PLA not printing to scale and not bonding well

[nrbelk]

This is two of the most recent issues I'm dealing with.

I'm trying to print a spear head that will be used in a costume. It is designed to the the spear head has a part that will slide over the shaft. When it finished printing, I could easily separate the layers, just a little squeeze (which made a crackling noise) and then I could almost pull off the plastic layer by layer. Is this a heat issue, meaning I need to print hotter? Or is it possible that they way I did the design is an issue. I made the design in inventor as a hollow shell at about 2.5mm thickness. Then in the print settings I set it to 100% infill.

The second issue is that it seems to be printing 1mm to 1.5mm small. Instead of being able to slide the head over the tube that will serve as the shaft, it was too small (almost as if I printed more tube itself lol). I went back to inventor to make sure the dimensions looked right and they did at first glance (I'll go back and make sure the measurements were at the right spots).

I know that PLA shrinks with larger pieces, but is 1mm to 1.5mm normal? Are their scaling settings I can use to account for it?

I've added a picture of the spear head for reference. It was still being printed but I hope it might help.

[nrbelk]

I forgot to mention, after it happened, I printed a solid cube that was designed to be 20mm x 20mm. It printed close to that size, like 19.92x 19.65 x 20.01, according to my cheap calipers.

[stonewater]

when printing circles it is rarely the correct diameter. with my V1 printing ABS if I want a .500 hole I need to draw it at .540 and then it will clearance just fine. it has to do with how the extruder lays down the filament, and how the slicers print cirlces, its in segments not true radius.....

.5 nozzle
240 hotend
90 bed
purple gluestick

Tom C

[Nylocke]

What temp are you printing PLA at? If its separating easily then you're printing too cold, and/or your extruder is having a hard time pushing it out, causing thin extrusions. The second of the two problems can be caused by the first, or it can be caused by a partial jam in the hotend or another reason.