So unfortunately my brushes gave out in the middle of a cut.
Last time this happened I just ordered a 2nd router (Amazon delivers those within 2 hours while brushes take like a week)… but I’m wondering if there are any options out there for a brushless router since, well, I’m sort of tired of changing them (dewalt also makes it not so easy to do)
(For normal woodworking I use a battery based router which is brushless but not so sure I want to use a battery based cutter in my shapeoko)
Or is “brushless router” a mispelling for “spindle” ?
(also… since this was in the middle of the cut… Carbide Motion could really use a button in the pause screen to re-bitsetter the bit since I’m sure I’ll destroy the Z point as part of changing the brushes)
There is someone here who has adapted a brushless router (they are only available as cordless routers). Be aware that the torque curve of a brushless motor is VERY different from a brushed motor - the torque at low speed is very low and somewhat narrow by comparison. Brushless has some nice advantages over brushed in a cordless tool where you’re willing to give something up for cordless, but not so great a tradeoff for a corded tool.
That’s unfortunate that the incorrect information is being published and believed. Brushes should last a minimum of 2000 to 3000 hours of run time. Trust me this is the correct information.
I wore my first set of DeWALT brushes out in around 400 hours. Then I got wind (sorry) of the old sock trick and the second set has so many hours on them that I’ve lost count. Eventually a spindle will be in the cards…
Edit: A good point to remember is that all that dust and debris that wears out the brushes is also in the air we breathe, for those without enclosures. I use to have a ready supply of N95s at hand, remember when they were easy to find and inexpensive at the big box stores?
I am running a brushless Makita Router. It is currently highly modified, but it actually worked great mostly unmodified. I took it apart and replaced the battery mount with two wires run to a 350W 24V power supply.
Brushless DC (BLDC) routers/spindles have speed/torque curves very similar to HF Spindles, so they’re ideal for CNC machines. Unlike AC routers, both attempt to limit torque at low speeds to limit cutting forces. BLDC spindles can do that even better than HF spindles because torque is proportional to current, which is directly controlled by their drivers.
The one linked above is nice in that it has a speed reducer available to increase torque if necessary.
I don’t think this is really “attempt to limit torque” - it’s just inherent in the design. Torque is a factor of current spindle speed AND size of the mosfets because of the distance between poles. DC motors are efficient, lightweight, compact, and low maintenance. And have very peaky torque curves. This is why if you’re used to cordless tools and pick up an AC drill you’ll think it’s gonna tear your arm off if you try and use it to drive a screw. An AC motor is still a better spindle across a wide range of RPM. Ideally in a spindle you want 100% of torque all the time so you can set feed and speed on RPM and tool, not force yourself into 3-4+ variables.
Here are typical torque curves for DC and AC motors. AC has the big advantage of highest torque available at low RPM, which simply can’t be done with a DC motor.
AC - notice how maximum torque is available from zero rpm. Wish I had a manufacturers chart, but this one is typical of shape.
Which appears to show that DC brushless has the highest stall / starting torque but that the torque then falls away very quickly with increasing speed.
The AC motor has a much wider flatter torque curve which is the sort of thing we want for cutting if I’m reading that right.
Not sure how those translate into continuous operating conditions though, I’ve seen that universal motors and old AC induction motors frequently come with fixed cooling fans that severely limit their real operating speed ranges.
It’s also dependent on the current provided by the motor driver. BLDC motor controllers/drivers monitor speed and control it by controlling motor current. They also limit torque/power to safe values by monitoring and controlling current.
That’s why universal motors are poor choices for spindles. Their drivers only control speed and do nothing to limit torque/forces.
(dewalt also makes it not so easy to do)
