Weak/Flimsy parts

Hello all,

I am am new to my recently purchased Solidoodle 3 and 3D printing as a whole.  I am having difficulty trying to pinpoint the correct settings to print out parts that are more rigid/strong.

So, I opened the SD3 last Thursday.  Excited to start printing, I get the software installed on my Mac, download the bracket stl and start printing.

First part came out like this:

Very stringy, brittle and basically useless.  Hell, it was my first print...exciting!

So, I make some educated guesses at some settings and things improved dramatically.  My next print came out much more solid  and dense though now the part had warped.  Did some browsing around and quickly found that I should have leveled the bed and done some of the initial setup of my new printer.

Watched the bed leveling video, quickly got that done.

Next was to calibrate the extruder.  Followed the video, first step was to measure the filament 100mm and extrude 100mm of material.  Well, it fed well over 100mm and even went so far past 100 it extruded the second mark.  Hmm, not good.  So, I fumble around for hours trying to get the Arduino software configured to update the EEPROM which was a miserable experience (I am pretty familiar with Arduino also).  The software would keep erroring out on the compile step due to missing libraries that were actually installed.  Anyway, I found an alternative method using the G-code.  Read the current settings running command M501.  Made a change to the extruder value from 138 steps to 99 by using the M92 command, then wrote settings changes using the M500 command.

Now I get 100mm of extrude

Ok, so ever since I've done the extruder calibration, the printer will not print a solid part.  Or maybe it's something else, that's why I am asking.  I've printed some decent quality parts though they are really weak layer to later (if that makes sense).

Here's a part that I printed, came out looking perfect.  Gave it a little bend and poof, snapped right in half.

Same part printed again trying different settings.  It did not print like this, the part looked pretty normal actually.  But I squeezed it/bent it to test it's integrity and it turned to mush!

The white material is Taulman 618 Nylon and the black is ABS.  Both have the bed heated to at least 95C and the extruder was anywhere between 195C and 220C (trying to see if temperature had anything to do with the bonding issue).

Any input would be greatly appreciated!

Thanks in advance and sorry for the lengthy post!

Nick