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View Full Version : What size allen bolts?


keiron99
21-01-2014, 19:08
One of the allen bolts that holds my SME arm to the mounting board is missing.

I measured them and thought they were 2mm, and so ordered some M2 x 8, but they arrived and they are TINY!

Does anyone know what size I need?
YNWaN
21-01-2014, 19:55
Most likely M4 or M5

A common mistake is to confuse radius with diameter - M4 means the bolt (including thread) is 4mm in diameter - 2mm in radius.
CageyH
21-01-2014, 19:57
My Rega arm takes M3 bolts to hold it to the Armboard.
I suggest the easiest thing to make sure you get the correct fastener is to remove one of the others and measure the diameter and length.
YNWaN
21-01-2014, 19:58
Rega arms take 3.5 as I recall
keiron99
21-01-2014, 20:34
Thanks. I did remove and measure it but it is hard to do so. It looked like 2mm on my steel rule but clearly my eyesight is hopeless!

I just measured again. It's impossible to tell with the naked eye! The ones that were sent to me I am convinced are no more than 1mm DIAMETER (not radius).

I guess I'll just have to buy a selection and see what fits.
CageyH
22-01-2014, 04:32
What armboard do you have?
shane
22-01-2014, 07:17
M2.5 usually.
shane
22-01-2014, 12:49
Here you go:


http://www.ebay.co.uk/itm/CARTRIDGE-MOUNTING-KIT-Universal-Set-of-Bolts-Screws-Nuts-etc-for-any-Headshell-/290947523860?pt=Turntable_Parts_Accessories&hash=item43bdd2e514
CageyH
22-01-2014, 12:56
Shane,

I think that's the wrong end, but useful info anyway.
;)
keiron99
22-01-2014, 20:23
So it's somewhere from 2.5 to 5 !
The kind ebay seller who sold me the original pack is sending me one of each.
shane
22-01-2014, 20:46
Note to self: read post carefully before replying!!

Having said that, I reckon M2.5 would be about right for the SME baseplate, if you're retaining the rubber isolating bushes.
PaulStewart
22-01-2014, 21:14
If it helps, my SME IV is fitted to my composer with M3 bolts.
keiron99
22-01-2014, 21:48
Having said that, I reckon M2.5 would be about right for the SME baseplate, if you're retaining the rubber isolating bushes.
What are the bushes you refer to?
keiron99
24-01-2014, 15:25
Update: I received a selection and it looks like it was the 2.5 (which seems considerably larger than the 2mm)

So Shane wins :)
CageyH
24-01-2014, 15:33
A lucky guess! :lol: