Wich spindle is best??

[quant]

Hi all,

I'm designing a cnc milling machine.
The scope of this machine is for milling metals like aluminium and soft steel. But except metals I also want to be able to mill plastics and even route wood. In other words it needs to be very precise for small pieces of alu, steel or plastic and have a "large" working area, (750*750mm), for use on wood.

Now I'm looking at different type of spindels and don't really know wich one is best for wich application.

First one on my list is a Perske HF 3phase spindle with a power rating ranging from 0,3 to 1kW and a max speed of 24000rpm.. These seems te be very robust industrial machines.

A second option would be an HF spindle of the brand "Precise" with a power rating of 1,1kW and a speed ranging from 15000 to 60000rpm.
These units on the other hand seem really fragile in comparison with the Perske spindels.

The third option is an HF spindle like the "Precise" one but from "Fortuna".

I suppose that option 2 and 3 are more precise than the Perske spindle, is this true? Also what difference is there between a spindle at 24000rpm and one at 60000rpm??

Is it possible to use one of these to cut all above material? I heard that aluminium and plastics needs slow speeds, while wood needs high speeds with lots of power? Is this correct? And what about steel?

Wich one would best suit my needs do you think??

Many thanks in advance.
Regards,
Qeuntin

[Cruiser]

your really mixing up your materials, and that is what your going to have to consider. matr'l vers cutter equals speed ! may need to be able to change between spindles ! what you need to do is look into cutting speeds and the cutters you'll be using and see which speeds best suit those selections !

[quant]

Yes, I am indeed mixing materials. I know this doesn't seem like a good idea.
But I want to make one machine to to do everything, since I don't have the place for two machines and I think it's better to invest in good screws and motors for one machine instead of using lowergrade for different machines.

What you say about changing spindle doesn't seem to be a bad idea, had thought about that too. But what is the real difference between a perske spindle wich looks a big heavy motor and little light "precision" spindle?
Wich one should be used for wich material??

Regards

[Cruiser]

you missed the concept a bit, the spindle is for transmitting torque and speed to the matr'l ! 60,000 rpm would run a diamond burr quite nice or a very small cutter in most matr'ls but most likely won't slow down enough to run larger cutters, say 1/2". I'm not familliar with the spindles specifically that you are looking at, but, that is irrellevent. decide what you want to cut (you did that) then decide what cutters you'll be using and at what speeds they like to run in your matr'ls. Do some research on cutters and high speed cutting, and also how rigid is your machine going to be .... a little vibration can ruin a high grade cutter at speed ! I guess that what i'm saying is its going to be the whole of the picture and all its details that matter most on your spindle selction, you will probably find that a good router motor might fit the bill quite well for starting out with little impact to your budget too then if you design to upgrade later and find more speed and power can be utilized economically then go from there ! what i have to think is that if your asking this question then you really need a better answer than what i'm giving, I've been a machinist for over 20 yrs and i'm still learning some of this stuff ! it changes daily and its the whole picture that makes it work. speed is nice if you can afford to pay for very high end cutters that can take it. forget about the low cost carbon cutters. Do some reading on cutters and what they will do and how they are recomended to be used ! it is surprising and there is a lot to learn ! (subject to change without notice !) had to put that in there too ......... good luck

[quant]

Yes, indeed I was a little wrong with the word I used.
With spindle, I meant the motor itself with the precision bearings.

You are probabely right and I should look this into further details before being able to have a descend awnser.
However the reason why I'm not going for a classical router first is that I can have these for a good price and it would be shameful to buy a router if I can get a quality HF spindle(motor) for about the same price..

Thank you for your help!
Best regards,
Quentin