Chinese 2.2 water cooled spindle / Which VFD ?

[stuboy]

I have a Siemens Micromaster 420 on my 2.2Kw Chinese spindle, have mach3 controlling it just my breakout board frequency to voltage converter is not linear as far as i can tell!
Cheers
Stuart

[dudz]

Ok, you win ! .... I know you people have far more exp with these things than myself. I have canceled my order for the Kress, and I am ordering the Chinese spindle and VFD.

[Jonathan]

Ok, you win ! .... I know you people have far more exp with these things than myself. I have canceled my order for the Kress, and I am ordering the Chinese spindle and VFD.

:) I'm sure you wont regret it. You'll probably want to get these to go with it:
Brand new precision ER20 collet set 12pcs (2mm-13mm) | eBay

[dudz]

Thanks Jonathon. Please could you post a link to a set of bits/endmills that would be used for Alu with this setup. ?

[Jonathan]

Depends on what you're cutting of course, but for general 2.5D machining I use the 6mm single flute cutters. I quite regularly use the same style cutters from 3mm to 8mm. The tool deflection is proportional to the length of the tool to the power 4, so a small increase in the length of the tool can lead to a much higher deflection and thus poorer finish, hence you should always buy the smallest ones you can use, so ideally keep a selection...

[dudz]

is that the same bit for "rough cutting" and "finishing" or is there no such thing on Alu ?

[Jonathan]

is that the same bit for "rough cutting" and "finishing" or is there no such thing on Alu ?

Yes, for roughing use it at whatever the maximum depth the machine will tolerate is, but leave the part 0.1-0.2mm oversize. Next do a finishing pass the full depth in one cut, which just removes the 0.1-0.2mm.
13000rpm @ 600mm/min is a good speed for the 6mm single flute tool. Start with a smallish depth and work up, keeping the feed and speed the same, until you find the limit of the machine/cutter.

Roughing cutters do exist for aluminium. They have a serrated edge which is designed to break the swarf up into small pieces which can easily be washed away by flood coolant.

[dudz]

What do I use for drilling and countersinking Alu?... seems a daft question. I want to make a new Z plate soon, to hold the Chinese spindle, as the one on the machine is only 100mm wide. The spindle holder for the Chinese one is 140mm wide. So I need to accurately drill the holes for mounting on the machine and for the spindle holder. Links on ebay would be fantastic if poss.

[wilfy]

i'm not sure about countersinking so hopefully someone will jump in.. but drilling alu is very easy as it's really quite soft, any HSS drill bit should be good enough, just pilot with a 3mm or similar first then open it up with the right size bit for your bolts and even tap it with standard taps if you want it threaded

[Jonathan]

You can countersink it with some countersink bits that would be used on wood, but the ones designed for metal do work better. Don't countersink the holes since the bolt will align to the hole if it's countersunk, so you have no room for adjustment which is important to get the spindle aligned properly (i.e. in tram). If you need the head of the bolt below the surface of the aluminium, then counterbore the holes and use socket cap head bolts.

Other option is to make a 100mm wide spindle mount. If you can bolt it from the back then it shouldn't be too difficult. I've made one that's 110mm wide.