Spirix to make a worm gear & drive gear

I am looking to make a worm and drive gear using Spirix extension but am baffled by all the boxes.
I have looked around for a video but to no avail.
The worm gear is 9m dia and 9m long so not sure how many turns is needed.
The drive gear is 13m dia and a max width or 8m
It will be 3d printed.
Figures are in meters and will be scaled down to mm.
Any help pse.

I can help you with this, but I won’t be able to dive into it until later.

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Thanks Jim, no rush as I am playing with other gear plugins and trying to get my head around pitch angles and all the jargon that goes with gears.

Is 9m the pitch diameter or overall diamter? What is the module? Lead angle? How many starts?

How many teeth on the worm wheel? Is 13m the pitch diameter or overall diameter?

Its best if I attach a file. I am not sure what all the jargon means.
I am after a worm gear on the axle and drive gear on the motor.
It is to drive a model train loco so ideally not too many turns on the worm gear as the motor is already geared down.
I will be 3d printing this so the chunkier the better.
Not asking for a lot am I :wink: :wink:


Gears.skp (10.6 MB)

From the dimensions you gave, this is what I came up with. However, I don’t see how it will fit into your model. Can you give more details?



Looks like Jim has you sorted on the worm and worm wheel. Hopefully that will work.

He said he’s modeling in meters and would scale it down to millimeters. Maybe it’ll fit when scaled.

@eddy_99 if you export the .stl with the units set to meters you shouldn’t need to scale the model down. Export in meters, import into the slicer in millimeters.

FWIW, if you need to 3D print the chassis, it’ll need some cleanup to be printable.

This is where I’m confused …



BTW, the worm gear has to be on the motor to turn the other gear. It won’t work in the opposite direction.


You caught me!! I never checked that chassis but I know it prints as you say I export the STL as mm and it scales it fine. In my slicer I always run the model through NETFABB which picks up any errors that might make the print fail and tries to correct them. Also, if the object is 2 parts needing to fit together, I will rescale in my slicer only because it is easier than SU.

Sorry Jim, it’s me not understanding gears and when I went to bed I thought to myself it wont work the way I want it to!!.
The way you have shown is spot on, the worm gear on the motor and the drive on the axle.
You say it does not fit but the dimensions are not set in stone.
The worm gear can max out to the width of the chassis and the drive gear sized to fit.
I can make the drive wider and skew the teeth to give me a bit more strength.
My original design used an O ring as the drive, it was fine but it wore out to quick and was not reliable.
Hopefully it will be possible to put some gears in to improve performance.

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Jim, the gearing wants to be as close to 1-1 as possible as in my original design the gearing was done by the motor and I had a 1-1 gear ratio on the output shaft to axle.
I know this won’t be possible but if all else fails I can swap the motors for a higher RPM.

Worm gears tend to have a big reduction, so nowhere near 1:1…
I think your best bet is to try conical gears with the same number of teeth.

I know it not possible but it’s worth a try to see what happens.
I will have a play with conical gears. One problem I have is the drive gear cannot be bigger than 10mm due to the loco wheel size.
I knew it was ging to be a problem, is it not always the way when you change a design?


Make the second conical gear on an extra axle combined with a normal gear and another normal gear the same size on the axle that drives the wheel…

I think that is going to be too complicated. The gears will be about 10mm max and will be 3d printed not metal, I am looking for a chunkier solution.

Helical gears can also mesh when on perpendicular axels like a worm gear.

But looking at some catalogs, it seems 10mm may be too small.


I have spent all day digging into gears and have found a couple of good programs where I can design gears but they use Blender so I think I will spend some time working on that.
Screw gears seem like a good option but as you say, can I get a working 10 mm gear?
I have nothing to lose but my own time.


well, I know that one

gives you 2d files, you have to make the 3d yourself. no screw gears though.

my two cents.

Thanks, another program to add to my gear making list.
I have a good one that does parametric gears in Blender just need to get the angles right.