Direct Drive vs. Non Direct Drive?

Dudes,

I was tearing up some aluminum in my less-than-a-year-old VF2 today. 7500RPM (Max) .625 EM, .500 DOC, full slot, 75 ipm. That puts my spindle at 100% on the the load meter, which is where I like to see it most of the time these days. But, I had to switch my set up for the next operation to my 2007 VF3 because it has twice as many slots in the table (I hate that the VF2 doesn't have as many slots). I set up in the VF3, run the same parameters, and the spindle load jumps to 200% and stalls my machine. Perplexed, I dial back my feed to the point that I'm at 100% on the VF3, and it's 33%. So effectively, my VF3 is 3 times slower than my VF2. Same damn decals on the front of the machine, except that the VF2 says "Dual Drive" (I think) and the VF-3 doesn't.

They both have 20hp motors, so I figured the Dual Drive thing is the only difference, or there's something wrong with my VF3. These machines are only a year apart from each other and I just couldn't figure how anything could make one go 3 times faster than the other. Thoughts anyone? I also have an 05 VF3 with 10K spindle and 06 VF5 with the standard 7500. I didn't have time to play with it today, but I was gonna take cuts in the other machines and see what they do. I guess I'll be doing most of my work in the VF2 when possible, since I'm the only one who really puts the machines through their paces...

If it has a sticker that says "dual drive" it must be better, right?

Actually from your post title you say Direct Drive - which means "no gear box". Dual drive is a constant torque wye delta thingy that provides a much better torque curve (supposedly), so that is why your vf-2 kicks your vf-3's ass.

From Haas' website:

Vf.......comes standard with a 20-hp vector dual-drive spindle that spins to 7,500 rpm and provides either 75 ft-lb of torque at 1,400 rpm, or 250 ft-lb at 450 rpm with the optional 2-speed gearbox. The Haas dual-drive system uses wye-delta switching to provide high torque and a wide constant horsepower band.

Yowzers! 100% spindle load at 23 cubic inches per minute? That's a 5hp cut.

20HAASpower = ???

It's supposedly the wye-delta thing doing it's trick - although how much of that is marketing combined with other upgrades is something I'm skeptical on, but our VF4 has a lot more torque at 7500rpm than a lot of the older HAAS machines in the machine shop down the road, we couldn't work out why we were shifting so much material until they realised that was the only thing different on ours.

The only thing you could do is drop the rpms and load up a bigger tool if the part allows, that'll get you more horsepower at the cutting end.

Joe788 said:

Yowzers! 100% spindle load at 23 cubic inches per minute? That's a 5hp cut.

20HAASpower = ???

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HAHAHA Joe. That's Powered by Oxnard, my friend.

StreetSpeed said:

.... I set up in the VF3, run the same parameters, and the spindle load jumps to 200% and stalls my machine. Perplexed, I dial back my feed to the point that I'm at 100% on the VF3, and it's 33%. ...

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Did you try dialing back the rpm a bit and experiment with different feed and rpm combinations. I have found on some Haas machines you can reduce the spindle load by using lower rpm yet keep the feed per minute the same or very close to the same. Not intuitive because the feed per tooth is higher at a lower rpm but I figure it is that the motor torque increase faster when the rpm go down.

Thanks for the replies. I looked at the Haas site and realized it was "Dual Drive" so I changed it in my post, but I couldn't change the title. Yes, I did mess with the spindle speed, but that did not have the effect you were speaking of. So, I guess the Dual Drive thing actually works, in a big way. Bummer. I was hoping I could go faster than the VF2 on my 10000 RPM VF3, but probably not. I'll have to mess with some more stuff. Thanks for the help.

I didn't notice in your original post that the VF-3 was a 10k spindle. I thought it was the 7500rpm regular gearbox 20 horse which I KNOW is a P.O.S. Did you run the tool at max RPM on that machine??? If not, you should. That way you'd have a lighter chip load, and should be able to run those speeds...if not more.

If you are running a 3 fluter at 10k you can run it at 90 ipm with only .003" chip load. I've run 3/4" endmills about .500 deep at 100 ipm without issues on a 10k 22horse Haas.

I have a vf3 with 10k and a vf3 with 7.5. The machine I switched to was the 7.5 because the 10k wasn't available and it doesn't have the renishaw probe either; which I can't live without. But I just had a PO come through for a few hundred sizeable aluminum parts, so I think I shall do some tinkering with the 10k.

I think you're better off with the 10k machine. From my experience, the 7500rpm spindle (basic one) was all but useless. Of course, being "spoiled" having all of my other machines with 10k spindles at the time I might have been a little biased from the start.

We would laugh listening to certain tools on that machine slow the spindle down so much. We could all hear how it struggled with programs we ran without trouble on the other machines.

Interesting about the Wye delta, though. Sounds like it helps a lot.

Thought I'd just throw out some info. Haas' rated HP is the 1 minute rating at 180% spindle load. To give some perspective, my 93 VF-0 has a 5HP continuous 100% rating, 7.5HP 30min 150% rating, and 9HP 1min 180% rating. So basically the 7.5HP is really the useful one, since I can run at 7.5HP for 50% of the time. Tool changes are free spindle HP, since they count towards the off duty cycle.

The wye-delta switching isn't really special. They basically took the same logic for the gear box shifting and ran it into contactors. They have a set of contactors that can change the wiring of the motor on the fly, the spindle drive doesn't care or know how the motor is wired, it's just running it normally.

A 10k spindle is more than likely just a different pulley combination and different bearings, Hardinge does that on the bridgeports CNCs. As for one 7500rpm machine vs the other, it would depend how the fixed phase motor was wired. They may wire the older motors for low speed torque and the new motors switch from the standard phase to the other at high rpms, giving additional torque at top speed. You *could* simply rewire the fixed phase motor to match the other at high speed and you would get the same torque at the same top RPM.

For extra credit you can scam the signals off the IO board for the shifting solenoids and wire your own wye-delta contactors to retrofit the non-dual drive machine. Then you just enable the gearbox shifting in the control, since all controls assume the machine has a gearbox and it's just disabled.

LOL Joe. That's hilarious, especially with the graphic. I laughed so hard I still hurt.

HAASpower.... I'm going to use that on somebody.

Joe788 said:

Yowzers! 100% spindle load at 23 cubic inches per minute? That's a 5hp cut.

20HAASpower = ???

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It might be worthwhile contacting Haas tech support and going over the parameter settings for the spindle drive on this 'weak machine'. Something sounds out of wack, almost as if the motor were derated.

I've had this happen with a Baldor DC spindle drive on a lathe: it would throw an error on startup, so reset, and the thing was gutless. Went into parameters and it had derated the max current setting because it had defaulted to a smaller motor type.

So effectively, my VF3 is 3 times slower than my VF2. Same damn decals on the front of the machine, except that the VF2 says "Dual Drive" (I think) and the VF-3 doesn't.

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Definately, need to buy new decals.