12-32 thread?

[myrickman]

Working on an old small steam engine and came across some 12-32 bolts I have to make. Last I recall, the only one using these was Henry Ford on the Model T coil boxes. Anyhow, the plan is to get the dies from MSC's special size dept and thread them on the lathe after turning the blanks from hex stock. Anyone ever run into this oddball size? Is this what they call 12-NEF ??

 

[rake60]

The 12-32UNEF thread is still used in some gun works.
The EF is an "Extra Fine" designation.

Rick

 

[Powder keg]

I did a 1/4-32nef one time. Still have the Die. I think?

 

[rake60]

A #12 screw has a nominal OD of .216" and the Unified Thread Form
Double Depth of a 32 pitch thread is only .03834"

Does your lathe have threading capability?
At .019" depth per side that would be a relatively easy
job to single point thread and would cost a whole lot less
than buying a die that you me never use again.

Rick

 

[hammers-n-nails]

i havent ever got a die to work that well myself for some reason??? could be because they where cheap but anyway i agree with rick ive heard people make a big deal about single pointing threads but it really couldnt be easier. if the part your building is too long to stay rigid you could always turn a bushing to put between the points on the steady, mabey? i dont know ive never tried that, i just now thought of it. sorry for the rambling.

 

[tel]

Hmmm ... .216" x 32tpi. T'were me I'd modify slightly and use either 7/23 x 32 ME, which I don't have, or 7/32" x 40 ME, which I do.

 

[shred]

Brownells will (if you're in the US) sell you a #12-32 tap for $2.71, but oddly enough they don't seem to sell the matching die. A while ago I ran across an article on making your own dies, but I can't recall where.

 

[Mainer]

This place http://www.victornet.com/report/Dies-Round-Special-Pitch-up-to-1-2-quot-/210.html
has 12-32 dies, as well as lots of other weird and wonderful sizes.

 

[myrickman]

Thanks for the responses gents. I ended up getting the die from MSC and was taking a bit of a chance as last experience with their oddball dies was poor. This time I took a piece of 5/16 stainless hex and turned it down to the correct OD and using Anchorlube, it cut/threaded like butter. I had to chase the mating holes with a tap as the originals were a bit undersized. Anywho.... I am off to completing the engine sans flywheels which are going to be cast soon. Will post finished pix to the engines from casting section where I posted original as-found pix. I'll have to bookmark Victornet.com as they have a lot of neat stuff.