Good starting figures.

Hello there

I'm getting real good at homing, adjusting the z endstop, leveling the bed, and removing messy plastic blobs.

I'm looking in the forums, and see that pretty much everyone has its own recipe.

So far I printed like 3-4 "successful" 10mm cubes. Everything else was a blob.

I'll tell you what I do, please tell me what I'm doing wrong.

It's a prusa mendel, with 1.75mm PLA feedstock, a jhead Mk4-b nozzle (0.4mm nozzle)
I'm extruding around 185C. I'm measuing the temperature with a different meter to make sure.
I have to set it to 205 to get 185.
I'm using sprinter firmware, all my e-steps are right. When I ask a 20mm extrusion, 20mm of feedstock goes in, and the filament goes down straight, extruded at 0.4mm.
I use pronterface and SFACT, with all the default values, except for feedstock, which I changed to 1.7mm, and filament, chaged to 0.4mm. With all the failures, I tried to slow down all the feed rates to 3/5 of the default values. It seems better, but not much.

My main problem is to make the first layer stick. I didn't get the blue tape yet. That's my next move.
But the layer height is very critical. I have an adjustable z-endstop screw, it's a .8mm per turn, and sometimes a quarter of one turn (0.2mm) is enough to make a difference between scraping off the tape or just oozing black spagetthi all over.

I'm using masking tape right now, because I don't have anything else at hand. The only way to make anything stick to it is to almost scrape the tape with the nozzle.

Also, when I extrude plastic in the air, it take a bit of time after the motor has started to actually see the filament going out. And the when the motor stops, it keeps going. There is an extrusion lag on my machine, and I can't figure out how can this be solved.

If someone out there is happily printing with a similar setup, please give me some starting figures for the feedrates, speeds, and so on.

Thanks in advance!

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Don't force it, it will break. Stop. Think.

Masking tape won't work at all; if you're printing PLA you need blue tape. Start from there and once your first layer is adhering properly, then we can start to solve your other problems. And honestly, I'd recommend starting with Slic3r. SFACT is a bit better than Skeinforge, but there are still a zillion knobs to turn. With Slic3r, you input your desired temperature, nozzle diameter, and actual filament width, and you're off to the races.

Thanks for the reply

I got the tape and some glass today. I was using repsnapper and then I switched to sfact.

I find it soooo much better, printing the perimeter,making a z-move before the first move...

Will slic3er do all those tricks? Will it center the print? Can I use it with pronterface?

Thanks!

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Don't force it, it will break. Stop. Think.

> Will slic3er do all those tricks?

Yup!

> Will it center the print?

Yup!

> Can I use it with pronterface?

Yup!


That's all pretty basic stuff… Slic3r has a lot of tricks up its sleeve. Just about the only thing it can't do that Skeinforge/SFACT can is support material.

All right, I'm printing littles 10x10x10mm hollow cubes again now. They are not super square, but it looks like it needs some flowrate calibration.

Now the first layer sticks to the tape most of the time. But I run the printer in a cold room, that doesn't help, since I don't have a heated bed. yet.

The next big issue I have, is printing the first layers. My tip is picking up some of the deposited material, and ends up building some bumps on the first layer. Then when it gets back there for the second layer, you can hear the tip running over the now solid plastic bumps and I'm hearing nasty clunks and I shutdown the sequence. I don't want to tear my hotend appart.

I haven't tried slic3r yet, but I'll give it a try right now, I'll keep you posted.

Thanks for your help

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Don't force it, it will break. Stop. Think.

I must admit, Slic3r is truly amazing.

I just entered feedstock and filament size, and it started printing.

It has perfect retract settings right off the bat.

But now I'm back to having problems with the sticking.

The first layer is laid down perfectly on the bed.
Then is moves up to the second, speeds up, and rips the first layer off.

I guess I just gotta have that heated bed.

Is there some other way? I heard some people can do without a heated bed...

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Don't force it, it will break. Stop. Think.

Kabory Wrote:
-------------------------------------------------------

>
> The first layer is laid down perfectly on the
> bed.
> Then is moves up to the second, speeds up, and
> rips the first layer off.
>

Have you verified the calibration of your Z axis ? The hotend should not touch the previous layer, but if it doesn't move up enough it could happen.

Otherwise, really go for scotch blue tape, it really does miracle for bed adhesion with pla. Common masking tape can't compare.

In the mean time you could try reducing the flowrate a bit for the first layer. Bad trick, but could work (I'm not sure you can do that on non-skeinforge slicers).

DeuxVis Wrote:
-------------------------------------------------------
> Kabory Wrote:
> --------------------------------------------------
> -----
>
> >
> > The first layer is laid down perfectly on the
> > bed.
> > Then is moves up to the second, speeds up, and
> > rips the first layer off.
> >
>
> Have you verified the calibration of your Z axis ?
> The hotend should not touch the previous layer,
> but if it doesn't move up enough it could happen.

I agree. If you're using standard threaded rods for your Z axis, then the Z axis's steps_per_mm value should be something like 2560. It sounds like the nozzle isn't moving up far enough for the layer transitions. If you haven't calibrated your e_steps_per_mm values in firmware, that's the absolute first thing you need to do before doing anything in software.

x y and z axis are calibrated ok.
For E, maybe I need some work, but I'm almost there.
Working on a heated bed now, meanwhile I'm receiving and MK2 ordered yesterday.

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Don't force it, it will break. Stop. Think.

After printing a bunch of 10mm calib cubes, I somewhat successfully printed most of my first part. W00t!

During my 10mm cubes printing, I had to lower down the extrusion multiplier to .75 because the first layer got too much plastic and it started to build up and when the second layers comes in, is scrapes it and lifts the part off the tape. So after lowering that multiplier, I had less plastic and the cube printed. Not too square, but it worked. So I went for something bigger. It's a split lm8uu holder. [www.thingiverse.com]

I made the part stick to the blue tape, but when the second layer printed, the first one started to lift just by the corners, and that kept going for around the first 10 layers. But the part kept on the tape. Then it printed most beatifully, until I ran out of feedstock. (Have to work on some quick spool, I know)

When I took the part in my hands, It did not felt too solid. Then I pushed the bearing in, and all the layers started to fan out. They were not stuck togheter very tightly. I twisted the part in my hands and most layers fan out, and the part broke in half.

What I'm suspecting is that my filament settings are not correct. I have a J-Head Mk IV-B Hot end. Orifice is 0.40 mm and I use 1.75mm feedstock. I measured my filament and I got .45, .46mm, but it's .4 in my slic3r settings. So lowering the multiplier kind of compensated for that.

I'll try tomorrow with .45mm filament setting in slic3r. In the wiki, there's a calibration guide: [reprap.org], talking about this:

>>Layer height, Extrusion width
>>These are simple to visualise. When your extruder draws a line of plastic, that line has a height and width. You get to >>choose these values. Best results when layer height < nozzle diameter, and extrusion width >= nozzle diameter.

Is this the advanced setting in slic3r? How do I set it?

Thanks again

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Don't force it, it will break. Stop. Think.

The maximum layer height you can use is actually 0.8 times the filament diameter, i.e. 0.8 * 0.45 = 0.36, 0.35 would give some margin. The width would need to be 1.5 times that and you can set that on the Advanced tab.

You can use lower layer heights until the filament is stretched too much and starts to break, or cut corners at which point you can increase W/T to compensate.

W * T must always be less than the cross sectional area of your filament extruded into free air. W/T needs to be at least 1.5 to get strong objects.

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[www.hydraraptor.blogspot.com]

Thanks for the tip!

There is a need for a good manual, to "visually" explain all the slic3r settings. Kind of like the visual guide to building the prusa. That was such a good thing I had it.

I'll try these seetings and keep you posted.

Also, do you have a quick tip for cleaning the nozzle? All those print failures are making more PLA stick on the tip. I take some off with longnose pliers, but the're a film on the tip, and sometimes it picks up on the part and smears it all over. What do you use?

Thanks,

Kabory

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Don't force it, it will break. Stop. Think.

Here's what I got with your suggested settings. The part on the left was aborted after the first layer, and the part on the right after the second layer.

[i1130.photobucket.com]

My E-steps are calibrated perfect, If I ask for 100mm extrusion, I get 100mm dead on.

It really looks like the tip is picking up some plastic while it's moving. What can I do to improve the print?

Here's my actual slic3r ini file:

bottom_layer_speed_ratio = 0.3
bridge_speed = 60
duplicate_distance = 6
duplicate_x = 1
duplicate_y = 1
end_gcode = ;M104 S0 ; turn off temperature\nG28 X0 Y0 ; home X axis\nM84 ; disable motors
extrusion_axis = E
extrusion_multiplier = 1
extrusion_width_ratio = 1.5
filament_diameter = 1.65
fill_angle = 0
fill_density = 0.4
fill_pattern = rectilinear
first_layer_height_ratio = 1
g0 = 0
gcode_arcs = 0
infill_every_layers = 1
infill_speed = 60
layer_height = 0.35
nozzle_diameter = 0.45
perimeter_speed = 30
perimeters = 2
print_center = 85,100
retract_before_travel = 2
retract_length = 1
retract_lift = 0
retract_restart_extra = .5
retract_speed = 40
rotate = 0
scale = 1
skirt_distance = 8
skirt_height = 1
skirts = 1
solid_fill_pattern = rectilinear
solid_infill_speed = 60
solid_layers = 2
start_gcode = G28 ; home all axes
temperature = 220
travel_speed = 130
use_relative_e_distances = 0
z_offset = 0

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Don't force it, it will break. Stop. Think.

If the tip is ploughing through the plastic on solid layers then the flow rate is too high. It can also do it on the bottom few layers if the nozzle height for the first layer is too low.

Since you are feeding the correct length, perhaps the diameter is bigger than 1.65mm you have set in Slic3r. Other than that I have never used Slic3r so I don't know if its calculations are correct. It is is suspicious that the nozzle_diameter appears in the settings, as it shouldn't appear in the flow calculations. I can't think why it needs to know it.

I don't generally clean the tip. It only gets a thin coating of burnt on plastic when the flow rate is correct. Before it has burnt on excess plastic can be removed with by wiping with a rag while the nozzle is hot but it easy to burn your fingers.

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[www.hydraraptor.blogspot.com]