Painfull problem @ first layer

Not specifc to slic3r since sfact is doing the same thing.

it's hard to explain, i'll do my best.

in short, "The first layer is grinding awfully my filament!!!!!". Why I don't know!!!!
but all other layers, are just fine ??? this is driving me crazy. and since the filament is ginded, all the other layers do not print at all... So...

here is my painful workaround to come over that problem

1- I Print the first layer.
2- press "pause" then Home after first layer is done.
3- unjame manualy the filament, notice that the filament has been grinded ALOT!
4- press resume, and then everything become wonderfully fine for the rest of the print.... no grind at all!!!!!! at full speed!!!


Why only the first layer??? Is this possible that i print the first layer too close of the surface(glass) and then there is a pressure building up along the nozzle up to the barrel, and then this pressure getting too high preventing the filament from going down, creating the grind.....????

And yes! i'm using a wade's extruder
I can extrude up to 70 mm/s without any problem. my print speed is around 40mm/s, my first layer speed is 30% of that speed.

Show us a picture of your first layer after it's extruded.
It's probably a combination of the fist layer being too close the bed and probably the screws holding the idler against the filament aren't tight enough.

The height of the first layer should be the same as the normal layer height, If it is less then it will create more nozzle pressure, however it is normal to do the first layer more slowly so this the usual outcome of extruder problems is for the first layer to be fine and the second layer to fail.

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[www.hydraraptor.blogspot.com]

Yes I used to print very neer of the glass because otherwise, the abs does not stick to the glass i use a heat bed at 100C but as soon i use the Paper
height trick, i'm too high. so actualy i'm trying the "ABS juice method" to print the first layer farther from the bed.

as soon as i have news , i'll post my observation.

Edited 1 time(s). Last edit at 07/23/2012 12:33PM by Carignan.

Abs Juice (10ml acetone+10mm ABS filament) gives astonishing results. I'm printing the fist layer way faster, the first layer is is at good distance from the bed, so no more pressure build up in the barrel that prevent the extrusion. so ... no more filament grinding... So far so good

kapton tape sicks very well to ABS to the point I have trouble getting the part of the bead afterwards some times. I use a 3x5 index card for my spacing. An index card is just shy of 0.2mm for my first layer. I've also had an extruder jam once, a few more turns on the idler fixed that issue.

I will try Sugar Water @ 8g per 100ml applied with a brush @ 100C on the glass, someone on the forum seems to have great result with that bond, i'll let you know if that work

So in short, my problem was not a Slic3r problem but:

1) a first layer that do not stick on the my glass
2) to stick,at the glass I needed to set the nozzle very near the bed ( soo near in fact, that it clog the nozzle hole, bottle necking the extrusion, creating a great pressure on the filament, that was causing a grinded filament, and a jammed extruder )

The Solution:
1)Set the nozzle height a little higher
2) use ABS juice so the bed get sticky


ABS Juice : Work great to make the glass sticky
Sugar Water: a more healthy solution without fume that seems to work great
Sandblasted Glass : according to this video http://www.youtube.com/watch?v=n_bgJ_lZNEc this is supposed to do the job without applying any coating

I only have a small current power supply, so I modified my heating bed to have a higher resistor. So I only get 65°C.

I'm using kapton tape, and I clean it a little bit with acetone before each print, and I don't have any warping problems. As RustyPaint said, @100°C, it can be hard to remove the parts from the tape! But 65°C is fine.

Carignan, are you using kapton, or do you print on the glass, with the abs juice?

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Frédéric

For now, since i'm printing with ABS, I'm using ABS juice applied on glass at 90°C. Removal is easy, it peel right of the glass passed 60C and lower.

Hi folks, I told you that I planed to test the sugar water Technic.... well I did, .... and it works pretty well, not as well as the ABS juice because I had to lower the speed of the First layer quiet a bit ( 30% of the normal speed ).

4 sugar cubes per 100 ml applied at 100°C, let it dry, applied 2 to 3 coats.

But I still prefer ABS juice, ,ore sticky = more first layer speed

I tried the ABS juice, yesterday: epic fail

How do you put the juice on the glass? How much is needed?

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Frédéric

Set your extruder motor current low enough that the motor starts skipping steps before it chews the filament. Even with everything working normally, every now and then the extruder nozzle will end up trying to extrude somewhere where there is already plastic and the backpressure causes the bolt to chew the filament if the motor current is too high. It's much better to get some skipped steps instead.

fma Wrote:
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> I tried the ABS juice, yesterday: epic fail
>
> How do you put the juice on the glass? How much is
> needed?


I apply the juice with a paint brush then let it dry for a minute or two, and it look like this

ttsalo Wrote:
-------------------------------------------------------
> Set your extruder motor current low enough that
> the motor starts skipping steps before it chews
> the filament. Even with everything working
> normally, every now and then the extruder nozzle
> will end up trying to extrude somewhere where
> there is already plastic and the backpressure
> causes the bolt to chew the filament if the motor
> current is too high. It's much better to get some
> skipped steps instead.

That's a good idea,but is this to the detriment of the high extruding speed?

And since this thread had nothing to do with slic3r are we not supposed to move this discussion elsewhere?

Edited 1 time(s). Last edit at 07/25/2012 12:56PM by Carignan.

Thanks, Carignan!

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Frédéric