High Speed Spindle 10,000 to 40,000 rpm

This thread is referanced to a previous thread:
MetalWorking Machines >> Benchtop Mills
"High Speed Spindles for SIEG X2 Mill - getting technical"

The thread contributors came up with a lot of great ideas. The ideas focused on high speed hand held routers/carvers/engravers, and pointed to commercial routers. The problem statement identified a source of information "High Speed Spindle Design and Construction" which develops the mechanical critical factors. The number one factor is the bearings, and the criteria are ball material (silicon carbide ceramic), pre load during spindle heating, dynamics, and cooling alternatives. Two configurations were developed in the article - belt drive (limited to 20,000 rpm max), and built in motor (good to over 50,000 rpm). Oh by the way high speed spindles are deadly, and the machine must be incased in a bullet proof "box". 5,000 rpm is considered a high speed spindle.

So what am I getting at. The solutions pointed at commercial high speed spindle systems costing $2,000 to $5,000 --- and hobbyist hand held high speed integral motor "spindles" costing $500 to $1,000.

There has got to be something in between. Taking a look at the Roland milling and engraving MDX-500, with spindle speeds of 3,000 to 12,000 rpm for high torque milling (~$800 spindle), and 5,000 to 20,000 rpm for engraving (~$1,700 spindle) -- the spindle motor and spindle assembly look small. Belt or gear driven, no spindle collant system, good duty cycle capability, and tried and proven technology.

My question is: what motor and controller system would be used to turn a low inertia spindle, with 1/8" to 3/8" engraving bits, continuous duty cycle at 15,000 rpm for 5 hours per engraving job?

AC or DC motor, what kind? How would you controll the speed? Can such a motor run continuously for 5 hours under load at 15,000 rpm?

Some body must have done this. I seem to know that commercial routers run at these high speeds, under very punishing loads, for long duty cycles. Can anyone suggest a commercial router for $500 to $1,000 that has an ER collet system, that can run continuously for 5 hours under load?

Thanks for your help.

Whelen

Outline of the information on the MetalWorking Machines >> Benchtop Mills
thread "High Speed Spindle for SIEG X2 Mill - getting Technical"

Description of the bench top mill that is being converted to CNC
Brainingstorming - PROXXON Micro MILL MF70 spindle head
Torque equation - machining
Torque equation - motor
Spindle price points
Article, url for "High Speed Spindle Design and Construction"
Motor ???????????????????????? Where's the motor and controller?
Flashcut CNC "spindle" price points
Toolswitch "spindle"
Cncmasters "spindle"
Air motor spindle
Roland MDX-500 engraver and milling
High speed spindel - deadly danger !!!!!!!!!!!!!!!!!!
Many feeds and speeds urls, some high speed machining
High speed machining - metals - soft to hard
High speed machining of soft and hard plastics

I have just joined your group and part way through building my CNC router, i too am looking at high speed spindle drives, and i am looking at brushed motors as these will run at high speeds on both ac and dc supply, speed control for ac is relitivly easy as a commertial lamp dimmer will work well dc speed control will require some electronics in the form of pluse width switching, but in either case not impossible.
As these motors will run up to 10,000 under normal loads i have decided to use a belt drive to step up 2:1, the horse power of the motor should be able to cope with this load, i have chosen a vacume cleaner motor rated at 1400 watts.

I have yet to build this part and may yet find problems not so far thought of.

one point mentioned in the thread is strong casing to stop bits flying off, could be problematic.

I am and will always be a skinflint & a tight fisted project engineer so every thing is always an up hill struggle but the results when thay work are just fantastic.

regards
to the group

CNCEzee....Roger

Hello all,
High speed indeed, what kind of tooling will hold up,carbide?
What depth of cut? Seems to me you end up in the grinding arena
at those speeds?
Bear

Hi,

There is now available a huge range of carbide bits cutters and burrs and the smaller in dianiter you go the higher the speed you require, i know an engineer who regularly runs his machines at 30,000 rpm usinf bits as small as 0.3mm diamiter engraving brass steel and stainless steel, if you do not run at high speeds you will break the cutting bit.

CNCezee

CNCEzee....Roger
Developing your own solution is the way to learn. Functional analysis of the main functions - motor, spindle, and controller will uncover the pros and cons of a concept. You already have the knowledge for the motor and controller. A process we used in advanced development was to first understand the functionality, price, and value of existing commercial solutions. Some candidates I have found may be useful to you.

#1 Hitachi KM12VC Router - $179 - 120v AC, 11 amps, 2.25 HP, no-load rpm 8,000 to 24,000 - collet capacity 1/4" and 1/2" only. Two stage motor release clamp for quick and accurate depth adjustments. Nickel plated motor housing, for smooth depth adjustments. Electronic speed control, maintains constant rpms even as load varies. Class leading noise level, only 79.5 dB. Fine depth adjustment.

#2 MILLING MOTOR KRESS 900 W ELEKTRONIK / $ 295.- www.debece.net
This powerful milling motor is fitted with a six-step speed control adjustment for speeds between 8,000-26,000 rpm. The set speed remains stable even under load. Comes with manufacturers one-year warranty.

These two commercial products are possibly, examples of what you are trying to accomplish.

Good luck.
Whelen

CNCezee and Bear
I was surprised to find that since the 1960s, when I worked as a Manufacturing Engineer, that a new technology has revolutionized the machining industry - high speed machining. This technology was adapted in the 1990s and required the development of high speed spindles. I have shared some of what I learned in
MetalWorking Machines >> Benchtop Mills
"High Speed Spindles for SIEG X2 Mill - getting technical".

The engraving industry has been using high speed machining for decades. Remember that spinning tool bits, and carbide inserts at these speeds is deadly. Also the collet chuck technology, collet design, and tool locking mechanism is unique to high speed machining.

So, yes Bear, running at these high speeds requires specialized knowledge of the speeds and feeds required for the specific materail to be machined, the tool bit cutting geometry, and the tool bit material. The traditional feeds and speds are not applicable.

Whelen