Hi, i'm dont know where to post this topic due dont find "heated bed" related subform. I have a custom made heated bed with some 6.8 ceramic resistors and 6A 12V PSU. My thermistor was broken. the heated bed was go really hot !. Tile doesnt broken but some pieces was "sodered" onto ABS. Glass sure was broken by high temp. I think wall tile is better than glass for heated bed. As u see, i dont use PTFE tab. wall tiles is easy to find, multiple colors an sizes, cheap, easy to cut, flat surface, less flexible than glass for big printers.. https://reprap.org/forum/read.php?1,100132,100132#msg-100132 Tue, 15 Sep 2026 14:15:54 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,100132,139775#msg-139775 https://reprap.org/forum/read.php?1,100132,139775#msg-139775 banthafodder7400 General Mon, 25 Jun 2012 12:25:45 -0400 https://reprap.org/forum/read.php?1,100132,139703#msg-139703 https://reprap.org/forum/read.php?1,100132,139703#msg-139703
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limestone tiles]]> johnn34 General Mon, 25 Jun 2012 03:27:35 -0400 https://reprap.org/forum/read.php?1,100132,100291#msg-100291 https://reprap.org/forum/read.php?1,100132,100291#msg-100291
Another point is that thermal stress can be avoided even when the thermal expansion coefficient is high, as long as the temperature is kept very uniform over the entire plate.]]> jbayless General Thu, 06 Oct 2011 13:08:56 -0400 https://reprap.org/forum/read.php?1,100132,100258#msg-100258 https://reprap.org/forum/read.php?1,100132,100258#msg-100258 plonly one porcelain is listed - no clue if it is representative.
[www.matweb.com]
9.50e-6/K

Bleh matweb sucks for glasses appearently.
Here is a comparison [hyperphysics.phy-astr.gsu.edu] note the factor of 2 from from soda-lime (ordinary) to borosilicate and factor of 8 from there to quartz. The borosilicate should be good enough and is a bunch cheaper than the quartz.

Tyro]]> Tyro General Thu, 06 Oct 2011 07:07:47 -0400 https://reprap.org/forum/read.php?1,100132,100241#msg-100241 https://reprap.org/forum/read.php?1,100132,100241#msg-100241 windprotocol General Thu, 06 Oct 2011 03:45:10 -0400 https://reprap.org/forum/read.php?1,100132,100225#msg-100225 https://reprap.org/forum/read.php?1,100132,100225#msg-100225 Now some important questions. .. I used a lot of subjective terms in that description - hot, cold, close, etc. How can one tell if a material is going to explode due to thermal stress? The coefficient of thermal expansion allows materials to be compared to each other (as well as directly predicting stress levels and potential part failure if a few other details are known). Www.matweb.com is a great source for thermal expansion coefficients.

Compare thermal expansion of soda lime glass (windows and other common applications), borosilicate glass (Pyrex, schott brands, cookware, heat sensitive applications), quartz, and floor tile ceramics (tiles are made of a variety of ceramics some better some worse for this). Quartz is extremely thermal stress resistant, borosilicate is good, and most soda lime glasses have large coefficients and break easily due to relatively small temperature gradients.

Tyro]]> Tyro General Thu, 06 Oct 2011 01:21:22 -0400 https://reprap.org/forum/read.php?1,100132,100152#msg-100152 https://reprap.org/forum/read.php?1,100132,100152#msg-100152 * Material (over a custom beared dispenser with test parts recycled):
[attachment 5531 abs_over_custom_dispenser.JPG]
* Glue used for resistors (this cement is used for mufflers or similars and can handle up to 1000ºC):
[attachment 5532 glue.JPG]
* Final print with that ABS over tile (custom piece, need learn more skeinforge):
[attachment 5533 capture_3.JPG]
* Final print take of heated bed (you can see particles of tile in the final plastic printed):
[attachment 5534 final_piece.JPG]
* PSU used for heated bed (12v 80w, 6.6A):
[attachment 5536 psu.JPG]
* Resistors:
[attachment 5537 resistors.JPG]

Tile is 200x200mm
Resistors all are 6R8 (6.8 Ohm) 5W ceramic. Price 0.418€ each.
Remember my thermisor was broken so i'm running too hot my heated bed.
There are connected 2x4 so resistance is (6.8*2)/4 = 3.9 ohm.
As you can see, need to be less close.
Tomorrow i'll go to buy more resistors and re-plug then for bigger area covered.

About Tile explosion, i think that is for roof cement due have a abestos layer. but i'm not expert. sure my tile is very hot and not explode yet... but 3 glases breaks for now...]]> danx3 General Wed, 05 Oct 2011 13:34:26 -0400 https://reprap.org/forum/read.php?1,100132,100135#msg-100135 https://reprap.org/forum/read.php?1,100132,100135#msg-100135
I was going to try out a wall tile as a bed, but realised it would have to be heated for it to work. How did you attach your resistors to the tile? Do you have a photo perhaps?

One thing I noticed with the tiles I have (which I found in the basement) is that there is a slight lip on one edge. Other than that it seems pretty flat.

I was a bit worried from hearing about tiles "exploding" but maybe I should give it a go. In a controlled environment of course.

Cheers,
Gary]]> garyhodgson General Wed, 05 Oct 2011 10:29:36 -0400 https://reprap.org/forum/read.php?1,100132,100132#msg-100132 https://reprap.org/forum/read.php?1,100132,100132#msg-100132 I have a custom made heated bed with some 6.8 ceramic resistors and 6A 12V PSU.
My thermistor was broken. the heated bed was go really hot !.
Tile doesnt broken but some pieces was "sodered" onto ABS.
Glass sure was broken by high temp.

I think wall tile is better than glass for heated bed.
As u see, i dont use PTFE tab.

wall tiles is easy to find, multiple colors an sizes, cheap, easy to cut, flat surface, less flexible than glass for big printers..]]> danx3 General Wed, 05 Oct 2011 09:30:25 -0400