manual radiator valve cap

thingiverse

here in the UK it is common to have central heating radiator with TRVs (Thermostatic radiator valves) and on the other end a manual valve with a tamper proof cap. If you want to turn of the water to the radiator you turn the TRV to off (easy) but to turn off the other end you generally need a pair of grips or adjustable spanner. It is a pain in the bum.. as the spindle has flats only on two sides for a spanner or adjustable spanner so only fit 180 degrees and usually awkward. What i really wanted was a knob to push on temporarily.. I could not find one to buy.. not saying they are not there.. So I made one in Tinkercad... ps I domed the top of the inside of the recess so you don't have flat roof inside that needs supports when printing and have posted it here... The spindle dimensions are a little strange 7.7mm dia across the flats 6.3 width of flats 4.8mm.. I added a minute amount to the figures for printing tolerances and it is a relatively soft push fit... I have printed a few to keep in case i want to work on more then one radiator. Since doing this and actually trying them out on some of the valves that were hard to turn (through little use) the infill was not sufficient to keep the shape inside and rounded off. I recommend at least 50% and a thicker wall count so the shape can be maintained for multiple use or printing with a harder plastic; Nylon or ABS may be even more suitable. Depends on the stiffness of the valve.