.75 MM Nozzle Help ( experimental )

[kentd]

I recently ordered the .75 mm nozzle for my M2 machine and I am looking for some basic settings to get me going with this nozzle.

I am using Simplify3d for my software....... so maybe if someone would provide me with a profile that I could import into Simplify3d, or just some of the settings would also help.

Here is mainly what I am looking for guidance on:

On the Extrusion Width should I set that for a specific setting, or
should I set it on Auto?

What should the extrusion multiplier be set at?

Should I keep my nozzle temps the same as I am using for the
narrower nozzles?

Thanks in advance for any help on this.

[jimc]

I have not printed with anything that large but if it were me i would set the width to auto to atleast start out. Temp should be the same. Multiplier will vary per how you have the filament dia set so this will need to be tuned for each spool of filament.

[kentd]

I was able to get the .75 mm nozzle to work, but the problem I am running into is that its laying down 3 times as much material...... so It kind of defeated the purpose since the time savings will be eaten up by material cost.

I have attached a sample print of the same part printed with a .35 mm nozzle and .75 nozzle. You can see how much darker the .75 nozzle print is because of all the material used. ( both parts were printed using the same material )

I have also attached 3 screen shots from Simplfy3d profile for the .75mm nozzle.

Kind of a head scratcher...

Test Print.jpg

(412.67 KiB) Downloaded 645 times

.75 nozzle screen shot 1.jpg (125.49 KiB) Viewed 11173 times

.75 nozzle screen shot 2.jpg (130.63 KiB) Viewed 11173 times

.75 nozzle screen shot 3.jpg (115.21 KiB) Viewed 11173 times

[jsc]

Some of that difference can be accounted for because you are laying down two solid perimeters at 150% of what you would normally be doing with a 0.35 mm nozzle, so your perimeter is the thickness of a 3 layer perimeter.

I don't know what accounts for the rest of it. Presumably, 30% infill means lay down a pattern to cover 30% of the surface area, regardless of extrusion width. So you should be seeing no more than a 50% gain in weight.

[ednisley]

its laying down 3 times as much material

I think that's what the parameters call for...

For a 0.75 mm nozzle, forcing a 0.6 mm width requires the extruder to produce a thread narrower than the nozzle, which doesn't work well. Set the width to about 0.8 mm, maybe 0.9 mm.

Using a 0.2 mm layer thickness with a 0.75 mm nozzle doesn't take advantage of the material flow rate. That should be around half the nozzle diameter, maybe a bit more: try something close to 0.45 mm for starters.

Using an Extrusion Multiplier of 2.0 doubles the amount of material laid down. That number should be very close to 1.0.

You'll probably need more retraction, because a 0.75 mm nozzle has nearly 5 times the area of a 0.35 mm nozzle: there's a lot more molten plastic ready to drool out that bigger hole, so you must yank it back further.

Once you reset those values, calibrate the actual output using a series of thinwall boxes. When you get everything right, the single-thread wall thickness will be spot on 0.8 mm (or whatever you set). When you measure the filament diameter accurately, the slicer should come pretty close to the right output, whereupon you tweak the Multiplier to get the exact width you're specifying.

For the 0.35 mm nozzle on my M2, I use a thread 0.4 mm wide x 0.2 mm high = 0.08 mm². For a 0.75 mm nozzle, using 0.9 mm wide x 0.45 mm high gives a 0.4 mm² thread. That's 5 times the plastic volume per unit of XY length, so your prints will take maybe 1/5 (that's optimistic) of the elapsed time at the same XY speed.

However, the vertical resolution won't be what you're used to. If you cut the layer thickness back to 0.2 mm, then you double the print time. You probably can't double the XY speed to compensate, but some experiments would be revealing, because, at some point, the extruder heater won't be able to deliver enough power to melt the filament fast enough to keep up with the required output volume. Start slow and go faster only after you get good, stable results at "normal" speeds.

[kentd]

Thank You very much for the info Ed!

I will give this a try and let you know how it goes.

One question on the retraction value change.... what would you recommend for a setting?

Thanks again....

Kent

[Tim]

One thing with Simplify3D---just use "Auto" for Extrusion Width, and it will give you a reasonable value. As Ed said, the extrusion width value must be larger than then nozzle diameter (and S3D really ought to be generating a warning message if you're below that). There are valid reasons for tweaking the value, but in general the value S3D selects automatically will be close to optimal.

For everything else, I can't add anything useful to what Ed already said.

Retraction is secondary to everything else, so I wouldn't worry about that until you've changed all the other parameters and seen the effect. If it's noticeably dripping extra plastic in places like corners where the extruder slows down briefly, then start dialing the value up. Typically, for a 0.35mm nozzle, a value like 1mm will be used for retraction (when it's needed at all). Ed's argument is that the retraction is a linear distance of the filament at its original diameter, while the cross-sectional area of the filament coming out of the nozzle increases as the square of the nozzle diameter; so assuming you're still putting 1.75mm filament through this 0.75mm nozzle, you're going to need to retract nearly 5x the distance of filament to pull the same volume of material away from the nozzle opening. So it's likely that your retraction value may need to be somewhere up around 5mm, or even more. But get the other numbers under control first, then see how much of an oozing problem you have.

[jsc]

Ah, I hadn't noticed the 2.0 extrusion multiplier. That, plus the 1.5x amount going into your perimeters, would give somewhere between 2-3x the amount of filament, which is what you're seeing.

[kentd]

First off.... I want to thank EVERYONE for their input...... I am now much closer to success because of your help.

The .75 nozzle is now flowing great... and the parts are looking much better.

I have just a couple of follow up questions.

Question #1: I noticed that the two outside wall layers don't stick to each other. In other words they are just laying next to each other.
I tried adjusting the Extrusion width downwards to .75 and .70 mm and it looks like they get closer, but then I am seeing poorer quality print on the rest of the part.
Any suggestions of another setting change that may help fix this?

Question #2: Now that I have decent parts coming out, what would be my next tweak in my settings that may help me decrease even more the amount of material I am using?

The photo below shows my current settings.

Settings.jpg (93.57 KiB) Viewed 11131 times

[ednisley]

In other words they are just laying next to each other.

That says the actual thread width doesn't match the value you've told the slicer or that it's assuming in Auto mode. The way you fix that is to measure two values:

• The diameter of the filament going into the extruder
• The width of the extruded thread coming out.

Then you adjust the Extrusion Multiplier to make the answer come out right.

If you don't have one already, get a digital caliper; a cheap one will set you back under $20. You'll use it whenever you change filaments or printing conditions, so it's a Good Thing to have around.

Measure the filament diameter at a few spots along a few meters of filament. If you get consistent values, plug the average into the slicer. If you get inconsistent values, that spool of filament will give you troubles forever more; the slicer can't cope with a variable amount of plastic coming out of the nozzle.

Print a thinwall calibration cube and measure the actual wall thickness near the top of each wall:

Visualization of Thinwall open box model - 0.85x0.45 mm thread

Thinwall Open Box - 0.85x0.45.png (11.23 KiB) Viewed 11127 times

Because the thread width is so much larger than the typical cubes out there, you should build your own model with a 0.85 mm wall, so the slicer doesn't go nuts trying to lay a 0.85 mm thread along a path that calls for 0.30 mm. The attached ThinWall.zip file has suitable STL file generated with my OpenSCAD routine:

http://softsolder.com/2014/04/18/revise ... on-object/

Slice it, print it, measure it. If the wall isn't spot on 0.85 mm, adjust the Extrusion Multiplier by 0.05 and repeat until it is. You must re-slice the model each time you change the Extrusion Multiplier so that the printer knows about the new number. After a few iterations, you should get consistent results that match the values you told the slicer to produce, at which point you can re-slice your model and see how it comes out.

The walls should be exactly 9.0 mm tall, so you can check the platform height. If the cube is too tall (short), then your platform is too low (high) by the difference between 9.0 mm and whatever you measure.

Works for me, anyhow... [grin]

Edit: fix width vs. thickness typo, etc. Note that walls have "thickness" in the XY plane, where threads have "width". Just to keep you on your toes, thread "thickness" is parallel to the Z axis. Drive ya nuts, it will.