Support problem

[user_3441192770]

I have been experiencing an issue when I print with supports (Tree or Default). I’m not sure what I’m doing wrong.

When I remove the support the bottom layer (layer against the support) of the model looks terrible, almost unfinished.

The pictures below show the model on the plate using standard supports and printing the supports with the default settings. The filament is BBL Basic PLA Grey. I am using the BBL Support for PLA that came with the printer for the interface layer.

You can see the bottom of the model looks terrible.

Am I doing something wrong, and is there a way to improve the print quality on the layer above the supports?

[GenericUser]

That amount of overhang is going to be a drama, you can use PETG as a support interface and zero the z gap but it’ll still have some degree of linework as its not a solid plate the PLA is laying down onto.

I’d “remove” the block and make a small negative space, print the block separate and assemble afterwards.

[MalcTheOracle]

You are hoping for a lot there.

If you think about the job supports have to do, namely; provide a means by which areas that cannot support themselves can be anchored off to build upwards, whilst making sure the support material barely touches the actual model so one doesn’t bond with the other and is detachable.

Model quality is achieved by have each subsequent layer bond with the previous one.

You have asked for a very large area of the base to be supported, well over 80%, none of which can adhere to the actual model it supports or it will bond to it.

You could try something like PETG, but, you’re still asking a hell of a lot from that as well.

You could try dissolvable support material, you place the whole model in water and the support material dissolves.

Again though, you’re asking a lot.

If this is your design, redesign the bottom block, which at a guess marries to something else, reconsider how those two parts meet that has the top part be the socket and the bottom part the plug. Currently, your model (top part) appears to be the plug.

[DruiD]

@MalcTheOracle

If this is your design, redesign the bottom block, which at a guess marries to something else, reconsider how those two parts meet that has the top part be the socket and the bottom part the plug. Currently, your model (top part) appears to be the plug.

This is probabily the only think I ccan think of to to avoid that nearly 80% support on the base.
The supports on the front circle “port hole” may also beneffit more from PETG etc. bu that Bambu PLA support material your using is supposed to be good.

Can you share a screenshot off the support area in the slicer?
-How close is it ?
-How thick layers?
-Interface layers vs Base? etc etc
The WHOLE support section , in case we can try and tweak something … but as many have said - thats a challenging design with any support settings.

[user_3441192770]

Malc, thank you for the response, I appreciate your thoughts!

It is not my model, it is one I purchased from Gambody. I’ve only had my X1C about three weeks and am in the “drink from the firehose” learning period. I’ve watched countless videos and read the BBL Wiki but now it’s time to actually learn by doing. So far, my prints have been “easy” and I’ve had a lot of success. Now that I’m graduating to more complicated models my learning experience continues!

The idea of removing the plug so the base of the model sits flat on the plate is great, I hadn’t thought of that so I appreciate the idea.

[user_3441192770]

Druid, thanks for responding!

These are the settings

This is what the 1st layer on top of the support layer looks like in the slicer

[MalcTheOracle]

For a test, try the following.

Right-click your model and add a negative part - cube.

Select the cube and using the top toolbar, resize it and move it around your model so it covers everything above a couple of layers of the flat base (ignore the plug for the moment).

Now, select the assembly (this is the model with its negative part which should now be grouped in the objects list on the left panel). Using the moving tool from the top toolbar, move the assembly down until the plug is below the build plate, leaving just those couple of layers exposed that aren’t covered by the negative part.

Turn off support and slice the model and check that the real base of the model touches the plate and only a couple of layers will print. Move the negative part and the model up or down until that’s achieved.

Now print the model.

Ideally, you’ll see just a couple of layers printed. Wait until the plate is at or around 20°c and carefully remove it from the plate. Any warmer and major distortion will occur as it’s a large flat thin surface.

You should now find a perfectly flat base as you expected as no support material was trying its best not to truly touch the underside.

If this test works, you could consider printer a plug-less model and use glue rather than the plug to keep things together. A product called Gloop is great for large areas of contact.

[MalcTheOracle]

That’s a representative image not one or reality.

Currently, slicers can’t illustrate the real world effects support will have on contact points as there are far to many variables to consider.

Flat surfaces are achieved by the position of the hot end to the print surface which if flat itself will create a flat surface, if the surface isn’t flat, like support material (as it isn’t solid and is designed not to be adhered to, it can’t generate a flat surface.

The PETG as a support surface option could work, although this doesn’t guarantee a flat surface, it makes it easier to detach as PLA & PETG can’t bond together.

[user_3441192770]

Malc, thank you for taking the time to provide a great response. I will try this today.

[DruiD]

@MalcTheOracle

Now, select the assembly (this is the model with its negative part which should now be grouped in the objects list on the left panel). Using the moving tool from the top toolbar, move the assembly down until the plug is below the build plate, leaving just those couple of layers exposed that aren’t covered by the negative part.

Just trying to wrap my head around doing this and why - Its great advice and teaching the slicer, I am just following along to try and work out applying it here…

Pretending this model needs to be printed this way, and the right hand “leg” as it where was the “plug” in the OP’s model.

Adding the negative resized negative cube, a few layers above the “true” base (horzonital bit)

so - with the negative part correctly applied and lowered below plate

as sliced\printed - with the negative applied you get the result as you explained, no supports and should be a flat bottom.

[GenericUser]

Two alternative methods I’ve used.

1. Easy way.

*Split body. Cut somewhere above the block. Both halves can now be re-orientated so they’re flat on the plate. Print, glue three parts together (more gluing but can be effective in some cases).

2. More involved but easy once you’ve mastered it.

Split body at the block so the block is a part.

*Clone the block, move one aside to print.
*Right-click and Assemble the sacrificial block and the main part.
*Manoeuvre the block to the depth you want it to cut.
*Mesh boolean icon > Difference > Select Part you want to keep first, Select the block to cut. Tick Delete input. Make the cut with Difference.

Print the block place on the side, and the top part with the negative space. Glue

[MalcTheOracle]

I wrote the instructions with the aim of providing a solution to the problem with design they were trying to print that had a significant amount of support material that gave a less than satisfactory finish.

The problem

The problem as I saw it was this; the model appears to be the upper portion of something that marries to a lower portion by means of a plug and socket.

This was as much as I could ascertain from the images provided.

The portion in the supplied photos was the upper portion which appeared to have a ‘plug’ which would fit into the lower (unseen) portion with a matching socket.

The plug being located on the bottom of a model means that printing it is rather difficult to say the least. It is common to have upper portions with the socket and lower portions the plug. This means 3D printers have significantly less overhangs to print and significantly less support material, resulting in much better and stronger designs. In fact, if the socket was on the upper portion, no support would be required as the distance for overhangs is well within printing limits.

As the model wasn’t designed by the OP, it was unlucky the OP would be in a position to make structural changes to the model.

A workaround

By ‘removing’ the plug, the top and bottom parts would fit flush together, the top portion wouldn’t have all the support and quality issues exhibited in the photos. However, this would then mean the upper and lower portions would need to be affixed together in a different way. I suggested glue or the Gloop product.

How to

By moving the model below the print surface, the model begins printing where it first meets a layer above the surface. This technique can be used to ‘remove’ the plug without having to edit the model geometry.

The test

This was only suggested so the OP could see the difference in quality of the bottom surface of the model when the base was flat.

This test doesn’t form part of the ‘solution’.

Notes

I quoted a lot of things in there to emphasise this is a workaround not a perfect solution. I’m not suggesting this is ideal. Ideal would be editing the geometry, but, that seems like a big ask if the OP didn’t originally create it isn’t comfortable using CAD software or even owns any.

The OP only posted one portion of the model as that was the obvious focus of the question “why does this look so bad”. The answer to that of course was provided before I mentioned this ‘workarounds (more quotes).

[MalcTheOracle]

If this was all one model, rather than the parts it appears to be in, the other solution would be using the built in slicing method and using a dovetail joint option for the cut.

This would mean the model could be connected together with a common woodworking joint and may not require any glue.

[DruiD]

@MalcTheOracle

uoted a lot of things in there to emphasise this is a workaround not a perfect solution

Really appreciate your assistance to him (and explaining to me).
Yes I understood what your attempting to explain, I guess, with pictures I was asking if I had followd along - I see now that “yes, I understood what your trying to do” and I wasnt confused. End result\idea (after the test) - smack to ‘clean’ surfaces together without a redesign of the source model to remove the plug etc. I learnt something to, unique way of using negatives - so thank you.

[DruiD]

@user_3441192770

Druid, thanks for responding!

I think more info helps as well, like does this part in fact, as we suspect, meet a mating bottom part with a cut out for the block to lock in and secure into the bottom piece? If so, and you dont own the model, then yes I think as per others suggestions your kind of stuck to slicing off the block above - and in the mating piece, filling that void with this block or adding some cube to fill the space and glue etc.

Or some of the other suggesiions about slicer dovetail etc, but I think more info, pic of the opposing part or how its all meant to join would be ideal.

[MalcTheOracle]

You are very welcome.

It’s good to know my brain to fingers mechanism ends up understandable, it often goes the other way.