hex/allen key for compression fittings

orange_smurf · 12 Oct 2019 at 16:39

Hi, i'd like to use a Hex Key for my G1/4 compression fittings and i'm not sure what size to use - 10mm? I cant just pop into a local store to check so i'm hoping someone here could help :confused:

My fittings:

Alphacool Eiszapfen 13mm Deep Black Hard Tube Compression Fittings - Six Pack

LuckyBenski · 12 Oct 2019 at 20:43

Pretty sure it was 10mm

Either that or 8mm, as I don't own 9mm or 11mm allens and it's definitely metric. 8mm looks too small - G1/4 fittings have a roughly 12mm diameter.

Can't pop a fitting out of my build to check, sadly!

pastymuncher · 14 Oct 2019 at 09:06

Going by a competitors listing it takes a 8mm hex key.

To be honest you shouldn't be screwing in a fitting with a hex key as you can easily overtighten the fitting and disfigure or crush the O-ring. Fittings should be screwed in hand tight and tightening the locking collar down will probably tighten the fitting even more. The hex key will most likely be needed for the removal of the fitting.

orange_smurf · 14 Oct 2019 at 18:20

LuckyBenski said:
Pretty sure it was 10mm Either that or 8mm, as I don't own 9mm or 11mm allens and it's definitely metric. 8mm looks too small - G1/4 fittings have a roughly 12mm diameter.

Can't pop a fitting out of my build to check, sadly!

Hi, thanks for getting back. i tried out both 8mm and 10mm today and neither fit a EK-HDC fitting. I presume it's the same as Alphacool. EK's site recommends 9mm (how i missed this i don't know). The story of Goldilocks comes to mind!

orange_smurf · 14 Oct 2019 at 18:23

pastymuncher said:
Going by a competitors listing it takes a 8mm hex key.

To be honest you shouldn't be screwing in a fitting with a hex key as you can easily overtighten the fitting and disfigure or crush the O-ring. Fittings should be screwed in hand tight and tightening the locking collar down will probably tighten the fitting even more. The hex key will most likely be needed for the removal of the fitting.

My delicate fingers get cut up when i take the fittings so I very much agree!

tyler_jrb · 14 Oct 2019 at 18:37

orange_smurf said:
Hi, thanks for getting back. i tried out both 8mm and 10mm today and neither fit a EK-HDC fitting. I presume it's the same as Alphacool. EK's site recommends 9mm (how i missed this i don't know). The story of Goldilocks comes to mind!

The hdc fittings are 9mm from experience. I needed one that badly (was hoping they were 10mm). I just filed a spare 10mm key down until it fit lol.

Most 13mm compression fittings are 8mm.

I always put them on with Allen keys. Hand tight is fine until you need to take them out and the entire fitting comes off. The Allen keys from ekwb are usually shortened versions so you will struggle to strip them unless you go mad.

LuckyBenski · 14 Oct 2019 at 19:33

On that note, here's a good tip for avoiding overtightened components: put the long end of the allen key into the socket, so you have less leverage on the tool. This combined with a light touch helps set a "more than finger tight, less than cranked to death" setting that shouldn't end up too hard to disassemble.

Also, don't just buy one allen, buy a set! Problem solved

orange_smurf · 17 Oct 2019 at 14:51

tyler_jrb said:
The hdc fittings are 9mm from experience. I needed one that badly (was hoping they were 10mm). I just filed a spare 10mm key down until it fit lol.

Most 13mm compression fittings are 8mm.

I always put them on with Allen keys. Hand tight is fine until you need to take them out and the entire fitting comes off. The Allen keys from ekwb are usually shortened versions so you will struggle to strip them unless you go mad.

Ta. I went old school and wrapped sellotape around the 8mm

orange_smurf · 17 Oct 2019 at 14:57

LuckyBenski said:
On that note, here's a good tip for avoiding overtightened components: put the long end of the allen key into the socket, so you have less leverage on the tool. This combined with a light touch helps set a "more than finger tight, less than cranked to death" setting that should end up too hard to disassemble.

Also, don't just buy one allen, buy a set! Problem solved

Thanks. I'll try that on my next build.

I don't know why but most sets don't come with a 9mm. I sought out one that did only to find that the description was wrong!

All in all, it's not like this is an essential bit of kit...

tyler_jrb · 17 Oct 2019 at 16:34

orange_smurf said:
Thanks. I'll try that on my next build.

I don't know why but most sets don't come with a 9mm. I sought out one that did only to find that the description was wrong!

All in all, it's not like this is an essential bit of kit...

Metric wise 9mm isn’t used on any standard metric threaded bolts.

You can get 9mm hex keys cheap enough though from the likes of RS for £2 free delivery.