How do I increase spindle speed?

[cnczoner]

Hi all,

I have a CNC'ed HF geared-head mill, which has a 110VAC 1-phase motor (1.5hp). It apparently generates 1750 rpm at the motor shaft and is geared down to 6 speeds from 95 to 1500rpm. Is there an easy way to increast this to about 3000 rpm?

I've heard of VFD's and spindle speeders, but so far haven't found a 110VAC 1-phase in 1-phase out VFD that handles 1.5hp, and spindle speeders are quite expensive (if they even fit on my mill).

Is it a bad idea to flip around some gears in the head (if that's even possible)?

Any other ideas?

Thanks,
-Neil.

[Al_The_Man]

220V 4 pole 3 Phase motor, 240v VFD, 1 phase in, 3 phase out, 120 hz max, 3450rpm.
Use gear box speeds 1:1 & 6:1 (for low).

[cnczoner]

Al, I was also having a discussion about this today on an electronics forum, and doing some research. According to Automation Direct's tech folks, I should be able to find a 1-phase in, 1-phase out VFD, and I've been given a number for a tech guru at AC Tech re: one of their drives (to verify if it's 1-ph out).

In the meanwhile, the motor swap seems to be feasible and if it's a bolt in, I will probably go this route. I've figure out that my motor type is YL90L4. Google got me lots of hits on this (from chinese sources that sell these) and also some dimensions. See near the bottom of this page... http://www.fuxing-motor.com/Motor/yl.htm

I'm not familiar with AC-motor size standards, but hoping I can get a drop-in replacement for it, then I don't need to worry about the VFD. I estimate the prices for this motor to be <$200 and I should be able to get about half that for my used motor. $100 for the upgrade is very appealing!

If you or any motor guru knows about these size, clue me in please. More investigation to follow...

Cheers,
-Neil.

[Al_The_Man]

If it is a capacitor start only motor, then you most likely will have problems trying to run on a VFD due to drop out of run at low speeds.
There are very few VFD's made for 1 ph motors for this reason.
Al.

[cnczoner]

It's capacitor start and capacitor run. (I've been learning about all this motor stuff yesterday). Does that change anything? See photos below...

There are very few VFD's made for 1 ph motors for this reason.

But "few" implies that some do exist, right?

I also found ac motors rated for both 110VAC and 220VAC (on the same motor). I'm still not sure if this is 1-phase for the 220V or 3-phase for the 220V. I suspect 1-phase, but if 3-phase, I'd be able to keep 110VAC operation and later I could just add on a 1-phase to 3-phase VFD (which I've found already) if I ever decide I need speed control.

I'm also hearing that I can re-wire some motors to be 3-phase and then just add on a VFD. I'm still investigating that. Toooooo much to read!

Thanks,
-Neil.

[ger21]

Originally Posted by cnczoner I'm still not sure if this is 1-phase for the 220V or 3-phase for the 220V.

A 1 phase motor is a 1 phase motor, whether it's wired 110V or 220V.

A 1 phase motor has 2 wires + a ground, a 3 phase has 3 wires + a ground.

You can find 3 phase motors pretty inexpensively on Ebay.

[cnczoner]

A lot of googling got me specs on NEMA and IEC (metric) motor frame sizes. My existing motor is a 90L frame size (IEC), but I'm finding mostly NEMA-sized motors (mostly size 56 for the power motor I'm looking for), including at HF, etc.

I need to pop the head open to see how the existing motor is mounted and determine what needs to be done to adapt a NEMA-sized motor, but if possible, I'm leaning towards this motor . It's 1-phase (110VAC) and the "constant running machinery" statement gives me a warm and fuzzy, even at the bargain price of $120. (And I can sell my existing motor to offset some of that). Really avoiding running a 220V outlet from the subpanel in this rental house, and getting it from a 4-prong dryer outlet with an extension cord is hokey. Last time I did that btw (for a welder), the pieces for the (nice and beefy) extension cost me almost $100. Instead of that, I'd just go with a 3-phase motor now, and cough up the $$$ for a VFD instead. Still tossed up with this, but the VFD idea is still ahead because I prefer to spend money on equipment I can take with me.

BTW, do all/some/any VFDs provide any interface to allow it to be controlled by the PC (and Mach 3)? That would certainly sway me.

Hmmm... wonder if adapter plates/brackets for IEC-to-NEMA motors are an off-the-shelf item anywhere?

Thanks,
-Neil.

[tivoidethuong]

any body try using VFD driver PMSM motor . examp is AC servo motor?

[cnczoner]

Here are my results and options now...

[ FYI, I want to retain 110VAC operation as much as possible as I may be moving the machine to a small workshop that may only have 110VAC. Also FYI, my existing 1.5hp motor will run on 110V or 220V. ]

(1) I finally found a 1-phase o/p VFD from Minarik (minarikdrives.com). 1.5hp, 115-230V 1-ph in, 3-ph 230V output, but they said the manual show how to use 2 of those 3 phases to run the 1-ph motor (at 230V). I always like to get a bit of a higher capacity for these things, but they don't have a higher-hp drive. Total cost = ~$292.

(2) Change to a higher-RPM (~3500rpm) 1-ph 90L motor (drops into the existing mounts on my mill). I can switch gears if I ever want to come back down to 1500rpm. Still can't find this though.

(3) Change to a 3-ph 90L motor, with 1-ph to 3-ph VFD. If so, I would certainly upgrade to say 3hp. But the only ~3hp 90L motor I've found here in the U.S. is $775. Ouch! Add $400 for a 3-hp, 1-ph in, 3-ph out VFD. Idea here is that I could retain 110VAC operation, but be able to use the greater capacity later if I get a proper 220V source. Total cost = ~$1175.

(4) Swap to a NEMA 56 3hp 3-ph motor with a custom bracket/mount and a custom adapter to match the shaft diameters. My mill is geared (no pulleys) so I would need to adapt back to the same gears in the head. Motor comes down to ~$120-$300. VFD = $400. Total cost here is ~$520 to $700, plus the custom bracket/mount/adapter.

My direction... (1) is definitely good from a cost standpoint, but is still limiting and I'm not sure if I will need more hp. It would be hurtful to spend that money then realize that I should've upgraded the motor later. (2) probably does not make sense as (1) would still give me variable speed at (I'm sure) a lower cost. (3) is more expensive than my already-converted mill with controllers, PS, etc! (4) is bearable (cost), and gives me the flexibility of more power when I can use it, but I really need to see what's involved in the custom mounts still. Options 1 and 4 are leading at this point.

But I'm still not sure that I need higher spindle speeds? This all started with the search for a better finish in aluminum and higher spindle speeds is one parameter that most cutting-bit sources said would help, though they also state that I don't need more hp for what I'm doing. There are other things that I can do to achieve a better finish, so my plan now is to tackle those first (ballscrews/zero-backlash, and change from half-step to 8-step), then decide about the spindle speeds later.

Cheers,
-Neil.