T: Select Tool

Example: T1

Select extruder number 1 to build with.

The sequence followed is:

    Set the current extruder to its standby temperature specified by G10 (see above),
    Set the new extruder to its operating temperature specified by G10 and wait for all temperatures to stabilise,
    Apply any X, Y, Z offset for the new extruder specified by G10,
    Use the new extruder. 

Selecting a non-existent tool (100, say) just does Step 1. above. That is to say it leaves all tools in their standby state. You can, of course, use the G10 command beforehand to set that standby temperature to anything you like.

Note that you may wish to move to a parking position before executing a T command in order to allow the new extruder to reach temperature while not in contact with the print. It is acceptable for the firmware to apply a small offset [by convention (-1mm x tool-number) in Y] to the current position when the above sequence is entered to allow temperature changes to take effect just away from the parking position. Any such offset must, of course, be undone when the procedure finishes.

If the Z value changes in the offsets and the head moves up, then the Z move is made before the X and Y moves. If Z moves down, X and Y are done first.

After a reset extruders 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.

Extruder numbering starts at 0.