Nick Stanning walks you through the process of making a spring compressor. Not sure if you need one? He makes a pretty compelling argument here!
An air rifle mainspring is quite powerful, and may be under tension even when the gun is not cocked. This is known as preload. For this reason, it’s best to use a spring compressor to safely take apart your gun before you carry out any work on it. You can buy a compressor – but why not save some money and make your own from odds and ends likely to be found in any shed or garage?
1. Set up
The first thing you’ll need is a sturdy, flat board to mount everything onto, such as an old pine shelf. Next, you’ll need a vice screw, which you’ll probably have to go out and buy. This particular one was picked it up from a tool stall at a market for £10. It’s strong and has plenty of travel to accommodate even the longest and strongest of springs.
2. Fix it
A block of wood needed a suitable diameter hole drilling so I could run the screw through before attaching it at the head of the compressor. This is the only moving part of the apparatus, but it will be under considerable pressure, so a strong fixing is essential.
Once I had the block in place I realised that the centre of the screw was higher than I wanted above the board. It is very important to keep everything in line, so I cut another shelf to size and fixed it onto the base to raise the action to the required height. To finish this end, all I needed to do was make a small pad from MDF to fit the end of the vice screw so the gun’s metalwork didn’t get marked.
4. Mark it
With the height now set, I needed to give some lateral support to the gun’s action during compression. As with the vertical positioning, it is vital that all parts are in a straight line so no twisting occurs under pressure. This was achieved by presenting the action to the compressor, lining it up with the centreline of the vice screw and marking where the support needed to be attached.
5. Finish up
To finish, I had to fix an end block for the action to rest against. I toyed with having a complicated series of holes so an adjustable block could be bolted into position for different length actions; but I soon realised the simplest and most effective way was to have a fixed block at the end, and a few different-length blocks to fill the gap as required. Now I can use this compressor for everything from a side or underlever to a pistol without changing the basic set-up.