Problem, nozzle is squashing prints

[truenorthtrader]

Hey Folks.

I noticed a problem with my Rostock. As layers increase in height, the nozzle is squashing down on prints.

In the pics the solid cylinder is getting squished when the head moves over it as it's printing and the empty cylinders are getting warped from the squishing as well.

All other printers I see, there is always clearance and no movement of the printed item.

What can I do about it? Seems I need to increase something not sure what though.

thanks!

[Polygonhell]

If you print something 10mm high is it 10mm high?
If it is, then you're extruding too much plastic, you can turn it down tin the slicer o in the firmware.

[cassetti]

Don't know for sure since I'm still building my rostock, but I believe there is an option to retract on the Z when moving between objects - this way the head will 'hop' around, instead of slamming into the side of the other print.

From what I understand, this is more popular with Delta printers since they can move the same speed in x y and z, whereas on cartesian printers, moving the head up 2mm and then back down to print would take too much time.

Good luck!

[truenorthtrader]

Ah haa!

I remember now I had a tad more plastic coming out when measuring 50mm I had about 52.
I thought it would just give better flow.

I used the default 584 on the Arduino I'll calibrate this and make sure it's exactly the right amount
Thanks you yet again!

Ye Cassetti it does I tried that though and it always leaves blobs where it pulls back unless the retraction settings are perfect.
As you can see I'm still messing with proper settings.

The squashing problem is always there though when doing fill going back and forth.
Those 2 pictures are during fill you can see the left side bulge out.
There's alot of settings you have to get right, its a bit frustrating ...but FUN at the same time, especially thanks to the help on this forum!

When you get to it you'll have to adjust the speed of the extruder, I'm going to do it now a good writeup is here
http://richrap.blogspot.ca/2012/01/slic ... s-and.html
And a good youtube video here: http://www.youtube.com/watch?v=JZGdMc2e ... B5150FBF39

[MorbidSlowBurn]

With your extrusion feed measurement, make sure you measure the distance prior to entering the feed rollers. If you measure after, the feed rollers can compress the filament which makes it longer but with a smaller diameter after the rollers. You want just enough pressure to not slip but not so much as to distort the filament.

[truenorthtrader]

Yes good point! I read that a couple places but some don't mention this important point.
Thank you

[truenorthtrader]

Ok Calibrated it perfectly TWICE to be sure.
exactly 100mm each time extrudes.

Recalibrated motors as in manual again all the exact measurement.

Printed 5mm thin wall and it's still squashing.

So I measured the movement of the motors and am more confused.

In the Print Panel in Repetier, Clicking -10mm on Z makes all 3 motors go down 10mm
Clicking -10mm on Y makes the Z goes down 14mm
Clicking -10mm on X makes the Y tower go down 7.5mm

The motors are connected to the right ports on the Rambo, Y on Y, Z on Z, X on X.

My Movement settings in "Configuration.h" in Arduino is: #define DEFAULT_AXIS_STEPS_PER_UNIT {106.666, 106.666, 106.666, 560.0} // default steps per unit for rostockmax

I checked each tower on the top and base, they are all lined up with the LINE engraved in the Acrylic.

Is this normal or do I need to adjust the settings for each motor?

thanks!

[Polygonhell]

If you are not at the top of travel, pressing X+-10 ot Y+-10 in Repetier should move in the plane, i.e. 2 axis will move in one direction and the 3rd will move in the other.
You should not adjust the steps for each axis.

[truenorthtrader]

Ok great thank you. Still not sure what else I can do at this point as my prints are getting squished even though everything is calibrated. :/

[MorbidSlowBurn]

Did you measure you filament diameter in a couple of places, take the average and used the average for the filament diameter in your slicer program? To me it sounds like you are getting too much material through the extruder. Just trying to brainstorm and maybe trigger someone else's train of thought.

Btw what temperature are you extruding at?

[Polygonhell]

Ok great thank you. Still not sure what else I can do at this point as my prints are getting squished even though everything is calibrated. :/

I guess I can't tell what's happening from the picture and I don't understand what you mean by squished. Is there a clearer picture you can post that illustrates the issue.

FWIW calibrating the input filament should just be a starting point, you need to print a single wall test and measure the extrusion width vs the requested width, and I always verify with 100% fill cube print.

[truenorthtrader]

I found belts was fraying on the Y tower and X a tiny bit so I took them apart and cleaned the belts, checked everything, reassembled, retightened and cleaned the other belts checking every tread and recalibrated.

The belts either go to one side or the other of the 608 bearings on the tower as they are thinner than the space and causing fraying and some of it gets into the tracks.
Not sure if they were upgraded to be a bit wider to fit better or not.

Here's a video I just made after this work showing the squashing on the 5mm wall print and some settings, the work didn't change anything.
http://www.youtube.com/watch?v=np5L5GGy4V8

I already printed The Triangles, Cubes, 5mm thin wall and extruder calibration steps.
Got the steps looking perfect and the thin wall was great but it seems to have degraded it's quality.

Measured the walls of my 3, 5mm thin wall prints and they're all 1mm even though I printed 1 and 1.5mm
They're all bing compressed so I don't think the measurements are accurate

I've tried temps of 218 to 230 so far with bed from 60-70 and it's always the same.

thank you again so much!

[barnett]

Is the first layer squished too? If so, then your z height may need adjusting to give it a bit more room between the nozzle and the bed.

[Polygonhell]

Ok I see what you are talking about, the corners are curling up and the the Hotend is pusing them back down.
Before I suggest remedies, I'll not that you will see this effect on tight corners with overhangs even on a well calibrated printer unless you have significant active cooling.

First it's possible that you are intermittently missing steps on the rapid travel, this can be very subtle to see on a rostock like design, what it does is lower the print near one tower. To eliminate this as a possibility drop the travel speed in Slic3r to,say 50, make sure you acceleration is set to say 800 in the firmware and turn off random starts in slic3r, then print a single wall test.

The reason the corners turn up is that the filament is stretched as it goes down and as cools it contracts both because of the plastic shrinking and because of the amount it was stretched during the printing process. To eliminate this as an issue increase the width of perimeters you can go as high as 0.7 with a 0.5 nozzle, and print the single wall test piece.

You can have issues because you take to long to print a layer and the heat of the head melts the layers below, the easiest way to eliminate this is to print 4 of the single wall tests at the same time.

[truenorthtrader]

Ok did what you asked, acceleration is ( was ) at 800, random starts off, travel speed to 50, printed slower about 50-60% it's much better but not perfect.

Printed .5mm first layer and all layers, I couldn't go to .7, got error "Slicer exited with error"
By "width of perimeters" is that the same as layer height?

I readjusted the Z height a couple times as it was a bit high, the last print where it warped upwards seemed the best height.
Much less squashing but still enough so a print isn't useful
Last picture at .1mm with Extrusion multiplier at 1.1 as lower settings leave these spaces everywhere but looks like I should lower to 1.0. still not perfect but used a fan to cool

Hope this helps give some idea on what I can do. I used more than a half roll of filament and only got a couple decent prints on small items.
thank you again!