FLAT THREADS

[MrWhoopee]

The OD of the male part was definitely turned too small. What size thread is it and what size did you turn the stock?

 

[riversidedan]

Here are two charts....Take a look at 3/8 16 for examples...

Coarse Thread UNC Series

www.efunda.com

Thread Pitch Chart - Portland Bolt

Standard thread pitch explanations and a chart showing number of threads per inch for National Coarse, National Fine and 8 Pitch threads.

www.portlandbolt.com

so when it sez 0.375 is that the dia of the piece needs to be thats being cut?

 

[riversidedan]

The OD of the male part was definitely turned too small. What size thread is it and what size did you turn the stock?

if the male part was to small then how come it was so hard to thread?? and is that what caused the flat threads??? the thread is 1/2-13

 

[MrWhoopee]

if the male part was to small then how come it was so hard to thread?? and is that what caused the flat threads??? the thread is 1/2 16

If you're making a 1/2-16 (?) thread, the stock should be 1/2" diameter (a few thousandths under).
.4375 would be the drill size for the tapped hole.

1/2-16 is an unusual thread, 1/2-13 is standard coarse (UNC), 1/2-20 is standard fine (UNF).

 

[riversidedan]

This like pulling teeth. What size did you turn the stock?

dont rememeber.................will ask this>>>>>>>>> when turning a 1/2 piece down to 3/8 for threading should the major dia be 0.375??

 

[MrWhoopee]

dont rememeber.................will ask this>>>>>>>>> when turning a 1/2 piece down to 3/8 for threading should the major dia be 0.375??

If you're making a 3/8-(any pitch) thread, then yes the major diameter will be .375.
If you're making a 1/2-(any pitch) thread, the major diameter will be .500. The nominal thread size is the major diameter.

 

[SLK001]

Did you actually get a 1/2"-16 die in your set? A 1/2"-16 is an "Imperial Unified National" standard that is not used all that much any more. Your picture shows that you turned down your stock too much. If it is 0.500" stock, you shouldn't have turned it down at all, except maybe a skim cut to remove the outer surface.

 

[riversidedan]

Did you actually get a 1/2"-16 die in your set? A 1/2"-16 is an "Imperial Unified National" standard that is not used all that much any more. Your picture shows that you turned down your stock too much. If it is 0.500" stock, you shouldn't have turned it down at all, except maybe a skim cut to remove the outer surface.

if I used the 1/2 stock w/o turning it down the die would in no way start to even fit..........even if I chamferd the end/
>>>>>>>my mistake the die was 1/2 -13

I looked at the teeth on that die again and they are pointed not flat, still dont know why I got flat threads

 

[riversidedan]

Did you check the major diameter of the material, smaller than required will not form the peaks..

so what your saying is I made the work piece to small right, thats why I got the flat threads right???

 

[Grinderman]

The OD of your stock needs to be 1/2" or a few thou smaller. Put a good chamfer on the end. Are you doing this on a lathe or by hand?. The die has a larger end to start the thread. 1/2-13 is kind of tough to thread even on the lathe by hand.