Sagging, rough borders around holes, and some bobbling on corners

Just starting out with a Mendel90 - just wondering if anyone can advise on these two models I printed:

[marcos.scriven.org]

On the stepped object, wondering:

1) Why there's so much sag across a relatively small gap, especially compared to the almost horizontal line across the much larger gap on the iPhone case
2) Why the top step is so rounded

On the iPhone case:

1) Why it was a couple of mm too short (shrinkage, calibration) ?
2) How to improve the perimeter of the holes
3) How to remove the bobbles on the edges

Thanks

Marcos

Hi Marcos,

Congratulations on completing your build. As I am planning on building a Mendel90 in the new year I am looking forward to reading the build notes you say you'll be posting on your blog

Regarding the print problems with the stepped object - my guess is that because the deformed area is quite small it is not cooling down enough, i.e. the hot-end is keeping it pliable - hence the longe bridge in the iphone case coming out better, because the nozzle moves away.

What cooling settings did you use, and do you have the fan attachment installed?

Cheers,
Gary

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garyhodgson.com/reprap | reprap.development-tracker.info | thingtracker.net

Thanks for response Gary - 'build notes' is probably far too grand a term, think more 'my experience following pretty good instructions'!

I'll add it to blog this weekend, whilst trying your suggestion re cooling (I didn't have it switched on in Slic3r). I had planned to get it done sooner, but I took a frustrating step backwards yesterday, spending all evening wondering why my PLA suddenly stopped sticking - turned out to be the screen cleaning fluid I was using on the glass - obvious in hindsight!

Edited 1 time(s). Last edit at 12/14/2012 04:03AM by marcosscriven.

Ah yes, hindsight is often 20:20

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garyhodgson.com/reprap | reprap.development-tracker.info | thingtracker.net