Why do people buy the most rigid home CNC on today’s market and then seek to purchase the cheapest router they can find? Don’t you know that spindle runout contributes to chatter and premature tool wear?
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It’s the same people who bought them just to put juice grooves in their cutting boards. Run out doesn’t matter to them. 
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Hey John,
I think that the correct answer to this question is that when the Onefinity manufacturers had the idea for their machine and analyzed the market, this market was the hobbyist and DIY CNC maker scene, which shows cncs made with cheapest available parts. Specifically one machine that became very widespread (and by the way, offers such a router but with a serious ER-11 collet) uses a hand trim router as motor. So I believe they built their machine around a hand trim router for the same reasons that other competitors do: Ensuring a low entry price of the entire CNC machine by saving on everything (see what is lacking on Onefinity) and using cheapest (here: inappropriate) components.
A few thoughts initially come to mind.
- Most people will purchase/use the machine for wood where high tolerances (except maybe inlays, etc) are typically not required. Although relatively rigid compared to other hobby CNCs, I feel it is still not designed for efficiently working with metals.
- Most non Asian alternatives are often more than 10X the cost, so you can go through several of the less expensive spindles and still be ahead.
- They often are sold with inexpensive VFDs in kits that are easy to source and always in stock.
- Mos advertise radial TIR of 0.01 mm, which is 2X what many consider an acceptable runout, but still considered by some to be adequate for machining wood. I noticed some, like CNCDepot, do not make this information readily available (not even on their login only documents).
- Sometimes people will not also invest in high quality tool holding (collet nuts, collets, ISO tool holders, etc…) which also add to TIR, but often adds a great deal to the cost.
- I think sometimes, like most manufactured products, you get lucky and get the advertised or better quality/TIR and sometimes not - so it may be worth the gamble given the low cost.
- I am not sure how many people actually take the time to carefully and correctly measure the runout, or have the measuring tools to do so accurately, as they too become very expensive as quality increases.
For me I still like to measure everything I can, as I like data and numbers, and strive to get micron tolerances. I will say that I relaxed a bit when reading that standard CNC machining tolerances are +/- 0.127 mm, and I am easily surpassing that in most of my work.
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Hey Tom, hey John, hey all,
I think the biggest difference is between using a hand trim router and a spindle at all. A hand trim router is made for short, hand-held usage, looses its warranty as soon you put it into a CNC machine, and because of the type of motor, cannot deliver high torque and high speed at the same time (what you definetely want when milling wood), will burn your workplace down (video) if you overload it, and has a runout beyond what you want to know, while a spindle is an induction motor often with double front bearing even on cheap ones, and because it is always driven by a VFD, can deliver high torque over a wide speed range, and a spindle is never in danger to begin to burn because the VFD will sense overload and prevent that. Plus you have no carbon-brush commutators on a spindle.
However there are still differences between no-name spindles and brand spindles:
If you have not ordered your spindle I have a brand new one never upended for sale. I also have the vfd never opened in original box. Both for $200. O got lazy and ordered the PWM kit.
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