Hi everyone,
I would like to ask if anyone can please recommend a tap fit hole Min. & Max. tolerance for a 3/8" hardened steel dowel (.3751" Min to .3753" max OD) ? The pin will be tapped into 4140 Pre-hard steel.
The pin is being tapped through a bearing housing, 1" OD X 1.5" long. The bearing housing fits between two upright supports and there is one drawn cup needle bearing pressed into each of the upright supports. I want to insert the dowel pin through a bearing at one end, and then tap it through a hole in the 4140 housing and on through to the bearing at the other upright support. The housing and pin will rotate together, and the pin rotates in the bearings.
I will probably build simple fixture to locate and hold the housing as I tap the pin through. I want it to be fairly easy to tap the pin through, so assembly goes smooth, but I don't want the housing to rotate on the pin, the pin and housing must rotate together in the bearings.
In order to get a nice easy tap fit, can I have a very small amount of interference to do I need some clearance ? I was going to shoot for a hole size of .3748" Min. to .3751" Max.
I'm just curious what's usually recommended for an easy tap fit.
Thanks John