heated build platform

[Rayne Lang]

Alright, for my latest problem..

I am starting to print with ABS plastic and I am having trouble getting my bed up to 110 degrees. The highest temperature I can get the bed to, and have it hold steady, is 85. At this temperature the ABS is just not sticking well and so I am having problems printing. I have checked through old posts and found that I was not using both 12V lines form my power supply so i corrected that problem but it didn't help. I have also tried putting layers of aluminum foil under the heated build platform to help insulate it but that did not help much either. I have had success getting the bed up to 110 if i put towel onto to insulate the top of the bed, but the temperature quickly drops when I remove it.

Any suggestions to help get this thing to 110 degrees and hold it there? I would be fine with just using the towel to get it to 110 degrees, and starting my print as the bed temperature is most important at the start so if it dropped while printing I likely would still be okay, but I cant even get it to start printing as the software is always waiting for the temperature to be at set point and steady and it never is. since the temp is constantly dropping once I remove the towel (using slic3r).

Thanks, Rayne

[NCBob]

I had a problem like that, not quite as bad, but what I ended up doing was mounting the HBP itself on top of a piece of cork.  That helped keep the heat on the plate and the glass and has worked really well.  Now I can actually get the bed up to 110 without having to put a towel or blanket on it, and it maintains it's temp much better as well.

[Rayne Lang]

When you were using a towel/blanket, how did you get it to start printing? I always remove the towel and hit the print button and everything just waits... then once the temp drops all the way to 85 and holds there for a while things finally start moving. I could live with needing to use a towel if i could get it to print with a changing bed temperature.

[sfisher10]

What is the voltage across the bed when it's on?  Also how much current are you using on the 5V side of the supply?

[Rayne Lang]

I'm getting 9.65 volts across the bed when it is heating up. Whats a good way to check my 5v rail current without removing lots of wires?

[sfisher10]

The actual 5V current isn't too important.  If you don't have any 5V load, the 12V side of the supply will be severely current limited (hence the low voltage).  If you add a few amps of load to the 5V side, the 12V side should pick up and supply more current to the bed.  It will heat faster and reach higher temps.  Some people add power resistors or light bulbs to create the load.