Anybody here know BLDC motors well?

If you (spendy) source a servo-rated BLDC motor, it will tolerate all sorts of abuse, and may be loaded to a dead-stop without damage. And, if you are going to be doing this - purchase the correct speed control rated for the full shorted load of the motor. As there are no brushes, that is not the sa me as a short-circuit as it would be in a brush-type DC motor.

Peter Wieck Melrose Park, PA

I have played around with these motors making drones from scratch. You can 't just buy a motor and ESC connect them together and have it run. The inp ut to the ECS is a pulse that varies in width for the desired speed of the motor. the direction of spin is controlled by how the 3 wires to the motor are connected (reverse any 2 and the motor spins in the opposite diredtion) . I have run these motors without the cpu controller that makes a drone fl y but you need 2 things. A wireless control transmitter that usually has j oy sticks to control the speed and direction of the drone (Usually $50 on u p). A receiver that can be directly connected to the input side of the ESC to supply the appropriate pulse to the ESC (about $15). The ESC supplies the 5v back to the receiver so no extra power supply is needed other that t he high current one used to power the ESC itself.

There are probably controllers that can be used with these BL motors direct ly but I have not researched these. Since the price of a wireless controll er/receiver pair is so low I doubt that a dedicated controller would be wo rth the cost. If you were an electronics hobbyist you could build a contro ller that would supply the correct pulse to the ESC.

Hope this helps.

...bob

One more thing - an unbalanced motor spinning at 24,000 + rpm will destroy itself in short order. I suspect that the motor itself will be the least of your worries.

At the same time, is this engraving device for a pantograph, or similar, such that an off-the-shelf engraver would not be suitable? There are some pretty good ones out there.

That for the price will probably be competitive with your home-brew at the end of the process.

Peter Wieck Melrose Park, PA

Ebay shows 700 listings for such controllers: Most are for eBike and electric scooter speed controls but the smaller boards might be usable.

This engraving spindle is for use in a CNC mill. Ideally it will sit in the tool carousel along with the other 20 tools and be connected to power and cooling automatically. But I will probably need to manually plug in power and cooling connectors. I use different rotary tools for engraving and micromilling. The smallest engraving tools I use are .015" diameter at the tip. The smallest milling cutters I use are similar in size. The graver you linked to is a hammer type and is not the type of engraving I do. There are several ways to engrave and what my customers want requires rotary tools. I am really just doing shallow machining when I engrave, not any kind of artistic stuff. Letters, lines, numbers, that kind of thing. The top spindle speed of my main spindle is only 7,500 RPM. I do have a sub spindle that spins at 24,000 RPM but it is too big to fit in a CAT 40 tool and so is instead mounted in a clamp which in turn clamps around the main spindle housing. A kluge. I have some hobby BLDC motors but the ones with enough power for high feed rate cutting max out at 24,000 RPM and I really want 40,000 RPM. I have experimented with the motors spinning a tool at 24,000 RPM and surprisingly the things were pretty well balanced. But as I said they can't be fed along very fast. Eric

That makes a lot more sense in terms of your request.

Gets you up to 120,000 rpm. I expect that they will be pretty well balanced as well.

Peter Wieck Melrose Park, PA