From Spud Wiki
What is Sleeving?
Sleeving is the process of inserting one pipe into another pipe. This is very tedious and time-consuming process, but becomes necessary on some circumstances. One reason to sleeve pipe is to give the main barrel extra strength and durability. The second, and probably the main reason this technique is used, is to create more appropriate diameters for specific projectiles to be used.
Direct insertion is the method of sleeving one pipe into another without the need for any further modification to either of the two pipes. This exists when the main barrel pipe has a nearly exact outside diameter with the sleeving pipe's inside diameter, and therefore, does not need to be cut or split.
This method is commonly seen in the construction of golf ball barrels. Golf balls fit quite well inside 1.5" SDR PVC, however, the SDR pipe is somewhat frail. 1.5" PVC pipe has a nearly identical outside diameter as the inside diameter of 2" Sch 80 PVC. It can therefore be directly inserted into the 2" pipe without the need to be split.
Modified insertion is the method of sleeving one pipe into another that will normally not fit. This requires that the main barrel pipe be split and clamped in order to bring its outside diameter to match that of the sleeving pipe's inside diameter.
Although not required, it is generally a good idea to split the main barrel pipe so that it will not present a gap when sleeved. In order to accomplish this, simply subtract the inside diameter of the sleeving pipe from the outside diameter of the main barrel pipe. The answer will be the width of the split needed to be cut from the main barrel pipe so that no gap will be present.
Tips On Sleeving Pipe
- Start with both pipes a little longer than the desired barrel. This will allow for some error and can be trimmed later.
- If glue is to be used, make sure it is a slow drying glue so it will not set until the sleeving is complete. Please note, however, that glue is not needed in most circumstances as the tension between the two pipes will be enough to hold them together.
- When splitting pipe for a modified insertion, try to cut the split as even as possible. A table saw works great for this.
- If the pieces will not sleeve easily, place the sleeving pipe on a padded material and use a rubber mallet to hammer the main barrel pipe into the sleeving pipe.
- A vise will work nicely to squeeze the main barrel pipe together once it is split and hold it until the piece is started.
Commonly Sleeved Barrels
1.5" SDR PVC into 2" Sch80 PVC (direct insertion) - golf balls
2" Sch40 PVC into 2" Sch40 PVC (modified insertion) - golf balls
3" Sch40 PVC into 3" Sch40 PVC (modified insertion) - standard soda cans