lathe rebuild help

I recently bought a cheap (small) lathe) it's only about 3x12, and possibly a zyto (althoough unbadged)
At the moment, it's got two drill chucks on it - a "foreign" make
hand-tightened chuck of about 1/4" capacity mounted on the tailstock, and a jacobs no.34 mounted on the headstock.
no tapers in sight.
The tailstock chuck is threaded onto a (about) 5/8" BSF which is integral to the tailstock slide (ie, the threaded part can't be removed to insert a centre)
and the headstock arbor ends in a male thread to which the chuck is screwed.
main question - I want to make a face plate to fit on the headstock - does anyone have any idea what type of thread a no. 34 jacobs chuck would have?
I'm assuming it's a 45/64 16 - it's too big for a 5/8" 16
where can I get a tap for this size thread?
I don't have any gears for the screw cutting, so I can't cut it from scratch!
--
BigEgg
Hack to size. Hammer to fit. Weld to join. Grind to shape. Paint to cover.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:
<snip>

According to the Jacobs site (http://www.jacobschuck.com/pdf/Technical-Information.pdf ), the thread is either 5/8 or 3/4 x16 I assume Unified form although I didn't notice it mentioned.
Richard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The 3 I have are UNF threads
Chris.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
rack2000 wrote:

ta very much.
I'll measure the diameter of the threads and go searching for a suitable tap.
--
BigEgg
Hack to size. Hammer to fit. Weld to join. Grind to shape. Paint to cover.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Turns out it is 7/8" whitworth - I decided to buy some nuts, and I'll just weld on a plate
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.