Making parts with synthetic resins

The price of aircraft parts has gone through the roof. So sourcing cosmetic parts like specialised knobs can be a problem. One solution is to make your own. With very modest amounts of skill and patience, you can make some pretty satisfactory things using synthetic plastics. My first attempt was the magneto knobs, Then I got a little more ambitious and made the throttle quadrant knobs and some gauge faceplates. I still have to make the landing gear lever flaps lever knobs.

• The first pic is the master for the mag knobs. Then I made a mould with silicon rubber and then some knobs.

• I've started making the knobs for the throttle quadrant. So far I have the throttle and prop knobs. I wasn't happy with the mixture knob, so I will re-make the master knob for that. These first prop knobs are made with black filler in the resin, but I am going to make some more with blue. The third pic shows how I machined a rebate for the levers. The fourth pic shows how they turned out. One set for me and the other for Felipe. The 5th pic shows the updated profile of the mixture knob (3rd from left).  The last pic shows the knobs moulded with coloured resin.

• If you want to make multiple copies of specialized parts, casting them in plastic resin is the way to go. To do it requires some moulding silicon, shown in the first pic. When you make the moulds, they need to be poured into something. I used short lengths of plastic water pipe as shown in the second pic. The grey knobs are the master copies used to make the moulds. The masters were made from wood. Not entirely satisfactory for finish, but good enough. Once the moulds are made, they can be used multiple times to make the actual parts. The usual material is casting resin. I use ordinary polyester glass resin as used for fibre-glass. Reason: It's cheaper and sets a lot faster. When a filler is used with it, it's just as good as casting resin. The third pic shows the materials I use. You don't NEED to use the pigment paste. It is VERY expensive, each of those jars of paste cost more than the 2Kg can of resin. I use it because it give colour right through the part, not just on the surface as paint. The scale is not strictly needed if you use syringes for measuring. Most places that sell the resin sell syringes also. The fourth pic shows my knobs finished and mounted. The last pic is of copies I made of a gauge face sent to me by Felipe. You can see what happens if you're not careful enough when pouring the resin in the mould. The two big gaps are caused by air pockets in the resin that I didn't get out. The face on the left is how they SHOULD come out. Note: don't be afraid to try this stuff. It is very easy and not at all tricky to work with. DO read and follow the safety precautions though. This stuff is toxic and flammable.