Tips for press fitting a pin?

[JPMacG]

I need to press fit two .250 pins into a 12L14 part. The pins are W1 drill rod, not heat treated.

I did a test piece using a scrap of 12L14 and a ".249" reamer. The hole seemed to be slightly undersized, about .2485 I think, based on my pin gauges. I was able to press in the pin but it took an enormous amount of force. My small arbor press did not work. I had to squeeze it between the jaws of a large vise. I'm afraid I will damage the 12L14 part if I use that much force.

Are there any tricks that would help? Should I put a lead-in on the pin? If so, what angle and how long? Should I lubricate the pin and hole prior to pressing? Should I polish the pin? This is a one-of-a-kind part, so I could turn down the pin diameter, but I'm afraid it would be difficult to get the diameter just right.

 

[francist]

I think the general recommendation for interference fit is 0.001" per inch of diameter. At one thousandth undersize on a quarter-inch hole, you're four times that amount. Might need to reduce the pin size a bit?

-frank

 

[benmychree]

I agree with the above post, and also, lube the pin and hole, and have a lead angle on the pin.

 

[Nogoingback]

And, it wouldn't hurt to heat up your part and chill the pins.

 

[Mitch Alsup]

And, it wouldn't hurt to heat up your part and chill the pins.

This!

 

[cbellanca]

For a 1/4" pin you only need 0.00025" interference..( 0.001/ inch of diameter) Easiest option would be to reduce the diameter of the pin. Next option would be an adjustable reamer. With the amount of interference stated previously heat and chill could damage the part.

 

[mmcmdl]

Get yourself a .250 diameter reamer and run it backwards in your lathe . Stone off a few tenths ( make sure you taper it torwards the back ) I did this last night repairing that Parker gearbox .

 

[NortonDommi]

This might help.

 

[Moper361]

This might help.

Thats a handy little guide that now its tucked away

 

[Winegrower]

My bench arbor press works ok for light press fits, but if it’s tight, I put some penetrating oil on the parts (this really helps) and use the 20 ton HF press. It is pretty surprising what brute force can achieve.