Frage Service "par excellence"

Just before the New Year (Friday 30th), I had the misfortune to suffer a breakdown on my SC420/2 - right in the middle of etching a double sided circuit board. S**s law healthy and working full time again!!

Some weird symptoms led me to assume (wrongly as it turned out) that the control board had failed. More in hope than anger I contacted Rory at StoneyCNC to see if he could help with a replacement board.

Of course he could!! Moreover by the end of the day an emergency repair package was organised which would include a power supply adapter, control board and a Z-axis stepper motor. This would be shipped as soon as business resumed in the New Year. It was sent on the understanding that I would use what was needed to get me up and running and then to return the rest. Afterwards he would invoice me for the parts used.

Such outstanding customer service justly deserves a 5 star rating and I am grateful for Rory's wisdom in sending additional items too. It turned out that the fault lay with the power supply not the control board - so much for my diagnostic skills!! I had checked that the PSU gave the correct (30V) voltage, but not when under load - big mistake as it turned out.

Thanks again Rory - StoneyCNC has turned up trumps again!!

Nothing to see here, just Rory being Rory again.

That's great to hear Peter. So many companies offer average or poor after sales service these days it's refreshing to work with Rory & Stoney CNC.

I have the makings of another good news story with Rory regarding the Stepcraft HF spindle issues I've experienced.

I will report back in a few weeks on it if the evaluation works out positively.

For now, further disappointment on the Y axis mechanical operation front. I had it all set up perfectly before Christmas and running smoothly at 3,000 mm/min as evidenced by a succesful oak block cut but when I ran a dry test toolpath this morning the thing was rattling its drive belt, groaning, binding and lost steps during 10 mins it took to run it.

...solved. It transpired the drive belt was too loose! I'm not sure what happened there. All the setup tips basically coach you to not have the drive belt too taut. Since I removed powder coat from both end plates during mechanical tuning & setup phases, I've introduced free play at the driven end which probably means that I need the belt tension greater than 'average'.

Anyway, back to running free at 100% (3,000 mm/min). Phew.

Doug

Hi Doug,

Tensioning a drive belt is a bit of a black art so as not to put too much load on the pulley bearings, yet making sure it cannot slip a tooth. Sounds as though you've sorted it now.

Pleased your HF is getting sorted too - I think it's a good solution to have it controlled by software from the Gcode file. IMHO the alternatives are almost too heavy for the Z axis as is. Raising the spindle must be getting fairly close to the rated torque of the stepper, i.e. eating away at the safety margins - not a good axis on which to miss a few steps going upwards!!

Peter

Hi Peter.

Rory has offered to let me have a different type of HF spindle on evaluation. I'm not having a Stepcraft HF spindle back under any circumstances. It's basically a smaller version of their professional range of spindles that has been newly developed. I don't know what the brand is.

stoneycnc.co.uk/jbec-professional-cnc-spindle-options/

It is a high frequency (HF) three phase spindle powered by a variable frequency drive (VFD) which allows the machine to be powered by a single phase (domestic) supply. The motor has tapered bearings on the top and bottom of the main drive shaft, has a balanced squirrel cage rotor and has much higher torques at lower RPM’s than the Kress spindle. It uses a ER11 collet head the same as the Stepcraft so no requirement to buy all new set of Kress collets which are much more expensive than the ER11 collets.

Rory seemed very excited about its capabilities. I'm not sure when I'm getting it; Rory was going to see if he could expedite release of one (not sure if it's a pre-production model or what) in the next few weeks for me to test. Likely price would be about 20% more than the Stepcraft HF500 but the key factor for me is that it will have a built in suite of thermal and overcurrent protection unlike the Stepcraft outfit. It's also much lighter than the Kress, probably comparable with the Stepcraft.

Doug

Hi Doug,

Now that is really interesting - though my HF350 is proving OK but has a quirk in that it very occasionally fails to start properly when commanded. I just put a 5 second startup delay in the Gcode and stand by the "JC" button if it fails to start correctly.

The problem lies in the very clever, but not foolproof method of synchronising the energisation with rotor position without using Hall effect transducers common in more expensive brushless DC motors.

I would assume that the "Rory VFD Special" is capable of full control via the same interface as the HF350/500. There are lots of Chinese VFD spindles on eBay, but apart from being of dubious quality (they are Chinese after all), they all appear to have only manual controls on the inverter.

Peter

peterg1000 schrieb: Hi Doug,

Now that is really interesting - though my HF350 is proving OK but has a quirk in that it very occasionally fails to start properly when commanded. I just put a 5 second startup delay in the Gcode and stand by the "JC" button if it fails to start correctly.

The problem lies in the very clever, but not foolproof method of synchronising the energisation with rotor position without using Hall effect transducers common in more expensive brushless DC motors.

I would assume that the "Rory VFD Special" is capable of full control via the same interface as the HF350/500. There are lots of Chinese VFD spindles on eBay, but apart from being of dubious quality (they are Chinese after all), they all appear to have only manual controls on the inverter.

Peter

Hi Peter.

I have no details whatsoever at this time, sorry. I assume from what Rory said in his e-mail that it is the same brand (not Chinese) as those pictured on the StoneyCNC website link in my previous post.

If by "full control via the same interface as the [Stepcraft] HF350/500" you mean the orange Stepcraft control unit, I certainly hope and assume not because that is the unit that failed twice on me due to lack of said protection relays or fast rupture fuses, etc. I don't know whether it has its own control unit or whether all the electronics are in the spindle housing on the machine. Again, I assume because he said that it's much lighter than the Kress that it has a small spindle with motor and a separate cable out to a power and control box.

If you just meant the UCCNC or Mach 3 software interface or parallel/USB connection to the Stepcraft machine control card, then yes, I presume so. Rory said that it would "drop in" or words to that effect.

I'll post up details as and when I receive it, install it and attempt a cut.

Regards.

Doug

Hi Doug,

"I would assume that the "Rory VFD Special" is capable of full control via the same interface as the HF350/500."

Yes I did mean the same UCCNC or Mach 3 software interface, this would plug into the 3 phase variable frequency inverter of course, rather than the HF350/500 control box.

I don't think there is any alternative to a separate control box either, the 3 phase inverter has to deliver several hundred watts, worst case, to the motor. That inevitably means some fairly beefy MOSFET's and all the associated drive electronics too, as well as heatsinks etc etc etc!!

Disappointing that you suffered a couple of fried control units - the AC/DC adapters inside normally have built in overcurrent and overvoltage protection.

Anyway, do keep me posted if anything interesting comes your way.

Regards,

Peter