The Goliath chucks (same design pattern) I have appear to have machined scrolls, but if the SK100 has similar scroll sizing to that on the older precision 100mm chucks I have and the scrolls are indeed now cast then I could see a shear strength problem of the scroll gear, only 3 'teeth' engaged and carrying the load.
Re the comments about the metal chuck scrolls and comparing them with the Axminster standard, I noted some time ago that the axminster scroll tooth spacing is on a slightly courser scale than most metal turning chucks, this is even visible compared with the Vesa Chuck which is basically a chuck body aimed at metal lathe use.
I use predominantly axy standard (5 off +1 Versa with axy compatible carriers) as it gives me maximum versatility with my accessory jaws and have no reservations about the courser scroll for wood clamping but it does not give quite the same finesse and actuating forces that a good metal chuck does.
When first promoted I had a feeling that the little extra 14mm diam. was to allow better use of the Cole Jaws as on a 100mm chuck there is often a dead spot between standard button positions, so improving on the 100mm in that respect but cheaper in stock materials for production than the 5" goliath, maybe the aim was to also increase the number of scroll tooth engagements.
Some images of differing scroll sizing,
Axminster carriers.
Axminster Scroll on a 100mm Precision chuck.
Versa Chuck Carrier.
Versa Chuck Scroll.
Vicmarc carriers .(coutesy PaulJ)
Sorry no Vicmarc Scroll details.
Incidentally as PaulJ recently found out, the Vicmarc Jaws should you take them out have to be engaged in his chuck body in the 2-3-4-1 order due to the no1 carrier missing a first tooth.