Question Industrial Quality VFD spindle from StoneyCNC

After having had some very worrying symptoms of incipient failure from my HF350 spindle, I decided to purchase a small industrial VFD spindle from Rory. The HF350 frequently failed to start and potentially ruin a tool unless I was quick on the Emergency Stop button, and it was also uncomfortably hot after a few minutes at 18000rpm.

The kit arrived yesterday, and the unit was unpacked and running fully integrated into UCCNC within the hour.
It's a very impressive performer, running smoothly up to within a few percent of the demanded Gcode speed in about 6 seconds to 18000rpm . About to use it in anger for a small pcb soon, and then on to progress my wooden clock which has been on hold for several months since the HF350 started playing up (weird noises and fluctuating speed!!)

Peter

Great news Peter. I hope you have the same success with yours as I've had with mine (barring the random VFD failure).

If so, you'll be delighted with it. It made a big difference to my system.

I haven't posted the evidence, but on the lower side of my recent guitar neck cut, my wife switched a high current consumer on the downstairs ring main which caused the Z axis to jump down about 10 mm. However, the Stepcraft and StoneyCNC small industrial HF spindle kept on ploughing the roughing toolpath seemingly without losing XY steps until I hit the stop button.

Absolutely astonishing and surprising. A far cry from the dark days last year when I was struggling to get the thing to work without the Y axis jamming!

If that had happened with the Stepcraft HF spindle I'd be looking at a third replacement control unit for sure!

I only use mine in manual mode (i.e. speed not controlled by UCCNC) and the replacement VFD is possibly programmed incorrectly as I have to run all cutters in reverse.

Doug

Sounds as though yours is incorrectly programmed - I had a look at the Delta manual yesterday and am thankful that Rory had programmed mine for me.

I make a number of pcb's, and these involve a significant number of tool changes, so it's a bonus to have the spindle under Gcode control as it's too easy to forget to start the spindle after the n'th change (and I've an array of broken tools to prove it!!)

Like the way it starts up too, click of the relay and the spindle starts immediately with no fuss, then runs up to speed as smoothly as you like. I've already total confidence it will start when commanded, unlike the HF350 that always had me hovering over the "Jesus Christ" button - Just in Case!!!

Only slight downside is the noise from the cooling fan at 18,000 + rpm - but that is drowned out by the vacuum motor anyway. I now have to address the problem of a vacuum adapter - I think there might be a way of adapting the one I bought to use with my HF350, tomorrows problem to solve.

Altogether delighted.

Peter

Hi,

Managed to cobble up some bits to allow the HF350 vacuum fitting to be quickly removed and replaced when fitting tools to my new VFD spindle. Vacuum pipe adapter just lifts out - an O ring and suction keeps it seated when in use.

I turned the fancy screw on my mini-lathe, but an M6 screw with a washer araldited to the head would function just as well. The locking gismo I made from a scrap of 1/8" Al angle.







Hope this is useful.

Peter

Hi Peter.

The reverse rotation issue just required swapping two of the tails on the three phase wires feeding the spindle. Sorted. Nothing to do with the Delta VFD programming.

I drilled an M6 hole right through the mounting spigot with the intention of using a downward facing M6 coach bolt and wing nut to allow quick removal of the Stepcraft exhaust adapter until I realised that the new spindle almost blocks the suction and exhaust route. However, the main problem is that it simply isn't long enough for me as I'm using extra long cutters for guitar neck milling. The Stepcraft brush is just a section of ordinary draught excluder brush so it would be easy to obtain a longer brush (e.g. 50 mm), bend it round a circular former, remove the existing one and glue the longer replacement in.

However, at that point, I decided to do what many amateur CNC operators do and design my own dust skirt using a 12 mm thick acrylic plate into which I plan to cement a 38 mm o.d. acrylic tube to attach the vonHaus ash vacuum hose onto and thus dispense with the 24 mm Stepcraft hose. I'll use a piece of 15 mm acrylic tube as a new mounting spigot.

https://www.stepcraft-systems.com/en/forum/accessories/4114-long-vacuum-extraction-dust-skirt-brush?start=20

I plan to attach 75 mm lengths of brush to each side in its aluminium carrier which will be bolted on with M4 bolts screwed into M4 brass threaded press-in inserts.

Doug

Hi Doug,

Must admit that my fix is a bit clumsy, but it does fine when milling track on a pcb. Cumbersome when repeatedly changing tools though.

Your solution looks quite attractive, but does require a long brush. I'll investigate further at a later date as the present set up seems to be OK for long jobs with the same tool fitted.

Glad you solve the reverse rotation problem!

Peter

Hi Peter.

Rory solved the reverse rotation problem!

With my proposed skirt design, it would be relatively simple to change the four brush skirt sections for shorter (e.g. 50 mm) filaments.

I haven't had time to assemble it yet so I don't know whether it will work well or if the long brushes will be a problem.

Doug

Hi Doug,

I think the answer to my clumsy fix is to use a good strong Neodymium magnet in the fixed part, and a steel M6 screw in the removable part. These magnets are incredibly powerful and will give you blood blisters if mishandled (and I can prove it)!!

Later on I will use some self adhesive disc magnets to hold a copy of your masterpiece in place on the bottom plate underneath the spundle.

That spindle is magic isn't it - needs a good 7 second spinup delay though.

Peter.

peterg1000 wrote: Hi Doug,

I think the answer to my clumsy fix is to use a good strong Neodymium magnet in the fixed part, and a steel M6 screw in the removable part. These magnets are incredibly powerful and will give you blood blisters if mishandled (and I can prove it)!!

Later on I will use some self adhesive disc magnets to hold a copy of your masterpiece in place on the bottom plate underneath the spundle.

That spindle is magic isn't it - needs a good 7 second spinup delay though.

Peter.

I considered magnets but couldn't quickly come to a design in my head so I ended up with what I pictured. I inserted the 38 mm o.d. tube into the base plate this afternoon before coming to work. I was going to try cementing it in with a plastic weld (acetone + cyanoacrylate superglue) but I don't get on well with adhesives so I ended up just sanding around the aperture in the base plate and the tube itself until it was just enough to force in on a very tight interference fit. I'll stick with that - it ain't coming out in a hurry!

This weekend, I'll have a bash at drilling and heat inserting the brass threaded inserts to the sides. I need to think about how to keep the brush strips in their aluminium retainers because they slide out quite easily. I don't really want to epoxy them in so I'll have to think about that. The joys of desigining with your mind's eye and back of envelope.

Yes, the industrial spindle is an amazing bit of kit. I have yet to test the electrical protection suite on it and I hope I never have to. Since the spindle stopped being the weak point in my system, it has proven to me that actually a well tuned Stepcraft 2/840 can run for hours and do medium duty hardwood routing no problem. Phew!

Doug

Acetone + Superglue? What the hell is that, it sounds like something the Syrian government would drop on their citizens!!!

MMorao wrote: Acetone + Superglue? What the hell is that, it sounds like something the Syrian government would drop on their citizens!!!

Er, I think that's acetone peroxide.

https://en.wikipedia.org/wiki/Acetone_peroxide

Doug