The new tool changer uses the Bondtech Extruders 1:3 reduction to decouple the extruder from its motor. To make this work, the gears need to be aligned at any time (which sounds easy but it's complicated with open-loop stepper motors).
Another solution are rounded teeth which arrange themselves when they mate together. These gears are highly inspired by Lego gears (like Gear 12 & 24) which are beveled and often used for gear shifter models. I guess this method only works when one of the wheels is free, luckily that's the case when the extruder is heated up!
![](https://cdn.hackaday.io/images/6463201567444376165.jpg)
![](https://cdn.hackaday.io/images/1481751567444398858.jpg)
These gears would be really expensive when they where made on a lathe. But Igus, a german specialist for non abrassive thermoplastics has a SLS process which produces accurate longliving gears similar priced like shapeways.
![](https://cdn.hackaday.io/images/3750241567444969022.jpg)
![](https://cdn.hackaday.io/images/5174531567444992173.jpg)
I ordered them right away to test the tolerances and see if they are really self aligning, posting pictures as soon as they arrive!
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