Bolt size?

[Okeydokey]

I would like to replace two bolts that secure my OTA rings to the mount via rings, the bolts say SM 48 on them, I am trying to source 'wing' bolt variations.  Anyone go any ideas?  I can't even find SM 48 as a point of reference except a pop group

Thanks

[catman161]

It is just M48 which indicates the thread size. Search for M48 bolts HTH

[Okeydokey]

Brilliant thank you very much for the rapid response!

[catman161]

No problem

[Dude_with_the_tube]

M48 bolt??? I hardly believe that.any metric bolt is equivalent to diameter in millimetres.So in your case M48 is 48mm! that is just one huge bolt.

Take your bolt from the OTA ring and measure it with calliper or with any ruler and see what is the diameter.i would guess it is going to be either M6 or M8 bolt at the max. So if your bolt has diameter of 6mm then it is M6,if  dia is 5mm then its M5 and so on. Then measure the length of the bolt until the cup and you will get the length required,so if the length reads for example 40mm and diameter of the bolt was 6mm,then you need an M6x40 bolt.same goes for thumbscrew or wingscrew.

[Cornelius Varley]

M48 is a big diameter bolt (48mm). The bolt will be either M6 or 1/4"-20 TPI, can't remember which. SM48 is probably the grade of bolt http://euler9.tripod.com/bolt-database/22.html

[themaninthesuitcase]

The markings on the head have nothing to do with their size but their strength.  The size is measured by the diameter of the outside of the threads, probably metric for a telescope, and then a thread pitch but usual this is a nominal standard for the size.

M48 for example would be huge, ~2" across.