Z18 bridging issues

[Arafat Terron]

Having an issue when trying to print bridges. I used this http://www.thingiverse.com/thing:287033 but with some modifications for faster printing. Not sure if it is clear in the pictures, but when the printer is on the bridges line, it does two of them good, but the other two are so bad, both good bridges are parallel to each other, for example if both horizontal ones (seeing from the top) are good, then the two vertical are bad. I tried modifying the height a little bit so the bridges will be made 1 line higher than my last attempt and then the good and bad bridges swapped places now the horizontal were the bad and the vertical the good. What I saw is that when printing the bad bridges, when the extruder starts with the bridge it is looking good, but when it reaches the other side it doesn't go all the way into the tower and doesn't stick to anything so when it turns back to the starting tower it fells and leaves that shape. Is there any parameter that I could change to tell the extruder to go further into the other tower so the bridge sticks to something in the other edge. Hope I could explain myself.

[Jetguy]

We'd call that perimeter overlap in any other slicer- not sure in MW.

Hate to say this but H-bot mechanics and the sloppy extruder hanging down from the gantry like pendulum might be contributing to the overall nozzle positioning error and that's why some line are good and some lines are bad

Solution??? Rip the guts out, put in a known good controller and firmware we can actually adjust settings on, and move to a CORE XY belt system and real extruder- then it MIGHT perform as expected.

It's sad to say but if the hardware cannot follow the commands now, what makes you think changing the commands sent are going to improve anything?

[Jeff Davis]

Try printing it with no modifications to see if you may have done something.  Use standard medium settings.

[Jetguy]

I know you may not like my answer but I'm being honest and telling what is really wrong, even if you don't like it.

I've attached a Z18.json and I cannot see anywhere to edit how much overlap bridging or infill in general does to ensure the threads attach to the side.

It simply doesn't exist as a setting.

In fact, the only setting I even see that might help is enabling backlash control and actually try to use that to cover up the sloppy nozzle positioning but if it's not repeating every time- probably not a real solution either.

So then IF you had Simplify 3D since it now supports 5th generation models, you could try using these settings to adjust and compensate.

This first one is how much overlap the nozzle is going to pull the thread to to make it attach to the wall.

This is the speed and percentage of extrusion setting. If you make extrusion greater than 100% then the threads will droop because for a given linear length of nozzle distance, we are pushing more plastic out through the nozzle. Going less than 100% makes the nozzle push less plastic making it stretch the string tight (in theory- up to a limit).

On Tuesday, January 20, 2015 at 12:51:15 PM UTC-5, Arafat Terron wrote:

[Ryan Carlyle]

Can you post a screenshot of the gcode preview layer where the bridge happens? That will tell us if this is a mechanical issue (eg backlash) or a slicer issue. 

[Arafat Terron]

How can I get the gcode? I'm using MakerBot Desktop btw.

[Jetguy]

The thing file it exports.

[Arafat Terron]

Hope any of these help.

[Joseph Chiu]

If you want to "cheat" to get this to be successful, make one set of bridging start at one layer height higher than the other set.