Oh I see yeah. I was only able to drill with a low doc at RPM lower than 6000. I see some people drilling at 6000 prob for that reason too.
Oh and it also draws a crazy lot more current at lower RPM and even 14-16 AWG motor wires will start heating up a bit.
That looks way better than any VFD that comes included with the spindle. Sensorless Vector mode seems very interesting. EMI reduction would help the shapeoko a lot.
Certainly.
The question is then, what kind of facing is intended. If most of the material is gone but the face looks horrible after an aggressive roughing pass with, say, an 8mm 1-flute, then perhaps a fly cutter slowly peeling off 0.1 mm maybe just the thing because the finish can be nice. Provided that the machine is trammed to the micrometer (mine definitely is not).
If facing is about removing a fat slab as quickly as possible, then I absolutely agree that large-diameter tools need not be better if all we have is spindle speed and relatively fast feed capability, but neither much torque nor feed force.
FWIW I run a 10mm “face mill” at 10kRPM on the Nomad.
Whether that’s a good idea or not I’m not sure but it does work. I use it at suuuuper low DOC though.
This is where it gets interesting and the type of tool comes into play.
Here are three face mills I have lying around.
From right to left
- 60mm indexable face mill - turned down to fit in a spindle
- 19mm indexable face mill
- 30mm solid carbide face mill
The 60mm face mill will run in a shapeoko - but really really badly. It isn’t balance even at 100mm a min and 2000rpm a 2.2kw spindle doesn’t have the torque to make it useful. At 5000 rpm it’s max rated speed the vibrations are crazy. It is designed for a different type of machine. Yes it fits and will cut but it’s not a tool I would ever suggest anyone uses on a desktop mill
19mm indexable face mill - this is designed for HSM - it’s max rpm is 10,000 and it’s balanced, vibrations are noticeable at 12k rpm. It will chew through ali at 1mm doc 2k a min - however the atc spindle it runs on is 10kg and not suitable for a shapeoko (it also costs more than an XXL fully kitted out
30mm solid carbide face mill - this is a great bit of kit, it’s rated to 20,000 rpm, has 4 flutes and can leave a really shiny surface.
https://www.instagram.com/p/BvhUZcegxap/?utm_source=ig_web_button_share_sheet
The tool balance and max rpm make a huge difference. Personally my strategy with face mills is to hog material then a 0.2doc-0.1 finishing pass, however most of the time I will do this with a 8mm bit. Buying these large bits is ‘great’ but usually they don’t save much time unless you are running a project hundreds of times. The tool change time alone can take longer than the time saved by using one. Not to mention all tools above cost over $100. In order to get the most out of them the spindle also needs to be trammed. Note those terrible lines in the above insta pic - that’s bad tramming and on me.
3 Likes
Honestly, IDK. Not sure I trust the lost in translation support when I inquired Jianken (manufacturer) about the sensorless vector control. I also haven’t found any examples of HF spindles in use with vector control other than CNC Depot’s passively cooled spindle.
The main reason I started looking into it was because I’m used to the Makita feedback loop built-in (or in my case with the SuperPID) and it tries to keep up with my aggressive cuts and moving to a HF spindle got me worried I’d be losing that feedback loop that could cause the spindle to bog down and chip load to spike. It mostly seems to be a non-issue for anyone else and has just become an interest/overthinking/experiment while I still have yet to even use my spindle 
I pictured it could be useful for drilling ops and maybe if I ever dabble in steel
1 Like
I’ve been surprised not to see more mention of this tooling size — it’s markedly more rigid than 6.35mm (1/4") and affords some interesting tooling options — I’d be glad to know of other folks using such tooling and the specifics.
From the reading gmack and I did whilst digging into how current relates to torque on the spindles the slip angle of the motor is < 5% when you hit the break away torque and the motor speed collapses so you’re not really losing much speed (i.e. less than 5% of the drive speed). As you say, it also gives you an audible indication of the load on the spindle as feedback.
Once the spindle reaches breakdown torque is when things get interesting, there’s a bunch of different ways the VFD can respond, from momentary over-current, through re-start attempts to throw alarm and shut down.
So far as I can tell vector control is more useful in applications where the exact speed is really important or for things like pumps and fans where reducing the energy consumption is important and being able to back the drive current way off without risk of hitting break away torque when the motor has little load is useful (that’s where optimising the torque producing current is key).
I’ve used drills in the 1,500 to 2,500 RPM range and there’s no lack of torque from the 2.2kW spindle. The limit I’ve hit so far is machine rigidity, at 8mm dia in 6061 Aluminium the dril just starts to chatter horribly and bounce the whole spindle around, I’ve not found any combination of speed and feed rate that behaves nicely at that size yet. Of course, you have linear rails and I’m still on V wheels for now…
2 Likes
This thing
https://www.amazon.com/dp/B07WQG85HV/ref=cm_sw_em_r_mt_dp_pgAKFbFM9T08V
was given to me by a person that received it as a gift for writing a favorable review. Suspect, to say the least.
Sat in a drawer for 6 months before I thought about using it. Seller claims top rpm 16k, you have to ask, this number is nowhere in the description.
Added another sheet of lexan to my door, tightened the 1/2” collet extra tight, ran it at 1000 rpm on my 2.2. Gradually bumped the rpm up to, eventually, 12k with no adverse effects. Then commenced facing a pile of secondary waste boards. Worked great.
Use these as well. The ones with inserts for 6061.
3 Likes
Thx,
Do you know the make / model on the insert cutters?
Hmmmm, lemme dig that up…
Here you go… https://www.buschmachinetool.com/product-page/mini-indexable-face-mill-3-4-dia-3-8-shank
A recommendation from @Vince.Fab by the way.
1 Like
Don’t HY VFDs just use the adjustable motor over-current threshold to trigger these events?
Have you tried drilling endmills?
Do you think the cutting face on those is different to a 90 degree carbide spot drill?
Now I need to go and read to learn about what difference the tip angle makes whilst I’m trying to learn how to calculate moment of inertia and deflection 
Why not just run them fast enough that you don’t need to worry about torque and feed force?
It’s the vibration that’s the issue, not the torque, above the 5mm bit, the next I tried was 8mm and it builds up that characteristic triangular wavy pattern in the cut and vibrates vertically.
The 3, 4, 5mm are all fine at sensible mm / rev and produce a nice pre-drill that can then be quickly opened out with an end mill without having to get anywhere near a plunge, which is what I’m using the drilling for, having had “mixed success” doing boring ops at close to the slot drill / end mill diameter.
Here’s what Guhring says about their spot drills:
“NC spot drills are high precision drills designed specifically for creating an accurate hole location for a secondary drilling operation. NC spot drills due not have body clearance and are not designed to drill greater than the depth of the point angle. The 90º and 120º spot drills are primarily used to create an initial spot for 118º and 135º secondary drills respectively. The 142º point NC Spot drill, series 546, is designed to help center carbide drills with an angle of 140º.”
@Winters636 reported some impressive results with one of their 2mm drilling endmills.
2 Likes
Here’s one that CNCDepot is recommending for their high torque 4 pole S30F spindle. It looks like a really nice one - and it has motor torque monitoring option!
1 Like