tungsten carbide pins in and ground them to sharp points, then nickel plated any exposed brass. I have a set of stainless Fluke TPs also but they lose their points after a while too if you probe anything harder than tin or copper.

author: Muxr
author_rank: Super Contributor
timestamp: June 06, 2017, 05:52:42 am
content: Quote from: slurry on April 24, 2017, 05:58:33 amI love my TL910. They are great for probing small SMD parts, and hard to reach places (when troubleshooting for issues). They are not without faults however. As you said they are needle sharp which if you're not careful you can stub yourself on them. Also, and I don't know if this is an issue with just my set of probes, I've had the needle part of the probe fall out of the socket once when I was being rough with them. So as you said, pretty delicate.With that said, while not quite perfect, they are absolutely my favourite set of probes.

author: floobydust
author_rank: Super Contributor
timestamp: June 06, 2017, 06:24:02 am
content: So, I saw this on a youtube video, those Russians make their own probes out of old pens and sewing needles. We're all so rich.P.S. - I had bad luck with TL910's actually the Pomona version. Aluminum tube with stainless steel is crappy contact, and gold pogo-pin version was too soft.

author: komet
author_rank: Unknown
timestamp: June 06, 2017, 08:01:52 am
content: The Pomona 6341 is identical to the Fluke TL910 but costs half as much.

author: slurry
author_rank: Regular Contributor
timestamp: June 06, 2017, 01:13:11 pm
content: Yes, they are the same,also there is Keysight's 34133A which looks the same but has goldplated springy pogopin-style sharp tips,i use those only for my benchtop multimeter for SMD-use, they are

author: 2N3055
author_rank: Super Contributor
timestamp: June 06, 2017, 01:57:40 pm
content: Quote from: slurry on June 06, 2017, 01:13:11 pmThose are also same Pomona.. You can get Pomona with pogo stick type and with stainless solid tips.. Or both, where you get 4-5 pairs and you change them at will..I have those, they are really good for fine stuff, but not robust enough for general purpose use...I really like modular probes and cables.. I use those a lot at my desk.. Makes it quicker to change from medium to sharp tip, or clip or a crocodile...That is for low voltages.. For higher voltages, good solid one piece probes are safer..

author: CalMachine
author_rank: Frequent Contributor
timestamp: June 06, 2017, 03:21:13 pm
content: I've got a set of these ones at home. They've worked very well for me so far!http://shop.huntron.com/product.sc?productId=1

author: HighVoltage
author_rank: Super Contributor
timestamp: June 06, 2017, 06:35:04 pm
content: Quote from: slurry on April 24, 2017, 05:58:33 amI have these as well and not only do they come with great replaceable tips, you can also get all kinds of other high end tips that will fit these probes. I am using some Ingun gold plated tips.

author: nanofrog
author_rank: Super Contributor
timestamp: June 06, 2017, 07:34:55 pm
content: Quote from: 2N3055 on June 06, 2017, 01:57:40 pmFWIW, I've the Probemaster equivalents. Well made, and they have a better strain relief.Quote from: 2N3055 on June 06, 2017, 01:57:40 pm+1

author: floobydust
author_rank: Super Contributor
timestamp: June 06, 2017, 10:26:23 pm
content: Pretty sure I wrote flame email to Pomona because of the aluminum tube in thePomona 6341,6342,6275 series. Awful connection for ohmmeter measurements. No mention of aluminum in their datasheet eitherand $71 CAD at Digikey. OUCH