Spring gun tuning: Part 9
Cleaning and deburring
Spring gun tuning: Part 1
Spring gun tuning: Part 2 - Building a mainspring compressor
Spring gun tuning: Part 3 - Mainspring compressor continued
Spring gun tuning: Part 4 - Let's disassemble a gun!
Spring gun tuning: Part 5 - Powerplant disassembly
Spring gun tuning: Part 6 - Disassembly completed
Spring gun tuning: Part 7 - Disassembly of other spring guns
Spring gun tuning: Part 8 - Disassembly of other spring guns, continued
by B.B. Pelletier
We're ready to tune the Beeman R1. This will be a low-power tune using an aftermarket coiled steel mainspring and the factory piston and seal. The R1 factory piston is pretty good, and the piston seal is very good. I am looking for a smooth-shooting gun that cocks easily.
First, we deburr
There are several parts of the powerplant that have extremely sharp edges. Sometimes, these edges get mashed or rolled into the path of moving parts, so it's a good tip to remove the burrs before the tuneup. Be very careful when handling all parts, because they can cut as quick as an exposed razor.
Use a file to remove any burrs found on powerplant parts. The cocking slot shown here is a likely place for them.
I use Swedish files for this job. They make short work of the burrs. If you have never filed or applied stones to steel surfaces before, you'll want to go very slow. This isn't like sanding wood. Sometimes, all it takes is a single light stroke to accomplish your goal.
Parts that usually have burrs
1. The cocking slot in the spring tube.
2. The spring guide, where the piston passes through.
3. The cocking slot in the piston.
4. Any articulated linkage in the cocking link.
5. Any link between the cocking link and the piston.
Those are the usual places that have burrs on a new gun. You can find the others by running your finger LIGHTLY around all the parts that move. Be careful, because you can easily get a metal splinter this way!
Now we clean
We clean every surface of the powerplant and parts, both inside and out. Inside is the most important. The two hardest places to reach are also two of the most important places that have to be very clean - inside the piston and inside the mainspring tube. To reach into these two deep places, I have a screwdriver with an 18" blade that I wrap with paper toweling. It takes only a small piece of towel at one time. I use rubber bands to hold it on the blade, and I use denatured alcohol to clean the gun parts. It dissolves all greases and dries completely. Mineral spirits leave an oily surface that has to be dried before you can continue. WD-40 leaves a film that turns to yellow varnish. Alcohol is the best solvent I have ever found to clean a sprung gun.
Wrap a piece of paper towel around something long, such as a screwdriver blade or even a dowel, and secure it with a rubber band. Dipped in denatured alcohol, it dissolves grease quickly.
The smaller parts are cleaned with cotton swabs dipped in denatured alcohol. I always have a couple dozen clean ones when doing this job. You also need rags for general wipes, and I like to work on a terrycloth towel. It not only protects the surface of the table, it also prevents tiny parts from rolling far.
The next step is lubrication.