800w spindle - noise & controlling remotely

[Jonathan]

I agree there's not much point oversizing if you're getting a VFD from a reputable manufacturer - unless maybe it's being operated at an unusually high temperature. You'd be fine with the 0.75kW Toshiba VFD as you'll struggle to draw full power from the spindle, and the worst that can happen if you do is the VFD will just cut out to protect itself. It's better to select the inverter by current rating, not power rating.

The VFDs from China let you set all the relevant parameters, like current and voltage, accurately so there's nothing to worry about there.

Plenty of the 1.5kW VFDs available for £86:

http://www.ebay.co.uk/sch/i.html?_so...D&LH_PrefLoc=2

Maybe less if you use best offer...

[Boyan Silyavski]

I agree there's not much point oversizing if you're getting a VFD from a reputable manufacturer - unless maybe it's being operated at an unusually high temperature. You'd be fine with the 0.75kW Toshiba VFD as you'll struggle to draw full power from the spindle, and the worst that can happen if you do is the VFD will just cut out to protect itself. It's better to select the inverter by current rating, not power rating.

The VFDs from China let you set all the relevant parameters, like current and voltage, accurately so there's nothing to worry about there.

Plenty of the 1.5kW VFDs available for £86:

1.5kw VFD | eBay

Maybe less if you use best offer...

Thats what i was just going to tell. GOOD 2HP 1.5KW VARIABLE FREQUENCY DRIVE INVERTER 220-250V 7A VFD o4 | eBay

The one from his link is 380V and 230v input, that's why is more expensive than the 230V input.

[HankMcSpank]

The braking resistor (referred to in the drawing in this advert - HIGH QUALITY NEW 2HP 1.5KW 7A 220-250V VARIABLE FREQUENCY DRIVE INVERTER VFD T2 | eBay ) ....presumably this slows the spindle quicker when the spindle is stopped - is the resistor needed (in other words does the spindle take forever to stop without it)....is it as simple as a large wattage resistor...and what's the spec typically used for the braking resistor? (on the toshiba it said "braking module available separately" ....which suggests it'll cost a pretty penny!)

[Jonathan]

You don't need a brake resistor as the spindle will stop in a few seconds without it.

[Boyan Silyavski]

However its a good idea to program ramp time of 6 sec in the Vfd and 10 sec dwell time in Mach3

[HankMcSpank]

for what it's worth, this seems to be the spindle I have...

800W High Speed CNC Spindle Motor, View spindle motor, JST Product Details from Changzhou Jiesite Electrical Co., Ltd. on Alibaba.com

(the model is jgd-65c-800 - it has 400Hz stamped on the case)

[EddyCurrent]

The braking resistor is mostly for when a motor is connected to a load, for example imagine a motor connected to a 10ton flywheel and somebody hits the emergency stop button. There's a lot of energy to get rid of in a short space of time and it's the resistor that dissipates this energy, obviously a spindle in our application does not have a load connected.
Also re. ramp times, in the ABB I use on my pin router I have the normal ramp time set to something over 5 seconds (can't quite remember) but I can set another ramp for emergency stop situations and this is set lower and for this I use a braking resistor (because I already had one) which allows it to stop very quickly but in reality it's not doing a lot. Also the resistor is there to prevent damage to the drive, depending on how much protection is built into it the DC link voltage can rise and cause damage.

[Jonathan]

In my first post when I talked about getting the higher quality version of the 800W spindle to reduce noise (among other things), I didn't realise that you already had a spindle. I've made the video comparing the two spindles I have to hand:



Again, the video makes it sound worse - in reality the 3kW spindle is so quiet that you could almost forget that it's switched on.

[HankMcSpank]

Thanks Jonathan...quite a difference - even with the 3kw spindle lying on a large flat table (which will possibly 'amplify' the spindle's sound/vibrations ....just like a soundbox on an acoustic guitar).

The smaller spindle sounds quite loud to my ears...but again, that might be a trick of the camera mic.

(btw your audio in that youtube video drops out completely at approx 4m16s)

[Jonathan]

(btw your audio in that youtube video drops out completely at approx 4m16s)

Hmm, that's annoying as I just deleted the original so it'll have to stay like that. In the rest of the video I put the radio on again to demonstrate how you can't hear it with the old spindle running and also commented that it's all a bit insignificant compared to the noise generated when cutting unless perhaps what you're cutting uses very small/light cuts.