Urgent,need help,use Glass and PVA glue,but fail to stick

[garyxu]

warped edge problem solved,but still print fault.

QQ??20141126141558.jpg

[richardphat]

That is a general thumb of rules.
It is important to know that some parts must be print with heat bed despite the fact you are using PLA.

Seems like you have layers shifting on the picture?

[garyxu]

yes seems stick well now ,but has problems of have layers shifting

[RobH2]

Plastics have a property called the "glass transition temperature." You can Google it. Plastics more readily stick to bed materials around this temp. PLA's is about 60-65C. So if you have a room temp surface and one at 65C it will stick better to the warmer one. ABS is around 105C and is why we use beds for 100 to 110C for it. PLA's is low enough that it has some stick to unheated surfaces but ABS won't stick without some heat or an adhesive. Glad you are making progress. Yoda looks pretty good. It looks like your bed shifted just a bit, or something did, to offset your print.

[GOC]

- You don't technically need a heated bed for PLA, but your print quality may suffer without it.

[garyxu]

- You don't technically need a heated bed for PLA, but your print quality may suffer without it.

Ok ,thanks ,i think that is the problems is,we are thinking about change another printer have heated bed,then try again.

https://www.facebook.com/carol.hu.739

Think about it ,design it ,then print it.

[3dkarma]

Strictly speaking, you can print PLA without a heated bed. PVA tends to work best with a heated bed; painter's tape works better than PVA on a cold bed, as it provides a rough surface for the plastic to adhere to.

If you have a cooling fan directed at the hot end, make sure it's turned off for at least the first three layers, to allow the filament to adhere properly to the bed. Cooling the filament as it's laid down in the first few layers can make for poor adhesion.

Regarding the print faults in Yoda (which apart from the obvious is a pretty good looking print), it looks very much like skipping steps at two specific points. If I had to guess, I'd say that the print head hit an obstruction - possibly some curled up plastic - which caused it to miss a couple of steps and made the following layers misaligned. Do a visual inspection on your printer to make sure there's nothing that can obstruct travel and calibrate e-steps per mm to make sure you're not over-extruding - the latter can cause excess filament to curl up and snag the print head.

Apart from that, it's a pretty good looking Yoda. There are some challenging overhangs that came out quite well. The droopy chin is caused by printing in mid-air.