[BobF]

You could use a high frequency "motor". My lathe has a variable speed drive. This is simply a 3 phase motor running with a variable frequency inverter drive. The electronics take a 220 volt single phase input and output 220 volt 3 phase at variable frequency. The frequency control gives you variable speed within a range. You can buy a drive and a motor in 2 HP range for about $500. This is a motor designed stationary installation and it wieghs about 45 pounds. You could use belt drive to run a spindle. If you have a moving gantry style machine it would need to be pretty beefy to hold the motor, and need some stout motors to move all the wieght. You might want to consider a moving table design. This type of motor runs at 1750 rpm in normal operation (connected directly to AC). With the variable frequency drive the drive would output 0.5 to 360 hertz. You would have a speed range of 200 or so to 3000+ rpm. If you used a router as a spindle the variable speed routers run a low speed of 8-10000 rpm up to 22-24000 rpm. This will be the big difference. Most mills designed for metal run spindles at the lower speeds of the motor example above. The biggest challenge of the spindle design is the side loads imposed by cutting and the accuracy needed for some cutting jobs. Here is drive designed for the motor example above and at the bottom of the page is a suitable motor.
http://www.driveswarehouse.com/Drive...0-015NFU2.html
A similar motor runs my lathe. It has a 2 step pulley system for the belt drive to the spindle. Changing the belt step gives you a choice of higher torque and lower speed limits, or higher speeds and less torque. This is a wood lathe, but I have cut aluminum on it with wood cutting gouges. I can't do high precision work, but I can cut aluminum with some care.

[axkiker]

so im curious why no one has made their own spindle and attached a motor via belt etc. Seems to be a pretty easy task if you have some machining equipment. I hear alot of people talk about the router being the weak link due to bearing and power. Well why not eliminate it by making a spindle of your own. Am I missing something here.

Also since a router seems to not be large enough has anyone tried running multiple motors. Ex: multiple treadmill motors runing a spindle via a belt.

any thoughts

[EL34]

When I was looking at potential designs for a new router a few months ago, I looked at a lot of web sites of home made machines.

I saw lots of pics of home made spindles with one and even two motors. Some had multiple pulleys so you could change speed.

Crusing the web gave me a ton of cool ideas. Takes a bunch of time, but it was worth it.

[Gads]

your thoughts sound ok motor belt etc. I converted a small clausing knee mill
and run a 1/2hp 1750rpm. you don't need rpm you need torque and rigidness.
the drawbacks i have found with my system have all been due too machine
rigidness and play, backlash, wear, etc.

I put a 2h/p 3750 on my mill and it was too much for the machine to handle
not the cnc. I think my motors are 400oz. or so 2 to 1 ratio. i believe i have
made it go 50ipm but leadscrew and bearings cant take that speed for long.

running short on time hope this helps, any questions just send me a message

[axkiker]

hey thanks for all the help. ill do a search for home made spindles and see what I come up with. I have a friend of mine who is an aircraft mechanic checking to see what type of bearings they use. I figure if I can use thoes they sure as heck should hold up.

thanks

[LeeWay]

The proper bearings for a home made spindle that is built for high speed aren't cheap. This coupled with the precision needed to build the spindles and the cost of a big enough motor and controller with the desired qualities are what puts most guys off on attempting to build their own. It can be done. Some guys have and are doing these. Just do a search for spindle designs on here and several should pop up.
The end result though is that you really can't make these much cheaper than you can buy them for unless you have a full blown machine shop already. Then perhaps slightly cheaper.
There is however, always that next great design or building technique that is waiting to be found or exposed. Give it some thought and research. Come up with something that we can make ourselves.

[axkiker]

The proper bearings for a home made spindle that is built for high speed aren't cheap. This coupled with the precision needed to build the spindles and the cost of a big enough motor and controller with the desired qualities are what puts most guys off on attempting to build their own. It can be done. Some guys have and are doing these. Just do a search for spindle designs on here and several should pop up.
The end result though is that you really can't make these much cheaper than you can buy them for unless you have a full blown machine shop already. Then perhaps slightly cheaper.
There is however, always that next great design or building technique that is waiting to be found or exposed. Give it some thought and research. Come up with something that we can make ourselves.

lucky for me i have a good amount of machine tools at my disposal. I have been checking around and I think my first task will be to tackle this spindle problem. I want to me sure I can pull it off prior to going to the trouble of building everything else.