1 Topic by MungoBBQ (edited by MungoBBQ 2014-04-23 20:03:36)

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Topic: Constant overhang failure

I can't seem to print anything with even the slightest overhang on my SD4.

This print was made using .100 resolution with ABS plastic, 200C extruder, 100C bed, but I've tried many different settings - both other layer heights and slower speeds.

As soon as the tiniest overhang comes, there is upward curling which leads to the nozzle bumping into the plastic on the next layer, leading to complete failure as seen in the picture. :(

As you can see, the print was going fine otherwise.

What can I do to improve this? Slower speed doesn't seem to help. Could I be over-extruding? Are my temperatures off? I'm grateful for any help.

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2 Reply by DePartedPrinter (edited by DePartedPrinter 2014-04-23 20:13:06)

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Re: Constant overhang failure

The simplest solution for this is to get a fan and aim it at the part as it prints.

If you want better results get something like this put together...http://www.thingiverse.com/thing:30828

SD2 with E3D, SD Press, Form 1+
Filastruder
NYLON (taulman): http://www.soliforum.com/topic/466/nylon/

3 Reply by IronMan

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Re: Constant overhang failure

DePartedPrinter wrote:

The simplest solution for this is to get a fan and aim it at the part as it prints.

If you want better results get something like this put together...http://www.thingiverse.com/thing:30828

+1...alternatively, you may want to try .15 resolution - infill every 2 layers.

SD2 - Stock - Enclosure - Heated Bed - Glass Plate - Auto Fire Extinguisher
Ord Bot Hadron - RAMPS 1.4 - Bulldog XL - E3D v6 - 10" x 10" PCB Heated Build w/SSR - Glass Plate
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4 Reply by MungoBBQ

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Re: Constant overhang failure

Hm, but I thought that the heat was needed for the print to stick, and the enclosure is to ensure that there is no draft to make the print wobbly? If I add a fan, won't that mess upp other things?

5 Reply by grob

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Re: Constant overhang failure

For overhangs and bridges, a fan helps to cool the plastic coming out of the nozzle faster, which is a good thing - it makes them firm up quicker, which reduces droop and dropped loops (which looks like what's happening in your pictures).

Usually the fan is a small computer fan (40mm is common) attached to the extruder, and blows air from inside the enclosure in a focussed stream near the nozzle. The fan is controlled by the board (slic3r has settings for this) to only run when it's required. The thingiverse link will help you achieve this.

In general, you want to keep the heat in the enclosure yes, so the whole part cools as slowly as possible and doesn't crack/warp/break off the bed. Putting a desk fan next to the printer blowing air from the room is likely to create more problems than anything, so I'd avoid that as your instincts suggest! smile

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6 Reply by DePartedPrinter (edited by DePartedPrinter 2014-04-25 16:20:18)

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Re: Constant overhang failure

grob wrote:

Usually the fan is a small computer fan (40mm is common) attached to the extruder, and blows air from inside the enclosure in a focussed stream near the nozzle. The fan is controlled by the board (slic3r has settings for this) to only run when it's required. The thingiverse link will help you achieve this.

^great explanation


While the fan can be controlled by the board you most certainly do not have to have it do it this way. It will work just fine running off an external power source.

SD2 with E3D, SD Press, Form 1+
Filastruder
NYLON (taulman): http://www.soliforum.com/topic/466/nylon/

7 Reply by MungoBBQ

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Re: Constant overhang failure

I've got a fan on the extruder, it came mounted with my SD4, but I'm guessing this is what not you are talking about since this fan is going non-stop from the moment I plug the printer in?

8 Reply by DePartedPrinter

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Re: Constant overhang failure

MungoBBQ wrote:

I've got a fan on the extruder, it came mounted with my SD4, but I'm guessing this is what not you are talking about since this fan is going non-stop from the moment I plug the printer in?

No

More info here.

http://www.soliforum.com/topic/204/fan-installation/

SD2 with E3D, SD Press, Form 1+
Filastruder
NYLON (taulman): http://www.soliforum.com/topic/466/nylon/

9 Reply by MungoBBQ

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Re: Constant overhang failure

Oh OK, I see now. Thanks everybody, I'll see if I am clever enough to mod it. smile

10 Reply by MungoBBQ

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Re: Constant overhang failure

Well I've got a fan now (they were hard to find here in Sweden). Does anybody have a pointer on how I should connect this to my SD4? The guides I find are for SD2 and my printer looks different.

I've printed a mount which will work, but I've got three cords (yellow, red, and black) coming out of the fan and I'm not at all sure where I can connect them on my printer?

11 Reply by MungoBBQ

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Re: Constant overhang failure

Actually, after tinkering with it for a bit, it turns out it's quite the other way around. smile

I managed to solder the cables on to the board, and the fan is now spinning when I turn it on in Repetier Host, so that's good.

However, the mount and the fan holder that I've printed simply will not fit the SD4. The round part will not go around the hotend, there's just no room. And the holes in the mount part are not lined up with anything on the extruder.

Did anybody make new parts for the SD4?

12 Reply by Photog

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Re: Constant overhang failure

MungoBBQ wrote:

Actually, after tinkering with it for a bit, it turns out it's quite the other way around. smile

I managed to solder the cables on to the board, and the fan is now spinning when I turn it on in Repetier Host, so that's good.

However, the mount and the fan holder that I've printed simply will not fit the SD4. The round part will not go around the hotend, there's just no room. And the holes in the mount part are not lined up with anything on the extruder.

Did anybody make new parts for the SD4?

Take a picture of your SD4 hotend. If it's like my newer sd3 hotend you won't find fan mounts on thingiverse that fit it, but I made some custom fan holder I can send you stl for

My SD3:  Clear plexiglass case, case heater, X axis stabilizer, Z axis stabilizer, thumb screws, filament guide, heatsinks on all motors, extruder fan, controller fan, heatsinks on motherboard, Y rod pillow block, USB and Power on/off switch, fully calibrated including trimpot tuning. Am I missing anything?

13 Reply by MungoBBQ

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Re: Constant overhang failure

Thanks, that would be most helpful.

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