Hi Lycanthrope!,
haha, you've got me cornered here! First of all, please forgive me for my late response, i rarely visited the forum in the past months, due to very hectic duty schedules.
1. Since i don't own a Quartermaster and only ever saw one in a picture, i'm not able to take one apart and compare it to the inside life of a Safetymaster. The latter was clearly advertised as a double insulated tool, so, if the Quartermaster was built to that specification, the difference between the two may be in the motor construction and switch layout. But this is only a guess.
2. Didn't the Challenge have a metallic light blue livery, with black and white checkered decals, like on UK police cars and F1 finish flags? If so, i have once been in the position to buy two brand new ones for a bargain from a shop closing down. I was tight on money around that time, there were also two vintage metals B&D drills and a streamlined all aluminium and highly polished French made Val d'Or drill. These are very rare and they are the drill equivalent of a Citroën DS, so i spent my money one that item. I went back for the other drills a few weeks later, to find that the shop had been cleared out entirely. The phrase "you can't have 'em all" was very apt, but also little help.
These light blue Wolf drills i saw, indeed looked like a spitting image of the Cubmaster. They may have been a budget version, although the Cubmaster already has quite a few sleeve bearings. The motor power may also have been different. Like you, i have yet to encounter another one, so these models are rare indeed.
3. Cast lettering and ornaments were popular in the 30's up to the 50's. To achieve quality detailed results, both mould finshing and casting require extra care and thus cost, with possibly a higher amount of rejects that have to be recycled. On the other hand, cast details stay recognisable much longer than housestyle colours, riveted typeplates or brand decals, which are prone to become scratched or worn down. Examples of tools with cast lettering are from Fein, Stanley, Porter-Cable and Rockwell, Mafell, Milwaukee, Elu, Holz Her, Ackermann + Schmitt, Stihl, Festo, Siemens, AEG, Millers Falls, Hilti, Gotthold Haffner, B&D and Outillage Peugeot, with many brands using contrasting paint colours to bring out the name or logo from the surrounding cast housing. Most of these brands ceased to use cast lettering around the 60's, often when the conventional moulds and the tool models they would produce, were obsolete or due for refurbishment anyway. In the new moulds, the cast details were simply ground away or filled out, to crank up the mould's filling speed and loosening properties.To cut cost and still give products a distinctive appearance, paint colours and decals were adopted as the new tool identity trend.
The same goes for Wolf, with the cast detailed models in general being older then the smoothed down ones. Early models without cast details were also common among tool brands, since flaws in such details tend to give away imperfect mastery of the casting process and require grades of metal liquidity and filling pressure that were not yet advanced enough in that era. From around 1890 to the 20's, alloys didn't yet have the ideal mix ratios and properties that exist today. Cast details in early tools tended to be a bit more coarse and irregular and if time and money were an issue for a manufacturer, he may not have bothered or would choose branded riveted or screwed-on badges instead. From around 1850 to 1930, there was a whole industry of platemakers available (brass, bronze, cast iron) to cater for many markets, from locomotives and household appliances to ships, bridges and machines. Often a very vintage electric tool with a smooth housing is merely so because its original badges or plates are missing, leaving only tiny telltale screw or rivet holes.
4. Vintage Wolf catalogues and advertisement prints are very rare worldwide. Wolf tools were considered to be workhorses with glamour coming second, and i have the impression that the firm didn't spend as much on marketing as B&D or Bosch or Festo did. Although it must be said that the Pioneer Works did show their association and good reputation with the British aircraft industry with considerable pride. On my trip to the Ealing Council Library (which stock the archive on London's Ealing and Acton, including the Hanger Lane region where the factory was), there were more newspaper articles on Wolf in relation to aircraft manufacturing, than there were advertisements on the brand in general. Wolf was never big in Holland, there were very few sales points stocking the brand, although most Dutch users knowing the brand, tended to stay true to it all their lives. Still, for most things on Wolf, i have to shop abroad.
That's how far my knowledge reaches at the moment. You've given me some homework to do first, before i can comment more accurate than this.
Best regards
gerhard