Nozzle drag

When I get to the last few layers especially the last one I get nozzle drag on the surface which ruins the look of my prints, using SF41 and Gen 6 I don't know if it's a SF setting or whether I need to look at my Z height, any suggestions out there?

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Experimenting in 3D in New Zealand

Is it on every thread or just at the end of the print?

JB

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Check out my blog: AdventuresIn3-DPrinting

It's mainly at the end of the print, take a look at the picture not the clearest but you can see what I mean.

Ignore the overlap between the edges around the oval I know that's wrong and why. Under the word Reprap you can see the drag and yet this wasn't the end of the print, the bar across the top is higher so the nozzle had to go up to there

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Experimenting in 3D in New Zealand

The flow rate is too high, so when you get to the solid layers there is nowhere for the plastic to go so it builds up above the nozzle height.

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[www.hydraraptor.blogspot.com]

I'm currently using a feed and flow rate of 30mm/s with a 25% fill which gives good fill layer and I'm using an additional height over layer thickness ration of 0.3 for that part. I don't know if that makes difference I usually use 0.7 although the default for SF is 0.5.

What would a recommended feed flow rate be to try?

Edited 1 time(s). Last edit at 06/27/2011 06:25PM by NelsonRap.

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Experimenting in 3D in New Zealand

Are your width over thickness ratios set in repsnapper as well as skeinforge? That was my problem. Look in the edit bar - printer settings in repsnapper.

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Germanicus

@germanicus

Are you sure about that? I think that if you feed g-code from SF into Repsnapper, repsnapper does not add add'tl settings. It just reads and executes the gcode that was loaded.

That's what I thought too, but changing those settings in repsnapper to match skeinforge resulted in excellent prints with no other changes being made

I'm using a width over thickness of 1.5 and I can't see any setting in SF to change that only to change the layer height

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Experimenting in 3D in New Zealand

Skeinforge has 2 places to change the width over layer height: in Care and in Fill. Repsnapper also has a setting for width over thickness - it is in the edit bar at the top next to File. When You click edit-printer settings there is a menu with a lot of options. The three that are affected according to Rick from makergear are extruded material width ( effective width ), extruder multiplier, and layer thickness. For 0.30mm layer thickness settings in Skeinforge I set Extruded material width to 0.45mm, multiplier to 1.0, and layer height to 0.30.

These settings have worked pretty well for me for 0.3mm layer height and1.5 W.O.T. with skeinforge settings.

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Germanicus

Waiting for my latest print to finish, turned flow/feed rate down from 30mm/s to 20mm/s. Once I get the result from that I will have a look at the Repsnapper settings. I'm currently printing with a layer height of 0.4 as that is my extruder size

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Experimenting in 3D in New Zealand

Well print is finished and you guessed it. It did still drag across the corner but not as bad so will look at the Repsnapper settings tomorrow. Have to go out tonight

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Experimenting in 3D in New Zealand

Just a thought I'm using 3 solid layers on each face, what are most people using?

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Experimenting in 3D in New Zealand

I wasn't going to say anything because Nophead gave the the answer early on. You need to reduce the flow rate or increase your width over height to compensate for the extra material coming out of the nozzle.

It also may just be that your nozzles face it not parallel to the build surface which means that one edge of the very tip is dragging below the extrusion hole which causes a rough finish.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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I have reduced the flow and feed rate from 30mm/s to 20mm/s under the speed tab

So should I increase the increase the infill width over thickness (ratio) in the fill tab?

Or increase the additional height over layer thickness in the bottom tab?

Sorry if these questions seem a bit dumb still getting my head around which settings alter what, it's is appreciated though

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Experimenting in 3D in New Zealand

You should just decrease the flow rate.

When you change the width over thickness, SF adjusts the flow volume accordingly. So if you have the correct feed and flow settings for a width of 1.5, changing that to 1.3 or 1.8 should still give you a perfectly filled layer, just with thinner or wider lines.

That is my current understanding, at least.

EDIT: THIS APPEARS TO BE INCORRECT

Edited 1 time(s). Last edit at 06/29/2011 09:32AM by Andrew Diehl.

OK so is 1.3 thinner and 1.8 wider?

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Experimenting in 3D in New Zealand

I believe you could change a number of different variables to get the same results. The key to learning what they all do is printing 10mm cubes and changing one setting at a time to see how it effects the build. I printed 50 10mm cubes to get usable parts with correct dimensions, then another 5lbs of stuff to get my machine calibrated to what I feel is near perfect. Most if not all of the stuff was usable. Just not perfect, blobs, out of square over larger pieces, learning how to print faster, etc......

But to answer the question you adjust one or the other ( flow or feed ) reduce flowrate or increase feedrate.

Once you get close, lets say you find feedrate of 30 and flow rate of 25 in skeinforge gives good prints. This means your E_steps_per_mm is off by 25 / 30 = 0.833333333 you then can multiply your E_steps_per_mm in the firmware by 0.833333333 , re-upload your firmware with the new value. Then set the flow rate back to the same value as the feedrate. This will allow you to increase or decrease the speed easily by changing both number to the same value at once.

Edited 1 time(s). Last edit at 06/28/2011 05:28PM by Sublime.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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I would post the STL file, have others print it and post a similar photo, then match the settings from the best results. With all the SF41 setting to choose from, hitting on the optimal might take forever.

NelsonRap Wrote:
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> OK so is 1.3 thinner and 1.8 wider?


Yes.

So to get this straight in my head.

I originally set my extruder up to move 100mm and changed my e steps to suit but it seems my flow rate might still be too much. Will reducing the infill width over thickness from say 1.5 to 1.3 compensate for this or should I raise the feed rate or lower the flow rate.

Just want to make sure before I change the E steps. Off to print some cubes

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Experimenting in 3D in New Zealand

Right now your extruding to much material.

If your layer height is .4mm and the width is set to 1.5 you should have an extrusion .4mm high by .6mm wide (.4 x 1.5 = .6mm)

But it sounds/looks like the extrusion is more like .72mm wide so you either need to tell skeinforge that is what you are using by setting the width over height to 1.8 (.4 x 1.8 = .72mm)

OR

Fix the E steps per mm to match the current .6mm width by using the maths I gave you before.

All my numbers are just pulled out of thin air.

Edited 1 time(s). Last edit at 06/29/2011 12:59PM by Sublime.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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No. If you tell SF that width over height is bigger it will extrude more plastic to cover the increased volume. You have to reduce the flow rate / feed rate ratio or the Filament Packing Density. I am not sure why if you set E_steps_per_mm correctly.

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[www.hydraraptor.blogspot.com]

Quote
http://fabmetheus.crsndoo.com/wiki/index.php/Skeinforge_Fill
Infill Width over Thickness (ratio)

Default: 1.5

This parameter tells skeinforge how thick the extrusion is expected to be in relation to the layer thickness. The effect of increasing this is to cause the lines that create the infill to be further apart. So if your solid base infill is sparse decrease the value. If solid infill appears too full increase the value. Infill Perimeter Overlap (ratio) also effects solid infill by shortening the lines. If you look at a solid base layer that has been laid down on glass or tape without a raft you can often see how the plastic flows and see which to alter for the best result.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Quote

If solid infill appears too full increase the value.

I think that was true before SF40, but not afterwards. Perhaps somebody could confirm that as I don't use any of this.

Edited 1 time(s). Last edit at 06/29/2011 03:37AM by nophead.

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[www.hydraraptor.blogspot.com]

Hi Nophead,
thats still holds true... The number there gives spaces the lines further apart.So you can fight overfill with that... A number of 1 gives you line centers (paths), that are exactly your perimeter width apart... Lower numbers will give you tighter lines...

Anyway: Most of whats written here is not true, wrngly perceived yielsing the same result. But for a third person if you try to combinethe info here they contradict...
The problem if you just hit correct settings by chance is that they are fucked up as soon as any variable is different and you cant tune it anymore. You have to start from scratch...

Go on the IRC channel in the evenig (european time) there I can help you interactively ( #reprap on freenode.net)... My nick is Action68

It spaces them further apart but the volumetric version of SF is supposed to calculate the correct volume of plastic from the height and the width of the print roads, so it shouldn't affect the overfill from SF40 onwards.

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[www.hydraraptor.blogspot.com]

nophead Wrote:
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> It spaces them further apart but the volumetric
> version of SF is supposed to calculate the correct
> volume of plastic from the height and the width of
> the print roads, so it shouldn't affect the
> overfill from SF40 onwards.

I was under that impression as well. I just ran some simulations in SF which proved me wrong. Changing the infill width over thickness only changes spacing between lines and not the volume extruded per line.

I've searched and searched and can't seem to locate the step by step I had seen somewhere on here on how to measure, calculate and input the E_steps_per_mm. I remember something about marking the plastic 110mm up, but that's about it.

Could someone point me in the correct direction?

I have a guide to sf41 on my blog, and also some examples of how to get your correct fill ratio.

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[richrap.blogspot.com]