Trouble printing PLA on heated bed

[thorleif-jacobsen 0]

Hello!

I just got a HEATED BED kit to hook up to my ultimaker. I've installed a custom firmware, installed a 4.7k pull up resistor and set it up. Everything seems to be working from hardware part

(The kit i bought: http://www.ebay.com/itm/Heated-Bed-Kit-for-Ultimaker-Reprap-3d-Printers-MK2-PCB-Aluminium-plate-/161157442118?pt=LH_DefaultDomain_0&hash=item2585bb6a46 )

It heats fine, goes up to a 100c and down to 0 on the UltiController.

So i start to print on a glass plate, and it seem to be "dragging" the pla, when it starts extruding the edges it dosent strick so it's beeing ripped up against the extrution head.

Well after adjusting the level of the bed a little i may be able to get it to extrude better but its kinda random if it sticks or not. When it does it prints a big flat line, looks really good. Then it starts on the inner wall, and making some holes starting from the biggest hole going down. (image of the printed object: http://link.jepb.no/Vdmj)

When it lays the edge for the third circle from the bottom it dosent stick and is beeing kinda deformed. The nest 2 until the end is perfect. Then it starts filling the item from the bottom hole. It goes forward and backwards, after a few times it starts "lifting" the pla it already laid down just the last maybe 2 strokes.. and when it get to the thinnest place to fill it sticks the edge to the extruder and deforms that too!

I had it working perfectly without a heated bed, but i was really struggeling to get objects OFF, i sometimes ripped the object in half when trying to get it off the bed. So thats why i want this heated bed.

Yesterday i just "let it print" even if it was deformed. After it was done it cooled down and the items was loose So good improvement.

But anyone got any tip for me?

Ive tried:

- Less distance from bed to extruder, making the line so thin its transparent. Not good.

- More distance making the line more "square ish" not sticking - at all!

- Middle thing making it flat on the bed, sticks good some places, less good other places.

- Starting off with 85deg, no luck

 

 

[thorleif-jacobsen 0]

 

Vid

 

[jonnybischof 60]

85°C is much too hot for PLA.

Try starting at 40°C (which is probably too cool), then increase bed temperature slowly until you notice it gets better. Usually, something between 50°C and 70°C is ideal, depending very much on the type of PLA you're using.

You want your material only to be sticky, not liquid and very soft.

It also helps sometimes to print the bottom layer with hotter than usual nozzle temperature. I usually print the bottom layer 20°C hotter (nozzle temp) than the rest of the print.

Sometimes it can help to print the bottom layer "too hot", after the first layer cooling down a little so that it hardens, but still sticks to the bed.

 

[burki 1]

One more hint: don't use glass cleaner or alcohol. Clean your glass plate with a dish washing detergent. And of course avoid finger prints.

 

[thorleif-jacobsen 0]

I'm using Acetone to clean, 70degrees 220 hotend and it works flawlessly! Just an update!

 

 

[eldrick 65]

No-one mentioned the use of gluestick on the glass, which aids adhesion and makes it easy to release the parts after cooling.

 

[anon4321 16]

I'm using Acetone to clean, 70degrees 220 hotend and it works flawlessly! Just an update!

 

 

Those are the numbers I find work well. Some say cooler on the bed like 60. One of the mods here did adhesion tests are various temps and concluded that 60 was ideal. I found 70 works better for me. Maybe my bed runs cooler than reported.