Low reactance screwdrivers? - Page 1
Forum section: electronics / projects

author: 0culus
author_rank: Super Contributor
timestamp: December 04, 2018, 11:06:18 pm
content: Any good recommendations for a quality set of small low reactance screwdrivers? I've been looking for some for things like aligning radio IF stages and oscilloscope compensation. I've looked at ceramic ones, but mostly what I've seen is cheap junk on amazon that has a lot of negative reviews about breakage.

author: bd139
author_rank: Super Contributor
timestamp: December 04, 2018, 11:08:14 pm
content: The ceramic ones always break and the plastic ones too. I just use a metal flat blade now and pull it out and recheck the IF cans. If you smash the core it's game over though but I broke one with a ceramic driver too.The ceramic drivers I had were really expensive (£50 .~ $70 /set) from a respectable supplier.

author: unitedatoms
author_rank: Frequent Contributor
timestamp: December 04, 2018, 11:19:02 pm
content: you can make a screw driver from a pcb material. either FR4 or this macabre like old brown material used in old radios.edit: found correct name. it is phenolic cotton plate for making gears

author: Bud
author_rank: Super Contributor
timestamp: December 04, 2018, 11:31:14 pm
content: I have a genuine HP (not that Agilent/Keysight rubbish) alignment tool which is simply a small flat metal blade molded into the round hard plastic shaft, the whole thing maybe 3 inch long. The blade extends from the shaft by maybe 1.5-2mm or so. Works a treat.

author: helius
author_rank: Super Contributor
timestamp: December 05, 2018, 12:06:47 am
content: Is the normal PA66 glass-filled nylon adjustment tool (Vishay Spectrol 008T000) not suitable? It's cheap and rugged.

author: mc172
author_rank: Frequent Contributor
timestamp: December 05, 2018, 12:27:22 am
content: The ceramic screwdrivers I use are made by Pro'sKit.https://www.proskit.com/screwdrivers/ceramicThe weak bit about them is the reduced diameter plastic part into which the ceramic bit is located. So, what I do is snap the entire thing off, heat it up and pull the ceramic out, drill a hole in the now shorter handle and Araldite it in. Modified like this, they never break, even when aligning filters with inductors made using Ø2 mm enamelled copper wire.Also bin the yellow cap (it won't fit after you modify it anyway). I drop mine on the floor all the time, never broken one.

author: rhb
author_rank: Super Contributor
timestamp: December 05, 2018, 03:33:03 am
content: A google search on "micarta sheets" turned up this:https://www.eplastics.com/sheets/fiberglass/g10-fr4-epoxyThe only issue is one sheet is a thousand year supply of blades to glue into a piece of glass or hard plastic tubing. But you can always sand a piece thinner. After all gunsmiths, jewelers and other skilled mechanical craftsmen routinely grind screwdriver to fit a particular screw.Of course the hexagonal and + shapes are more challenging.Thanks for posting. I'd been running into this but hadn't devoted any time to solving it except by mangling what I had on hand.FWIW Micarta is a tradename for phenolic resin impregnated cotton cloth developed in the early 1900's by George Westinghouse according to Wikipedia. It's still great stuff over 100 years later.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2018, 04:13:26 am
content: are ceramic drivers really bad? I assume its a ceramic head on a plastic shaft.I use ceramic knives (exacto and utility knife and box cutter) sometimes, if I feel like it, and the material seems pretty good. I can't imagine it snapping because of a trim pot or trim inductor.I only ever used plastic ones for things like an oscilloscope probe adjustment.Am I missing out on something? Are you guys talking about heavy duty stuff to adjust giant inductors? I just have a hard time imagining adjustment screws on electronics breaking anything unless you put some kind of threadlocker (loctite purple maybe) on them...i also love ceramic tweezers and I only managed to break them by dropping them on the floor. I leave a heavier metal box on the table when I work with ceramic tweezers (its the old box that the wiha mini screw driver with 50 bits came in) and make it policy to never place the tweezers on the work bench when I am done with using them, but to always return them to the safety of the box which is fairly hard to knock down from the table. Even when I broke the ceramic tweezers *just the tip*, i used a diamond stone to even them back out and be left with a slightly thicker pair of tweezers. I noticed the shitty ones I bought from china broke alot easier then the expensive 25$ ceramic tweezers from the swiss or something.I think pretty much most of my glass or ceramic tool breakages occurred because I decided to set them down into the bench area rather then a special location for fragile objects to be protected in. You need to accept your working with something fragile that requires special procedures and that you will absolutely not gamble with it in any sense to save time and effort. Then you save money.

author: 0culus
author_rank: Super Contributor
timestamp: December 05, 2018, 06:44:25 am
content: Thanks for the suggestions! That Vishay adjustment tool looks promising, as are those pro's kit ones.

author: Ian.M
author_rank: Super Contributor
timestamp: December 05, 2018, 07:21:07 am
content: You'll have a lot fewer problems with alignment tool fragility if you check the force to turn the trimmer isn't excessive using a regular screwdriver before using a non-metallic one.Cores are a different matter. Traditionally, a strand of elastic was often stretched through the former to provide friction before the threaded core was originally inserted, and if that elastic has degraded to goo, the core may be very well locked in place, so attacking it with a metal tool is likely to result in it fracturing. There's also the possibility its been locked with hot wax, and again, attempting to move it cold will probably be a disaster.Hollow cores with a hexagonal center hole are some of the worst - the wedging action of turning a hex key in the hole is extreme and ferrites (and other ceramic magnetic materials) are brittle with relatively low tensile strength. Old iron dust cores are probably the worst - they crumble at the slightest provocation.For slotted cores, a soft brass blade, filed to an exact (but not tight) fit, with all edges and corners 'broken' on a fine stone is probably the safest compromise between strength and kindness to the core, for initial adjustment. For hex cores, using anything except a plastic hex trim tool is a last resort. Before reaching for the Allen keys, try heat and solvents as trying to shift a stuck core with a metal tool seldom goes well, and even if you have an exact replacement core handy, it may be impossible to remove the broken fragments of the stuck core without wrecking the former.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2018, 03:29:36 pm
content: sounds like most of these problems are confined to older equipment. I assume modern stuff would use teflon tape?