C9
Aluminum
- Joined
- Jan 17, 2005
- Location
- N/W Arizona
This one's probably been discussed before, but I did a search and didn't find a specific comparison.
I hang out on a few hot rod oriented boards and I'm seeing a few comments about weak threads in the NF category and the recommendation to use NC in most applications.
My understanding was that NF was the stronger of the two due to more threads engaged.
Even if the depth of thread is shallower.
Perhaps it has to do with the choice of metals used.
I make a lot of hot rod oriented stuff, simple engine parts - both internal and external - and in most cases the choice of material is 6061 T6 aluminum.
A lot of the threading is done under power in the lathe and NF is the thread of choice - 1/4" & up fwiw.
The lathe is reversed 2-3 times - depending on thread size and depth - and chips are cleaned out.
I do start the smaller taps in the lathe and finish them by hand.
The biggest reason NF is chosen is because it's easier on the lathe or mill/drill.
I understand as well that full thread strength is generated by cutting threads to a depth at least equal to the diameter of the bolt to be used.
IE: 1/2" bolt gets 1/2" worth of threads.
NC is used - in my case - for threaded weld bungs that get welded into the chassis as well as for decorative items like escutcheon plates.
These finish off the holes for the brake pedal - and helps hold the carpet down - as well as for the throttle rod to enter the cockpit area.
To my eye, a much nicer look than a sewn carpet binding around the hole and the aluminum escutcheon plate doesn't wear away.
I note as well that NF is used in the engine internals in several areas utilizing smaller bolts - 3/8" rod bolts for example - and NC is used for main cap bolts or studs.
Externally, most engine threads seem to use NC.
Is the choice between NF and NC simply a manufacturing convenience or a strength consideration for rod bolts and oil pumps?
I see that most torque values listed for NF vs NC have NF getting a bit less torque.
I understand as well that this lesser torque with NF generates the same clamping force as the higher torque of the NC threads when similar sized bolts/studs are used.
Color me confused....
I hang out on a few hot rod oriented boards and I'm seeing a few comments about weak threads in the NF category and the recommendation to use NC in most applications.
My understanding was that NF was the stronger of the two due to more threads engaged.
Even if the depth of thread is shallower.
Perhaps it has to do with the choice of metals used.
I make a lot of hot rod oriented stuff, simple engine parts - both internal and external - and in most cases the choice of material is 6061 T6 aluminum.
A lot of the threading is done under power in the lathe and NF is the thread of choice - 1/4" & up fwiw.
The lathe is reversed 2-3 times - depending on thread size and depth - and chips are cleaned out.
I do start the smaller taps in the lathe and finish them by hand.
The biggest reason NF is chosen is because it's easier on the lathe or mill/drill.
I understand as well that full thread strength is generated by cutting threads to a depth at least equal to the diameter of the bolt to be used.
IE: 1/2" bolt gets 1/2" worth of threads.
NC is used - in my case - for threaded weld bungs that get welded into the chassis as well as for decorative items like escutcheon plates.
These finish off the holes for the brake pedal - and helps hold the carpet down - as well as for the throttle rod to enter the cockpit area.
To my eye, a much nicer look than a sewn carpet binding around the hole and the aluminum escutcheon plate doesn't wear away.
I note as well that NF is used in the engine internals in several areas utilizing smaller bolts - 3/8" rod bolts for example - and NC is used for main cap bolts or studs.
Externally, most engine threads seem to use NC.
Is the choice between NF and NC simply a manufacturing convenience or a strength consideration for rod bolts and oil pumps?
I see that most torque values listed for NF vs NC have NF getting a bit less torque.
I understand as well that this lesser torque with NF generates the same clamping force as the higher torque of the NC threads when similar sized bolts/studs are used.
Color me confused....