HELP - NEED KEENSERT DATA

[cnckid]

I have a project that requires the installation of stainless steel keenserts into aluminum plate. The internal thread is 1/2-20 and the external thread is 11/16-11-2A. The Mil spec is MS-51831-206. I have done a couple of sample pieces and was not able to seat the locking keys properly. I bored the hole to .646 diameter as listed on the alcoa fastener site prior to tapping with the .687-11 tap. Since the keys would not seat or would bend due to the force needed to seat them, I started boring the hole out until I could seat the keys without damage to either the keys or the part. I bored the hole to .656/.658 and then the keys would seat. Basically .010-.015 larger than listed size. Could the tap drill size of .640-.646 be incorrect? I saw mention of a special broaching tool to pre broach for keys if uing inserts in hard material like steel, but should not be required for aluminum. All comments and suggestions are greatly appreciated.

Thanks,
Mike

[RICHARD ZASTROW]

How are you seating the keys? I didn't see any mention of a piloted seating tool in your post. You might check and see if one is available for your Keensert size.

Dick Z

[cnckid]

Yes, I got the special piloted tool for installation. When using it the keys will start into the aluminum, but about half way or so they will crush on top of the insert instead of going further into the hole and flushing out on top. I have tried slow, manual arbor press and I've tried a hydraulic punch press, both crushing the keys before they seat completely. I'm really stumped on this one, and I have 800 to install.