Hi Mike & Rick,

Thanks for your replies,

My gut feel is to just go with it, but I don't have the investment and
responsibility you do. Anything you can do to smooth the transition
between
the two should help. A fillet of silver solder, for example, will help
minimize the localized stress where they come together.

I'm just going to give it a try with the longer roller, I was just very
surprised at how much a .06" increase in the roller length made towards
stress reduction. The space is so tight it may be very hard to assemble
with solder, I may be able to wipe a thin film on the shaft first, then
heat the outside of the roller to seal after it is assembled (like
plumbers do with pipes sometimes). Another option may be loc-tite (if I
can keep it off the bushing ID during assembly). I think they make a
loc-tite that even works in conjunction with a press fit.

What's the allowable shear stress of your material? You're at 20,000 PSI...

The shear stress for most hardened dowel pins I have seen is 130,000
PSI. Mcmaster Carr lists 130,000 PSI for the inch size pins meeting
ASME B18.8.2 standards. The metric pins meet DIN 6325. I am assuming
the hardened metric pins would have very similar maximum shear stress
ratings. Mcmaster Carr lists the single shear load rating for the 2mm
OD pin at 710 pounds, but does not give a PSI rating for metric. I have
a copy of ASME B18.8.2 standards but not the DIN 6325.

As long as the pressed together roller and dowel act fairly close to a
solid piece, I think everything will be fine, I will know for sure
soon.

Anyway, thanks again for all your help guys, especially Mike for
running the FEA for me. It sure helps to get some different opinions
and viewpoints sometimes.

Take care,
John