Если я вас правильно понял, то можно тогда действовать по рецепту из описания T команды с использованием команды G10, после чего уже ставить T3
https://reprap.org/wiki/G-code/ru#T:_Select_ToolThe sequence followed is:
1.Set the current tool to its standby temperatures specified by G10 (see above),
2.Set the new tool to its operating temperatures specified by G10 and wait for all temperatures to stabilise,
3.Apply any X, Y, Z offset for the new tool specified by G10,
4.Использовать новый инструмент.
Также может оказаться полезной и эта информация
Some implementations (e.g. RepRapFirmware) allow you to specify tool-change G Code macros2. There are normally three specified (any of which can contain no commands if desired) that execute in this order:
1.Actions to do with the old tool before it is released - macro name: tfreeN.g where N is the tool number;
2.(Old tool is released);
3.Actions to do with the new tool before it is selected - macro name: tpreN.g where N is the tool number;
4(New tool is selected); and
5.Actions to do with the new tool after it is selected - macro name: tpostN.g where N is the tool number.
With such implementations there is no wait for temperature stabilisation. That can be achieved by an M116 in any of the macros, of course. However be aware that recent RepRapFirmware versions does NOT run any tool change macros if the axes are not homed.
After a reset tools will not start heating until they are selected. You can either put them all at their standby temperature by selecting them in turn, or leave them off so they only come on if/when you first use them. The M0, M1, and M112 commands turn them all off. You can, of course, turn them all off with the M1 command, then turn some back on again. Don't forget also to turn on the heated bed (if any) if you use that trick.
Tool numbering may start at 0 or 1, depending on the implementation. Some implementations (those that use the M563 command to define tools) allow the user to specify tool numbers, so with them you can have tools 17, 99 and 203 if you want. Negative numbers are not allowed.Из красного текста следует что если мы отключим ВСЕ инструменты командой M1, то когда мы обратимся к любому из них Tn, он автоматически включится, но после этого нужно не забыть включить горячий стол, иначе он остынет, а это не очень удобно.