Involute gear and worm gear plugin?

An entry level question… I have just downloaded Sketchup 2017. I have a Toshiba Satellite laptop, and have been unable to download an involute gear plug in. Maybe it does not have a 1024 graphics card?.

I’m trying to download from google but no success.
Please help,

Downloading a plugin has nothing to do with your graphics card.

This help page explains how to manually install a rbz file.
If you have a plain rb, zip it up into a zip file, and rename it rbz, then follow the instructions.

You mean from Jim Hamilton’s code site?

Hi Dan, Thanks for responding! I looked at the extension Warehouse and didnt find any gear plugin for SU 2017.

I dont think that the couple I tried were from Jim Hamilton. Just tried tht one and it lets me download a .rb file but when I go to the app store to open it ther were many options but not to rename it. (was not able , don’t know how to remame it) .

I think you did get me closer! but need a further clue to get it done.
Thanks vm for your patience.

Involute Gears is listed on the SUPlugins site -

It is listed as an .RBZ file which should install properly using the Extension Manager dialog.


Try this link instead … it’s basically the same as gear3, but allows you to optionally make a linear (rack) gear as well. It’s already in RBZ format so it should install with the normal extension installation procedure.

The original gear3 produces a very faceted tooth profile when 3D printed. I modified Doug Herrmann’s original plugin to use more points in creating the involute profile. There is a parameter to vary this as needed. For example, comparing a 12-toothed 1" pitch radius gear made with both plugins, the one on the left will print much better than the one on the right:

When the output is used in conjunction with the Spirix plugin, you can create true helical gears and worm gears as well:


Hello Dan, Chris and Jim,
Thank you all for your inputs so far! But I’m still stuck. I can go to the links that you suggest and download. but it seems that in my system these files always default to Adobe PDF and then Adobe fails to open them. same result on all.
As always, i’m sure I’m only one keystroke from success, and it seems in tis case the issue must be a switch in my Win 10… any suggestions would be welcome!

Peter, you do not open them. You install then from inside SketchUp.

SketchUp 2016 and older, from the menu:
Window > Preferences > Extensions > Install Extension… (button)

SketchUp 2017 and newer, from the menu:
Window > Extension Manager > Install Extension… (button)

Browse to the RBZ archive file, select it, and click the OK button.
Answer Yes to the security prompt.

Dan, Thanks that worked! and I have installed the involute gear, Key involute gear, and the SU grid.

Other extensions that I need for my project are, and I would be greatful for help locating them (dont see them in the but maybe I am not looking correctly).

  1. the ability to draw a spur gear in 2D plan view showing the smaller on top ( this I should be able to do now ) .
  2. a Worm gear that has to mesh with the larger gear of the spur combination
  3. A Rack gear that meshes with the smaller gear of the spur combination, ie this gear is the pinion. This rack gear must be cylindrical, around a cylindrical shaft, not a flat section on a shaft.
    Noting that the working loads will be very light so for now I’m not concerned with accurate design of the teeth or other loading issues.
    Your help is much appreciated!

Were Jim’s post above not helpful ?

Hi Dan,
Thanks for the follow up!. I looked on Spirix but could not find the worm gear Jim shows so a further assist there would be helpful. I think it is an issue of my not being able to find my way around this whole business yet! I’m not wanting to cause you guys fatigue with too many entry level questions but at this stage a lot is non intuitive for me.
So any further assist with the gears will be appreciated, meantime I will start the rest of my drawing with lines and curves etc and leave space for the gears. ( I have used other drawing programs occasionally in the past but it is not my main activity).
THen I will be able to come back and ask better questions.
Thank you guys so much , it is reassuring to know there is help available.!

Something I might try on my 3D printer just to see if it works . . got the skp file for the gear ?

Spirix is an extension to help you create complex geometry of various shapes. I don’t think it has a specific “worm gear” feature. Instead, you will input the parameters provided by the extension in order for it to create the object.


I made two gears and a simple base for them to sit on.

They’re in three separate groups and you should be able to select one and export it as an STL file making sure to check the “Export selected geometry only” option.

gear_train_10.skp (709.5 KB)

Hi Jim, thanks for the two gears + a base. On your email, when I click on the .skp link, all I can do is save it to a folder Plugins which does not show up on my Sketchup…

I do not get an opportunity to Export it as you suggest….

Further thoughts?

I don’t know if this would make a difference but I have the Free version not the paid Pro version of Sketchup.


Hi Chris,

Oh, OK I understand that now thanks.

But I still am stuck … I see jimhami42_rack_and_pinion.rbz on the spirixcode tab of the spirix site, and downloaded it and installed it from my Sketchup. It appears in my Window>Exensions Manager list but it does not appear under the Draw dropdown list . It does appear under my Extensions as Rack and Pinion. BTW my attempt to download Sketchucation resulted in it also showing under Extensions, but neither are live.

Any further suggestions?

Thanks VM,


If you successfully install the jimhami42_rack_and_pinion.rbz plugin, it should show on the Extensions menu as “Rack and Pinion”. When you click on the menu option, it should show something like this:

I posted that model of the gears at @lynne’s request … the Export option is referring to the STL export module which is not included with SketchUp. If you click the link for the SKP file, you can save it in your regular documents folder and then open it from inside SketchUp. The SKP file shouldn’t be saved in the Plugins folder.

This looks like a lot of knowing the way the gear turns and all that stuff . . Will take a few months of reading all kinds of pages . .

Hello all,
I’m also having trouble with the extension. I’m using sketchup 2018 and have successfully downloaded the extension. Is there a way to have it automatically change the tooth size when changing the pitch radius?

Or how do I calculate this for myself? I cant seem to get two different sized gears to mesh because the tooth size gets changed.