Where does one purchase a complete (less drive motor) milling spindle to hold end mills of 1/8- 1/2" diameter? This milling spindle will be mounted by me on a purpose built Z-slide with 10" of travel for my B'port mill. Though built on HSR-25 slides and driven by a 20mm ballscrew I would think that a 1/2horsepower cut would be all this would be capable of, especially for jobs that require the slide to be extended 6-10 inches.
Where can one buy a medium duty milling spindle? I will build the spindle mount so its base configuration and drive pulley location are not critical. This must be suitable for cutting steel mold components at times (with small cutters) though it will more commonly be used to machine plastics. No wood router spindles please! Thanks.

Hello
I don't know how much ability you have, but you may want to make your own spindle. The cost on custom spindles can get pretty high. One place to look for a supplier though is Thomas net. Good luck!

Hi, I think that K2cnc offers spindles (in addition to routers) Here is a link to a cnczone forum section on their products, and they have a web site link as well in there.

http://www.cnczone.com/forums/forumdisplay.php?f=352

I bought a book on making machine spindles. It was offered by "ohojim" on ebay. Very informative book. Even though I was a mold maker back in the day, making a spindle scared me more than a little. Could I make it accurate enough with my present equipment (no I.D. / O.D. grinder), would it end up as another started but never completed project? I then took a look at the K2 spindles. Very expensive. I think I am once again motivated to build a spindle, unless most of a spindle could be pirated off a B'port or other machine on its way to the scrap yard. Even if I had to replace the worn out bearings it would be a lot less work than making the whole thing.
thanks,

little machine shop sells r8 spindles a few different ways. just the spindle, the spindle in the head, & the spindle with the motor & controller. they have trouble with the plastic gears but you could get a belt conversion & be able to run aprox 6000 rpm. also hoss has a cnc conversion on here under benchtop mills where he makes his own belt conversion. hope this helps, greg

We built a 5'x10' CNC router/mill, very heavy all out of steel. 4"x6"x1/2" wall tube for all framework. The Z has a drilled grid plate that we can bolt various things to, I believe in maximum versatility. We can bolt a router to it for wood/plastic/aluminum, or a milling spindle for steel etc. If you look around you should find a cheap mill to steal parts from. We were given, just for the cost of moving it, an old (obsolete) Moog Dynapath that we took the spindal out of and belt drove it. It even came with a complete set of tool holders and collets! The other thing to keep in mind is that horizontal mills are even easier to get for free or very little ($100.00). Don't forget to check with schools and school boards, they don't know how to get rid of old equipment. I took the beam off a couple of them, slide in a ground down to fit "I" beam, and mount a common drill press head on that. It makes a drill press with a table a thousand times better than average. Then take the spindle out of the horiz. mill and make a "holder" for it and turn it vertical to use in your mill!!

Where does one purchase a complete (less drive motor) milling spindle to hold end mills of 1/8- 1/2" diameter?

http://www.finleyspindles.com/index.htm

I checked out www.littlemachineshop.com. The mini-mill head offered there with a R-8 spindle looked a little light but they say it weighs 20 pounds so it can't be that frail. I ordered it. With the retrofit belt drive system they say it is good for extended operation at 4,300 rpm, though I'll have to wait for the belt drive as it's out of stock for now. This system looks like it's a good solution and way less work than building a spindle. If i need that heavier spindle another day I'll see about pulling one from a defunct B'port.
Thanks to all who offered suggestions.

I bought the mini-mill head from littlemachineshop.com. One needs suitable expectations when he buys 10 pounds of "precision" machine spindle for $100. Add onto that a draw bar and spanner an the total is more like $125. It is made for R-8 tooling so no new tool holders needed.
I installed a 36 tooth 5mm HTD pulley on the top of the spindle (internal gears, shifter removed) and a 48 tooth pulley on the 1/2 horse PM motor that would drive the spindle. A 'L' shaped bracket was made, holes laid out for the motor and to attach to the head and lastly slots for the belt to pass through. The spindle sounds good though not quite as quiet as a new B'port spindle. Remember it's only $100. I clamped the spindle onto the table of my mill so i could use it to drill the holes in my Z-slide without taking that structure off the mill. Alternatively I could have drilled the hole pattern into a steel plate, clamped that onto the slide and then used a hand drill. I then bolted the head onto the slide and began shimming and tramming the head. The spindle centerline is at an angle with the machined back of the head. A 0.006" shim fixed that. The sides of the head are at a much greater angle but no big deal to cock things around to get the spindle centerline parallel to the Z-slide.
The new spindle works pretty well. No problem for the 1/2 horse motor to pull a 3/16" ball endmill in aluminum at 80 volts. Max power would be at 90 volts. It's a good enough solution and it only took three days including making the HTD pulleys from alum. baar stock.

Another day i will make a better spindle and use a 1 horse motor as well. Making a spindle takes more time but like the projects I and others have completed, just work on it every day for a half hour or a half a day. If the project is planned out well there won't be too many dead ends and soon enough it will be done.

thanks for suggesting LittleMachineShop for the off the shelf spindle.