Low-speed high-torque spindles availble to the US?

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Brad,

@U007D

The PwnCNC 4-pole spindle I am looking at starting with not in the same performance (or price) class as the Mechatronic. For sure.

Or as the GlockCNC who explain what e.g. angular contact bearings are in their videos .

In cheap chinese spindles, usually there are none .

@U007D

@Aiph5u

I didn’t know Daniel can provide 4-pole spindles. 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.

I hope you report on it when you have it!

@U007D

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).

What additional information this 202 page manual provides?

@U007D

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.

With my 2-pole, 6,000@100 Hz – 24,000 rpm@400 Hz spindle, the manufacturer states in the manual that it is not allowed to run it lower than 6,000 rpm and that it is required to set the lower frequency limit in the VFD appropriately.

– Source: Mechatron HFS-8022-24-ER20 Datasheet (with comments added by Aiph5u)

So I would only buy a spindle with which my intended operational speed is clearly within the constant torque horizontal line! In the image above, it is nothing under 6,000 rpm!

@U007D

Daniel wrote me back today to let me know that his supplier is providing him with some high-torque spindles (4-pole/800Hz), so I will be able to do my initial Onefinity build with a PwnCNC water-cooled spindle and VFD setup.

If Daniel says their 4-pole spindle needs 800 Hz to run at 24,000 rpm, it is very probable that its constant torque range is somewhere between 3,000 rpm and 12,000 rpm, like here:

But you cannot be sure without the reliable information from the manufacturer. Yet I have not seen a torque/speed diagram from the cheap chinese spindles.

@U007D

Daniel is providing the correct VFD settings for the spindle

And also make sure you buy the ready-to-use spindle cable with it (and make sure there are the correct connectors at the other end)! Usually it is not possible to fit a reasonable spindle cable into these “aviation connectors” (that in fact are no power connectors), but I think Daniel makes this in a way like Warren described here with the heat shrink tubing as additional strain relief.

@U007D

The both the VFD and the spindle kit as a whole is quite a bit cheaper (at ~$1000) than any of the alternative next-step options I was looking at

Many people go this way (and stick with it) but have in mind that if you switch to something better quickly, the money is wasted, regardless of how cheap it was.

@U007D

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!

Okay, for acquiring experience, it is not totally wasted.