Jump to content
Ultimaker Community of 3D Printing Experts
bobrich

Trouble with raft first layer, possibly due to incomplete perimeter print?

Recommended Posts

Hey folks,

I'm new to everything, cura, gcode, 3d printing, etc.  I'm currently using Cura 15.04.3 and a Wanhao Duplicator i3 printing with PLA and ABS.  I'll try to describe the problem I'm having, unfortunately I don't have an easy way to get pictures at the moment.

Basically when I print a raft, the very first layer consists of a single perimeter 'bead' that traces the outline of the raft, followed by fill lines that run every 1/8" or so across the width of the raft.

This seems to work pretty well, except for the fact that every single time there is a bit of this perimeter missing from the print.  It's just that there's no PLA laid down for maybe 3/4" or so.  Then, when the fill lines are laid down, they ALWAYS curl up right at this part, presumably because there's no perimeter to stick to?

Is there something I can do to help with this?  I'm running the DiiCooler which tends to snag on these curls and basically the print gets hosed before it gets off the ground.

Any suggestions are greatly appreciated.

Thanks!

Bob

Share this post


Link to post
Share on other sites

This is actually happening to me as well. To describe a bit more in-depth (at least for my issue). It seems like the extruder starts to push filament through and print before the nozzle is making contact with the print bed. This causes a portion of the raft perimeter to not print and subsequently provides nothing for the supports to stick to so they curl or drag with the nozzle marring the raft. It looks like it tries to start printing while moving to the starting position but while the z axis isn't far enough down.

Share this post


Link to post
Share on other sites

I have this issue too, but it doesn't seem to effect my prints because my cooler is 3mm up from the nozzle tip:

The print head moves from home to the start position of the raft. Its at the proper Z height and travels around the perimeter of the raft but doesn't extrude any filament for at least 30mm or more. Its trying to extrude, but the nozzle is not pre-primed.

Now I have an incomplete perimeter of the raft as it starts printing the surface lines. Because there is missing perimeter on part of the raft, those edges tend to curl up.

A possible fix:

In the Start gCode there is this:

 

G1 F200 E3              ;extrude 3mm of feed stock  

 

Try increasing the E value. Maybe 5 or more until you get your nozzle properly primed for when it starts printing the raft perimeter.

The Start gCode is on the Start/End-Gcode tab in Cura 15.x

Edited by Guest

Share this post


Link to post
Share on other sites

If you are using an Ultimaker 2 then it uses UltiGCode flavor and there is no start/end tab in Cura. The firmware does the priming automatically.

But just to test @DaHai8's assumption, you could go into the advanced menu (on the printer) and select "move material". There rotate the wheel at the front until filament comes out. Keep rotating slowly until you have a filament strand that touches the bed and curls up a few times there. Then remove the excess filament, go back and start a print. The nozzle should be fully primed now.

Share this post


Link to post
Share on other sites

Sad to see this problem hasn't been addressed in over a year. I have both a Monoprice Maker Select (Wanaho Duplicator) and two Monoprice Select Minis (Mylan M200). They all exhibit this exact same behavior. It's not a bed leveling problem (I used to have a job maintaining optical tables to Angstrom tolerances: I know level beds). It isn't a surface problem -- I've used many. On prints that can use a skirt instead of a raft, I can make it work by increasing the Skirt Line Count -- but there's no equivalent for rafts. Using different bed and filament temps doesn't change it. It's definitely, 100% certainly a problem in the Cura-generated gcode and how it interfaces with these Monoprice printers.

 

I'm going to try disassembling the gcode this weekend and see if I can figure out a way to fix it, but an option in Cura to increase the line count of the frame on the first layer of a raft would be quite welcome.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Our picks

    • Taking Advantage of DfAM
      This is a statement that’s often made about AM/3DP. I'll focus on the way DfAM can take advantage of some of the unique capabilities that AM and 3DP have to offer. I personally think that the use of AM/3DP for light-weighting is one of it’s most exciting possibilities and one that could play a key part in the sustainability of design and manufacturing in the future.
        • Like
      • 3 replies
×

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!