having a hard time locating some 1918 al inserts.  these are going to go on the old farboglass G arrows.  1916 inserts fit inside diameter but the shoulder too small to cover.  am i heading in the right direction?  any suggestions?

The outside diameter of the 1918s shoulder should be the same, 19/64s. For more of a lip/shoulder you might try a 2018 or 2020, its 20/64 or 5/16.

As hvyhitter said,the first two digits in the aluminum shaft number is the outside diameter in 64th's of an inch.The last two digits are the inside diameter in 1/100 ths of an inch.

You are going the wrong direction.If you want the shoulder to match,you need 22 diameter,ie.22/64 or 11/32.You could modify some 2219 inserts to work.2219 would have the right shoulder diam but the body would be too fat.

1.Screw a field point into the insert.
2.Chuck the field point into a drill press.
3.Turn the drill press on and use a mill file to reduce the body of the insert about 5/100" total diam.
4.If you have a short piece of cut off shaft,you can occasionally stop the drill and easily check progress.

You won't find an aluminum insert to fit your shafts exactly.If you don't mind spending 1/2 to an hour of your time,you can modify these to fit exactly.2219 would be the closest with the least material to remove.

I believe the 1918 shaft is 19/64 inches overall outside diameter, 0.297 inches.

The second pair of numbers (18) is the thickness of the shaft wall on one side, in 1/1000 th's of an inch, or 0.018 inches,

Since there are 2 sides to the shaft the total wall thickness is 2x0.018 or 0.036 inches.

Subtract 0.036 from 0.297 and you have a insert diameter of 0.261 inches.

Charles.

thanx for the quick response guys, can always count on the tradders for help. you know, an arrow is an arrow, but these farbonglass babies have a special meaning.  on a recent trip back to the home state of iowa,  my uncle had these arrows, a homemade hickory longbow and a ben pearson 48# hunter, still hanging in the floor joices of the basement.  after serious haggling and the promise that i kill a deer with these items, they were bought for $25.00, then he took my wife and i out to lunch.  he drove a hard bargain eh? must have known something was up, he died three months later. i aim to uphold my end of the deal. thanx for keeping the promise alive