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Hotbed temperature question

Posted by skeetman 
Hotbed temperature question
January 15, 2018 05:11PM
Howdy...I have a question about heating the hotbed...for ABS, if the default settings stipulate 115C for the first layer to be printed, my RepRap takes over an hour to reach that temperature (inside a heated house in south Texas)--if it ever reaches it. Can anyone tell me if 115C is too hot for the RepRap Mendel Pro Tricolor? Or, is there an adjustment somewhere I can make? Thanks, David
Re: Hotbed temperature question
January 15, 2018 05:52PM
If it has the type of power supply that has a row of terminals and a potentiometer at one end, you can turn up the power supply voltage from 12V to 14V. That will increase the heating power by 36%. It will also increase the hot end power, so you may have to re-run heater or PID tuning.

If your electronics has a linear 5V regulator, check that turning the voltage up doesn't cause the regulator to overheat.

Also, if there is no thermal insulation below the bed heater, add some.



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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Hotbed temperature question
January 15, 2018 06:09PM
Quote
skeetman
Howdy...I have a question about heating the hotbed...for ABS, if the default settings stipulate 115C for the first layer to be printed, my RepRap takes over an hour to reach that temperature (inside a heated house in south Texas)--if it ever reaches it. Can anyone tell me if 115C is too hot for the RepRap Mendel Pro Tricolor? Or, is there an adjustment somewhere I can make? Thanks, David

Howdy y'all (ya allah)

The temperature seems to be right in the ballpark! as 5C would not make a bit of difference.
You could connect a solid state SSR between the controller and the hotbed change out to a 120v hotbed and reach your desired temperature very quickly.
Re: Hotbed temperature question
January 16, 2018 07:43AM
Seems like its to hot for your machine.
Many people with low cost kits have trouble getting their beds over 90 and that can take over 30mins.
The easy fixes are as DC42 sugested. You can reduce the heating time by putting insulation on the top of the bed (corugated cardboard). If doing this i suggest you manualy set the temp first, then remove the cardboard before starting a print. This ensures the temperature is stable.
Another trick i use is that once the print has started i put smaller pieces of cardboard on the unused areas of the bed. This insulation reduces the heat loss and hence reduces the load on the heater.
I run mine at 110C as 115C would have the bed on permenantly so there is no control in case of drafts etc.
If you are using painters tape on an Ally bed you may be able to run a lower temperature. If you have glass on the bed you may need the higher temperature as the glass has less conductivity and there a potential air gap to the bed.
If you can't get the temperature to what you want then you will have to follow Roberts lead and look at changing the bed and wiring.

Hope this is of some help
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