Now Cutting! - Auckland NZ

[smreish]

...Thank looks about right!
Great work Chris.

[litemover]

Thanks Sean.

I found a great price on rack, if i can use mod 1 rack 12mm thick x 15mm high. Is that doable?

[Gerald D]

Yes, that size is okay

[litemover]

Thanks Gerald.

Have one more question about VFDs. I found a good 10hp ABB VFD drive for reasonable, if I buy a 5 hp spindle will I be able to use the 10hp drive for it without problems? Also will Mach3 be able to control the ABB VFD?

Thanks in advance for the feedback on this one.

Chris

[litemover]

Well, I just purchased a 7.5kw 15amp 10hp ABB VFD, the ABB ACS350-03U-15A6-4 with advanced control module and full case for a killer deal at $199USD plus shipping. Worth at least $1600. They were going so fast I had to get one, if it don't work out right, I can send it back.



The guy has 2 left if anyone is interested. Link is here: link to ebay auction

[domino11]

Hey Chris,
Do you have 3 phase power at the shop or are you going to run a single to three phase inverter for the vfd?

[litemover]

I have 3 phase power, but I read somewhere you can connect this to single phase and get 2/3 power out of it? Is that true? My spindle only draws 10amps at 5hp 4kw.

[danilom]

The number 4 in the model number means 380 - 480 V input voltage
to get that you need voltage between phases so its 3 phase

later in manual they say that 3U in model means
03 = 3-phase (200 - 240V and 380 - 480V)

Do you know if they got a Modbus RTU (RS485) to go with it?

[litemover]

That's what I figured, but I do have 3 phase in the upcoming shop so it should be ok. I do not know if it has mod bus, but I did purchase a spindle controller from either PMDX or smoothstepper. Is that going to help? I'll be glad to buy whatever I need to make this VFD work with the Chinese spindle and Mach3.

I assume this is the bit I need to make it work properly? It does not come with it.

[litemover]

I just read in the manual that it does have embedded field bus for control through the RS-232 panel connector. Wil that work?

[IMG]
[/IMG]

[danilom]

usn RS232 or RS485 you can control the VFD like this

http://www.mechmate.com/forums/showthread.php?t=3411

[litemover]

Awesome, thanks Danilo. I'll check it out now!

Just had a test of rack sent to me. It doesn't look too bad about a mill or two in the cut. We're working on laser cutting it, this is the test with 12mm MS. I'm going to try 10mm and cross my fingers. Does anyone know if I can lessen the pitch line of the teeth? My gear design doesn't make it to the bottom of the teeth, should it mesh exactly?.

[IMG]
[/IMG]

[Tom Ayres]

I believe that the teeth are supposed to hit the sides and not bottom out. Great work Chris.

[Gerald D]

That rack looks horrible, the pinion too. Are you seriously thinking of laser cutting it?

[litemover]

I figured it looked rough, but don't have it in my hands yet to check out. I was thinking of it, if it could get good results, but not sure that it will work out. Maybe water jet would be better?

I'm having a bit of difficulty with my VFD to Spindle. Can I use a 220v 5hp spindle on a 380v input 10hp Drive with no problems or do I need a 380v spindle for it? Is there something I could use to derate the power down to 220 v in the VFD? Any help would be appreciated. They do have the 380v chinese spindles at 5hp but I'm just hoping that I can figure out if it will work with my VFD.

Thanks for any advice.
Chris

[danilom]

You can set any voltage at output of the VFD as long as it is in the VFD limits

[litemover]

I guess that means my limits are within 380 - 480v? Do you have this VFD Danilo? Unfortunately, the manual applies to all the ABB 350 series VFD so it doesn't say which one does what. It does state though never to connect a motor with a lower voltage than the input voltage of the drive... The drive input voltage is 380 to 480v. In ratings it only has amperage, kw, and HP.

[domino11]

Chris,
I do not think waterjet cutting will give you a better looking rack and pinion.

[bradm]

It's not clear to me that either laser or water cutting are going to have the precision you need for a small rack. That photo pretty clearly shows a huge amount of backlash; the pinion is not in mesh, but just floating in overly large valleys. I suspect there are no shortcuts in making precision rack and pinions.

While you can limit the AC RMS voltage coming out of the VFD, you should recognize that the "AC" output is really PWM pulses of DC. Those pulses will be at SQRT(2) = 1.41421356 times the input AC voltage. So a VFD at 220V has an internal bus voltage around 330V, and outputs pulses at 330V. At 380V, the bus voltage and pulses are at 540V or so. That means that all of the wiring, including within the motor itself needs to be safe at the higher voltage (insulation, etc). Whether or not a given installation will work without undue heating or insulation failure is a topic for experts, of which I am NOT one. I'd get some specific usage advice from someone offline on this one; there are potential safety issues that can't be resolved from a theory based conversation.

If I were a VFD manufacturer I'd post the same warning in my manuals; one misconfigured setting on the VFD, and you can end up sending a whole lot of high voltage at high amperage through circuits and devices not rated for same.

[litemover]

Thanks for the info Brad. Much appreciated. Guess I'll call ABB and see before buying a spindle. It wouuld be fantastic if I could run 230 off it.

I'll have to see about the rack when I get it...

On another note, I've drawn up a sheet metal enclosure. It's 400x600x250, 16 ga. Here's the flat pattern and plan for it. It has a lip for the seal which I'll put a rubber seal in and hinges. Haven't drawn a removable plate yet, but will... Now just need to mock up a press brake and a plasma

[IMG][/IMG]

[litemover]

Refinement of enclosure. Added acrylic perspex window, added a few hems on the edges.

[IMG]
[/IMG]

[KenC]

VFD takes in single or 3 phase Sinusoidal wave form AC electricity, rectify it to DC electricity, than reshape the DC electricity into 3 phase Sinusoidal or psudo-sinusoidal waveform (or in a layman term digitized Sine wave) AC electricity of your specified voltage & frequency using PWM technique.
HECNCE, You can use any motor with any voltage as long as it is equal or lower than your input voltage.
There should be input & output voltage selection in your VFD manual..
The VFD output is ALWAYs 3phase unless you connect it otherwise. hence you can use a 220~240V single phase supply for the VFD to feed 200~240V 3 phase motors.
When you use Single phase input, for 3 phase output, the single phase will have to supply enough current to sustain the 3 phase out put current. which is Sqrt(3) (1.732) of each output phase current. With this you should be able to "derate" your VFD appropriately.
eg, on a 240V single phase with a 13A fuse, your max. 3 phase 220V is ~7.5A.

BTW, I won't put those rack & pinion on any of my CNC machines.

[litemover]

Thanks Ken, interesting. So as I read before, I can connect a 3 phase 380v vfd to single phase 230v and it will still work but derate to 2/3 the original output? Correct? Hence, my 3phase 380v 7.5kw vfd will still drive a 4kw spindle if it is connected to single phase 230?

[bradm]

Chris, I wouldn't make that assumption. There are effectively two power supplies inside a VFD. The primary is high amperage one we've been discussing above, which does the AC to DC conversion with no change in voltage, and Ken's explanation is good - and applies when you are using a VFD with the voltage level it is designed for.

However, there's a secondary, small power supply that drives the control circuitry - one or more very small DC voltages like 3.3v or 5v or 10v or 12v. That small power supply has been built or configured for whatever the rated input voltage is of the VFD in question. Only the manufacturer can tell you what will happen if you feed it over or under voltage. Within a certain range, there's a decent chance it will work, just like modern laptop power adapters will accept pretty much anything between 100v and 240v and work just fine, albeit at slightly varying levels of efficiency and heat output. But trying to take a supply designed for 380v input and feeding it 230v isn't guaranteed unless they've designed for it.

Also, since the software in the VFD may be calibrated for 380v and not 230v, there is also a good chance that even if the control power supply is fine, the VFD parameters will have varying degrees of inaccuracy.

So, again, get some input from ABB and/or an experienced tech on the proposed usage.

[pblackburn]

Chris, that pinion and rack should ride on the pressure angle. Do not use that rack and pinion, I do not see the multiple angles that should be on either. A gear gauge would show you if they were anywhere close to accurate. They are visibly not. With your VFD, the installation manual that is supplied with it or from their website should have all the information that you require. If not, I would call the manufacturer and ask for tech support. I have only ever found a few companies that would not help with there products.

[KenC]

Originally Posted by litemover

Thanks Ken, interesting. So as I read before, I can connect a 3 phase 380v vfd to single phase 230v and it will still work but derate to 2/3 the original output? Correct? Hence, my 3phase 380v 7.5kw vfd will still drive a 4kw spindle if it is connected to single phase 230?

You call it derate, I call it precaution.

With the maths I illustrated, you already knew the 7.5kW VFD will survive the scenario.

the million dollar question is will your house go down in electrical fire when you pull 4kW worth of electricity from your electrical circuit? Only you can answer this question.


#Ps,
Don't just look at the equipment. you gotta look around too. such as how much total load you are exerting on your other basic system. Electricity supply isn't always unlimited.

[pblackburn]

To hopefully add to this discussion. Most VFD manufacturers recommend for heavy duty use to upsize the VFD for the next higher horsepower rating. It is usually within the first couple pages of the manual. We have to do this with presses where I work because of the load generated and regenerated from the flywheel. Same principles can be applied here.

[litemover]

Thanks Ken. The circuit is commercial 3 phase in a commercial building. But I was just curious if I wanted to hook it up to 230 single phase 16a breaker, if that would be ok too.

[danilom]

To add something about consumption, you will rarely see 100% or 4kW consumption on vfd, running with 6mm endmill trough 9mm pass on plywood 2.8m/min produces around 26% load on my 2.2kw spindle.

and 4kw is on a small side here, as we got heaters and other stuff that can pull more than that

[litemover]

Thanks Danilo,

Just an update. Still looking at spindles, saw that most of the Chinese are now offering a beefed up version of the 3KW spindle for cutting metal that looks interesting, though it is twice the price, also saw a smallerspindle that does 60000 rpms at 1000hz. Most of the new metal spindles are with a red background. Does anyone know anything about what the big difference is? I asked and the guy said that the 4kw can only do wood, and the 3kw metal can do wood, metal, and acrylic.

I finished the stop blocks and started mounting my proximity sensors. Am programming an Arduino with shield to handle the proximity sensor logic since I had an UNO R3 laying around already.

Working with electronics. Photos to come shortly. BTW, the rack was too rough to consider as a cut.

Cheers,
Chris