Final Bed temp and Bed Plane compensation

Hi

New to 3D printing , have just built an Ormerod 2 and done the usual things: snowman, whistle etc. and also created some simple models which I have sliced using the latest version of SLIC3R available on the net using the RepRap supplied configuration. All going smoothly but I have some beginners questions.

1
1a The custom code in SLIC3R leaves the bed temperature at 40C at the end of the print, is this to avoid having to use the hair dryer trick (idea courtesy of Google) to release the print from the bed or is there some other reason?
1b Notwithstanding the above are there any other tricks to release thin but relatively large surface area (e.g the snowman) from the bed. Objects that are taller "ping" off the Kapton taped bed with slight leverage but thinner object are more difficult?

2 The bed compensation procedure using the supplied bed.g file (amended for exact locations) uses a G30 P3 S Z-100000 command to generate the equation
2a What are the units of the factors reported (?mm) and are + values above or below the plane of the bed?
2b Are the constants and equation generated stored in non volatile memory, meaning that you don't have to run the procedure each time you apply power to the printer?

Thanks in Advance

1a No idea, the custom gcode I use turns everything off.

1b Put the bed+print in the freezer for a few minutes. Or print PLA on plain glass like I do. When it cools, the print just falls off.

2a The heights are in mm. I don't know whether using G20 to change the units to inches affects them or not. Sorry, I can't remember the sign, but you can easily find out by putting a piece of thick white card on top of one of the bed corners.

2b No. But once you have worked out the adjustments, you can put them into G30 commands in config.g if you wish. In the G30 commands, set Z to the height error at that point instead of -100000. However, I used the bed levelling screws to get the bed as level as I can, and now I only use bed compensation on large prints.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks for the rapid answers, for the record positive values are above the plane of the bed. As the printer is new and I'm still getting used to it I'm following the RepRap directions at the moment and this was an attempt to see which way the bed was out of line before I started to adjust it. Thanks again

btw if you find you can't adjust the 3 bed levelling screws to get all 4 corners level, it generally means the Y axis is slightly twisted. There are a few threads on how to correct this.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

i have used some leftover [www.amazon.com] (not exactly this but simular) tuned it upside down and blow 1 time on bottom of the print and it releses instantly(it instantly freezes the area). But it is flamable so be careful