<VV> head stud update

[Mel Herwald]

First I thank everyone for their replies. I just finished reading them.
Today went better. Allow me to explain.

 

The first order of business was to get the broken stud out. I went to a
neighbors shop who has a Tig welder and we welded a hut to the stud. Two
times the weld broke but we got the stud partway out.

The stud happened to be one that was in a thru hole. We turned the case half
upside down and hanging diagonally of the back of the mill table. We clamped
it securely, found the center with an edge finder and center drilled
followed by a drill that was slightly bigger than .312". It worked perfectly
and amazingly the threads looked basically ok.

 

We then took a std stud and using a cut off wheel cut 3 flutes in it and
welded a nut on the other end. We used this as a tap in all the holes except
one. They screwed in easily and no Aluminum shavings were observed. For the
last hole we did the same thing but made a tap with a .006" oversize Clarks
stud. Now all the studs easily threaded into the holes. I loctited them and
will test all 12 to 40 ft-lbs before assembling the case. I will report on
this to the group when I do it. So it looks like I'm out of the woods.

 

Several observations and questions remain.

 

1)      A standard tap did NOT remove any metal from the case and Therefore
I don't believe any harm was done. 

2)      The threads on the studs are not standard class 2 threads. There is
a distinct flat instead of a point on the od of the threads.

3)      I still don't know why some studs went in fine while others galled.

4)      The studs had to be removed because the threads on the head end were
very rusty-the worst I've ever seen.

5)      The taps we made from studs were crude and maybe not correct but
they worked.

6)      Russell Davis is researching what the stud threads and case threads
actually are and one of us will report back.

7)      I can't be the first one to ever deal with this so chime in!!

8)      The oversize studs do not have a bigger diameter-they have a
different pitch diameter and a wider flat on the thread od.

9)      We did not measure any discernible taper on the stud od but there
may be a taper on the pitch diameter. This remains to be seen

 

Thanks again everyone.

 

Mel Herwald