1 Topic by Claghorn

  • Claghorn
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Topic: Is this just impossible to do?

I've printed holes horizontally before with slic3r arranging to do a little overhang as it moves up the layers until it can join them at the top.

Now, however, I'm trying to print a hole near the top of a fairly tall part, and every time it tries to bridge the last gap the nozzle knocks against the slightly upraised opposite edge of the hole and because the part is tall, has enough leverage to knock it out of place.

Is it just too much to expect that this would work, or are there obscure magicks I can do in the slicer to improve the odds?

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2 Reply by pirvan

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Re: Is this just impossible to do?

I used to have similar problems with the print head knocking down or otherwise hitting slightly curled up edges , so a while ago, I decided to try the Z Lift function, and I haven't looked back since.

http://www.soliforum.com/misc.php?action=pun_attachment&item=3834

Try it, you might like it. smile

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To print or, 3D print, that is the question...
SD3 printer w/too many mods,  Printrbot Simple Maker Ed.,  FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.

3 Reply by Claghorn (edited by Claghorn 2013-11-02 04:43:56)

  • Claghorn
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Re: Is this just impossible to do?

Yea, I tried that, but the problem is this happens at the time has decided the overhangs are close enough that it can run filament all the way across, so it has no reason to lift, it thinks it is going to make a straight run all the way across the top of the part. (Which is probably why it blowed up at the exact same point in the exact same layer on two separate tries.)

What I finally did was just print the part solid, then drill the dadgum hole (which makes me wish there was a way to tell the slicer about subsets of the part I want to have solid infill).

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4 Reply by muddtt

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Re: Is this just impossible to do?

You can try to use cooling to slow it down. Sometimes with really small parts that curl when overhanging I use an xacto knife to push down the curling part. It also helps to cool it and harden it so its flat. also use the the knife to help bridge the part. Not a great solution, but it works.

5 Reply by Claghorn

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Re: Is this just impossible to do?

I did wonder if this was evidence that fitting a cooling fan would be a good idea. Drilling the hole was probably easier though :-).

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6 Reply by rickq

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Re: Is this just impossible to do?

Claghorn wrote:

(which makes me wish there was a way to tell the slicer about subsets of the part I want to have solid infill).

We have used a smaller than needed hole (that prints successfully) and used a higher perimeter value in the slicer.  That way you have a pilot hole and enough solid wall to drill through to dimension and still have a strong part.  I do this even when we don't have problems just to have a better fit for fasteners and such.

Slowing down can help as well.

7 Reply by chuddly

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Re: Is this just impossible to do?

yeah i was going to say that drilling a solid printed part give your no wall or support around that screw hole.  I agree with the fan adding and i to have pressed the curling part down with things and its cools it and flattens it.  But as stated that is not the best solution.

8 Reply by Briggs

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Re: Is this just impossible to do?

I would throw a side ways feature into the design to get the extruder to slowdown at that one spot. These and other tricks found on this forum have made it possible for almost any part I need to be printed.

9 Reply by Claghorn

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Re: Is this just impossible to do?

These all sound like good ideas. Thanks for the info. Some other flaws I've seen in other prints make me think the next biggest bang for my buck will be to add a cooling fan. Just have to figure out how I want to mount it and get headers added to my printrboard to plug it in.

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10 Reply by rickq

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Re: Is this just impossible to do?

Claghorn wrote:

... add a cooling fan.

Always to sides to a coin.  Cooling the ABS too quickly during the print weakens your part.  You will need to raise the extruder temp some.  And you may have more issues with shrink induced warping (the whole part is being cooled from the top by a rather broad convection).  You will have to get used to these things.

Best is to add gcode to start and stop the fan during layers that cause you grief.  But that takes more skill and is tedious.

If the part I am making is going to be under load, or I need it to last a long time, I don't use a fan and do 2nd ops where needed.

Also, for big sideways holes, I make a paper tube the size of the hole and slide it in while there is still a gap in the "roof."  The extruder runs right over the paper when it has to, but the paper supports the thin edges as the "roof" completes.  This also works really well for sideways square holes.