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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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25th Feb 2021, 7:16 pm | #1 |
Octode
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 1,177
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What Allen Key Size?
I'm trying to remove a grub screw on a piece of test gear and I don't know what size it is or whether it is Imperial or metric.
2mm is too big and 1.5mm is a bit too small. The piece of gear is from the '70s. Does anybody know the correct size? Thanks |
25th Feb 2021, 8:01 pm | #2 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: What Allen Key Size?
Could it possibly be 1/16" (approximately 1.59mm)?
I've often found that small, cheap (in particular) Allen keys can be a bit vague and prone to tolerance as to size, sometimes it's necessary to try a few different makes of what claims to be the same size to find one that is a comfortable fit and won't slip round and mash up the profile of either key or fastener. It looks like a hex key fitting from the pic, but sometimes alternative types turn up, like Bristo spline- I was intrigued to find that the tiny aerial trimmer knob of a WW2 US receiver was retained by a titchy grub screw with something like a four-spline version of a Bristo fitting, but with a Maltese cross profile. What would one ask for there?! |
25th Feb 2021, 8:02 pm | #3 |
Tetrode
Join Date: Oct 2016
Location: Manchester, UK.
Posts: 78
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Re: What Allen Key Size?
Possibly imperial 1/16 inch. I would try cleaning the muck out of the socket as that will stop the key going in properly and encourage rounding of the hex.
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Mark |
25th Feb 2021, 8:12 pm | #4 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
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Re: What Allen Key Size?
With lower quality allen keys sometimes the ends look badly sheared off like a piece of licorice, have a close look before using it. It can be remedied with large ones by grinding, but these smaller ones are best discarded.
Dave |
25th Feb 2021, 9:01 pm | #5 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
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Re: What Allen Key Size?
Looks to be a Farnell oscillator, possibly an LF1, maybe that will help with identifying the grub screw Allen key size.
David |
25th Feb 2021, 10:45 pm | #6 | |
Octode
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 1,177
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Re: What Allen Key Size?
Quote:
I had a similar issue with an early 60's Marconi O/P meter that must have used the same Allen head. I 'cheated' and used a similar sized Torx bit. This might not work with the Farnell as the bit is recessed. 1/16'' or 1.59mm could be right. |
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26th Feb 2021, 2:23 am | #7 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
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Re: What Allen Key Size?
Are you sure it is Hex and not Torx? A few years ago I bought a miniature 10-turn pot and its knob, which was supplied with a Hex Allen key. It was impossible to tighten and it turned out that the grub screw (0-80 UNF) had a Torx socket recess.
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26th Feb 2021, 6:00 am | #8 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,188
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Re: What Allen Key Size?
And are you sure that was Torx? I have a piece of equipment (Trend TDMG2C teleprinter test signal generator thing) with a 10 turn pot and dial. The grub screw in that takes a Bristol Spline tool.
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26th Feb 2021, 2:15 pm | #9 | ||
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
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Re: What Allen Key Size?
Quote:
David |
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26th Feb 2021, 2:27 pm | #10 |
Octode
Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
Posts: 1,177
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Re: What Allen Key Size?
Thanks for confirming the Allen head size. Wilco sell a handy Imperial and metric set that includes a 1/16" key.
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26th Feb 2021, 2:33 pm | #11 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
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Re: What Allen Key Size?
I had downloaded the manufacturer's technical data sheet for the knob, which stated that the grub screw was Torx. With such a small size it was difficult to see with the naked eye. The distributor sent another unit as the splines of the original had been damaged by my attempts to tighten it with the hex key they had supplied, and small unified grub screws are not exactly off the shelf items in the UK.
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26th Feb 2021, 2:56 pm | #12 | |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,706
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Re: What Allen Key Size?
Quote:
David |
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26th Feb 2021, 9:01 pm | #13 |
Nonode
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 2,346
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Re: What Allen Key Size?
Comments have been made about accuracy of low quality Allen keys. Your photo shows "Rolson", one of the really cheap purveyors of every sort of rubbish, from timing guns (useless) to, well, Allen keys. Try some by one of the USA tool manufacturers, or even a (genuine) UK manufacturer, if you can find one.
Les. |
26th Feb 2021, 9:29 pm | #14 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,583
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Re: What Allen Key Size?
I agree with Les and I'd reconsider purchasing the cheap Wilco set. Bondhus (US company) is considered by some to be one of the best. Worth spending a few pounds more for decent quality. For example:
https://www.ebay.co.uk/itm/Bondhus-9...MAAOSwokNgNkuL Alan |
26th Feb 2021, 11:56 pm | #15 | ||
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,526
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Re: What Allen Key Size?
Quote:
Interesting Metric set in the picture- it has a stray imperial key in it. 1.27mm aka 1/20" or 50 thou. Often found on small knob grubscrews!
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27th Feb 2021, 11:58 am | #16 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,838
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Re: What Allen Key Size?
Many years ago, in the early 60's, to supplement a lowly airman's wage, I ran a wee stall in Paddies' Market, Liverpool,(off Casnau Street nr. Scotland Road), on a Saturday. Before it opened, stall-holders would poke about in each other's junk & cherry-pick wee bargains. My wee bargain was a tobacco tin full of small to medium imp. Allen Keys. They were of the best quality & still in regular use today. I've since seen modern cheapo Allen keys & guess that some are just mild steel as the flats wear very easily.
As a tip regarding loosening reluctant grub-screws :- insert a gash or worn cheapo allen key, then briefly heat it(& hence the grub-screw, but not the plastic or bakelite knob) with a soldering iron. As it cools, drop in a wee dose of "looseoil" or WD40. This enhances the lubricant being drawn right into the tight grub-screw/knob's thread. Then proceed with a decent allen key after a minute or two's cooling time. Regards, David |
27th Feb 2021, 12:16 pm | #17 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
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Re: What Allen Key Size?
My set of metric Allen keys are the real thing, having actually been made by the Allen company. Bought from a long defunct local shop that used to carry an excellent range of quality precision tools and fasteners.
Until it moved to Wales in the 1990's, the Patent Office's Classification Section used to have a little-publicised free service in which one of their examiner's official duties included answering enquiries from the public. If he didn't know the answer himsef he would ask an examiner responsible for the relevant technology. They had files covering the most popular questions, and always had bursts of enquiries when competitions were being run in magazines. The most popular query from men was "Who invented the Allen key?", and from women "Who invented the brassiere?". (The Allen key was never patented.) Last edited by emeritus; 27th Feb 2021 at 12:27 pm. |
27th Feb 2021, 1:09 pm | #18 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,552
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Re: What Allen Key Size?
Unbrako always used to be the name to go for, both for allen keys and allen screws and bolts.
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27th Feb 2021, 1:20 pm | #19 |
Heptode
Join Date: Jun 2019
Location: Oxfordshire
Posts: 719
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Re: What Allen Key Size?
I recently needed a set of small Allen keys and got these:
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1 They have been useful for small Allen key grubscrews and seem good quality. |
27th Feb 2021, 2:42 pm | #20 | |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,188
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Re: What Allen Key Size?
Quote:
As an aside I find it amusing that many sets of 'metric' feeler gauges have 0.38mm and 0.635mm blades. Better known as 15 thou and 25 thou. |
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