What temperature to use for first layer in ABS to make raft separate easily?

I'm having a lot of trouble removing the raft after I print something. I'm using Skeinforge and I see that it has options for setting the temperature of the first layer so it does not bond well to the other layers. Currently I'm printing most stuff at 215 C and the first layer at 180 C. Could someone who has figured this out post your settings so I can try to improve mine?

Here are my temperature settings:

Temperature Change Time Before Raft (seconds):	0.0
Temperature Change Time Before First Layer Outline (seconds):	60.0
Temperature Change Time Before Next Threads (seconds):	60.0
Temperature Change Time Before Support Layers (seconds):	0.0
Temperature Change Time Before Supported Layers (seconds):	0.0
Temperature of Raft (Celcius):	220.0
Temperature of Shape First Layer Outline (Celcius):	180.0
Temperature of Shape First Layer Within (Celcius):	180.0
Temperature of Shape Next Layers (Celcius):	215.0
Temperature of Support Layers (Celcius):	215.0
Temperature of Supported Layers (Celcius):	215.0

I print my ABS objects at 240C and the first layer at 195C so it looks like your temperature control is out, or your ABS is different.

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[www.hydraraptor.blogspot.com]

It is probably the temperature is off since I have never calibrated it to make sure. I just went by the thermistor data sheet and hoped that the tolerance on my resistors weren't too bad. When I run at 230 C my ABS turns yellow and doesn't appear to be as strong. I'll try 45 C less as a ball park figure and start experimenting at 170 C.

With it set to 180 C, I find I have to use wire cutters or some kind of knife to remove the last layer of the raft. Is this your experience?

At 195C I can peel it off with a blunt penknife.

I do blow a fan on my raft for two minutes to make sure that it has cooled back to room temp before extruding the first layer.

If the raft is 10C hotter then that is the same as the first layer 10C hotter.

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[www.hydraraptor.blogspot.com]