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hot end not reaching temperature when heatbed temperature goes higher

Posted by mlaustin66 
hot end not reaching temperature when heatbed temperature goes higher
April 26, 2016 04:37PM
So prior to moving over to glass, I had my heatbed at 75C and had no issues with my hotend going to 260C or 265C. Since glass is a shitty conductor, I needed to raise my bed temp to 85C to get it to actually be at 75C. With the bed at 85C, my hot end is a few degrees off from where it should be. It's been PID auto tuned as well as the bed. Without the bed on, it gets to temp and maintains it no problem. With the bed on, to get 260C I need to raise the temp to 263C. The heatbed has difficulty going over 95C (tested for the heck of it). I'm using a 200W 12V Silicone heater. The power supply is 12v, 25A Chinese LED brick. I've read that these silicone heaters often eat more amps than they are slated for. Also, who know if the PSU is actually 25A or something less.

I had purchased new Mosfets IRLB3034 to fix another RAMPS board I have. I had extras, so I replaced all the Mosfets on the installed board with these. The stock Mosfets got extremely hot. The new ones get hot too but a bit less. However, the new Mosfets did not fix the problem. The heater wires get warm as do the 14 gauge wires from the PSU to the RAMPS board. A side issue I noticed is at low print speeds the x and y motors seem to pause a bit. They didn't do this when the bed was at 75C.

Is it possible I need a PSU with more amp load? I was thinking of going the ATX route as they go through more QC than the Chinese based LED supplies..

Edited 1 time(s). Last edit at 04/26/2016 04:48PM by mlaustin66.
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