Test Equipment Anonymous (TEA) group therapy thread

[AF6LJ]

I also thought about this method but couldn't locate any left hand drill bits, are they available then?

If you can't find left hand bits, look for a screw extraction kit. Same idea.

Rarely do these work out well for very small fasteners. 
Commonly they bust off and then the very best of luck trying to drill the broken stub out.
They're as hard as shark sh*te and impossible to drill with normal gear.

Absolute last resort IMHO.

Screw extractors are a waste of time on anything smaller than #8 and harder than grade-5.

So then, effectively, unless I can source another knob so that I can cut through the brass boss in order to gain access to repair it, it is likely to be consigned as a parts donor for another one 

If you have a reversible drill motor buy a couple of left hand drill bits.
As long as the set screw is a hex or spline head screw the left hand drills will likely extract the set screw.

[Fungus]

Just drill a triangular hole in the top of the grub screw and use one of these:

[Specmaster]

Just drill a triangular hole in the top of the grub screw and use one of these:

Drill a triangular hole, how do I do that? 

[bitseeker]

Left as an exercise for the reader.

[bd139]

Got outbid on three bits of test gear today 

If it was any of you, boo and hiss 

[bitseeker]

Innocent!

[tautech]

Just drill a triangular hole in the top of the grub screw and use one of these:

Drill a triangular hole, how do I do that? 

There's a chance that a triangle driver might work in something larger but for your 50 thou grubscrew.....forget it.

I've done a lot of hex driver work and there are two things you need ensure, first that your key is in good condition, edges sharp and not rounded and the end square too.....grind as needed.
The hex hole need be clean to full depth to ensure full engagement.

Neither matter much for most fasteners but when you get a tight one it really does.
With something as small as 50 thou there's not many options when things go wrong, only three IMO, heat, percussion (to loosen the bond), and drill the bugger out but that generally results in damage to the thread.


I've been racking my brain (what little I've got) to remember if you need to remove the timebase knobs as IIRC the retaining collars on the shafts near the two timebase PCB's actually hold the shafts in....I should whip the covers off the 1740A I have here but it's a job I don't want to get into just right now.
Have another look....and IIRC the two timebase shafts need be 'timed' so that they can be slid out the front without fouling on the way.....or maybe it was the selectors on the PCB's.  (main and delayed)

[AF6LJ]

Left as an exercise for the reader.

Maybe..
BOLTR knows how. https://www.youtube.com/channel/UChWv6Pn_zP0rI6lgGt3MyfA

[bd139]

It's Friday night, the wife is out, and I'm bored, so it's 80's night at home. Designing a 600Hz BPF for my direct conversion receiver, Queen in the background... currently measuring current consumption and the Q of the filter to make sure it matches the design parameters, which it does 



NEED MORE RED LEDs. I should have got the 8600A out but it's dicky.

None of the gear above makes a whisper (unless it's exploding). Damnation to anything with a fan in it!

[Specmaster]

Got outbid on three bits of test gear today 

If it was any of you, boo and hiss 

Not me, I got outbid as well

[Specmaster]

It's Friday night, the wife is out, and I'm bored, so it's 80's night at home. Designing a 600Hz BPF for my direct conversion receiver, Queen in the background... currently measuring current consumption and the Q of the filter to make sure it matches the design parameters, which it does 


NEED MORE RED LEDs. I should have got the 8600A out but it's dicky.

None of the gear above makes a whisper (unless it's exploding). Damnation to anything with a fan in it!

And the queen being? Nice to see the new counter in use 

[bd139]

Queen as in "Live at Wembley '86"

Counter is really nice actually. Much more sensitive than the Rigol piece of crap. I might sell that when I get my hands on a suitable RF signal generator (an impossible task as you know!)

[Fungus]

Drill a triangular hole, how do I do that? 

With a triangular drill, obviously.

Or drill a square hole - depending on what screwdriver you prefer.

but for your 50 thou grubscrew.....forget it.

Yes, that is a bit small to work with. 

You can't just pop one of those old Teks in a drill press either so any sort of precision drilling plan will fail.

I'm wondering is a small nail might get enough purchase to get it out. You can get them with quite sharp triangular tips (or file them to a better shape). You could tap it a bit to bite into the screw. Or maybe the screw will bite the nail, I'm not fussy.

I wouldn't use power tools, do it by hand.



OTOH if the screw's jammed in so tight it broke when you tried to get it out, it's probably doomed.

[bd139]

I still think my idea of buying another scope with a working knob is the best one 

[bitseeker]

Well, it is the TEA way to solve the problem.

[Specmaster]

And in true TEA fashion it is being considered 

As mentioned, the knob needs to be replaced anyway and the chances of getting another, that isn't connected to a scope are...well lets say I might have more chance of winning the lottery..if I did then I could go out and buy the latest new modern stuff. I think my shelves would give a sigh of relief and I'd be able to get even more test gear on them as well 

[Cubdriver]

Got outbid on three bits of test gear today 

If it was any of you, boo and hiss 

I can plead innocence as well - have been trying to stay away from the 'bay.  It's been a week so far.  I doubt that my hiatus will last much longer, though - a good part of the reason for this past week's absence was because I was in the field for work the entire time, and that didn't prevent me from buying a clock kit from the evil mad scientist site...   

-Pat 

[BU508A]

I still think my idea of buying another scope with a working knob is the best one 

I would give something like this a try:

http://www.ebay.com/itm/112081203535

[Cubdriver]

I'd be leery of trying to use an extractor on a screw that small - I'd expect that as thin as the walls are, the extractor would distort them and wedge the screw even MORE tightly into the hole in which it's stuck.  I'll third, or fourth, or fifth the suggestion to try a left handed drill bit.

-Pat

[AllTheGearNoIdea]

I don't know about you guys but I often buy at least three parts machines to make one good one. Logic suggests I just by one that actually works. It would be cheaper . I now have more broken logic analysers then can be considered sane.

Chris.

[BU508A]

I'd be leery of trying to use an extractor on a screw that small - I'd expect that as thin as the walls are, the extractor would distort them and wedge the screw even MORE tightly into the hole in which it's stuck.  I'll third, or fourth, or fifth the suggestion to try a left handed drill bit.

Yes, I saw your remarks but a drill can cause this kind of damage as well. You have to clamp the drill into something like this:



but it can be, that you cannot get the screw out (not enough force, drill will slip in the tool holder etc.)
But it is hard to give proper advice without e.g. a picture of the problem.

[Cubdriver]

Chris, I think most of us in this thread have at best a rather tenuous grasp on sanity. 

-Pat

[tautech]

I also thought about this method but couldn't locate any left hand drill bits, are they available then?

If you can't find left hand bits, look for a screw extraction kit. Same idea.

Rarely do these work out well for very small fasteners. 
Commonly they bust off and then the very best of luck trying to drill the broken stub out.
They're as hard as shark sh*te and impossible to drill with normal gear.

Absolute last resort IMHO.

Screw extractors are a waste of time on anything smaller than #8 and harder than grade-5.

So then, effectively, unless I can source another knob so that I can cut through the brass boss in order to gain access to repair it, it is likely to be consigned as a parts donor for another one 

Not at all.
I checked.
So bugger it, all this incorrect speculation.......loosen the 3 collars on the timebase shafts, align the main and delayed and remove the shaft complete with the knobs still on the shaft. Takes 2 minutes. 90 thou key.
No need to remove them to get the 1740A apart.

Edit
FFS, the procedure is clearly outlined in 8.24 in the SM...........I'm back to beta testing. Have fun.

[AF6LJ]

I still think my idea of buying another scope with a working knob is the best one 

I would give something like this a try:

http://www.ebay.com/itm/112081203535

Nice tool and, it may work...

I will be removing a seized set screw from the sweep time control shaft on an HP8569B spectrum analyzer as soon as I finish my current project.
I will be using a drill motor with a left hand .050 drill.
I think this is a time when a "Woman's Touch" will save the day, and the threads in the brass insert.

[bitseeker]

Yes, your suggestion sounds prudent, wilfred.