Marshall
Posts: 44
Joined: Sat Jun 20, 2015 8:15 pm

FR: The Ultimate Way to Begin a Print

Wed Jul 13, 2016 9:46 am

Hope the catchy title works. :D

I feel that skirts are one of the best ways to solve print-warp and stick a part to the bed. I have used and now managed to evade slurries with ABS or glue, because skirts can hold my parts down so tightly to finely-sanded Kapton.

There is one problem that can cause me to rush the emergency stop button upon a print start. The problem arises from the fact that S3D starts the skirt on a corner, such as the cube example below. There's an obvious contributing factor to a potential print fail that arises from this (and the faster speed of a skirt combined). If the extruder does not stick the starting extrude point down, it will quickly run away pulling the strand as it arcs the corner attempting to gain grip--dragging the plastic right across the part area.

Solution:
It is much easier for plastic to adhere to a bed as a print begins to prime up and equalize to print pressure when the plastic extrusion is traveling none other than a straight-line path. I suggest S3D incorporates a straight-line path to begin all print additions like skirts. This should improve the success rate of many types of print starts greatly if implemented.

Also:
A beneficial modification to this technique exists already at the start of every print in the very G-code allowing the nozzle to wipe. As the line example would begin extrusion, if the nozzle reduced in Z height while traveling, making a "dip" and then resuming set print height for layer 1, this "press down" effect would further increase success rate of the initial extrusion bonding with the bed, without the entire layer being compressed to such degree.

Image

This straight line incorporation could even solve some of the deeper issues people have such as common troubles with intricate support structures not gaining initial adhesion. This is often a result of multiple retracts quickly, where the nozzle needs some distance extruding to get flow going steady again. Some amount of a straight line before a corner can almost always solve this problem. ;)

CompoundCarl
Posts: 2005
Joined: Wed Aug 05, 2015 7:23 am

Re: FR: The Ultimate Way to Begin a Print

Thu Jul 14, 2016 5:59 am

I do this exact same thing in my starting script. I just draw a long line of plastic on the bed to help prime the nozzle, then it moves to the skirt.

It's literally 2 lines of gcode, so it's quite easy to add :D

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