Uneven / waviness on surface of curvature geometry

[svsadatia 0]

Hello friends

i am using UM3 extended.I am using 3d printing for Investment casting pattern. 

For cost feasibility i mostly use 10% infill and below support setting

Please share me your opinion and suggest me settings in cura.

 

Issues:

• Supports are damaging part curvature surface
• I am extencively working on ABS

 

[gr5 2,170]

You have some difficult overhangs here.  Ideally you want 45 degree angled supports but I assume that is not allowed for this part.

 

Pretty ugly.  ABS is difficult to print - this would be a lot easier with PLA but I assume that is a problem with investment casting?  Also keep in mind that white is the most difficult filament regardless of the brand/manufacturer because they put something in it (chalk I think?) and there is too much of this powder and not enough plastic to make it print as nice.

 

Also with PLA you could use PVA support and get really gorgeous prints here.

 

So I strongly recommend you get some BAM (breakaway material filament) which works just fine with ABS.  It's a kind of support that you just remove with some needle nose pliers and works quite well - it breaks away from the ABS without damaging the print.

 

If you can't wait for BAM,  the first thing is you need some fan.  My UM3 prints with 100% fan power even when set to 10% and so I like around 2% fan for ABS but you could bring that up to 5% or so.  If you use too much fan you get bad layer bonding which can be fixed by enclosing the printer (I just put a 1 gallon ziplock on the front and a box on the top).  My UM2 I would set this to 30% fan.  If you play with the fan in the tune menu you want to find the % where the fan is still spinning but at maybe 1/3 to 1/10 the volume (for PLA you want 100% fan all the time).

 

The other thing I would do if you can't use PVA support is to design my own support in CAD.  I would design a wall that supports the outer edge of each overhang platform but no supports in between and then cut it off with a razor knife after the print is done.  ABS (and PLA) bridge very nicely so if you include walls on the outer edges of each level it will bridge reasonably well (not perfect) across that.  Fan amount is critical for a good bridge.  In general more fan is better for bridging but ABS will have bad layer bonding if fan is too high and can sometimes split on the outer shell of the part when it cools down.  Again, enclosing the printer gives you the best of both worlds: more fan and no layer bonding issues.

 

[svsadatia 0]

11 hours ago, gr5 said:

You have some difficult overhangs here.  Ideally you want 45 degree angled supports but I assume that is not allowed for this part.

 

Pretty ugly.  ABS is difficult to print - this would be a lot easier with PLA but I assume that is a problem with investment casting?  Also keep in mind that white is the most difficult filament regardless of the brand/manufacturer because they put something in it (chalk I think?) and there is too much of this powder and not enough plastic to make it print as nice.

 

Also with PLA you could use PVA support and get really gorgeous prints here.

 

So I strongly recommend you get some BAM (breakaway material filament) which works just fine with ABS.  It's a kind of support that you just remove with some needle nose pliers and works quite well - it breaks away from the ABS without damaging the print.

 

If you can't wait for BAM,  the first thing is you need some fan.  My UM3 prints with 100% fan power even when set to 10% and so I like around 2% fan for ABS but you could bring that up to 5% or so.  If you use too much fan you get bad layer bonding which can be fixed by enclosing the printer (I just put a 1 gallon ziplock on the front and a box on the top).  My UM2 I would set this to 30% fan.  If you play with the fan in the tune menu you want to find the % where the fan is still spinning but at maybe 1/3 to 1/10 the volume (for PLA you want 100% fan all the time).

 

The other thing I would do if you can't use PVA support is to design my own support in CAD.  I would design a wall that supports the outer edge of each overhang platform but no supports in between and then cut it off with a razor knife after the print is done.  ABS (and PLA) bridge very nicely so if you include walls on the outer edges of each level it will bridge reasonably well (not perfect) across that.  Fan amount is critical for a good bridge.  In general more fan is better for bridging but ABS will have bad layer bonding if fan is too high and can sometimes split on the outer shell of the part when it cools down.  Again, enclosing the printer gives you the best of both worlds: more fan and no layer bonding issues.

 

Thanks for reply

 

I am already using encluser to cover printer.Second thing i can go with PVA support for sure but it takes time to disolve in water.

I have already played with fan speed .

 

Can you please suggest us best suitable support settings for ABS?

Do you think if i changed White ABS with any other coloured ABS then may be i'll not face this issue?

 

 

[gr5 2,170]

I don't really use the support feature much, sorry, so don't have recommended settings.  The triangular pattern I believe you chose I think is good - some of the patterns can fall over if they are too tall (e.g. lines infill pattern).  But as far as the quality of the surface where you break off the support - I don't think the color or type of filament will help.  Using PLA won't help either.  It's going to look ugly where you break off the support.

 

However, if you use BAM you can break it off instantly - no waiting for anything to dissolve in water and the surface will look much better.

 

I just meant that for *bridging* which is when the printer lays down a string/trace of filament supported on each end - like the top of a door frame if you printed a door - that will look better with other colors.  But really I recommend BAM in this case (break away material). I think you'll be impressed with it.

 

[svsadatia 0]

2 hours ago, gr5 said:

I don't really use the support feature much, sorry, so don't have recommended settings.  The triangular pattern I believe you chose I think is good - some of the patterns can fall over if they are too tall (e.g. lines infill pattern).  But as far as the quality of the surface where you break off the support - I don't think the color or type of filament will help.  Using PLA won't help either.  It's going to look ugly where you break off the support.

 

However, if you use BAM you can break it off instantly - no waiting for anything to dissolve in water and the surface will look much better.

 

I just meant that for *bridging* which is when the printer lays down a string/trace of filament supported on each end - like the top of a door frame if you printed a door - that will look better with other colors.  But really I recommend BAM in this case (break away material). I think you'll be impressed with it.

 

I am extensively using 3d printing for investment casting patterns so can you suggest best lowest acceptable infill % ?I will definitely try BAM 

 

[gr5 2,170]

infill?  You only need it to support top surfaces.  I recommend the variable infill - saves you lots of time.  You want around 20% just before it prints the top layers (which may not be on the actual top - I'm talking about any locally upper surfaces like each layer of a cake or the entire top half of a sphere).

 

So... um...  maybe:

infill density 24%

gradual infill steps 3

gradual infill step height 1mm

 

That will do 24% infill for the top 1mm before starting solid top layers

And 12% infill 1mm below that

And 6% infill 1mm below that

and 0% infill 1mm below that.  

 

I think.  Play with it and look at it in layer view.  This will typically save 20% printing time (gradual infill) which is significant.

 

Another good time saver is to use larger nozzles.  An  AA 0.8 can print twice as thick a wall in a single pass and can do 0.4mm thick layers very easily.  Of course the layer lines will be more visible and sharp outer corners will have a 0.4mm radius on them.