Mike Young wrote:
"Christopher Tidy" wrote in message
...

Glenn Ashmore wrote:

I need to make a couple of adapter plates for the new 56HP Yanmar to
fit the CV
joint to the prop shaft. The gear box flange has four M10x1.5
threaded holes on a 78mm
pitch circle and the CV joint has six M10x1.5 holes on a 93mm pitch
circle.

At anything other than a 15 degree offset between the two circles the
holes interfere. At 15 degrees I have 3mm between the holes. I am
limited to 22mm in thickness so I can't drill blind holes on either
side. Is 3mm between holes sufficient or is there another way to lay
out the bolt circles?


Hi Glenn,

Surely the least metal you can have between the holes is 5 mm? The
outer edge of the holes on the 78 mm circle will be at a radius of 83
mm, and the inner edge of those on the 93 mm circle will be at a
radius of 88 mm. So I figure there's a minimum of 5 mm between them.
Someone correct me if I'm wrong here...


It's customary to specify bolt circles as the diameter, not radius. It's
a tight fit.

If that's the case, it's a very tight fit. Mike's idea of only omitting
a couple of bolts could be a good one. Perhaps other people can add
their thoughts?

Chris