UNC

[chillybilly]

Need to make a female bit to fit a 1"UNC male ,not really dealt withe UNC before and am little in the dark regards pitch .

Are they a metric pitch as it fits the .125mm gauge really well ,or is it in the threads per inch system .

My lathe cuts metric so i am in the Kazy if its imperial !

As to what it is ,a coupling for an airshifter on my mates dragbike :big:

 

[Jasonb]

1" UNC is 8tpi

This is the chart I usually use when an American thread is specified

http://www.sizes.com/tools/thread_american.htm

You sure thats a metric pitch gauge and not one that reads 0.125"? (1/8 = 0.125)

Jason

 

[chillybilly]

the measurements are coming over the phone so i have not actually seen the bit ,which is nice .

Yeh had a look at some stuff on the net,thincking it might be UNF etc whats wierd is some of the tables i have looked at give a pitch in mm also .If push comes to shove and i have enough material in the wall i could skim off the thread and make them both one of the metric larger sizes ............So many threads in the world

 

[Jasonb]

No reason the pitch can't be stated in metric but it would be 3.175mm not 0.125mm as thats 203tpi, rather on the fine side

Jason

 

[Blogwitch]

CB,

I think someone has made a slight mistake, stating 0.125mm instead of 0.125 inches, which is correct for 1" UNC (Unified Coarse) at 8tpi. It is also the same for 1" BSW (British Standard Whitworth), just that the BSW has an angle of 55 degs (a standard angle for British threads), whereas the UNC is 60 degs (the same angle as metric threads).

It is definitely an Imperial thread that will be required, but saying that your lathe can't do it is a little odd.

Most lathes usually have a means of cutting both types of thread, and it is usually a gear change and technique change that is required to be able to cut them.
Normally to cut Imperial on a metric machine, you leave the half nuts engaged permanently and reverse the lathe to get back to the start of the cut rather than disconnecting the half nuts and using the drop in dial.

I would suggest you have a good look at your threading chart that comes with your lathe.


Bogs

 

[chillybilly]

The limitation on the metric imperial thing is i dont have a 127 tooth gear or a 63

Have the Harrison 11" with a very comprehensive metric gear box but without the above gears .

Regards the bit ,gave up with the phone thing as the more i here the odder it gets ,should get hold of the male part on Sat so will have a good look and get back to you fellas Ta

Probably be UNF :big:

 

[Dan Rowe]

Yes, I have the same problem only in reverse with my South Bend heavy 10. There is a guy on eBay making a 127 tooth translation gear for the South Bend 9 and heavy 10.

Dan

 

[John S]

Bill,

Got 1" UNF and UNC taps here.

John S.

 

[chillybilly]

You are star JS ,will be in touch when i have the mental part in my hands ,

 

[chillybilly]

Well i got the bit .......some serious measuring and it came back at 25mm dia with a 1.25mm pitch ,well a nats out and what i could best tell as a 60 degree thread angle .

Had a think its only to mount the airshifter manifold to the plate on the back of the gear box and will take no load .

Wizzed up some ally bored out to 23.2 mm and set the machine for 1.25 mm pitch proceded to cut and when at the depth put a couple of 0.005mm flancking cuts down the thread .....and jobs a cock bird !! fits a treat .
Shouldered the front to give a weld point and bored out the first 3mm of thread to make it look tidy parted it off JD .
On insperation i used the bit of ally left to make the nitrous oxide gauge housing that fits on the rear of the motor so the mechanic can purge the system down after the burn out .................Wonder whats next thanks for all the help