SPINDLES
My machine has a air cooled 2 hp 220v Perske ER-16 Router Spindle. It is not a hand held router.
I use 1/8 shank and 1/4 shank cutters 90% of the time. I really wish I could use a 1/2 shank.
It is true that a LOT of CNC routers use a hand held router as a spindle. But consider this: Routers are purpose built. A hand held router is purpose build to be used occasionally - not constantly. As an engineer I know that machines are designed around "design intent". A hand held router is a brushed motor and the bearings are not constant service designed. Those are the failure points. The CNC Router spindle is an induction motor (no brushes) with constant use bearings. That is a huge difference.
Can you use a hand held router on you CNC machine - YES - of course you can. IS it the best choice? Not in my book.
In my mind the jury is still out on the Air Cooled vs Water Cooled - but I am leaning towards water cooled - only because of the noise factor.
I do work with industrial machines and I have worked with a CR Onsrud twin spindle twin table 25 hp columbia spindles - they were air cooled. The 15,000 RPM horizontal machining centers I work with are air cooled. There are not many water cooled machine spindles that I see in the industrial - except maybe the Studer S33 precision grinder I just bought that is capable on sub micron tolerances - but that is a different story.
I will select a ER20 Water Cooled spindle when I eventually go to the 48 x 48 machine.
The ER series is an industrial series that is precision to less than .0002 and you can buy extra precision to less than .0001. Certainly more that is needed for most of our applications.
As Jason (beamer) said - I have a counterweight on my machine. My spindle is 15 pounds and I have leadscrew but the design of the machine with a small stepper on the "Z" axis caused lost steps more times than I want to remember - so I counter balanced the "Z" axis. I think better design and stronger stepper would be better than a counter balance.
CUTTERS
This is my world - cutters. It is what I have been doing for 40 years - BUT - in the metal cutting industry.
So Wood is a different material and cutter geometry is a
"little" different, but VERY similar to non-ferrous materials like brass and aluminum.
Onsrud is a GREAT cutter - I will take nothing away from Onsrud. I have used them a lot - mostly cutting aluminum.
I may present a bit of a different viewpoint on cutters, but that is because of my background in manufacturing in the metals industry.
I know I have gotten it wrong a bunch of times, but that experience has taught me what is wrong.
**CHIPLOAD**
Chipload is going to be the buzz word when is comes to Cutters and speeds and feeds. That is the biggest question most people have.
The variables here are: material (notice I did not say wood), number of flutes, Cutter material (mostly carbide), tool diameter
I have a spreadsheet to calculate the RPM and feedrate based on chipload. I have a chipload matrix based on tool diameter and material on the spreadsheet. I also have reference to the places I derived the chiploads from - it's not just my opinion. There is also a picture of cutter showing what RPM and FEED and # flutes means. The spreadsheet works - but I want to do more to it to have more cross section to chipload and to make it more user friendly and understandable.
If anyone wants the spreadsheet I will email it but please know - it is not finished.
I wish I could post a spreadsheet here - but that does not seem possible.
**BRANDS**
There are a lot of brands out there. I don' t like and I don't use "cheap". I like great quality but I don't want to pay more for it than I need to. I know a lot about cutters so I shop to find what is going to work best for me and the lowest possible price. After all I am a New England Yankee. I get SGS cutters from
http://www.carbidedepot.com/Dynamiclanding.aspx?CategoryID=4243 They have the best prices I can find for the quality cutters I want. I get all my straight and ball nose cutters from them.
Onsrud is a GREAT cutter and they have single flute which helps to get the chipload where you want it. I don't use Onsrud ONLY because of price. I can get what I want for less money.
Beckworth, MCLS, Bits n Bits, Centerion, Burchett, Think & Tinker Precise Bits, Melin, Garr, SGS - Just to name a few other brands I use.
For the 3D stuff - my most common cutter is a 1/8 ball nosed tapered end mill from Burchett In this video cutting HDU
https://www.youtube.com/watch?v=BdBpddb0jbs I also have 1/16 ball nose tapered and 1/32 ball nose tapered. These cutter are NOT inexpensive, but I have found the cheapest on the market I can find. They just do a job that no other cutter can do.