Bolthole on forks sheared: Mudguard idea's

[danson67]

OK no problem,

You can always have the Helicoil option as a backup if it goes wrong
...Helicoiling would use a 5.2mm hole for M5 thread and a 6.3mm hole for 6mm thread.

All the best,

 

[Thaumaturge]

Absolutely, a comforting insurance policy as i approach this with some trepidation! I saw a vid on the helicoil too.. what a great idea that stuff is. Presume i match drill holes with taps .. m5/5mm bit etc?

 

[Andy R]

Absolutely, a comforting insurance policy as i approach this with some trepidation! I saw a vid on the helicoil too.. what a great idea that stuff is. Presume i match drill holes with taps .. m5/5mm bit etc?

No, the tapping drill size for M5 is 4.2mm. That's the size that you need to drill, in other words.

 

[Matthews]

Bolt size minus thread pitch gives you the hole size to drill.(M5 X.8 is therefor e 5-.8 = 4.2 as Andy R stated. M6 x1 is 6-1 = 5 and so on .)
Matthew

 

[Thaumaturge]

Ooh i seee.. i took pitch to mean the properties of the thread helix.. i.e. its spacing/speed. That makes for some odd drill sizes though doesn't it.. so there are special bits just for predrilling?

 

[hamster]

Yes!

 

[Thaumaturge]

In the interests of closure, one of the taps i had was a nice round pitch number of 1mm so was able to drill it and tap successfully

 

[danson67]

was able to drill it and tap successfully

Surely some sort of Right of Passage in bloke-shed world?

All the best,