So... let's return to the wool prep proper, and in particular: Wool combs!

Here's the basis on wool comb using: You have a pair of them, used together. Wool is placed on the tines of one of the combs, then gets transferred onto the second one, straightening and aligning the fibre in the process. Dust, debris and short cuts either fall out during the process as well or can be removed relatively easily. Once everything is aligned nicely, the wool can be drawn off, ready to be used.

There are several different ways that can be used to transfer the fibre from one comb to the other; most of them involve holding the combs so the tines are perpendicular. While it is possible to work with one comb held in each hand, most images also show one comb as fixed somewhere, and only one held in the hands to work with.

Modern wool combs are used in a similar way; usually, there's some combing station or pad included with them (unless it's very small ones) or available to go with them. One comb is held in that station, and the other is used to work, held in the hand(s). If you look on youtube, there's (of course!) a number of combing videos and tutorials. (Note, also, that modern wool combs may have several rows of tines, and very frequently have two; the medieval ones I know of have only one row of tines.)

This medieval-style version can be seen on a number of images, showing the process in more or less detail, and a more or less, hm, trustworthy way. For instance, the British Library manuscript pic here has a woman combing in a setup that has one comb looking like it's held by, as we in Germany would say, "Siemens Lufthaken" - an invisible device holding anything at any place. (Hard to get, unfortunately. Let me know if you have a source.)

Much more detailed, and looking a good bit closer to actual life, are two images from the Hausbuch der Mendelschen Zwölfbrüderstiftung - one here, and the second one here. The images date from the 15th century.

In both cases, one of the combs is held in the hands of the worker, while the other is fixed in some contraption: A stool-like support for the t-bar holding the tines, and an upright pole coming out of the floor or fixed to the floor, a bit further away, forming a brace for the end of the handle. This far, we're still in sort of a similar vein as modern combing. Both modern and medieval images show the worker in front of the fixed comb's tines, the handle pointing away from the worker.
However... modern combs are fixed in a way that allows the worker to stand or sit in front of the tines of the fixed comb, yet work towards oneself. The wool is pulled through the tines on the far side of the handle (close to the worker), towards the worker. This only works when the comb is fixed very firmly, though, and in a way that will bear the force of combing (which is not to be underestimated!).

Logically, and very obviously with the medieval setup, that work direction will not work - the comb could slide away from its brace and support towards the worker. Maybe there is some additional way to help the comb sit properly on its support - but it might not be necessary as the work direction is quite clearly adapted to the bracing construction: Both workers in the Hausbuch images use the hand-held comb on the far side of the tines, the handle side. Which obviously means they work away from themselves, not towards themselves.

This... is intriguing. I haven't gotten around to try this setup properly yet, but I can definitely tell you it feels very different from the "modern" wool combing, where you have full freedom downwards with your working comb, as the fixed one is clamped to the front of its support. This might mean some other technique for medieval-style combing is necessary. It will definitely be very quick and easy to switch the fixed and the handheld comb with such a construction, though.

If you know of more combing pictures, I'd love to hear about them. And of course if you have wool combs and try this out, please do let me know about your results!