How to make internal threaded holes m3

I wish to make internal threaded holes in my project for m3 screws
Can someone please help me convert the m3 dimensions to whorl compatible dimensions?

Whorl Dialog

m3 iso metric coarse threads

I plan to leave project without fill-in so making solid and then tapping threads is not an option

Based on the table you provided, the first five fields would be 1.3375, 1.3375, 0.5, 0, 0. It shows dimensions for external threads but by referring to tapping the holes you seem to imply you are interested in internal threads. The radius values will be larger than those given. That table doesn’t give you the information for the last three data fields but those numbers are calculated off the thread pitch and diameter. You can find that information if you search for metric screw thread dimensions. Start here.

You should be planning to model this in meters, not millimeters. For 3D printing, you can create the whole model in meters. When you import the STL (which is unitless) into the slicer software, tell the slicer that the units are millimeters.

By the way, please update your profile with the correct SketchUp version. It currently shows you are using the 2015 free web version which doesn’t exist.


thank you for the dimensions
unfortunately the extension whorl is not cooperating

I have created a new project with meters as you have recommended this did not resolve the issue because whorl does not output anything. If i retry the input values they are all zeros

Meanwhile i tried the Bolt Thread Settings generator tool on, however this preferred inches therefore i had to change the template from meters to inches but that also did not resolve the issue

I do not understand

I don’t understand what you mean by this sentence. Are you intending to 3D print this project?

If so, unless your printer has exceptionally fine resolution, you wont get usable threads in the print.

However, if the material is plastic (e.g., ABS or PLA), you could probably just screw a metal M3 bolt or machine screw into a plain cylindrical printed hole 2.5 to 2.7 mm diameter and it will force its own thread.

I have a better way to model accurate machine threads but I’m on the road right now. When I get home I will send them to you.

John has a point, though. It might be expecting a lot from the printer to print threads this small. Tapping will most likely give you better threads.

Despite the wonders of 3D printing, I believe that one should follow the same practice as foundry castings have always used: don’t expect the result to provide precise surfaces or holes, expect to mill, drill, and tap to get precision fits. There’s too much shrinkage, sag, etc. involved.


Guess this isn’t my day with sketchup extensions. Tried ‘EP Fasteners and Holes’ but does nothing after i select ‘metric’ and ‘threaded holes’ so i raised a ticket at Customer Support.

Customer Support doesn’t normally provide support for 3rd party extensions nor for SketchUp Make.

EP Fasteners works here when you click on a face. It does require that you are clicking on a face not a group or component, however.

My preference for machine threads is to use Curvemaker to draw an appropriate helix and Eneroth Upright Extruder to extrude a profile I’ve laid out to match the dimensions from the link I provided. (both from the Extension Warehouse)

Here are some examples.


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FWIW, I am working on a model for which I need some left-hand threaded acme rod. Here’s the basic process I used to create it. I prefer this method over using a screw extension because I can ensure the threads are modeled correctly.

For this model I need 1 inch diameter rod with 5 threads per inch. I set the units to decimal meters before I started.

Using the Helix tool in Curve Maker I drew a helix with the following parameters: Radius 0.5, From Turns 0.0, To Turns 7.0, Sides/Turn 48, Height/Turn 0.2. Then I drew the profile of the threads based on information from the Engineer’s Edge website. Once the profile is drawn, I explode the group containing the helix.

I selected the helix and the face of the profile and then run Eneroth Upright Extruder. Correct the face orientation as needed and erase the original helix.

Next I cut the threaded rod into a suitable unit. In this case I wanted an inch of rod so I put rectangles 1 meter apart and intersected them with the geometry.

After that I trimmed of the waste and cleaned up the geometry so that I would have a solid component when finished.

After that the geometry in the component is scaled down to 1 in. diameter. I can copy it as many times as I need to get whatever length I want. 1 in. increments are done by making a linear array with the Move tool. Other lengths can be created by trimming a section. To make a single solid of whatever length, Outer Shell can be used.

For internal threads I would use the appropriate dimensions for the profile.

Admittedly this requires a little more work than the various thread-drawing extensions but I think I get a better result. For me it’s worth the little extra effort. Once the process is sorted out, it doesn’t actually take very long to do.

For the internal threads I did the same sort of thing and created a solid threaded shape with the appropriate dimensions. I used Trim to cut the threads in the block but Intersect Faces would work just as well. I also created a shape to chamfer the edges of the holes so the lead in to the threads is better.