creating a nice bottom surface with a 90degr overhang

[bschulte 1]

Hi guys,

i've got a question: I've got this model with a 90degr. overhang which I print with support. It comes out great except for the bottom layers that are resting on the support layers. I see some possibilities in cura with support z distance but so far no better results.

Anyone a suggestion?

[yellowshark 147]

I recently printed something seemingling similar. with similar problem. I turned it upside down and it came out great

[bschulte 1]

really? with support? I thought about it and thought , nah, that will never be as good. I'll def. give it a try now.

thanks

[Marrut 6]

maybe you can create an extra layer below the surface that has to be good. Most of the time i'm using an offset 0.1 à 0.2 mm, extrude it with +- 1mm and there under comes the support.

normally you can peel it easy from the printed part.

sorry for my bad english, i hope you understand what i mean.

[bschulte 1]

Hi Marrut,

thanks and your english is fine although I am not sure I get it :-)

How do you create that extra layer? With that offset? In Cura? I would like to experiment with these settings. Can you make it a little more specific for me?

thanks

[Marrut 6]

Hi Marrut,

thanks and your english is fine although I am not sure I get it :-)

How do you create that extra layer? With that offset? In Cura? I would like to experiment with these settings. Can you make it a little more specific for me?

thanks

 

I do that in the drawing application. There's no possibility to do that in cura, but another question, witch version of cura do you use? If you have the latest version, than you have the possibility ti print "a roof" o' your support, that's almost the same as making an extra layer.

[Marrut 6]

Maybe you can also take a look here

https://ultimaker.com/en/community/39185-trying-to-get-better-underside-surfaces

Edited March 20, 2017 by Guest

[tomnagel 79]

@bschulte

turn the part upside down, and use PVA as support. It will create a very good surface.

If you lift the part 0.6mm from the buildplate, you will prevent a shiny circle in the middle (bc it rests on the glass).

Be sure to use Cura 2.4 (not the beta), as this has the best PVA/PLA profiles.

Edited March 20, 2017 by Guest

[SandervG 1,201]

@bschulte, I would also recommend to print it with PVA (upside down or like this). With a support roof (solid top support layer for good surface quality of the build) you should get a good quality.

Is there a particular reason why you did not want or think of printing it with PVA?

PVA adheses well with PLA or Nylon as build materials.

[bschulte 1]

Hi Sander,

I guess it's because I have to print 50 pieces of them and it significantly increases the price of the batch.

you talk about solid top support layer, which setting is that because i can't find it? even though I guess it won't work as well with pla support?

[bschulte 1]

Sorry guys, my notifications where set at weekly so I just now see I missed some responses. I will check the link you send Marrut. thanks!

in the meantime I am wondering: Is it possible in cura to split support in two parts so that only top layers are printed in PVA and bottomlayers in PLA?

[SandervG 1,201]

Unfortunately with PLA supports this would only work counterproductive, so I would not recommend it. The setting I meant is called support interface > support roof.

If you have modeled this design yourself, I could also recommend to make an attempt at modeling your supports yourself too.

The automatic generated supports in Cura are meant as a one size fits all, which in an ideal situation it can be good, but it is never perfect.

Perhaps you can find some good tips in this thread

There are some other interesting threads and replies

Another question you can ask yourself, what would raise the price the most.

The one or two reels of PVA, or the testing and researching various alternative solutions for PLA support (although you could say that this research is an investment for future projects too).

Good luck!

[yellowshark 147]

really? with support? I thought about it and thought , nah, that will never be as good. I'll def. give it a try now.

thanks

Yup no support, of course it will depend but your curve looks very similar to my piece. Settings I used - for my printer - were

.100 layers

30mm/s print speed

205 extruder temp.

Flow 100%

bed temp 65 continuous

1st layer speed 15mm/s

walls 1.2

26% infill

Infill before walls

Skirt

Top layers 8 ) These two settings may need reversing; that is what my notes say but as the piece

Bottom layers 3 ) was turned upside down I may have reversed these settings and not updated the notes

Regular fan speed,100%, at layer 5

[geert_2 320]

If your model and function allow it (we can't see the inside here), another option might be to cut it in parts, and glue them back together again after printing. Or design some holes for hex nuts and screws, and mount it with screws. This might go a lot faster than other post processing, and might be good enough.

[bschulte 1]

Thanks for all the tips guys! I'll have to start monday with printing for client and I've decided to go for one more test run with PVA and see how that turnes out. I havent tried iet yet on the UM3 so great opportunity to find out.

I'll keep you posted next week for what my final approach was :-)

[tomnagel 79]

Some considerations about the orientation on the build plate.

- the way you have it oriented in the picture in your opening post will need a lot of PVA. But it will probably have very good results. the clickfingers on the bottom will be printed accurately

- if you rotate the part 180 degrees ("upside down"), less PVA will be needed, but the PVA to support the click fingers needs to attach to the PLA. This is not 100% reliable. An improvement has been made in Cura 2.4, by lowering acc and jerk of the interface layers, so be sure to use Cura 2.4 (not only for this reason).

- maybe the best orientation is to rotate the part 90 degrees. The 3mm horizontal expansion that is standard enabled for PVA will make sure the PVA that is connected to the buildplate (and adheres very well) is also connected to the PVA that is built in the shell, keeping it in place.

Second benefit of this orientation is that the top of the shell will be much nicer, because you don't get the height lines on this surface. It will enable you to increase the layerheight, and decrease printing time.

Edited March 24, 2017 by Guest

[SandervG 1,201]

Thanks for all the tips guys! I'll have to start monday with printing for client and I've decided to go for one more test run with PVA and see how that turnes out. I havent tried iet yet on the UM3 so great opportunity to find out.

I'll keep you posted next week for what my final approach was :-)

 

Make sure to use PLA or Nylon with PVA. Not ABS. PVA does not bond with ABS, so whatever you try to deploy won't stick.

In regard of Tom's reply, I don't know what the bottom / inside looks like, but I recently did a pretty small print (15mm) with quite some detail at 45º angle, and the details came out really good. Just an fyi. Dunno if it helps.

[yellowshark 147]

Just to note that the suggestion to rotate 180 was just that, not to use supports also.

[bschulte 1]

Well, i've decided to go for PVA but not upside down. Top surface isn't as nice as when I have the curved side on top. Since it doesn't cost a lot of extra PVA I do it like this.

Thanks guys for all the support..slowly getting the hang of my UM3... do have some other questions though but create new topic for it.

[SandervG 1,201]

Thanks guys for all the support..slowly getting the hang of my UM3... do have some other questions though but create new topic for it.

 

That is what the community is for <3