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"Touching buildplate" question

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I have an alcove/indentation on one side of my project that touches the buildplate, and I want support for it.The support structure begins to be created, but the problem is that it never actually reaches the top of the alcove where the support is needed.

I know it must have something to do with the fact that the bottom of the alcove goes deeper into the side of the product than the top does. The bottom of the alcove goes in about 3/8 inch then it angles back to 1/16 inch at the top. The support structure goes up a little over half way and then stops. The top of the alcove prints really ugly and jagged.

Can someone tell me what settings I can adjust to make sure the support structure goes all the way to the top of the alcove please?

 

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I suspect the wall of your alcove, at the bottom, is leaning over more (i.e. to the horizontal) that at the top. There is a setting for the overhang angle for support in the Expert dialogue box, which I think defaults to 30 degrees and I suspect the top of your alcove is leaning over less than this which is why no support is being generated.

You are probably printing too fast, too hot and maybe without enough fan, to get good overhangs. If you post your settings we can help and as Bagel Orb says, a picture would help (a print screen from Cura would be fine). Generally speaking overhangs need slow speed, 20-25mm/s and 100% fan and speeds all the same (this does though depend on the size and geometry of the piece; if the piece is filling the entire print bed then printing everything at 20mm/s is probably undesirable) :)

 

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Ah I see now, I think. It is the 1/16th inch bridge at the top which is the problem, not the sloping surface in the alcove, yes? It is though a very short bridge and the printer really should be able to cope with that quite easily. What are your settings for print speed(s), wall thickness, layer thickness, fan, extruder temp.?

You will probably need to test some different settings to find the best result; in Cura you can sink the model in to the print bed so you only have to print say 10 layers before printing the bridge, which will save you a lot of time; Advanced tab, "Cut off object bottom". If you have the free Meshmixer software you can also cut the model so you are only printing the front portion of the model (shown in the pic) rather than the entire model; i.e. get your 22 hour print time down to < 1 hour.

Mind you if you have Meshmixer you can use that to create supports - I have no idea why Cura is not doing it.

 

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Here are my print settings:

Layer height: 0.1

Shell thickness: 0.8

Enable retraction: Yes

Bottom/Top thickness: 1.4

Fill Density: 20

Print speed: 50

Support type: Touching buildplate @ 45°

Platform adhesion: None.

All other settings are just the default settings that come with Cura.

Here is a picture of the print. Notice the bumpy and uneven top of the alcove.

alcove printed

 

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Ok, it is really difficult to be very precise here because many things affect overhang; it really is very much a case of try it and see, even including trying another filament. I think I would start with.

1. Change shell thickness to 1.6mm - this will stop any infill in that area. 1/16th inch = 1.5nn mm

2. Fans 100%

3. Change layer height to .200; I accept you may not want to use that but in terms of testing to get a good finish it is worth doing; maybe even one pushed to .300

3. Try it at 30mm/s and at 60mm/s

4. Go for a cool extruder temp; the initial layers will show you if you have gone too low, if so you can always push it up a bit via your printer controls (?). .200 at 30mm/s you can probably do at around 205 maybe 200

5. If that filament is white then change to another colour; white tends to be more problematical than other colours in my experience and I have seen others on the forum make the same comment

 

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