Some layers come unstuck during print

As I leave my printer going for a longer print, say 5+ hours, at some parts the layers are partially coming undone! Does anybody know what causes this and/or how I can fix thi?

Thanks,

-Jake

Jake,

The plastic is shrinking more at the outside than the inside of the print, so it cracks. This will be worse with ABS than PLA, as ABS shrinks more. You didn't mention if you are using PLA or ABS.

For ABS - one solution is to contain the heat, near but below the glass transition temperature of ABS so there is less shrinkage while printing.

I had problems like you show when I used an Afinia printer to print wide with ABS, without a chamber, but still had some problems with another Afinia with a chamber - this only contained some of the heat.

You also may want to try printing some narrow parts and try breaking them to see how much adhesion there is between layers, and adjust your temperature.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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Thanks for the reply!

It is with ABS. When you say contain the heat and chamber, do you mean to say I should enclose the printer? I have been thinking of doing that because I turn the AC way down at night, and this mostly happens when I'm printing overnight. Also you say after the first few layers I should lower the temperature of the extruder? Currently I am printing at 230 C for the whole print.

Thanks for the help!

-Jake

Not necessarily lower the temp but adjust up or down until you have the best layer adhesion. Enclosing the printer can be as simple as putting a towel hanging around it but out of the way of hot and moving parts to stop drafts, putting a cardboard box over it, or building a full enclosure.

I agree with Zerodameaon.
If you find the adhesion is poor, and you are using a large layer height, then you may also want to try increasing the extrusion width in your slicer slightly.

Solution -> [forums.reprap.org]