To be honest it came well recommended and supported (manual, videos, forums, etc), which for me with absolutely no CNC experience, was important. It also was feature rich, as many are, so I felt it would be a one-time purchase knowing it should have me covered. Some discussions I had had warned that it has more features than I will ever use, or understand, which may turn out being true - but I still feel good about the investment. I don’t have the knowledge or experience to be more specific as to my choice.
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Hi @U007D
As a complete beginner to CNC and VFDs, I went with the Hitachi too for same reason @TMToronto mentioned - apparently the manual is much better than what comes with the cheaper Asian versions. I’ve been able to (slowly) read through parts that seem relevant and mostly be able to make sense of it. You might find these features of the Hitachi helpful (probably the main ones for me so far):
- pretty clear wiring diagrams
- Sensorless Vector Control. Better low-end torque. CNCDepot recommends the Hitachi for their FM series spindles for that very reason https://www.cncdepot.net/product-page/fm-series-spindles
- The “Spindle Pause Feature” thanks to @Aiph5u and @Alphonse . Hitachi VFD Connection - #29 by Aiph5u
@MikeH started a great post which was basically what allowed me to consider the Hitachi option. Hitachi VFD Connection
I’ve been able to go from zero knowledge to a basic working set-up, so for me, at least, I think the Hitachi was worth it, and seems to be a better option for any possible future upgrades. Of course, this is my first VFD ever, so I’m no expert!
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I have a Mechatron spindle HFS-8022-24-ER20. It is water cooled for better low rpm performance. It is driven with a Hitachi WJ200 VFD. My spindle was bought with the power supply cable as an extra. The quality of the cable and connector Mechatron provided is excellent. Their cooling water connections are also quite good.
I did some significant research before choosing this as my solution. I could not get adequate detail from any suppliers of Chinese spindles, including US resellers. My view of the Chinese VFDs is unfavorable when compared to the Hitachi offering.
The Hitachi offers a multitude of configuration options using intelligent inputs and outputs. As Martin also pointed out, you also get SVC.
My setup works perfectly with the OF controller via the ModBus. The VFD is configured/outfitted to turn the dust collector and the water cooler on/off with spindle operation. It is also easy to delay the shutdown of the water cooler if so desired. I also have it configured to allow a pause in spindle operation if you want to pause a program.
The Hitachi manual(s) are a bit complex but make sense after some study. I use the Quick Reference Guide as well as the WJ200 Manual. I have also found Hitachi Technical Service to be excellent. They have gotten back to me in a timely fashion if I had to leave a message and their technical competency is unquestionable. I have always felt very satisfied after a conversation with them. Full disclosure, they did ask if I were trying to run a Chinese spindle. They seem to have a cautious position on trying to help with that.
I already owned another Hitachi WJ200 which drives a variable speed metal lathe. It has performed flawlessly. My experience with it supported buying another one for the Onefinity.
BTW, I am not trying to trash Chinese spindles and VFDs. They are quite economical and many folks seem to use them with great success.
Have fun with your studies!
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I didn’t know Daniel can provide 4-pole spindles.
I guess this is a bit of an experiment for us to figure out how effective this solution might be. So I wouldn’t say he’s officially offering them yet, but he may in the near future if these experiments work out.
Did you get a datasheet or some information about it? I would not buy a spindle, especially for such a demanding application, without having seen the speed/torque diagram, in order to see that the “constant torque” horizontal line really reaches down to 3,000 or less rpm, before it goes low on lower speeds.
I haven’t seen one but I asked him for one. Yes, in addition to the one you showed, Mechatronic has a spindle over 2Nm @ 1500rpm. The PwnCNC 4-pole spindle I am looking at starting with not in the same performance (or price) class as the Mechatronic. For sure.
For starters, it will be 6,000 - 12,000 RPM, so it (probably) won’t even be giving useful torque at 3k, let alone 1.5k. But with the right feeds and/or mist or flood cooling it may work out fine.
And are you sure with the 800 Hz? VFDs with output frequencies above 600 Hz are suitable for controlling centrifuges for uranium enrichment and are therefore subject to dual-use export restrictions in the EU and the US since 2006.
Ooooh, that’s the other thing I wanted to do with my VFD! 
No, I had no idea that 600+Hz VFDs were particularly useful for uranium enrichment!
In my case it’s the spindle that is 800Hz. I assume that means you need 800Hz to get to 24K RPM. The VFD is 400Hz.
But one thing is clear, you will not get such a nice, technically accurate and instructive VFD manual like the Hitachi/Omron manual (418 pages) with Daniels VFD (25 pages)
While it’s clear the Hitachi manual is top-notch, I do have Daniel’s VFD and manual in front of me now. The VFD manual is 202 pages and is quite comprehensive. I have no doubt it is less comprehensive than the Hitachi’s, but it is in addition the 25-page Spindle Kit quick start guide (also ships with the kit).
BTW, I am not trying to trash Chinese spindles and VFDs. They are quite economical and many folks seem to use them with great success.
I feel the same way. It can be hard to know who you are dealing with. Fortunately Daniel has a relationship with G-Penny and I believe feels comfortable with the price/performance ratio of this kit. I think it’s a reasonable place to start for me because I want to be able to quantify what you get and don’t get for $1K vs $4K in a spindle + VFD package. Given my intent to go to ATC at some point, I expect I will be upgrading to the latter once I have some experience under my belt. I am glad I don’t have to make the outlay just to get started, though! 
Thanks so much for sharing your thoughts–I am getting so much from every reply!
All the best,
Brad
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Hey Brad,
Off-topic: I notice that you do not use the quote function of the discourse.org forum software, what has the disadvantage that there is no attribution in the text you quote. That is just the advantage of the discourse forum software: The automatic attribution! To use it, you have already noticed that when you select a piece of text from another posting, a little box appears that you can click on:
If you use that, your quote would look like this, with automatic author attribution:
This is especially important if you quote different authors within one posting, to know from who what was, e.g. here you quoted Alan:
With the quoting functionality, it should look like this:
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Hey Brad,
get the redline spindle.
I intend to, yes!
I photographed the complete ToC of the manual. It does appear to cover every VFD setting and value, with explanation, among other things.
Yes, I already have his cable. Time will tell if I need an updated version or not.
My thoughts precisely. The probability that this unit will suffice is also not zero.
The quote function works effortlessly even for multiple quotes in a single reply. Thanks again!
I wanted to update everyone on my steel-cutting adventure with the Onefinity Journeyman.
Tl;dr: If you are patient (i.e. can tolerate slow feeds), you CAN cut steel!
First, the bad news:
I have used small 2mm and 6mm carbide endmills to keep surface speeds lower (and broke them).
While I still have many parameters to tune the one I’ve used successfully are veery sllowww feeds–not for time-sensitive production runs.
How slow? My successful settings are clearing material @ 50mm/min in 1mm depth passes with an 8mm carbide square end mill. (This is made a lot slower by the free non-commercial version of Fusion 360 makes all movements at cut speed. This is remedied with a subscription.)
The next biggest problem I’ve encountered is chatter, so mass in the table, a firmly attached CNC and an extra-rigid spindle attachment are all your friends (I’d use a steel plate tabletop if plate steel wasn’t so expensive). As it stands, my tabletop is a thick layer (about 43mm) of plywood.
And now the good news:
It works! I am now milling mild steel with the Onefinity Journeyman successfully.
I ran my 8mm carbide end mill last night and made 8 successful cuts. I’ll be making another 12 today.
The steel looks great–no black-and-blue chips (and I’m still cutting dry) and the roughing passes look great.
I worked to find an inexpensive 4-pole 80mm motor which could mill steel. It’s a G-Penny 2.2kW water-cooled unit. Peak torque isn’t super high at 0.9Nm, and minimum speed for peak torque is a high 12k RPM, but running the unit at 9k RPM gives consistent speed (i.e. sufficient torque to not vary speed or stall during cuts) without being so fast as to burn up the steel stock.
Earlier in the thread, I promised to share specifications of the motor, if I got any:
For additional $$$, you can get more powerful spindles which will give you better (higher) feeds and more torque at lower speeds–for details, please see some of @Aiph5u’s comments in this thread.
From the CNC machine’s perspective, it seems plenty rigid so far (needs more mass). The weakest link is the 80mm spindle holder. A more rigid design for steel there would give excellent bang for the buck. Those are two areas I may explore in the future, but for now, I am unblocked, and consider the experiment to be a success. 
The above pictures show 5mm notches cut into mild steel. I have gone as deep as 10mm so far with the same performance. This has all worked well enough that soon I’ll be testing cutting 28mm diameter holes all the way through 13mm plate steel with 2mm 45° chamfers (building a welding fixture table). Wish me luck!
If you are interested in milling steel, let me know if you have any questions, and I’ll do my best to help you out!
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Hey U007D,
thank you very much for sharing all the data and the experience! I’m sure many appreciate this.
However I find it a little disappointing that despite the fact you got a 4-pole spindle which runs with 12,000 rpm at 400 Hz (and still 24,000 rpm at 800 Hz), it gives not more lower speed torque than a 2-pole spindle – it even gives less low speed range at the nominal torque of 0.9 Nm. It is a little surprising that according to the curve you show, the nominal torque only begins at 12,000 rpm:
Even with a standard 2-pole, 24,000 rpm at 400 Hz spindle, you could get 0.9 Nm at (substantly lower) 6,000 rpm:
Mechatron HFS-8022-24-ER20 (2 magnetic poles, 6,000 rpm – 24,000 rpm)
So at the moment I see no benefit to buy the spindle you show, especially for milling steel with high torque at low speed.
And of course as you stated, the 4-pole spindles you considered earlier in the thread, while being surely more expensive, give high torque at much lower speed, as shown here e.g. 1.6 Nm at 3,000 rpm:
HFPM-8022-24-ER20 (4 magnetic poles, 3,000 – 24,000 rpm)
or even 1.9 Nm at 1,500 rpm:
HFPD-8015-12-ER20 (4 magnetic poles, 1,500 – 12,000 rpm)
This shows me one thing very clearly: It is not only the number of magnetic poles that makes the difference here, it also depends very much on the manufacturer’s skills and experience in designing the windings and the rotor cage.
Yes, this was often discussed here. That is why I think of replacing the entire Z assembly by a universal Z assembly. I am not surprised that when milling steel, you encounter chatter, which I would see caused by this.
But I think for milling steel, the Onefinity is also not the right machine for another reason: Because its linear bearings are ball bearings. The cnc-step High-Z (discussed here, here, and here) is a universal machine explicitly made for milling steel. Its main difference is that it has plain bearings (instead of ball bearings) which run on its steel rails.
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The missing benefit is price.
The spindles you are referring to are about 5x the price of the spindle I am using. The Mechatron spindles are excellent and arguably 4-5x more capable (if/when I outgrow my G-Penny, I will almost certainly be moving to one of these), but for those looking to minimize their initial investment, the cash outlay for one of those is significantly higher.
With that said, I agree with most of the rest of what you have said; I too was hoping for maybe ~1.2Nm @ 6k RPM, but alas. 
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Hey U007D,
anyway, thank you again for reporting your experience and posting the data!
I have learned something too.
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Absolutely! Any time.
I very much appreciate all your input on these projects. When I first came here I was not even aware of the 2-pole vs 4-pole option. Your post on motor design was very informative and helped me get to a successful outcome.
The Universal Z assembly project looks very interesting. It doesn’t look like anyone has moved forward on it, but I’ll keep this in mind as I keep making progress. It’s something I’d like to do if I can find the time. I think I’ll pop a question into that thread.
Thanks again,
Brad
Hey Brad,
if you want to see how someone built a cnc machine for milling steel, you can see it here (it’s in german but as it is spoken in dialect-free high german, auto-translated subtitles work relatively well). As you rightly say, such a machine needs first of all mass, so first of all they cast the parts from concrete. The spindle is a servo motor with a reduction via a toothed belt.
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Hey Brad,
besides in that thread, the Z assembly is also discussed here:
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Das ist sehr wichtig! Sonst können Leute wie ich es nicht verstehen.
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Hi,
what do you think of the g-penny 2.2kw spindle for metal ?
the one that is 4 poles 400hz / 6000 - 12000 rpm / 1.75nm torque.
I asked them what append if I run it at 800hz. they answered it will not burn, it maybe will not go up to 24k, and the torque will decrease at speed higher than 12k.
it is very similar to the mechatron professional data chart. same high torque up to the rated speed and then torque decrease.
do you think it is the mechanical / electrical differences that makes the torque curve so different between a 4 poles 12k 400hz and a 4 poles 24k 800hz or just the vfd set for a 800hz spindle that gives only half power at 400hz and so half the torque ?
do you think it’s better (less risky) to overclock the g-penny 4 poles 400hz or overpower (full power at 400hz) the 800hz one ?
There is a member of a forum I frequent - CNCZone - that speaks highly of G-Penny in general for their ability to machine at lower speeds than most other spindles available. He has discussed differences internally that account for this, irrespective of 2 vs 4 pole.
I highly recommend asking your question there as well, as I am sure he will answer.
He goes by @joeaverage, but @mactec54 also likes to join most discussions - the two do not always agree, and you will learn a bit about them through the banter 
here is one discussion you may find interesting, although related, not exactly what you are asking…
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I know this will be much more expensive than the G-Penny, but consider a spindle from CNCDepot. (cncdepot.net)
They have a front mount 3Hp (2.2 kw) ISO 30 ATC spindle. " FM30F - 12,000rpm (400hz: 4-pole motor, for higher torque at lower rpm*)"
Considering many Haas machines max out at 6K RPMs, these are still spinning pretty fast.
They also have a mounting plate for the 1F Z-20
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