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Author Topic: Heated bed temperature variances  (Read 323 times)

92869

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Heated bed temperature variances
« on: December 21, 2013, 05:36:16 AM »
As a "newbie" I expected and have experienced the various ABS printing issues, and have tried all the known fixes yet one issue remains.  The corners of larger prints are warping and the quality of the first several layers of each print varies.  What I have found using a non-contact temperature gauge is that the temperature varies on my heat bed with edges being 10-15 degrees cooler than the center.  My Bukobot V2 Duo is housed in an acrylic enclosure to prevent drafts and temperature fluctuations.  I would like to know if anyone else can verify the same temperature variations with their heat beds.  As temperature is critical with this process I don't think that big a variation is acceptable and so I'm left wondering: is my heat bed faulty, the added insulation (cardboard) causing the variation due to poor insulation at the edges?
« Last Edit: December 22, 2013, 07:04:53 AM by 92869 »

whosawhatsis

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Re: Heated bed temperature variances
« Reply #1 on: January 03, 2014, 10:58:39 PM »
Some temperature difference between the edges and the center is normal, but that sounds like a larger variation than you should have. Have you tried letting it sit hot for a while to let the temperature even-out before measuring? It may also be that the non-contact thermometer is not reading accurately, as the D:S ratio (these devices measure an area, not a single spot) and peculiarities of emissivity can result in inaccurate readings. For example, if you had the dot pointed exactly at the corner of the platform, even if the platform's temperature was completely uniform, the I would expect the non-contact device to show only 25% of the difference between the platform's temperature and ambient, because 75% of the area it was measuring would be measuring would be outside the platform. In order to get an even remotely accurate measurement with one of these devices, you should have it almost touching the surface, and the distance from the sensor to the surface should be more than the distance between the center of your measuring area and the edge of the platform.

 

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