Author Topic: those  (Read 5431 times)

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Offline GEuser

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those
« on: May 27, 2016, 01:33:31 pm »
Q
« Last Edit: August 30, 2016, 12:41:44 pm by GEuser »
Soon
 

Offline BurningTantalum

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Re: Sharpen those Probe tips (1 method)
« Reply #1 on: May 28, 2016, 03:50:19 am »
The technique of rolling a workpiece 'backwards' to the direction of travel when sharpening is good practice. It was taught to me many years ago by a mechanical engineer who didn't have an apprentice so took the young electronics trainee under his wing. The same technique is used when filing a cylindrical piece- always rock the file backwards to the stroke. It eliminates or reduces flat spots.
Regards, BT
 

Online Ian.M

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Re: Sharpen those Probe tips (1 method)
« Reply #2 on: May 28, 2016, 12:44:29 pm »
Now you need some silver plating solution to finish the job, otherwise you'll have to buff them with fine grit w&d paper to take off the oxidisation whenever you haven't used them for a while.   Even silver plate will give trouble if you have a coal fire, eat too many beans or live in an urban area as if there are sulphurous gasses in the air, it forms a semiconducting tarnish film of silver sulphide, but OTOH its one of the easier metals to DIY plate with reliably.
 

Online Ian.M

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Re: Sharpen those Probe tips (1 method)
« Reply #3 on: May 28, 2016, 01:04:59 pm »
Tin plate would be nearly as good.  If they are brass, you could simply tin them with lead-free solder and wipe off the excess.   Wrap the base of the tip and end of the body in well soaked paper towel secured with a rubber band so you dont melt the plastic body, or the joint to the lead.
 

Online tautech

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Re: Sharpen those Probe tips (1 method)
« Reply #4 on: May 29, 2016, 02:52:37 am »
Also I've found I'm in maintenance mode atm , dunno how that happened , i did the cheapish snips (they have put in a good service for a cupla years) and now snip better than i ever recall , a quick belt with a hammer on that rivet also fixed up the wobble , i do need new ones though .
A few swipes along the cutting edge with a thin slipstone will make them better still.  ;)
Ones like these:

Avid Rabid Hobbyist
 

Online Ian.M

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Re: Sharpen those Probe tips (1 method)
« Reply #5 on: May 29, 2016, 03:03:47 am »
Test the snips on a cigarette paper - you are looking for an even full length cut with only light pressure.  The tips should cut first (but only just) as the blades flex away from each other.  Look closely at how the blades meet with a magnifier, as the contact is on the inside face of one blade as an anvil, which needs dressing flat and the edge of the other, which needs profiling to meet the anvil as evenly as possible, then final sharpening.

If you don't have decent slipstones, stick fine grit wet&dry paper to a popsicle stick with spray glue or thin double sided tape.
 

Offline peter.mitchell

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Re: Sharpen those Probe tips (1 method)
« Reply #6 on: May 29, 2016, 05:16:52 am »
if you are only probing logic signals, sewing machine needles are very good probes.
 

Online Ian.M

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Re: Sharpen those Probe tips (1 method)
« Reply #7 on: May 29, 2016, 05:55:09 am »
One can make very nice needle point probes from sewing needles (ideally gold flashed which for some reason embroiderers like, but for us, makes them solderable) mounted in Bic Cristal biros.  Remove the ink tube, push the brass part of the tip out of the plastic part, and punch the little ball out of the brass part using a pin or similar from the inside. Wash out with IPA.  You can then solder the needle into the brass part, with the length you want protruding, solder a test lead to the eye and reassemble the Bic with the lead exiting through a hole in the plastic plug.   The only major disadvantage is that the barrels are polystyrene, which is rather brittle in its clear form.

I wonder if one  could build a logic probe circuit with tristate LED indicators small enough to fit inside the barrel of a Bic?
 

Offline David Hess

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Re: Sharpen those Probe tips (1 method)
« Reply #8 on: June 18, 2016, 08:54:21 pm »
Good probes use a hard metal like steel, stainless steel, or beryllium copper allowing them to be sharpened so they will not slip and can puncture insulation or conformal coating if needed.  Beryllium copper has lower resistance and is easier to solder to but presents a hazard when sharpening so is rare.

I have a tray of thoriated tungsten TIG welding rods which I have been cutting up to make probe tips but piano wire or sewing needles work just as well if not better.

I have always wondered if one of those vintage K&E drafting pencil sharpeners would work for quickly sharpening probe tips but have never tried it.
 

Offline bdivi

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Re: Sharpen those Probe tips (1 method)
« Reply #9 on: August 26, 2016, 01:47:46 pm »
I have given up sharpening my tips and soldered some stainless steel needles.

I took some standard meter probes, filed the probe to about 50% of its cylinder body and solder a piece of needle as an extension. Then shrink-wrapped and tested  :)
 

Offline David Hess

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Re: Sharpen those Probe tips (1 method)
« Reply #10 on: August 27, 2016, 06:58:29 pm »
I have seen soft metal probes modified by cutting the entire tip off and using a lathe to bore a hole for the new hard metal tip which slides into position and may then be soldered.  It is actually kind of amazing that they even *make* nickel plated soft brass probe tips.

Good probes are already built this way.  I have some Pomona multimeter probes which have tips made of hardened steel.
 

Offline stj

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Re: Sharpen those Probe tips (1 method)
« Reply #11 on: August 28, 2016, 01:23:48 am »
go to a sports shop - a real one, not a "trainers & hats" place.
ask for a "dart sharpener"

http://www.a-zdarts.com/Category/Accessories/Sharpeners.aspx
 

Offline stj

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Re: Sharpen those Probe tips (1 method)
« Reply #12 on: August 28, 2016, 01:55:55 am »
i dont think you put the dart in to the end, you roll it around with the dart / probe on it.

hmm - i didnt explain that very well - you'l work it out  ;D

ahh - the package in the 3rd pic has a diagram!!!  :-+
« Last Edit: August 28, 2016, 01:58:44 am by stj »
 

Offline stj

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Re: Sharpen those Probe tips (1 method)
« Reply #13 on: August 28, 2016, 03:13:16 am »
you could make a block of aluminium and a rectangular stone into a device similar to a pencil sharpener.

but why bother - how often would you use it?
i just sharpen my probes on the surface of a (running) dremel cutoff disc.  >:D
 

Offline David Hess

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Re: Sharpen those Probe tips (1 method)
« Reply #14 on: August 28, 2016, 05:43:22 am »
Good probes are already built this way.  I have some Pomona multimeter probes which have tips made of hardened steel.

Got a Pic of those too or a link ? , i was poking around the interweb the other week just looking about and noticed some stainless probes that were relatively cheap for a MM , real pointy ones like a needle and obviously looked sharp too .

Those scope probes that i had to do i would call "Not Vampire" ones , those MM ones i did are definitely blood suckers .

They are 20+ years old but these are close if not identical:

http://www.pomonaelectronics.com/pdf/d5672a_101.pdf

Tip: Stainless Steel, Wire: 18 AWG

On mine the tips look gray like tarnished music wire but some stainless steel is more stainless than other stainless steel.  They are dangerously sharp like a needle and have drawn blood several times.
 

Offline stj

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Re: Sharpen those Probe tips (1 method)
« Reply #15 on: August 28, 2016, 07:49:00 am »
maybe you could get an old electric pencil sharpener and replace the blades with stones.

if it's like the electric sharpeners we had at school, you'l take a few mm off the probes each time!!  >:D
 


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