Tilt housing is printing with holes


#1

I have been trying to correct the holes in this object for many days, but I find it very difficult. The prints are failing in a few places.

Can someone please help me to fix this model of a robotic elbow?

Also, if anyone has any advice about how to chop this up / revise the design a bit for easier printing, any help would be appreciated. The components are hollow to allow wires to run through. I have an Ultimaker2 3D printer.

pan tilt 2015-12-06.skp (1.9 MB)


#2

I played with this for quite a while, and it’s going to take so much work I’ll tell you what I’m doing!

For something to be printable it needs to apparently be a volume. One thing that would stop it from being that would be disconnected geometry. For example, that black smudge in the lower left of your screenshot, at the origin, is Steve. Your model doesn’t need Steve, you can delete him.

There are a lot of floating bits of geometry, those can’t be helping.

There are a lot of lines in the model that don’t affect the shape. I’m not sure if those matter.

Several faces were reversed. Switch the Face Style to monochrome, and look everywhere for darker surfaces.

If you look in the Outliner window, and click on each group, look at Entity Info to see if it’s a volume. If it’s not, there are things inside that group to be fixed.


#3

Thanks so much for taking the time. I could try redrawing it for the fiftieth time from scratch, but I will always face the same problem - I cannot accurately crop shapes in Sketchup. I have been putting a rectangle through things and trying to highlight the half I want to delete, but there are always hundreds or thousands of micro edges that are impossible to highlight. The eraser tool is an almost useless tool, but that’s the only way I can delete crummy edges, aside from the even more laborious method of clicking each line with the mouse and pressing delete. This is nearly impossible most of the time, as the lines disappear if I try to zoom in to see them. These error lines often require a zoom level of 100x + before they are even visible. The solid inspector tool nearly always autocorrects incorrectly, so this makes that tool a hindrance as well. It may be that this shape is simply beyond the capabilities of sketchup. Sketchup does not deal with curves well at all. I’ve spent over 300 hours on this one image, mostly restarting from scratch. If there was a way to simply slice parts off shapes accurately, and to place one curve over another without sketchup producing thousands of error lines due to its polygonal circles being incompatible almost 100% of the time, then I think I could draw components at least a hundred times faster. Most of my time is spent trying to delete tiny error lines in sketchup and its extremely frustrating. I understand that sketchup pro might allow slicing properly, but if I paid for a drawing program, I would want it to understand what a circle was, so I would try a different program. Unfortunately, its taken me a long time to figure out sketchup so far (so hopefully there’s a simple sketchup trick that will make all my problems go away).


#4

Elbow should be made in two parts and place the pin in after making the parts . .Like a box I made lid had a step in it and so did the bottom so they fit together Top had a downward step outside and bottom had the reverse . .


#5

Hi Paul (Zxen),

I don’t entirely disagree with what you say. And the real truth here may very well be that SketchUp isn’t the best program for you… Just in term of it’s methodology with how you have to construct your model. And Yes it is weak on curves, but then again it wasn’t designed to specialize in them so this isn’t exactly a complete shortcoming.

I’m not sure what user level you’re coming from… but I think you’ll be better served here if you break down this project into its individual components – and deal with each one independently. That way you can get peoples feedback in terms of how best to approach each part. And of course it’s good that we see what the end goal is here.

But I just think that you’re not going to get all of good advice can than come from modeling each of these parts if we deal with them as a complete whole.

Each shape has its own set of tips which help avoid the hassles of modeling it.

I suspect if look at how others approach each piece… you’ll end up filling in the gaps between a trouble free construction, and the approach you’re currently taking.

So Far this isn’t a model that’s outside of SketchUp’s capabilities. But it does have enough tricky parts where it’s a pain to deal with, if you’re coming from the typical self–taught approach which is so common for most folks.


#6

Firstly: To start the model is like 100m tall while the print vol. may 12x12x12. I am not going to try and read the manual.
Second: Form follows function so my question is the gimbal configuration correct. I assume you are trying to make a real gimbal and not toy? The pic leads me to think you have a elevation over azimuth design which to actually operate over the total hemisphere the motor drive rate would go to infinity as it try’s to pass over head. That is the reason in pics you see three or more axis gimbals or x, y mount.
Cable management is often a problem so you will have to decide what to use there. You can wind up on spool or buy actual cable wrap;
2. Thirdly: how do you know the gimbal position. If not very accurate requirements stepper motors can possibly be used and it can be controlled open loop. They can be geared down to get in the decimal degree output step size.
Just some thoughts for you, gimbal can be very complex designs.
this my or not help http://3dprintingindustry.com/3d-printing-basics-free-beginners-guide/processes/
You attached skp is what I would call assembly drawing although I did not see any bearings, some gears which I assume are just place holders.
IMHO think your design approach should consist of two separate design, azimuth and elevation. As part of each there should be components for gears, some design for position read outs; bearings etc. You then 3d print the housing and then assemble from there
You have two groups showing as solid, rest are not. The mounting base and next part up. As test I would try to scale those to proper dimensions and see how they print considering info in the link I gave above. This will give info to model rest of design. Strongly suggest you use groups vs components and name them some thing meaningful. You model will get complex and will make it easier to work with. Consider using layers to make items you are working on easier to see


#7

You should try to create simple and clean parts of your model and combine them to more complex shapes. With this, you will get cleaner geometry and solids (which are necessary for 3D printing). For example:

pan tilt 2015-12-06_cotty.skp (2.3 MB)


#8

Very good advice. When creating anything, it’s always good practice to spend some time thinking about a good strategy and to try to break up the ‘job’ into smaller, more easy to make, elements. Make copies of the individual steps (just like in the picture) so if you need to refine anything later, it’s a more easy task


#9

Thank you for all your suggestions. Cotty, you always help me so much by redrawing my shapes which is always super helpful, but of course I don’t know what I’m going to draw BEFORE I draw things - its all about tape measures and real world adjustments as they become apparent or changing my mind 20 times a minute about how screws will hold things together, etc. My experience with Sketchup is just over one month I think. I have basically taught myself, but as a coder, I know that if software is not intuitive, then the coder is to blame. People reiterate that sketchup does not fail to create circles properly because it ‘wasn’t designed for that’, but you can bet that the coders will EVENTUALLY make accurate circles work in this software because so many people are now using sketchup for 3d printing, and there are almost zero designs that contain no curves. Polygons are 1900s mentality. For a clear idea of this elbow, I guess I should attach my failed prints. Each part takes around 20 hours to print, so its essential that I have a program that doesn’t make things even more time consuming than necessary. I will download Rhino and play with it because it seems better suited to 3D print design. But I am still hoping that I will become better at Sketchup so that I can continue with my existing work so far. I will check out everyone’s advice here in more detail now, I just thought it would help to see the print in context, and the reality of the situation:


#10

FYI: exported the next to bottom group as STL to NetFab and it reports as solid so you should be able to print it. Su reporting as solid is necessary but not sufficient for printing given the printer and materials used.
Make sure you have dimensions set correctly.


#11

Two of the groups are good volumes, and no doubt show as being solids. It’s the other 5 groups that need fixing.


#12

I don’t think the discussion “polygon vs. true curves” is the right one in this context. The main problem you will get here are those overhangs which are not well-suited for a FDM home printer. It would be a good idea to take into account the printing technology here.
Even if you have true curves to model those parts, in the end the slicing program has to generate GCODE out of them, which are in fact coordinates for polygons too…


#13

Alternate approach to consider
Converted groups to components, the green part is the drive housing could not tell if the ultra torque has both az and ev drives. Concept is to print parts separately and then assemble and that gives you option to redesign areas as required. For example the print problem you show is with the spherical top of the drive housing. Obvious approach would be to mod design in that area. I would get rid of spherical surfaces every where unless those are driven by some design requirement.
Approach possibility allow FDM by inclusion of supports which are removed before assy. MeshMixer has option to analyze that case.
Just some thoughts


#14

I’m going to redraw the tilt housing without errors. I was shown a few plugin tricks by my friend today, which should be super helpful. Also, I’ve allocated the shortcut ‘H’ to toggle ‘Hidden Geometry’. I never knew how important this function was. I also now have ‘curvizard’ and ‘amc soften edges’ plugins. Also, a huge bonus is knowing that I can hold ‘alt’ + the eraser tool to soften edges instead of ripping holes in things without the alt key.


#15

I have started drawing the tilt segment again.

I managed to slice a sphere in half, then to give it volume, I used the ‘follow push pull tool’ by fredo6. This causes the underside of the dome to protrude as an angle. I don’t know how to slice it off to make it flat. I could try to press the cylinder into the dome (and cover the sharp edge) but I’m afraid that will create inaccuracies later. It also results in solid inspector errors.

dome angle.skp (1.0 MB)


#16

You are on the way to new problems already:

You should start with a simple follow-me for this task…


#17

Hey, that’s a good idea! Thanks!


#18

Hours of work and its still broken :frowning:

broken tilt segment.skp (1.0 MB)


#19

It’s hard to know exactly what tolerances you are aiming for but with some cleanup you can get there.

Shep


#20

Sorry, what do you mean by tolerances? I’m printing robotic components.