When you have a 3D printer "lash up" is probably not the right term as quite sophisticated parts can be made easily.
Here it is pulling a spring balance with a piece of HDPE filament.
It got to 10 Kg and then the coupling from the GM17 to the 4mm shaft of the pinch wheel let go.
Not surprising given the torque involved and the fact that it was made with 25% fill. I made it again with 100% fill. I can't remember the last time I made a solid part.
It is coupled to the shaft with a hexagonal steel insert drilled out to 4mm and tapped M3 for a set screw onto a flat on the shaft.
With the 100% fill coupler it easily pulled the scale to the end, i.e 12.5Kg. The motor was powered from 8V (to stop it getting too hot) and stepped at 200pps. With a step angle of 15°, the GM17 default gear ratio of 228:1 and a 13mm pinch wheel that gives a feed rate of: -
200 × 15 / 360 × 1 / 228 × 13 × π = 1.5 mm/s.That would give an output rate of 54mm of 0.5mm filament per second. I think that is comparable to the rates Adrian Bowyer has reported from a NEMA17, but it only weighs about 60g whereas a NEMA17 is about 200g. There are a lot more parts to wear out though, so a NEMA17 may be a better option. Darwin can easily throw 200g about and HydraRaptor is moving table, so the head weight has little relevance.
I have some NEMA17's arriving this week. I tried one from an old disc drive but it didn't have much torque. I don't know if that was because it had aged in the 20+ years I have had it or whether modern motors are much better.