On 13 May 2005 20:41:39 -0700, "
wrote:

I make spinning tools for a lady who owns a sheep farm. They look like
a long slender top with a 3/32" drill rod shaft and a 1" diameter x
.100 thick brass flywheel to generate the needed inertia to keep it
spinning. These are for spinning cotton fibers.

The problem is that some of them do not stay fixed in the hole. The
hole is drilled and then reamed .0005 undersize and then the brass is
tapped onto the shaft using another piece of brass the same diameter
with a hole drilled in the center for the shaft to pass through. I
think some of the brass is being displaced by the much harder steel
shaft and it will spin on the shaft.

I have tried everything from Loctite to Super Glue to Epoxy. Loctite
was hit and miss even thought the brass and shaft were thouroughly
cleaned prior to assembly. Super Glue was the same but left an opaque
film. Epoxy was too unsightly and the customer did not like it.

I know that a shrink fit would be best but too much heat discolors the
brass. All I have to heat the brass is a toaster oven I use for
tempering. It was a max temp of around 500 degrees F. The other problem
is how to shrink the drill rod. I do not want to have to deal with dry
ice or liquid nitrogen to do this. It is too expensive to get those and
the profit margin on these is not there.

Any suggestion on how to put these together would be greatly
appreciated. The bonding agent cannot be seen on the outside of the
piece. I also tried soldering but it did not look too good.

Thanks, Steve

Chamfer or slightly taper the rod so that it slides into the brass
rather than "broaching" a new diameter? Also, as was already
suggested, experiment with smaller reamed holes in the brass. You may
need to go down to .002" undersize.
Randy