And now I know that the leadscrew is indeed Acme . I mentioned in
the other thread about making a mold of the threads using a lead ball
and a c-clamp. Well there ain't enough room under there for a clamp ,
but there is room for a pair of vise grips . And now I have a perfect impression of an unworn section of the threads . You can't tell from
looking at the screw what the profile is . But after forming the lead
then cutting it with a utility knife blade to see the cross section it's definitely acme . I shall be setting up a fixture* to hold a cutter at precisely 14.5° on the mill and grinding the profile with my grinding
disc I bought for the end mill sharpening fixture . I'll need to hold
the small screwless vise in the mill vise to get a relief angle on the
cutters . I'll be recutting another piece of stock - with the proper
angle and dimensions - as a fit check .
Clare Snyder and Joe Gwinn were both instrumental in my decision to
make the lead impression ... Thanks Guys !
* I'll need to grind both a 3/16" cutter for the boring bar and a
1/4" for the OD thread . This project needs more precision than I can
manage freehand . And I'll probably end up making one for the Y axis too .
--
Snag
We live in a time where intelligent people
are being silenced so that
stupid people won't be offended.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 4/22/2025 4:57 PM, Jim Wilkins wrote:

"Snag"  wrote in message news:vu8utu$1cks5$[email protected]...

...This project needs more precision than I can manage freehand . And
I'll probably end up making one for the Y axis too .
Snag

Before Tools4Cheap closed I bought a Univise clone from him to surface
grind precise angles on lathe bits etc. Its base could be a good mount
for a square 5C collet and tilting collet holder, such as the indexable
one from an endmill sharpener or a spin index.

https://www.penntoolco.com/precise-uni-vise-grinding-fixture-202-2615/?

Dammit , I have more tools than I have room for now ! 'Sides , I've
already got it figgered out what to use and how to hold it . Actually ,
if I design the fixture right I won't need to use the screwless vise . Eliminates one possibility to screw it up .
--
Snag
We live in a time where intelligent people
are being silenced so that
stupid people won't be offended.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)