The WASP pens were Sheaffer's lower line - made by Sheaffer without the trademark name. WASP stood for "
Walter
A Sheaffer
Pen, and dates from the 1930s or so.
You'll need a knockout block and a punch to knock the nib and feed out of the pen. If you don't have a knockout block, use a drill gauge, which will give you a variety of sizes and will support the section properly. Make sure you have enough clearance under the block so that the nib won't hit the table when it falls out. Instructions on how to make one are in my articles on how to make
cheap tools.The sac size depends on the size of the nipple. The sac sizes are in 64ths of an inch. The Pen Sac Co says to measure the nipple in 64ths of an inch, so you'll have the sac size. More practical is to see what fits into the barrel and go down a size or two. Most pens take a 16 or 18. If it's a really big pen,
maybe a 20, if a small pen, maybe a 14.