Misc: Everything Else Helicoil questions

vibrac

Well Known and Active Forum User
VOC Member
I have a an M8 and an M6 helicoil set both have taps market ST followed by what I believe is the finished thread size when the coil is inserted. I also have a 5/16" BSF insertion tool and a set of inserts (for a very long time!) I seem to have lost the tap in all my taps so am I looking for a tap marked ST 5/16 BSF? also can anyone tell me the drill diameter for a 5/16 BSF Helicoil tap?
I guess I was in a tidy up too much mood sometime back
:rolleyes:
 

Nulli Secundus

Well Known and Active Forum User
VOC Member
VOC Forum Moderator
At £30 Tracy Tools sell a 5/16"BSF kit and it says it includes an 8.3mm drill, so that must be the drill size you require.
 

Nulli Secundus

Well Known and Active Forum User
VOC Member
VOC Forum Moderator
It might be worth phoning them for a 5/16" BSF oversize tap to suit the helicoil? Does ST = Second Tap, so not a taper tap?
 

vibrac

Well Known and Active Forum User
VOC Member
Yes Tracy tools do a special Helicoil tap its not on line you have to phone
Great service email answered in 5 mins
Thanks all I will try and be more tidy and exact in future :rolleyes:
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Tim my handsome, Tracy tools might just supply the tap for you. Never used a tapping drill for a Helicoil, the reason is the Helicoil is being fitted because the thread is missing so one puts the tap straight in, if fitting into a plate or casting for a stronger fixture the tapping drill would be the size of the bolt being fitted , this case 5/16". Tracy no longer sells Helicoil but "V coil" the same thing using the same inserts.
bananaman.
 

robin

Well Known and Active Forum User
VOC Member
Cromwell Tools sell metric and imperial helicoil kits or the individual components separately. They have outlets nation wide
 

clevtrev

Well Known and Active Forum User
VOC Member
Tim my handsome, Tracy tools might just supply the tap for you. Never used a tapping drill for a Helicoil, the reason is the Helicoil is being fitted because the thread is missing so one puts the tap straight in, if fitting into a plate or casting for a stronger fixture the tapping drill would be the size of the bolt being fitted , this case 5/16". Tracy no longer sells Helicoil but "V coil" the same thing using the same inserts.
bananaman.
Be careful doing that, as using an undersize hole when tapping gives you an oversize thread. If you need to know the tapping size for any thread, simply subtract the pitch of the thread from the diameter. Not quite for helicoil taps unless you know the correct diameter, in this case it`s not 5/16".
 
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