Help How to restrict the amount of PVA on the 3D print

[Paramesh 4]

Hi All,

 

below is the pic of the cura where I am setting up a new part to be printed. when sliced we see that thee is lot of support on vertical walls through PVA material. I just want to limit the support upon to base only, that is 10-15% from bottom, and the rest of the walls could be built without the PVA support.

 

could someone please guide me how to do this, restrict the PVA support to bottom. PVA support not required on walls

 

 

 

[GregValiant 1,411]

If you are confident in the bridging capability then you could use a support blocker on the wide structure in the middle.  Just scale it and move it so it covers that overhang the wide support is attempting to hold up.  You might try adjusting the "Support Overhang Angle" to 55°.  That's about as far as you can go.   Over 63° will air print.

 

Unfortunately, the structures in the corners are holding up the tips of those clip looking features.  They would print in air and so they need support.  You could build a custom support into the model - something easily removeable that would start below the clips and come away from the model at a 45° angle.

 

You might also play with the settings for the support structure itself.  A grid at [0,90] line direction, support density at 7° to 10°, those kind of things.  I use "Connect Support Lines" to keep down the number of retractions but it does add more material to the support structure.

 

Photos are hard to work from though.  If you were to post the STL file somebody will take a look.  If it's proprietary that's OK, just try the suggestions above.  

[Paramesh 4]

it would be really great if someone works on the STL file and guide to me the best set-up in the cura for a perfect print and restricted PVA supports to bottom on the print only.

please find attached STL file

DXS 310F.STL

[GregValiant 1,411]

"...for a perfect print..."   Sorry.  You got the wrong guy for that one.

I see two problems with the part as designed.

#1.  The tips of the clips would air print and so they need support.  It isn't about the corners or walls of the box.  Tall thin supports are subject to failure.  There is always a certain amount of drag as the print head moves across (even with zHop turned on) and those supports are prime candidates for a failure do to side loading caused by the normal nozzle movement.  At that point the clips would fail as the tips would be printing in the air.

#2.  The tips of the clips are printed with the layers going the direction of minimum strength.  Not good.

If that were mine I would remove the clips and print them separately laying on their sides.  That would introduce maximum strength to the tips and eliminate the need for the tall skinny supports.

 

The way I locate parts for assembly is to add matching 2.2mm holes in each part.  Then I glue pieces of filament into one part to act as locating pins.

With matching 2.2mmm holes in the mount surface of the clips, and in the matching surface of the corners of the box, the clips would be glued on in their exact position.  You didn't mention, but if the print material is PLA or PETG then cyanoacrylate super-glue works very well.

 

I don't know if you have freedom to make or suggest changes in the design but I have learned that allowances for the FDM printing process must be made in the design stage.  You are going to have a lot of time into that print.  I'm not sure what scale it was designed at as it came into Cura extremely large.  I scaled it down to 25.4% and I still had to increase my build plate size to 300mm in the X.

 

Maybe someone else here will take a look and advise better.

 

The black area is a designed into the part, easily removed, support for the tip of the clip.  It would eliminate the need for supports coming all the way up from the build plate.  In the yellow area you can see a support blocker but without support that area requires bridging across the gap.  That can be done with certain materials, others not so much.

 

[Paramesh 4]

the material is PLA BLUE, I scale it down to 10%

I totally understand now why CURA is suggesting the PVA supports. let me see how these corner clips and handles could be done

Thanks for your great input @GregValiant

[GregValiant 1,411]

This idea would require features so the two pieces would positive locate to each other and would be bonded.  A mortice or lap joint would be best I think.  There are two support blockers with one configured as a cutting mesh and located where the floor would start.  The side hole may need some attention but I don't think it's a show-stopper.  This is at 10% scaling on an Ender 3 Pro 230x230 plate.  Print time when down to 6:05.

757329581_DXS310F.3mf

Edited September 2, 2021 by GregValiant

[Paramesh 4]

this is a great idea and thank you so much for sharing updated STL file. a lot helpful for me to print. I will try this way and let you know where iam on this

 

Thanks