Adjusting print settings on the fly

Hi all from deep in the snow of northeast US.

I am just learning and tweaking my printer. I sratch built a Prusa i3. I'm using Marlin,Pronterface, & Slic3r.
My question is: how can I change printer/print settings while the print is ongoing? For instance adjust speeds for different areas, or layer height, or temps.
Thanks for any help
Peter

I'm relatively new to pronterface, but there are controls for speed and temperature in the main pronterface window. You can set them before you've started printing, but while a print is running they won't work unless you pause the print before making the speed/temperature change.

You can't change layer heights from pronterface- that has to be done in the slicing software. Slic3r will let you set different layer heights throughout the print. After you load an STL file, open the "object" menu and select "settings". In that window you can manipulate layer thickness as a function of Z height.

the only one of those you can control is temp, after the print is started. Everything else in in the G code.

Since you're using marlin, check out the M220 command. It allows you to specify a percentage of the g code speed to use. For example, if the g code says F3000, you can send M220 S50, and the speed will change to 1500 (50%). You can also double the speed by saying M220 S200. The multiple remains in effect until you change it again. To revert back to g code speeds, enter M220 S100.

The printer won't change speeds immediately. The M220 command needs to work it's way through the printers buffer.