Chinese CNC machine...whatchathink?

[HankMcSpank]

Actually, I hummed & hah'ed for a while (always a good thing as I often change tack!) then I happened upon a reasonably good site (well, by Chinese Standards anyway).... http://cncdiy.org/ ...they've got a 'which CNC is best for me' matrix listed on there ...and he actually makes some important points. I guess we're all guilty of trying to spec/buy a jack of all trades CNC machine , but as he poijnts out that's a mistake...I really only need a small machine to mill acrylic & PCBs, but I was going to buy a larger one in case I needs to do something bigger, but with size comes weight (obviously), noise, vibration, flexing etc (not welcome if 90% of my stuff is small anyway!).....so I'm just going to buy the minimal I can get away with size wise & go for this one (which his matrix recommends for PCBs)...

https://sites.google.com/site/cncdiyorg/2520 (I reckon about £600 + import duty + VAT)

if push comes to shove, I'll get a larger one for my other needs at a later date.

[M250cnc]

The only thing to be aware is that is gonna be a noisy machine at full revs

The noise will be coming from the tool spindle hardly any from the stepper motors/drivers.

To cut down the noise you need a water cooled spindle but they tend to be bigger in relation to the motor supplied with that machine so a water cooled spindle will not fit that machine.

Be careful of the shipping cost, the ebay machine looks almost identical and that would cost £746 inc shipping, plus any import taxes

Phil

[Jonathan]

The only thing to be aware is that is gonna be a noisy machine at full revs

The noise will be coming from the tool spindle hardly any from the stepper motors/drivers.

To cut down the noise you need a water cooled spindle but they tend to be bigger in relation to the motor supplied with that machine so a water cooled spindle will not fit that machine.

I agree, brushed motors like that are very noisy. Now I've got the water cooled spindle there's no comparison, however the cutting noise is, of course, still a significant contributor to the noise.

[HankMcSpank]

Maybe it's just the way they've all been recorded, but I'm struck at how much noise the Chinese water cooled spindles still seem to put out in some of the youtube videos folks have uploaded ! (perhaps it's just the microphone being too close to the cutter - but for example - http://www.youtube.com/watch?v=2OZCv...eature=related (2m16 in) ...or maybe the acoustic vibration/whine of the spindle is being amplified by the machine frame?

[ptjw7uk]

In the video it makes the point ' with a lot less noise' Best to sak JohnS as he has one of the spindles.

The noise will vary anyway when its cutting. If its less noise than a router at full tilt ... then its quieter.
If you cut anything at 24000 rpm then its going to make a noise anyway!

peter

[Jonathan]

https://sites.google.com/site/cncdiyorg/2520 (I reckon about £600 + import duty + VAT)

Seems expensive to me, why are you so sure you don't want to make one? A machine that size is relatively simple.
Anyway, it says the spindle speed is only 10,000rpm. That's good with regards to noise, but you're not going to cut PCBs very fast at that speed. I generally use about 25mm/min per 1000rpm. So 250mm/min with that spindle, which is a lot less than the machine is capable of.

[HankMcSpank]

Seems expensive to me, why are you so sure you don't want to make one? A machine that size is relatively simple.
Anyway, it says the spindle speed is only 10,000rpm. That's good with regards to noise, but you're not going to cut PCBs very fast at that speed. I generally use about 25mm/min per 1000rpm. So 250mm/min with that spindle, which is a lot less than the machine is capable of.

It's a time thing really...I've just been made redundant (20yrs with the same company! Hey ho...at least they gave me a big fat cheque, which rather than spend on loose women and fast cars - which my wife says I can't - I thought I'd put it towards some stuff that will make some stuff) ....so I now need to get some of these 'widget' ideas out of my head & into the market to see if they're viable! (if not, I'm gonna have some fun anyway! "March of the makers" eh"?!!)) I don't want to be dicking about spec'ing a machine. then ordeing a bit from here, a bit from there, then assembling blah blah....that takes time & for all you think I'd have loads of time on my hands, I don't (not to be building a machine anyways).

The more I mull this, I realise/concede that it's probably best to have a machine that's capable of milling aluminium...some of the widgets I have in mind are gonna need injection moudling (there only small simple pieces, but nevertheless the cost of getting them made is prohibiitve), so having a machine strong enough to mill steel/ali will be of great help if I do need to make simple injection moulds (but best do that when the neighbours are out!) .... a bench top injection moulding machine would be nice too!