Allen key size

[stewblack]

I've been doing my seasonal trussroderry as the weather cools and dampens.

I have one bass which none of my Allen keys will fit. 

Put simply, how do I find out what size I need to buy. I don't want to buy a massive set on the off chance that one will fit.

[ikay]

What type of bass is it? If it's US built the chances are it will be an imperial size. Anything else most likely metric. Using the allen keys you already have you can then narrow down the size to be somewhere between the ones that are too big and too small.

[rushbo]

Have you tried your local Wilko? I bought a set from there when I had a similar issue and one of them did the job. Currently £2.50. 

[John Cribbin]

Unfortunately, you may need a selection to try.

 

The nuts may start out as either 4 of 5 mm, but for whatever reason get rounded and the correct size no longer fits.

[BigRedX]

A decent set of metric and imperial Allen keys should cost less than £10. Then you'll never need to ask this question again.

[stewblack]

Thank you all. I should have said I don't want another set as I have so many already. And it's a new bass (or was last year - either way not rounded off) but made by a luthier who has ceased trading so I can't ask.

 

[BigRedX]

The relevant Allen keys are metric 4.0, 4.5, 5.0 and Imperial 5/32 and 3/16. If you have all of those one of them should fit. If not make sure you at lease have the all the metric ones.

[tauzero]

On 20/09/2022 at 14:17, stewblack said:

Thank you all. I should have said I don't want another set as I have so many already. And it's a new bass (or was last year - either way not rounded off) but made by a luthier who has ceased trading so I can't ask.

 

 

Have you got both metric and imperial sets?

[stewblack]

I have a box full of them, both kinds. I've never had a problem finding one to fit any of my basses. Which is why I'm snookered with this one.

I'm going to try gently pressing some blue tack onto it and measuring the impression.

[tauzero]

 

🙂

[ikay]

As mentioned above, have you tried using the allen keys you already have to narrow down the size? Metric sets usually increment in 0.5mm steps so if none of these fit then it's most likely an imperial size. If you can identify the metric size that's just too big and the one that's just too small, that should give you a pretty good bead on the imperial size which will be some multiple of 1/64".  Here are a few imperial to metric conversions. It's easy to see how imperial sizes slip between the metric keys, and not all imperial sets will include odd ones like 7/64 or 9/64 etc.

 

7/64 = 2.778125

1/8 = 3.175

9/64 = 3.571875

 

 

Edited September 26, 2022 by ikay