View Full Version : Taking this route for spindle

24-08-2010, 10:34 PM
I'm looking to use this senario of spindle drive rather than conventional kress/water cooled spindle.

It will use the (ER) type chucks and collets which will multiply the use of different bits rather than only have a limited tooling option using a kress ect,ect.

I have a brushless motor at hand,in the process of making a pully for the motor but don't know what size (ER) chuck to go for yet?

Whats the pros and cons of this type of set up? :tup:


24-08-2010, 11:13 PM
Hi George
Brush less motor and ER collet are good but not sure I follow the design (call your self an artist....:naughty:). Is that the ER collet shaft mounted parallel to the motor and the bearings are in the joining Grey bands? if so then there is quite a lot wrong.

The bearings need to be as close to the collet chuck as possible and the spacing and mounting type can be quite critical. running the belt like that will also cause problems. If I were you I would mount the motor up the other way so the pulley is driving at the opposite end to the cutting tool, Like nearly all spindles are, and lower the bearing mounts.

What speeds and diameter shaft are you looking at? as these are also quite critical. A low speed (less than 10000 rpm) 20mm shaft is not to difficult or expensive but larger diameters and higher speeds mean expensive bearings to reduce heat and lower the rotating mass, good balance is also needed and oil or water cooling at the extremes.

As usual I have probably got the wrong end of the stick, but hopefully there are some useful points :smile:

24-08-2010, 11:25 PM
First off,Ross...have you tried drawing with a mouse? :lol:

Ok,if all goes well? a guy I know has a treadmill he's wanting shut of for 25,the motor and its dropper and speed control can be housed in a seperate unit away from the motor or CNC and connected via cable.

I'm led to believe the motor is a 2HP?

The chuck will setme back 18 for straight shank ER25,sothis is not to heavy on the wallet:whistling: doing it this way.

The drawing was crude I know but the brackets affixed to the motor and chuck will be 20mm alluminium plate housing appropriate bearings for the chuck.

24-08-2010, 11:43 PM
First off,Ross...have you tried drawing with a mouse? :lol:

Yeah every day, the trick is to wrap its tail around you thumb then he cant get away :smile:

Anyway back to the spindle. Ok so a bit more info, but still need to know speeds and shaft diameters really.

Even with the 20mm plate you are never going to get both bearings concentric (let alone be able to preload them) unless they are machined in the same operation from one piece of metal, Fact. also how are you going to keep dirt out? 4 friction seals will just generate more heat and problems.......anyway with out knowing the speeds, bearing types and usage its all speculation

I'm not professing to be a spindle expert its just I have spent the last 2-3 weeks looking at every design conceivable and its usually the tried and test ones that work:whistling:

25-08-2010, 12:05 AM
Ok,can't give a speed till I find out how many RPM's this actual motor does,but an average treadmill motor is in the region of between 42 and 4800 RPM's think its 180vDC?

Shaft diameter of motor?shaft diameter ofchuck...well thats easy if its ER25 then its 25mm :lol:

25-08-2010, 12:17 AM
OK, so is that speed acceptable for what you what to cut? If its 2 hp then you should be able to gear it up.

Have you seen Steve Hiltons DC spindle tread? it sounds like you are building a very similar spec spindle, might be worth a read! a couple of points worth noting is not to use toothed belts and normal deep grove bearings seem to be fine :o)

25-08-2010, 12:28 AM
I was thinking of gearing rather than belts,but think will have to wait till I have the motor simply because the ER25 chuck spindle is only 100mmin length and the motor is about 10" long,this could be a problem mounting the two together because as you pointed out the bearings need to be at the very ends of the shaft.

The motor doesn't have a shaft as such but a screwthread sticking out the motos body.

25-08-2010, 12:36 AM
Have you seen Steve Hiltons DC spindle tread?

Nice one,didn't see this thread.

That motor is big and heavy,this one I shall aquire is nowhere near that size and weight?

25-08-2010, 02:49 AM
Hey george Ill have a 99 please, Oh sorry its a drawing of a spindle, must have missed that, Looks like an ice cream dispenser :smile:

25-08-2010, 09:23 AM
You just make sure your boxford doesn't go ding after its finished the work. :wink: