Making Your Own Custom Piston.

[slamfire51]

Making Your Own Custom Piston.

Like a lot of builders, I am not blessed with a fully equipped machine shop.
These modifications are done with basic tools.

AK pistons have a hard chrome plating to help protect against the effects of corrosive ammo.
After many attempts to drill, I found heating the piston and shaft with a MAPP torch to a cherry red, and then air cool, will allow drill bits to work better. This heating will not affect the hard chrome plating.


Most pistons have a divet on the top. Center punch piston dead center. Use a drill press and a machinist vice, and make absolutely sure the piston is parallel with bit.
Drill with 1/8" drill bit as deep as the piston is long, and add an additional 3/16". Go slow and use oil.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076001.jpg

Piston drilled. (1/8' bit) Leave piston in vice.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076002.jpg

Now use a 5/16" bit and drill slowly and use plenty of oil. Piston drilled with 5/16" bit.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076-1001.jpg

Piston drilled and cut off shaft.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076-5002.jpg

Notice piston was drilled dead center. A MUST!!!!

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076-5001.jpg

Cut shaft to needed overall length. This will be the total OAL of the piston Top of the shaft will be flush with the top of piston.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076-5003.jpg

Bevel the top end of the shaft so the piston will start slightly. Make sure the piston is square to the shaft. Lube the shaft with oil or grease. Set the two pieces in a press, and slowly begin to push, checking at all times that it is not binding.

http://i25.photobucket.com/albums/c80/Canis-latrans/piston11520076-5004.jpg

After pressing, I drill through the piston and shaft with a 1/8" bit. I then pin the piston to the shaft with a 1/8" tension pin (roll pin). Piston is now done.

http://i25.photobucket.com/albums/c80/Canis-latrans/pinnedpiston2-5-2007003.jpg

[Tx Dogblaster]

It's nice to see this back where it belongs. Thanks Slam!

[slamfire51]

It's nice to see this back where it belongs. Thanks Slam!

I just wish there were more building like the "old" days.
Still, there are some who haven't built the kits they are sitting on.

Time to build Guys!!!

[romak10/63UF]

Nice write up ! A+ Job with the pictures. Do you think you could of used a tap an die set to strengthen the piston head ?

[slamfire51]

Nice write up ! A+ Job with the pictures. Do you think you could of used a tap an die set to strengthen the piston head ?

That method is certainly doable. I choose this way because of tools on hand at the time.

[Tx Dogblaster]

Romak: There's no real strength needed for the piston. The roll pin is more than sufficient. Threading the shank & tapping the piston head would work but it would still need to be pinned or tack welded so it doesn't move. The press & pin method is simple and eliminates threading any of the parts.