?? VFD 110V in/220V out / spindle options for DIY CNC machine ??

[tyrone shewlaces]

Howdy again.

I need to upgrade my little CNC machine spindle. I guess I could use some general input on this, but what I think I'm considering is one of the high-speed 800W air-cooled motors off eBay. That is actually more than I need probably as single phase would work, except I need the shaft to be set up as a spindle with a collet on the end. And... well probably best to just list what I need it to do:

1) It only needs to grip 1/8" bits.
2) The work will range from engraving with a pointed cutter - equate that to ≈ .005" cutter diameter, thus the high-speed desired - to cutting with a 1/8" end mill.
3) Materials will be things like phenolic, copper-clad PCB material and various plastics. Probably never cut metal on this machine (beyond the copper on PCB sheets).
4) Needs to be pretty high speed. the eBay spindles rev up to 40K rpm but I could probably live with 25 to 30 if other requirements were met.
5) I'll probably never need or want it to spin in reverse.
6) I will want to spin it at various RPMs depending on the operation, controllable from Mach3 in both RPM and on/off. I figure that a high-speed spindle will probably have a fairly high minimum RPM too and that's ok - I'll work with that.
7) spindle needs to be solid and run true. I figure .001" runout would be fine. It needs to stand up to sideways thrust without vibrating and flexing (within reason), i.e. needs to be TONS better than a Dremel.
8) Needs to run off 110V because I intend the machine to be portable for occasional demonstrations and such.
9) Cost is a factor, though if I can't find a suitable cheap option I'd be willing to blow around $300 to $400 if I have to.

So with that in mind I was thinking of two options.
1) get one of the .8KW spindles off eBay, but either try to find one which runs off 110V instead of the 220V ones which are the only ones I see available on the net. So either the spindle can use 110V or maybe there's a VFD I can get which takes 110V single-phase input and outputs 220V 3-phase. I guess a 1HP VFD is slightly under the 800W spindle spec, but it's close so I'd think that would work OK. This spindle would be a little overkill for this machine, but if that's the only thing that will work I'll go ahead and just bite that bullet.

2) get some kind of small router or something which will be rigid, spin true and take 1/8" bits. The wrinkle here is that I want it to be variable speed. I've seen VS controls for routers for pretty cheap, but I've never seen one work and don't know if they are junk or if they burn up motors or what. I could replace the potentiometer in one of those controls with a little circuit to convert the Mach3 or Gecko output to whatever the VS control would need... I think. Seems like it's probably just a potentiometer controlling some stuff in the unit, so it's likely to be something I could hack to make it work with Mach.

So those are the two options I can think of, and I don't know enough about either one to know what to do yet. Any help is welcome.

Basically I'm looking for a way to have a decent little spindle to be controlled with Mach. I haven't really considered DC motors because what I've seen seem to be pretty bulky for their power, slow RPM and not set up to be a spindle. Maybe I'm just looking at the wrong motors? I do have a DC motor controller for 90V motors though. Hmmm. I could maybe machine a motor shaft to accept 1/8" bits and make a collet closer for it... Any better ideas out there?

This spindle will be going on my little home-made machine (link to the build thread here).

I have a larger machine in the queue on which I plan to use at least a 1.5KW motor and Hitachi VFD. That will be a much nicer machine and warrant the expense of the slick spindle setup. I'm trying to stay inexpensive as possible on this machine in part because I'd like newcomers to seeing this kind of thing not to be scared away from it because they think it's too expensive to dive in and try. But above it all, I need it to function well and my two cheap tries so far have fallen short.

Anyways, thanks for any input.

[lakeside53]

You can get vfd's 120 in 220 out up to 1.5hp.

The 1hp will likely work - the "800 watts" is dependant on how you load it.

[macona]

Doing PCBs you will never see .8kw power usage. You can use a 1hp vfd without any problem. In the off chance it faults out during spin up just set the acceleration longer.

[RussZHC]

re: # 2, something like this http://www.boschtools.com/Products/T...x?pid=pr20evsk

but don't see an 1/8" collet listed ...?

[John Stevenson]

re: # 2, something like this http://www.boschtools.com/Products/T...x?pid=pr20evsk

but don't see an 1/8" collet listed ...?

That thing will drive you mad with the noise.
Bite the bullet and go for one of the air or water cooled spindles from China.
The 0.8kw has an ER11 collet chuck in built and is very good.

I have had one of the air cooled versions on my router for 4 years with not one problem.

[EVguru]

The Hyunyang VFDs are in essence a 415v design. For 240volt operation they modify the input stage to put the smoothing capacitors in parallel rather than series and change the firmware for the lower voltage. It would be easy to modify one to work on 120 volt by putting the capacitors back in series and then feeding the centre point from the bridge rectifier. This is a standard voltage doubler circuit as use in many PC power supplies.

[tyrone shewlaces]

Thanks a lot for the good replies!

@Russ. Yea I was looking at that exact router. John mentions that it would be loud which is true. I don't think it would be much worse than what I've had so far and I could probably deal with the noise. My biggest question remains then, would those speed controls they sell (i.e. this link) work or would they reduce performance to a problem or burn up the motor or something, and do they work well enough in the first place. An on/off relay arrangement is simple enough.

@John. I could go with that. But are they available in a 110V version for a similar price or is a 1hp 110V in/220V out VFD available for cheap enough? I really need it to operate on 110V single phase power. Damn USA power grid

I've been surfing some for this and all I can find is either much more money or "almost but not quite" a match, i.e. frequency only goes up to 200Hz rather than the required (desired) 400Hz, etc. . I can get a 1.5KW 220V setup (spindle and VFD) for around $420 and would think that a .8KW 110V setup should be less $$, but so far everything I've found is actually more expensive. It would seem that a .8KW setup should be around $300-$350.

A single-phase simple router thing would be significantly less expensive so that appeals to me of course. But I need the runout to be pretty tight and I don't know if they worry about that at all for woodworking tools, so that might be a good argument for the .8KW spindle. I don't have facts or even anecdotes either way except that from firsthand experience I know a Dremel is absolute crap for this application.

@EVguru. That is interesting. I'm not quite sure what you're describing but I'll look into it and see if I can decipher your voodoo. If I hack the VFD and change the capacitor configuration, does it then require a firmware change too? If so, that is likely above my raisin. I was looking into the Hitachi X200 but they don't come in a 110V flavor as far as I can tell. At this point if I could find a 110V 1P in/220 3P out that would go up to 400Hz for less than $200, I'd probably pull the trigger.

edit to add: I see that there are step down transformers in 1000W capacity for fairly cheap for using USA widgets in Europe. Is it as simple as reversing the flow to make it a step up transformer or would I lose efficiency or burn it up or otherwise not work? If that would work, it might be a reasonable solution to expand my VFD options.

[Jaakko Fagerlund]

237 USD, 1.5 kW spindle, 110 V available by asking: http://www.ebay.com/itm/1-5KW-AIR-CO...item20c021c730

200 USD, 0.8 kW spindle, 110 V available: http://www.ebay.com/itm/AIR-COOLE-MO...item3cbfc91065

[lakeside53]

If you want a quality VFD, the current Hitachi 120v input 240 volt output VFDs go to 400hz. Look at the L100 series, not the SJ200, X200 or L200 series.

Right now they are changing product lines so there is some scarcity of 100v class series product.

When they release (might now be out - supposed to be released Q2 2012) a version based on the WJ200... It will likely be 1000hz like its 200v class siblings. Look for a WJ200-007M or call a Hitachi dealer.


These guys stock the L100-007MFU2 http://store.controlcomponentsinc.com/HitachiVFDWJ200

There is usually no need to go the transformer route. If you do, take care with just reversing the in/out of the smaller transformers - the reverse primary impedance may be too low. Generally, over 3KW it's ok, but best if you look at the manf data to see if it's listed for such operation. Also, transformer windings are usually adjusted in ratio such that any voltage losses under load are masked. When you reverse drive, the inverse is true so you can end up with a higher voltage (10-15%) than you expected.

[tyrone shewlaces]

Thanks guys.

I went ahead and pulled the trigger on the VFD. I found a Hitachi L100-007MFU2 for just under $200 including shipping from Texas. Looks like a pretty handy VFD.

Now I just have to settle on a spindle and get that going. The cheapest price I could find on the .8KW is $249 including shipping. Seems like it ought to be around $150 or so but I guess it is what it is.

The 1.5KW and matching Hitachi VFD would actually be about $30 or so cheaper than going with this .8KW one at the prices I can find. But that would require 220V so... I can still go another route with this spindle if I change my mind in the next day or so since I can see the VFD I ordered being useful for more than a couple other applications around my shop too.

Then again, if I ever retire this machine and the spindle/VFD is still working, I could pull it and have the nicest "Dremel" on the block.

By the way, I had a little trouble figuring out that the standard documentation for the L100 VFDs only show 220V input, but they have a couple MFU2 supplementals which show the specs and use of the 110V units. I found the selection of documents from this page: http://controlsourceintl.com/scripts...?idproduct=576
Once I found the applicable documents, it was gold.