1 Topic by Lurkios (edited by Lurkios 2013-06-16 09:40:45)

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Topic: Gaps on Horizontal Surfaces

So I went ahead and tried to calibrate my flow rate as per the instructions here: http://solidoodletips.wordpress.com/201 … flow-rate/

That bit went very well, vertical walls are now exactly .42mm (and my backlash suddenly became very apparent, time to order a well nut...) - but I did have to scale back the flow rate from the default .79 to .64.

However, horizontal surfaces have gaps up to about the third layer, where the did not before (obviously caused by the decreased flow rate). I'm guessing the solution here is more lines per surface, but I'm not sure how to accomplish that. Any ideas?

EDIT: To clarify, all horizontal surfaces have gaps, not just up to the third layer. I meant it takes about 3 layers in order to get a surface I can't see any holes in.

Things I've tried:
-Calibrate filament feed rate
-Find/set proper extrusion multiplier
-Calibrate Z-offset
-Check extrusion width

2 Reply by dteck

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Re: Gaps on Horizontal Surfaces

I had a similar problem when I first got my SD2. I had to turn the flow rate down to something crazy like 0.5754 to get proper widths, but it also gave me gaps. I fixed it by using this guide to calculate the steps per mm. Then updating the EEPROM. Super easy to do in repetier host
http://solidoodletips.wordpress.com/201 … libration/

It meant I could turn my multiplier back up to about 0.9-1 which got rid of my gaps. mostly.
My red still gives me troubles with making a decent surface if i don't put enough solid layers after the 0.2 infill, but the white and black behave a bit better.

3 Reply by Lurkios

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Re: Gaps on Horizontal Surfaces

Thanks for the tip dteck, unfortunately it didn't make any difference. My extrusion multiplier is now higher and my steps per mm a fair bit lower for the extruder, but the problem remains exactly the same.

4 Reply by dteck

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Re: Gaps on Horizontal Surfaces

Hmm if you can id say take some pictures and post them here so people can see exactly whats going on. Better printers than I might be able to help you out then.

5 Reply by Lurkios (edited by Lurkios 2013-06-15 18:59:46)

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Re: Gaps on Horizontal Surfaces

Alright, this is what's going on.. Bottom half is a single layer, top two. As you can see, even at two layers there are clearly visible gaps.


http://i.imgur.com/C9CRirO.jpg

6 Reply by ronsii

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Re: Gaps on Horizontal Surfaces

What settings do you have in RH for the fill layers?

7 Reply by Lurkios (edited by Lurkios 2013-06-15 19:15:57)

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Re: Gaps on Horizontal Surfaces

ronsii wrote:

What settings do you have in RH for the fill layers?

Sorry, I'm pretty new to this - not sure I'm looking at the right thing. Where would I find those settings? (Infill?)

Right now I do have the Horizontal Shells setting at 4 and 4 solid layers for top and bottom.

Infill is .4, but at two layers I shouldn't be there yet, should I?

8 Reply by Shotline

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Re: Gaps on Horizontal Surfaces

While I am new to this (so take what I say with a few grains of salt) but it looks like your extrusion width might be off, check if it is set to .42.  Also, ensure you have set your Z offset appropriately (if you don't have a problem with the print coming loose from the print bed you are probably ok).

Good luck.

9 Reply by Lurkios

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Re: Gaps on Horizontal Surfaces

Thanks for the advice Shotline, but my extrusion width is correct and the Z offset has been calibrated. (It's not just the first layer that experiences this issue, it's any horizontal surface.)

The part that's really confusing me is that the perimeters are all fine, it's just the fill that's an issue.

10 Reply by Shotline

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Re: Gaps on Horizontal Surfaces

Might be a temperature issue.  If you are at the lower ends the plastic might not have time to "spread out".  You do seem to get some connection at the ends where the extruder changes direction which is where it would remain the hottest.

11 Reply by IanJohnson

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Re: Gaps on Horizontal Surfaces

I run into that too.  If the flow is giving me the right thickness of single thread walls, and the right dimensions, I tend to get gaps on the solid layers.  If I turn up the extrusion multiplier a little, the gaps close up but then the dimensions come out maybe .15mm or .2mm larger.

You could try setting the nozzle diameter a little smaller, like .33  It might make the rows a little closer together, though I'm not sure what other effect it would have on dimensions.

12 Reply by Lurkios

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Re: Gaps on Horizontal Surfaces

Thank you for the reply IanJohnson.

I think I may have gotten this one figured out. When I upgraded to RH .85b a few new setting concerning extrusion width under the "Advanced" category in Slic3r which it had set to 0 - 0 being "default", which was .42, exactly what I wanted.

Seems something's a bit wonky there though, as manually setting the 0 values to .42 fixed the problem, despite that being what they were supposed to have defaulted to anyway.

13 Reply by gettingbored

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Re: Gaps on Horizontal Surfaces

The same thing happened to me, but the gaps appear vertically as well as on the top layer but that's fairly minor. I already tried the fix Lurkois posted above, but it just looks like the layer height, although correctly set for .3mm printing, isn't right...

Anybody know what's up with this? Should I just decrease my layer height?

Here are some pictures of what I'm talking about.
https://dl.dropboxusercontent.com/u/8410101/IMG_6675.JPG
https://dl.dropboxusercontent.com/u/8410101/IMG_6676.JPG

14 Reply by 2n2r5

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Re: Gaps on Horizontal Surfaces

Your Z steps/mm might be off. Do you have a dial indicator that you can check to make sure 10mm of Z travel = 10 mm of actual travel

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15 Reply by MolecularConcept

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Re: Gaps on Horizontal Surfaces

when i get gaps in my layers like that i move the bed closer to the nozzle, been workin for me.

16 Reply by Gomisan

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Re: Gaps on Horizontal Surfaces

Wow, I thought the gaps in the flat surfaces were normal!

But I also have my flat layers more like a mess than a solid surface.

So things to try:

a) increase temp to 'spread out' the filament more
b) change the nozzle width in settings so it thinks it's a little narrower than it is.

I think I will need a good calibration test to watch the results of this.

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17 Reply by RavensCrest

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Re: Gaps on Horizontal Surfaces

2n2r5 wrote:

Your Z steps/mm might be off. Do you have a dial indicator that you can check to make sure 10mm of Z travel = 10 mm of actual travel

if the cube is the correct height, you might be looking at filament size setting.

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18 Reply by gettingbored

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Re: Gaps on Horizontal Surfaces

RavensCrest wrote:
2n2r5 wrote:

Your Z steps/mm might be off. Do you have a dial indicator that you can check to make sure 10mm of Z travel = 10 mm of actual travel

if the cube is the correct height, you might be looking at filament size setting.


Humm I don't have a dial indicator, although it seems like a worthwhile thing to invest in. I'll poke around the hardware store and the internets later today. If you've have a specific one you like and got it online let me know.

I measured the cube too, and it seems damn close to the correct height. It's just a 20mm cube I made in SketchUp and exported as an STL.

https://dl.dropboxusercontent.com/u/8410101/IMG_6683.JPG

I measured the filament again, and I think it was off a tad. Set at 1.72, when it's probably more like 1.68 though I'm not sure how big a difference it'll make, maybe just enough.

Anyways I'm heating up the printer to do another test print right now so we'll see soon enough!

19 Reply by IronMan

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Re: Gaps on Horizontal Surfaces

2n2r5 wrote:

Your Z steps/mm might be off. Do you have a dial indicator that you can check to make sure 10mm of Z travel = 10 mm of actual travel

2n2r5,

Just on a tangent, If you check the z-travel by indicator and it IS off by any significant amount, what is the best way to correct this?

I've noticed a height loss of up to 1.5mm on a 100mm high print, but I just attributed that to shrinkage.  Has not caused me too much trouble, but I am going to check the z-axis movement this weekend...

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20 Reply by Tomek

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Re: Gaps on Horizontal Surfaces

IronMan wrote:
2n2r5 wrote:

Your Z steps/mm might be off. Do you have a dial indicator that you can check to make sure 10mm of Z travel = 10 mm of actual travel

2n2r5,

Just on a tangent, If you check the z-travel by indicator and it IS off by any significant amount, what is the best way to correct this?

I've noticed a height loss of up to 1.5mm on a 100mm high print, but I just attributed that to shrinkage.  Has not caused me too much trouble, but I am going to check the z-axis movement this weekend...

Hi Ironman,

Best bet would be to change your steps per MM number in the eeprom. But I'd test the high up and down as you manually move it, and not your final print (as there are a lot more issues that could happen to a print.)

21 Reply by IronMan (edited by IronMan 2013-08-23 17:08:44)

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Re: Gaps on Horizontal Surfaces

Tomek,

Thanks!  Direct bed measurement is how I'm planning to do it...but if I do find a discrepancy, say, 1mm short over 100mm of intended travel, what is the best way to calculate the increase/decrease in step settings?

Edit:  I think I've got it...so if the default setting for steps / mm on Z is 2268 and I move 100mm, but the reading on my dial reads that I moved only 99mm:
- The move caused the Z motor to move 226800 steps (2268 x 100)
- It only physically moved 99mm;
- So 226800 / 99 = 2290.9 steps/mm
- Then my new setting should be 2290.9 (are decimal settings allowed?)

Is that correct?

SD2 - Stock - Enclosure - Heated Bed - Glass Plate - Auto Fire Extinguisher
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