Modding M bolt question

Can some one please help me understand this hol M3,M4,M5 bolt thing i dont get what it means does the "M" mean metric and what does the number after it refer to. anyhelp would be appricated thanks

DAN

 

AFAIK, it's the diameter of the bolt, in millimeters.

Often it'll be something like M5x25, which is 5mm dia. by 25mm length.

 

aaaaaargh so simple im embarrased, anyway thanks a lot for the help now i can order some and get modding

 

hi just another quick question, say ive got some 12mm thick plexiglass and i want to place a bolt in the 12mm bit to attach it to a case. it needs to be strong so i was thinking of a M4 bolt as that would leave 4mm on either side of the bolt, would this be risking cracking the plexi or should i go with a smaller bolt? thanks.

 

M4 should be fine, as long as you make the threads with proper tools and not overtighten them

 

thanks for the swift replies quys

 

Don't be embarassed. I had to look it up at one point too. Last weekend I tried figuring out how to convert imperial units to metric measurements. Now THAT's a challenge.

Now, if you came here before checking google or wikipedia, THEN you're right in being embarrassed.

When drilling into the plexi (to make the hole for the bolt, if it's not yet holey), go SLOW. That's where you have to worry about cracking.

 

Try to find the elusive acrylic drillbit made to lessen cracking i have heard the rumors.

 

Stuey, get a calculator that has built-in conversions. I have a TI-86. It's handy for fan airspeed calculations, case masses and tons of mod-related and non-related stuff. I mostly need it for school, though.

 

...or use Google Calculator.

 

Tape both sides of that plexi to reduce chances of cracks.

 

I've got a Ti-83 plus but I didn't know it can do conversions. I use Windows calculator for simple things and google's calculator as well.

I spent about 20 minutes now trying to refind the conversion numbers without luck. What I found the other was bold size * .013 + .06 = diamater in inches. I don't know if that's right or not. Oh well I could always find some calipers. =)