Hot bed reading 357 degrees and not getting hot

Hey all,

My reprap is almost there but some teetheing problems remain so after some advice.

My hotend is working now after I strapped a ceramic wirewound resistor to the side of my alloy hot end block.

Pronterface gets it up to 230 degrees fairly quick but when I try the callibration cube, the temp drops to 200 before it starts to print. I can get over this by setting the temp to 260 and letting it drop to 230 but this seems odd to me.

Also my hotbed reads 357 degrees and feels cold to touch.

Any help appreciated. I am so close to my first print, I can smell it. No, wait. that is probably the abs heating up...

Just tried another print and the temp now drops to 200 before it starts to print regardless of the setting in pronterface..Curious...

Edited 1 time(s). Last edit at 04/29/2012 07:36PM by gregted.

Have you got Skeinforge incorporated into Pronterface, if so check what the SF settings are for temperature, the Gcode could be overiding the Pronterface settings

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Experimenting in 3D in New Zealand

gregted Wrote:
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> Also my hotbed reads 357 degrees and feels cold to
> touch.
>

It sounds like your firmware has not got the right thermistor table. Or maybe you have PID settings incorrectly configured.
Either way, incorrect temperature readings are symptoms of the fimware thermistor settings not matching the actual characteristics of your thermistor.

gregted Wrote:
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> Pronterface gets it up to 230 degrees fairly quick
> but when I try the callibration cube, the temp
> drops to 200 before it starts to print. I can get
> over this by setting the temp to 260 and letting
> it drop to 230 but this seems odd to me.

The generated GCODE for your print will overide pronterface if the GCODE generator is configured to set a temperature at the start of the print (which is normal).

Thanks nelson,

I opened skeinforge and the base and interface temperature were set to 200.

Settings now are...
Base temp 230
Interface temp 230
Object first layer infill is 195.
Object first layer perimeter is 220
Object next layers is 230
Support layers temp is 200
Supported layers is ............... 230

How do i check my thermistor settings in my firmware?