Several designs and modifications of Gregs Wade Extruder are floating around the internet. I went for Gregs Wade Extruder Reloaded by Jonas Kuehling. The parts printed out nicely and bla bla bla but I still needed a hobbed bolt. They sell for ~5€ on eBay. Five Euros. That are 10 DM. Which is like 20 € which is like 40 DM !!!! Highway robbery !!!!
It’s a simple partly threaded M8x50 screw. Make one yourself is pretty easy. There are several tutorial on youtube using a drill press and a M4 tap. This one I liked best.
is even a are even several 3d printable jigs on thingiverse which use a rotary tool with a cutting disc to cut the teeth into the screw.
Still I did something wrong because the tap suffered really hard from drilling into the bolt.
It looks like the threads got abraded a lot. Applying cutting oil is really mendatory to maintain the lifetime of your tap.
Here is my result. Okay…a little bit off but it works.