Hey Festdewalkita,
In addition to what the others said about the trim router’s poor performance, it’s not only the runout on the collet with no load that matters, but the deviation under load. And this does not only concern the router axis/collet stability, but also the deviation of the entire holder/Z assembly. The router and the way it is fixed to the machine is not ideal. The router is slid very far downwards into the 65 mm holder, prolonging the distance between actual cutting edge and the fixation point on Z slider and finally on X gantry. There are strong leverage forces that act on the system at the moment when the machine drives the cutter trough the workpiece. You might be interested in the discussion from the other day (@Marty 's wooden top and bottom box fit), where I tried to explained it.
The conclusion is that you can expect very much improvement by switching to a spindle, not only because of higher quality of bearings, axis and collets, but also because you don’t have to slide it that much downwards into the holder (see here vs. here). This way you keep the distance between the cutting edge of the milling bit and the fixation of the motor on the Z assembly shorter, thereby reducing leverage forces exerted during mechanical load.
Completely different types of motor
Furthermore, if you use a spindle, due to the type of motor a spindle is, it will not be slowed down by the mechanical load during the feed, because frequency-controlled induction motors work in this way. The hand trim router, on the other hand, is a universal motor (= a commutated series-wound motor) where, due to its characteristics, the speed depends on the mechanical load, i.e. it is slowed down by the load (what a more or less sophisticated electronics tries to prevent) and has only one speed(load)/torque combination in its curve at which the motor attains a balance between speed and torque, whereas a spindle has a constant torque over its entire rated speed range (e.g. constant 0.9 Nm from 6000 to 24000 rpm for a 2.2 kW spindle).
– Source: Traute Meyer, CC BY-SA 3.0, via Wikimedia Commons (rotated and mirorred to reflect axes of Image 2 and with comments added by Aiph5u)
Image 1: Motor characteristic of a Universal Motor (=hand router)
– Source: Mechatron HFS-8022-24-ER20 Datasheet (with comments added by Aiph5u)
Image 2: Motor characteristic of a frequency-controlled Induction Motor (=“spindle”)
Of the above images, Image 1 shows the motor characteristic of a hand trim router like the Makita. Such a motor is called universal motor. As you can see, when you have speed, you have no torque, and when you have torque, you have no speed.
You might be tempted to say you’re fine with this, since you want high torque at low speed in order to mill metal or plastic. But with this motor, the speed is dependent of the mechanical load. This means with no mechanical load, such motors would run faster and faster until they would destroy themselves, here an electronics prevents that, while at high mechanical loads (i.e. when you give him something to mill) and also at a low speed settings, on this type of motor, when the electronics try to hold the set speed, the current increases exponentially, and this type of motor delivers its current through carbon-brush commutators, which produce a lot of sparkling and heat (and EMI and acoustic noise by the way). The more mechanical load you give to this motor, the more the electronics try to hold the speed, the more current flows.
At the same time when the speed is lowered by the mechanical load and the current is very high, since it’s only cooled by a fan sitting on motor axis, the fan turns slower too and finally fails to cool the device.
With this type of motor, as you can see on the motor characteristic curve in Image 1, the range of usable speed/torque combination is extremely narrow, and it is practically impossible to get high torque at high speed, but this is what you would want when milling wood with high chip loads. As explained above, with this type of motor, the speed depends on mechanical load, which means, it is slowed down by the load. The electronics try to prevent this, but it can do this only within the margins of the motor characteristic, and of course only within the motor’s power capability without producing self-destructing heat.
I always tend to grin when I see people measuring the speed of their hand router with no load (the idle speed), because the speed with no load has practically no relevance, since you want to mill something (and not to mill air). The only relevant measuring would be to measure how the speed breaks down when the motor is under load (=when it mills something), however I have not seen people measuring this, and especially not when feeding it with high chip loads.
On the second image, on Image 2, you see a frequency-controlled induction motor, also often called “spindle”. As you can see, you have a constantly high torque over the entire rated speed range of 0.9 Nm from 6,000 to 24,000 rpm. What a difference! And such a type of motor is never slowed down by any load, it always runs as at least at 97 percent of the set speed, no matter what the load is that you give him to “eat”. That makes an extreme difference, the chip load can be overwhelming.
Furthermore one big difference between these two types of motors is how they behave if the mechanical load should exceed their rated capacity. In the first case, with the hand router, it would be slowed down with an extremely high current flowing, producing high heat, in conjunction with a practical cooling failure, and it will burn out, as reported repeatedly, if you don’t have some emergengy current limiting electronics in it (more expensive power tools have that).
On the other hand, with a frequency-controlled spindle, when the mechanical load is increased, the spindle will never be slowed down by the load, and if finally the load should exceed the rated current (which is always set inside the VFD), the VFD simply trips and stops the spindle and, in case a correct emergency wiring is present, will immediately automatically signal the CNC Controller to stop the program.
You see it also makes a big difference on whether you can leave the machine alone and sleep well while it works, or not.
So especially when milling wood, where you want high speeds with high chip loads wich means high torque at high speed, you see that a motor like a hand router is rather unsuitable.
Also universal motors have a much worse efficiency than induction motors, since in fact a universal motor is a DC motor that runs on AC, and it’s the constant reversal of the polarity of the AC power inside the coils that produces effects that lower the efficiency, among other things. So in fact if you have a hand router with 710 W rated power, like the Makita, this corresponds only to a spindle of less than 0.5 kW power.
And remember, you can not choose from a range of speeds at constantly high torque with the hand router. As you can imagine, when switching to a 2.2 kW spindle, which can deliver its torque at any speed, you will be surprised what chip loads you can achieve, and this with very low motor noise and perfect cooling (since even with air-cooled spindles, frequency-controlled induction motors are not slowed down by the load so the fan always rotates fast enough).
The only advantage of a universal motor like found in the hand router is that you can connect them directly to a household wall outlet, you need no VFD. That’s why you find such motors mainly in hand tools.
The Onefinity is a sturdy machine capable of “eating” high chip loads, but you will never see this when your motor is not able to deliver high torque at high speed. So why buy the sturdy Onefinity when you only want to use it with a hand trim router which will not enable high chip loads.