[yngndrw]

Hi,

I'm wondering what would happen if you were tun run say a 3mm endmill at a really high speed, for example 50,000RPM using one of these: http://www.gison.com.tw/product/P000...4,000-rpm).htm

I know that higher speed means faster possible feedrates, but where's the limit ?

These air spindles have a high speed but a low torque, so if the endmill is spinning this fast it doesn't have to cut as much material away per revolution. (At a standard feedrate.)

So basically I'm asking what implications are there for running a 3mm endmill at 50,000RPM ?

If there are any problems, what is the maximum speed that a 3mm endmill could be used ?

Thanks,
-Andrew.

[kalmah]

It 'll work, it depend of your material. First, ask the power of your spindle. Generally, the power of air spindle is very low (25-100W). If the cutting power is bigger than the spindle power, the spindle stop.

You have a lot of litterature how to calculate the cutting power.

Personnaly, I use this air spindle.

http://www.nsk-nakanishi.co.jp/en/in...s/imf/hts.html

It works very vell, with very small tool diameter <0.5mm...

[yngndrw]

I was looking to aluminium.

Could you direct me to a site explaining how to calculate the cutting power, I searched on Google but didn't find anything of use.

Thanks for the link to that spindle, but I imagen it would be way out of my price range. I am looking for a very cheap temporary spindle for my home-made CNC mill. I need to mill PCBs which requires the high speed, however I also want to mill aluminium. I would be happy with a 3mm endmill for the aluminium, but for cost reasons I want to run them both from the same spindle.

The air spindle I linked to costs around £20 posted so obviously the price is ideal for me - I was just hoping that I could get away with using it for the aluminium too. Maybe after I look at the cutting power formula it may be acceptable ? I will find out how much power the spindle provides.

Thanks.

[Herbertkabi]

Why to play with this tiny toy. Take it in to your hand and try to bend inserted endmill - its not rigid at all this toy. Do it yourself - high-speed brushless spindle http://www.cnczone.com/forums/showth...t=12184&page=5 , you can use even much more smaller rc brushless motor/controller , the only thing what must to be perfect is spindle shaft - collet chuck. Shaft of this air spindle is not very good, its too short ... Many another shafts or collet chucks/extensions you can use. My first 50krpm spindle I used cheap R1212 bearings and work good long time, not for business production of course but anyway OK. All my next spindles, like this one on the pictures, uses precision angular contact bearings and works at least 12 hours in day 365 days in year ...
When choise motor then rotor diameter and KV is important, depends what voltage you use ( 50.000 / motor KV = voltage). When up to 3mm endmill then you need not big motor, amperage will just only few A, ok sometimes 5A when full speed. Motor and speed controll you can buy cheap from ebay, small PWM generastor (servo tester) you need for rpm control, some craftsmanship, mental faculty and nothing more.
Regards,
Herbert

[yngndrw]

Well that is pretty much what I intended to do, or to scale it up and use an X3 spindle with some bearings which can handle a higher speed. (Around 20,000RPM)

But untill I could afford that kind of setup, I wanted to be able to use my mill - This is why I was looking at these air spindles. If they are really that bad I will just wait, however.

Thanks for the link.

[kalmah]

http://www.mitsubishicarbide.net/mmc.../formula4.html

Here is a link how to compute cutting power

[yngndrw]

Thanks for the link, that will come in handy.

[5axisguy]

A 3mm dia endmill at 50k, would not be a problem at all for a ball in some cases. For a light finishing cut, taking say .003 for a finish pass, that would give you a working diameter of about .037, 50k rpm's would be less than 500 sfpm. Not an issue for carbide. I have run finishing passes on hardened cores and cavities at over 1000 sfpm without issues. Of course this is an example with a ball endmill, if your on the full diameter of the tool then your up to over 1500sfpm. That might be pushing it on hard material, mild steel you could get away with it. This would be with a premium endmill of course, no cheap generic tool.

[yngndrw]

Thank you for your help. It seems the only issue with this setup would be calculating the power output of the spindle and the required power of the endmill.

I contacted the company who seem to make them and they seemed to suggest that "Air tools cannot be measured in Watts.", I think there were quite a few translation errors mind.

I will use all of this information for a home-made high speed spindle however, so thanks again to everyone.

[kalmah]

Thank you for your help. It seems the only issue with this setup would be calculating the power output of the spindle and the required power of the endmill.

I contacted the company who seem to make them and they seemed to suggest that "Air tools cannot be measured in Watts.", I think there were quite a few translation errors mind.

I will use all of this information for a home-made high speed spindle however, so thanks again to everyone.

Strange... Personnaly, I've a 25Watt air spindle. If the cutting power is lower than 25Watts, it works, else the spindle stops