NEMA for better feeding

[andreisperid]

Instead of the small 28BYJ, a NEMA stepper motor could be used to increase the feed speed, precision and reliability.

Since there is no need to use both the char and feed at the same time, I had the idea of having a single A4988 driver to control both via switching. With that, the ULN2003 could be eliminated.

The down point is that a major structure redesign should be made, since the NEMA is way bigger.

[probably-Erwins-Cat]

Pancake Nema14 are only slightly bigger than the 28BYJ. However, they do not come with an internal gear reducing mechanism and are typically paired with external gear reduction:

The redesign of the printed parts will take some time, yes, but those pancake motors aren't that huge.
The advantage would be that the community can rely on high quality parts supply from gears etc. from the 3D printing community.

Using one driver to control two motors is not a good idea because even when idle, drivers will have a hold current. Placing a second driver slot is more feasible (assuming a defragmented PCB layout).

[andreisperid]

I guess we don't even need much precision/power in this motor, but of course, if we could crank it, embossing speed would increase a lot.

The main issue with the 28BYJ is that when we press the tape against it with the bearing (traction), its internal parts start creating friction against each other.

In a quick search, found this, which shows specs that could be compatible (1.8 deg/step, bipolar). Maybe we don't even need a gear reduction, only an assembly that mounts directly on the factory gear.

Since it has a bearing, we'll probably not lose much torque with the traction pressure.

Id expect some wear and tear on 3d printed gears though, but this is already the reality of the press anyways...

Agree with separate drivers...