Cheap chinese VFD spindles suitable for low RPM (plastic milling)?

[bootje]

Hi,

Looking for an upgrade for my stock cheap 3040 CNC with a brushed spindle 300-400W 8000 rpm max DC spindle, I would like to move to a better, more versatile spindle.
Right now I do PCB milling (at the highest rpm) and some plastics (at low RPM). But I want to raise the quality of the PCB milling (not that it is really bad, but a bit less burr would be nice, and I understand I need higher RPMS for that), and I would like to do some Aluminium as well.
I know that the frame is not very rigid, so Aluminium milling will have to be slow.

So that means: better, more power, higher max rpm, BUT: while keeping a reasonable low minimum RPM. And that is my problem.
Increasing the feed rate is not really possible with the frame and steppers I have. So I will have to keep RPM low for the plastics, like around 3000.
I haven't found any power/torque curves for sub-500EUR spindles, and many posts here say that 10krpm is like the minimum for most of them, unless I want to burn the motor out in no time.
The spindles I have found that have power/torque curves, and allow low RPM, are in the 600EUR+ range. Not what I wanted to spend.

My question: are there any not too expensive spindles or routers that would allow me to do PCB, plastics, and some Aluminium on my 3040 frame? With my limited knowledge and experience, I have translated that to: 3000-16000 RPM, 500W or more, spindle/router weight below 2.5kg. And not too noisy please.

Any aliexpress/ebay spindles that would do?
Or a Dewalt/Makita/Kress/AMB router would be a good fit?

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[CitizenOfDreams]

The next step up from your existing spindle would be this:



https://www.ebay.com/itm/ER11-Brushl...0AAOSwzoxd7bFD

Truthfully, I don't think putting anything better than this on a 3040 is worth the money. This spindle is pretty much the same mechanically as your old one, except it's a brushless DC motor. Works fine between 2000 and 12000RPM. The only thing you need to do is throw away the fan and replace it with something better balanced.

[joeavaerage]

Hi,
quite frankly you are asking the impossible, you want a spindle that can go slow with plenty of torque, never mind how its cooled, and can also
go fast.....and be as cheap as chips?????

I tried the same thing when I started, and I learnt that to accommodate wide extremes of operation can be done BUT AT A COST.

I ended up buying a 750w 24000 rpm spindle from Mechatron in Germany:

file:///C:/Users/User/AppData/Local/...08-24-ER11.pdf

And its been great and I use it a lot. Not to say however that I was disappointed with it when I realized that it couldn't really go below 9000rpm without
overheating and it has so little torque that it can't really cut steel like I had hoped. It was very much a reality check for me. I just had to learn and realise
that (cheap) highspeed spindles are just not cut out to run at low speeds.

There are spindles, all water cooled, that can run at low speeds but in order to have useful torque then the rated power of the spindle will be HIGH, 2 plus
kW with a single phase supply input VFD and 4kW plus for a three phase supply input VFDS, and ALL of them COST!!!!

What I did was make a second spindle using a 1.8kW 3500rpm 6.1Nm(cont) AC servo and Rego-Fix cylindrical toolholder and angular contact bearings.
Not a cheap undertaking but I now have a spindle that will cut steel and stainless.

I am building a new mill, one that can make circuit boards but ALSO have some serious power and rigidity to cut steel. This is the spindle I want,
again from Mechatron in Germany, the quality is so good indeed:

file:///C:/Users/User/AppData/Local/...SK_-_WEB_2.pdf

That's 2.2kW(100%), 42000 rpm, pneumatic HSK automatic tool change, pressured air seal, water cooled and ONLY 5400 Euro, that's without VFD, water pump or any HSK
toolholders!!! As much as I would like it I can't afford that....but it just goes to show you can have low speed torque AND high speed IF you are prepared to pay.

Craig