Hey Josh,
I own a Festool CTM MIDI I with cyclonic dust separator CT-VA-20. I use it as workshop vacuum cleaner and as dust extractor for some hand power tools that make dust, and also for drilling holes into the wall and into the ceiling (see drilling dust nozzle). I don’t plan to use it for the Onefinity CNC for the reasons explained here and also because I also own a thicknesser which requires a high air volume flow dust collection system anyway, but I think as long as you don’t have such a dust collection system, you may well use a mobile dust extractor/workshop vacuum like the Festool for the time being. To buy the largest dust hose available is the right way then (50 mm in this case). I would take care to use / 3D print a dust boot or adapter that does not reduce the cross-section area of the chosen hose.
I think that even if a dust collection system with high air volume flow is the better solution for a CNC machine, usually you need a workshop vacuum cleaner anyway (if you work with wood in your workshop), so in most cases you would buy one anyway.
Note that if you buy a CT 15, you don’t have dust class “M” but for extracting wood dust you should use one with dust class M for health reasons. Wood dust is carcinogenic. The dust class describes how high the harmful substance load at the workplace is, i.e. what is allowed to come out of the back of the device. That’s why I bought one with this dust class. You can choose a model suitable for wood dust with the Festool application advisor.
Note that Festool dust extractors allow you to attach a hose to their exhaust-air outlet as well, if you have the possibility to direct exhaust air outside the building.
As far as running a workshop vacuum cleaner on the Onefinity CNC for a long time, many hours, I think the Festool can handle it (it is explicitly made for “Increased loads during commercial use, according to IEC/EN 60335-2-69”) and it’s not quite as loud as some cheap workshop vacuum cleaners. But Festools are not cheap. For the money of a Festool mobile dust extractor and a separate cyclonic dust separator, you are already near the price of a high air volume flow Dust collection system that would be better suited for the larger amount of chips that a CNC machine can produce. This becomes especially relevant if you are upgrading to a spindle that will allow you to achieve high material removal rates/high chip loads that are not possible with the Makita hand trim router. Also a dust collection system would be quieter and last longer since it does not require servicing motor carbon brushes, because dust collection systems usually have induction motors that have no commutators and run more quietly and at lower speed.
Festool is a german manufacturer of high-end power tools, so of course their suction hoses are measured in millimeters. For their Mobile Dust Extractors they offer hoses with 36 mm and 50 mm, called D36 and D50, e.g.
The Festool suction hoses are expensive, but they are known for their high quality. They are antistatic and you can stand on them with your body weight without them breaking.
If you are looking for a local vendor, I suggest you go to the International Festool website and select your country. If you are in Australia, you can go to www.festool.com.au directly and click on “Find Your Nearest Dealer”.
The hose connectors that Festool uses are their proprietary system. If you want to combine Festool dust extractors with cyclonic dust separators from other manufacturers, you will need to buy or to 3D-print some adapter. Of course you could also put the adapter directly in front of the Festool dust extractor and buy cheaper, non-Festool hoses. But be aware that then you have to take care of earthing and bonding against the danger of electrostatic buildup yourself.
Note that Festool offers their own Cyclonic Dust Separator CT-VA-20 with disposable bags that nicely attaches on top of the dust extractor. It fits the MINI/MIDI models too. Also I would not buy a CT series mobile dust extractor without the Handle SB-CT, useful to push the device around and also as a small backrest in the break.
International versions:
Versions for the U.S. market:
(with specs given in imperial/US customary units and suitable for girly power):