I would suggest taking a slightly different approach and create the “disk” as one group (or component) and one peg as a component that is then replicated as needed. This will still 3D print just fine … no need to merge them into one solid. It also makes it somewhat trivial to later edit the peg dimensions and/or locations.
Note that my sample gear probably won’t work due to the size and spacing of the pegs. This article is useful in determining the optimal peg sizes, number, and placement.
What printer are you using? The sample gear I posted is acceptable to MakerBot, Slic3r, Shapeways, and iMaterialise:
You don’t need to make everything into one “solid” in order to have it print successfully, if each separate group or component is a “solid” in its own right. However, grouping them all together into a super-group can cause problems for some slicers.
In the gear program, I create the hole in the center first, then the gear, and then delete the face in the hole. If you reverse the order, it won’t work. Similarly, to extrude a peg from the disk, you need to create the circle first at the future top of the disk, then create the disk and extrude it to the bottom of the peg circle. Then you can extrude the peg face to create a solid group of a disk and peg. To create an array of pegs, you will need to create the circles first, keep an array of faces, extrude the disk, and then loop through the array to extrude the pegs.
I created a simple plugin framework for you that has this example coded for one peg to demonstrate how it works:
This is not correct. The online print services use some software to fix wrong 3d models and make them 3d-printable.
But I prefer sending an already correct model, as you can’t never know how/if the online SW will fix the model.
Using a SW like Netfabb or Meshmixer you can see the “3d errors” in my quick-and-dirt “pegged gear”:
Talking of “3d print errors” in Sketchup plugins, I also found this kind of errors (not in gear plugin of this thread, I’m just using a gear to show the issue):
They’re reversed faces; in coloured models they’re almost invisible, but they make a 3d model not-printable.
to extrude a peg from the disk, you need to create the circle first at the future top of the disk, then create the disk and extrude it to the bottom of the peg circle. Then you can extrude the peg face to create a solid group of a disk and peg.
Please forgive me for being persistent, but I’ve 3D printed a lot of different things for the past several years and never had any problems using clusters of self-contained groups. I don’t have netFabb and I’m curious what it shows with the STL file I attached to my last post. The image you show above is what I would expect if the components were exploded before being exported as an STL file, not what I would expect from importing the STL file I attached previously.
As I said, online services do the job for you by attempting to fix wrong models (inverted surfaces, unneeded faces, even small holes).
Your STL file shows no errors in Netfabb.
In my image I have hidden cylindrical surfaces of the pegs to show the circular faces (actually holes, being the model correct) behind.
The STL file is an export of 25 separate groups … one for the disk and 24 for the pegs. So if Netfabb shows no errors, it would tend to support the option of leaving things in groups for simplicity, yes?
The problems you are highlighting are what you get if you create pegs on top of the disk without putting them in separate groups.
Yes, they do. Some of them tell you that there are one or more errors and gives you the option to fix them. Since I’ve been using separate groups or components, I’ve never encountered the offer to fix them … every slicer I’ve looked at seems to understand that they are separate, and, as long as they are each a valid “solid”, merges them seamlessly.
Here’s a variation on another use of groups … I moved the pegs through the disk. I’m curious what Netfabb says about it … gear1a.stl (112.4 KB)
[added] BTW, Slic3r seems to be the most picky about things … here’s a preview run of the actual print:
Shapeways and Sculpteo just fix them without asking.
You can’t have multiple solids “building up” a single solid to print, because they have surfaces in common, which Netfabb shows as errors and Shapeways and Sculpteto just deletes.
This is what happens to me if I just “glue” together some pieces to build a single solid to print:
If I see “something yellow” in Netfabb, I know there is “something wrong”; it could be just coincident, identical, overlapping surfaces, or it could be a design error which would prevent model from being correctly printed and functional, so I must fix all errors by myself before sending to Shapeways.
But it’s weird that your last STL does NOT show in Netfabb the parts of the cylinders which fall inside the big cylinder; I did some more tests and I get same results: intersectings solids give no errors in Netfabb. BUT as far as I know they are not printable, because the whole solid is not manifold.
I think it’s one of those errors which are not automatically shown upon uploading model, but are only notified to user once a human checks by hand the uploaded file (and once you’ve already paid the order!).
If you watch the video of the Slic3r output, it prints the pegs, then the material-saving hollowed-out center, and then the rest of the pegs. It knows that the pieces of the pegs inside the disk are not relevant. In the bottom right-hand corner it says that it’s manifold:
The video simulates the actual G-code output that will successfully print this part on any extruder-based printer. While I understand that this approach seems to run contrary to almost everything you read about 3D print modeling, I would suggest trying it out. Works for me
It’s not clear how you made the parts, but if each of them was a “solid” component (or group), you should get something that prints just fine. As a simple example, here’s two component pairs (four in all) that are each a “solid”:
The file and STL file are here, if you’d like to check them out in Netfabb: sample.skp (46.0 KB) sample.stl (38.0 KB)
BTW, here’s an example of a model I had printed by Shapeways in steel … this is something I could have never created so easily if I had to merge things into one part:
I really appreciate you taking the time to run these things through Netfabb. I may download their trial version to learn more about it, but it’ll have to wait until the weekend. Ironically, Slic3r seems happy with it:
Getting the right peg size and radial dimensions for the gears to work doesn’t appear to be trivial. However, if you start with an assembly of components, you can animate the gears and make adjustments. As components, changing one peg changes them all. For simplicity, I started with two identical gears with 18 pegs spaced 20 degrees apart. I made the animation with 2 degree intervals, but 1 degree would probably be better. Running the animation and tweaking the dimensions gave me something that seems to be pretty close.
Hi guys, l’m trying to learn sketchup, but have stuck at the point where for my little project needs few gears of different size. As for ‘extensions’ l looked in to ‘extensions warehouse’, but cant find anything for it. What lm finding here is links of plug ins, but then l’m having problems by downloading/installing them.
So if someone could guide me trough this process, l would much appreciate it
Man you are legend, thank you very much for your time. It’s really helpful.
Btw is there any more plug ins (extensions) which l might be need for 3d printing? Maybe is there some other helpful tools for making 3d models? Is everything l might be need, l can find in this forum?
In my previous post I indicated that you need to exit/relaunch SketchUp after installing it, but this is not the case. Once you install it, it should be ready for use. BTW, if it’s grayed out on your File menu, it’s because you need to create some geometry first.
