What are the differences between a wood router and other spindles?

[maspeir]

I see a lot of discussion of water or air cooled spindles. What makes these better than a high horsepower(kW) router motor? I noticed that the prices on these start in the several hundred dollar range and go up past $1000.

What would make me want to spend that kind of money on a spindle if a router will do the job?

[awerby]

so it's hard to generalize about them, but the wood routers you're talking about were designed as hand tools for the consumer market, and they have a few drawbacks when put into service as spindles for CNC machines. I'll list a few:

Noise - These things are loud when you turn them on, and get really loud when in use, especially as the bearings age. Pro spindles are a lot quieter, especially per horsepower.

Life - Wood routers were designed for intermittant use, not for long part runs. The bearings aren't that great, and tend to wear out quickly in an application like this. The motors aren't continuous-duty either, and have various parts that wear out quickly.

Runout - The collets on wood routers aren't very precise, and often have quite a bit of runout (wobble). That's bad when you're running a big tool, but can be catastrophic if you try to run a small one, where the wobble factor (TIR) is a significant percentage of the tool's diameter.

Torque - Wood routers have a designated top speed, at which they run best. The electronic speed control units that slow them down also limit their torque considerably. Pro spindles have 3-phase motors that can have much higher HP ratings, and the VFD (Variable Frequency Drives) used to control their speed do that without compromising torque nearly as much.

Size - As I mentioned, pro spindles can be rated at higher horsepower, and they also can handle bigger diameter tool shafts. Most wood routers top out at 1/2"; pro spindles can handle larger sizes; 3/4" and above.

Speed - While wood routers have top speeds of up to 30k RPM, some pro spindles can go much faster. That often requires water-cooling, but it's worth it if you're doing engraving or something else which requires precise rotation of tiny tools.


Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Al_The_Man]

Originally Posted by awerby Torque - Wood routers have a designated top speed, at which they run best. The electronic speed control units that slow them down also limit their torque considerably. [/url]

Now for the Universal type motor Romans PID controller seems to have solved that.
http://www.cnczone.com/forums/diy-cn...ontroller.html
Al.

[brtech]

Originally Posted by awerby ... Runout - The collets on wood routers aren't very precise, and often have quite a bit of runout (wobble). That's bad when you're running a big tool, but can be catastrophic if you try to run a small one, where the wobble factor (TIR) is a significant percentage of the tool's diameter. ... ComputerSculpture.com — Home Page for Discount Hardware & Software

Precisebits seems to have solved that: Collets, Nuts and Toolholders

[maspeir]

My concern with my Milwaukee 5625 router is the life of the motor and runout. I'm not using it for anything else at the moment, and I paid $99 for it at a pawn shop several years ago, so I am not losing much if it goes. The biggest concern is runout. Precision Bits said they would have a Milwaukee collet in a week (two weeks ago). Most of what I am wanting to route will require 1/4" and less diameter bits.

I don't want to spend the money on a spindle, but I may not have a choice.

[ger21]

I'm going to add to and subtract from Andrew's post a little. There are things you can do to make a router work a lot better for CNC use.

Noise. True, good spindles are virtually silent at any speed. But if you're doing any serious cutting, cutting noise can be louder than the loudest router. But if you do a lot of 3D carving, which can take a very long time, then the quiet may be a major benefit.
Although variable speed routers are not loud at all when run at their lowest speeds, usually 8-10,000rpm.

Life. This is one of the major differences. I can replace both bearings in my Porter Cable for $25. The bearings in a $1500 spindle might be $300 or more. ceramic bearings in larger spindles can be even more. But these things are designed to run all day long, every day. A router is designed to run for a few minutes at a time.

Runout. The better routers aren't bad, but a good spindle is almost always better. Some users have gotten bad Chinese spindles, though.
There are aftermarket collets available for routers with very low runout. Precision solid carbide tools for woodworking and metal forming.

Torque. What Al said. But it'll cost you $150 more. But the SuperPID also offers rpm control via the PC.

Size. No spindle under about $5000 can use a 3/4" shank tool. The ones people are using here have ER20 collets, which also limit you to 1/2" bits. and btw, a 3/4" shank spiral router bit will usually cost more than a 2-1/4HP router.

Speed. Spindles for routing are usually only 18,000 or 24,000. Even on $100K commercial routers. There's absolutely no comparison between a 50,000 rpm engraving spindle and a router. There not even made for the same thing. Unless most of your work requires bits smaller than 1/16", than 18,000 rpm is plenty.

[cheetahcnc]

If you are interested in various types of spindle assemblies, Tormach offers a 5000rpm and 10,000rpm units.

CNC Mill Upgrades and Maintenance Products | Tormach | We provide personal small CNC machines, CNC tooling, and many more CNC items
(scroll down to the bottom of the list)

They are both R8 compatible and come complete with motor and dual grooved pulley for speed ranges. If you don't need the full 18,000 or so rpm for all out wood production, these look promising. I am considering one for an upcoming project. The 18,000 rpm 3hp router spindles I currently use can be slowed down for non wood projects, but the hp is reduced proportionally. Tormach also offers a quick change drawbar and tooling system.

Jim

[yamamura]

Precision Bits said they would have a Milwaukee collet in a week (two weeks ago). Most of what I am wanting to route will require 1/4" and less diameter bits.

[RomanLini]

I'd like to add a couple of points too.

Noise; As Ger21 said mnany of the newer routers are queit at lower RPMs. Cutting tool noise is louder than router noise on my machine up to about 14000 RPM and at <10000 RPM is as quiet as it's bearings.

Ridgidity; Many routers have plastic frames to hold the bearings, they will never be as rigid as an all-metal cased spindle especially for side loads. But many of the larger "pro" style routers are made for multi-hour use and do have full metal frames and are rated for some good axial and side loads, they can be more rigid than some of the low-end (skinny style) VFD spindles.

Torque and Power; Most of the large frame routers 3.5 hp etc when used with a PID speed controller will produce a lot more shaft power and torque than the smaller range of VFD spindles like the 850W to 1200W models.

Also, the VFD spindle if exposed to peak torque loads can get a momentary sync loss, (like a stepper motor skipping steps) so it has a lower peak torque than a router that behavesmore like a DC brushed motor and will allow very high peak torque loads. All in all a large pro style router with a PID style speed controller behaves like a very powerful servo motor and a VFD spindle behaves like a stepper motor.

[ahmed]

Hi All

I have a big problem with my spindle
here is the spindle link on ebay

NEW AIR-COOLE MOTOR SPINDLE 3KW AND MATCHING INVERTER 1 - eBay (item 170563970591 end time Jun-06-11 21:03:51 PDT)

spindle is 3kw 400h

the problem is :
when i try to engrave on mdf wood and set the depth of engraving to 4mm the spindle stopped and i have to move the z up to avoid spindle heat

my vfd setting as they sent it to me

Firstly, adjust the PD013 to 8 (set the setting to factory setting)
Secondly, adjust the PD005 to 400
Thirdly, adjust the PD004 to 400
Finally, adjust the PD003 to 400
Finally, adjust the PD144 to 3000
Note: you should set PD013, PD005, PD004,PD003, PD144 in order. It mean you should firstly set PD013, then PD005, then PD004, then set PD003, finally set PD144.
Note: after you set the all above parameter, then please recheck the PD005, PD004, PD003 value is 400 or not to confirmed that you already set it. (note: please do not check the PD013, or all the setting will go to factory setting)
The reason we let you recheck is that if you do not set it at 400, then when you run the spindle motor, the spindle motor will be over-current, then the spindle will very hot and then within 5 minutes, it will broken.

i do this steps and the spindle run fine but without torque
i tried to run the spindle at 12000 speed and 18000 and 24000

In the end I was disappointed


i hope any one help me to setting up the vfd to get me the spindle torque

best regards
Ahmed

[Treischl]

My two cents worth:

Anytime you cheap out, you get what you paid for. Buy a cheap spindle, you are probably going to get less than great results. Buy a cheap router, same thing.

There is probably a crossover point where a good quality router does a better job than a cheap spindle.

What I see a lot of on the forum is people talking about palm routers, which are the lower end of the router spectrum, plastic housings, etc. What I do NOT see people complaining about are good quality routers or good quality spindles. But I do see them complaining about cheap spindles. There seems to be a common thread there, the low end of anything seems to be a problem.

It is beyond me why someone would invest in building a machine, and then, when they get to the point (literally) where the tool meets the wood, they cheap out.

I would agree that routers are noisy. There is no getting around it.
You can improve the runout by getting precise collets as Ger21 suggested.
I do not agree about the life statement, my Porter Cable routers run for hours at a time.
Torque can be controlled with the Super Pid solution.

My feeling is that a good quality router may be the best bang for the buck if you are willing to put up the noise. Of course, this is all my opinion.