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RancherBill
01-31-2009, 10:04 AM
I am thinking of some changes and upgrades to my equip.

VFDs appear from all the other threads to be the way to go. When I look at the vendors sites they have a million styles. I get confused.

Is there a good site that has some basic education material on VFDs, motors etc?

AllanR
01-31-2009, 10:11 AM
The Practical Machist site has a very good thread on VFD's
I hopr this helps
Thanks
Al

AllanR
01-31-2009, 10:12 AM
The Practical Machist site has a very good thread on VFD's
I hope this helps
Thanks
Al

JoeFin
01-31-2009, 10:20 AM
http://www.practicalmachinist.com/vb/forumdisplay.php?f=11

Tons of good info

Try the search function first

lazlo
01-31-2009, 10:28 AM
The PracticalMachinist VFD forum is a great place to ask questions, but may not be the best place to get started.

VFD's are very simple -- you don't need to know the electronic theory behind them. They just take single- or three-phase power in, and generate three-phase out, in a way that allows you to control the speed of the motor.

Here's a great Intro to VFD's page if you want to know more about how they work:

http://www.joliettech.com/what_is_a_variable_frequency_drive.htm

For a home shop, you usually want a single-phase input, and you need to match the wattage of the VFD with the wattage of the motor on the machine tool.

I wouldn't get hung-up on Sensorless Vector drives -- they give you ~ 10% more torque at low RPM, so you'll be happy with just about any modern VFD from DrivesWarehouse, DealersElectric, ...

http:/www.driveswarehouse.com/
http://www.dealerselectric.com/

Bill Pace
01-31-2009, 12:03 PM
Yeah on the PM site for info ...I was way short of any info on the VFD's except what I was hearing about them in various posts which sounded rather like an interesting thing. Being enough familiar with the PM site and the crap you can get heaped on you, just went there and put vfd in search and read all the entries, was able to get a pretty good foundation of terms, sizes, apps, etc that I was at least a bit more comfortable in posing questions or looking for something. There IS a lot of info there, just not the most friendly place, especially if youre not a "professional"

I was able to gather enough info from PM, and many other sources, to jump in and do it, I now have 3 of the Hitachi SJ200 units and feel very comfortable installing one now.

MTNGUN
01-31-2009, 01:02 PM
What Bill Pace said. PM site has lots of VFD knowledge, just don't dare mention that your VFD application involves a chinese machine.

Moderator, how 'bout a VFD/Phase Converter/Motors forum for the Home Shop Machinst ?

lazlo
01-31-2009, 01:07 PM
Moderator, how 'bout a VFD/Phase Converter/Motors forum for the Home Shop Machinst ?

I think another forum is a really bad idea. We're already losing posts to the obscurity of the Digital Machinist and Welding Forums.

I think we just need a VFD FAQ.

Ryobiguy
01-31-2009, 02:54 PM
FAQs, or at least sticky posts with links to old good threads that cover each topic would be good for the revolving threads that come up all the time:

-Machine selection guide for those just starting out
-Old iron vs. imports
-VFD/rotary phase converter
-Why you can't turn a radial arm saw, dremel, etc. into a surface grinder or lathe toolpost grinder

But, I think people like to ask questions to get a personal touch to compare and contrast what is told from miscellaneous sources from Internet searches. I know if I were just about to launch a big chunk of money on something I'd want to ask real people about the specifics of my situation rather than weighting each differing opinion that I've randomly heard that might not apply exactly to my situation.

Back to VFD dicussion... I've got two of them and highly recommend getting any of them, you'll love it. I always got hooked on thinking I needed the more advanced features, but that generally doesn't rationalize spending double on it unless you've got some specific application that requires it.

In the end my last VFD selection was by price: 2HP for $80. Drive has a slight high frequency squeal from it (hey it's cheap,) has a chinglish but readable manual, and has a ton of features. I like the S curve acceleration and braking.

-Matt

lazlo
01-31-2009, 03:26 PM
Drive has a slight high frequency squeal from it (hey it's cheap,)

You can fix that. There's a "carrier frequency" parameter in the VFD menu that sets the synthesis frequency of the 3-phase output. It's often defaulted to 3 - 5 Khz, and the harmonics are audible to most people as a high-pitched whine. Most VFD's will allow you to set the carrier frequency up to 10 Khz. I find that 7 Khz will make the VFD harmonics almost silent for most people.

Pherdie
01-31-2009, 05:17 PM
Just to share...

I recently retrofitted my 13 x 40 gear head lathe with a Hitachi sensorless vector VFD and a new, metric series, Leeson 3 phase motor. The metric series replacement motor made the change of motor a simple bolt-in swap. The primary purpose of the change was to allow slower spindle speeds for threading than originally allowed by the original single phase motor/gearbox combination (70 rpm).

On initial startup, a significant change was immediately apparent. The lathe ran much smoother with considerably less vibration. Several test cuts proved to be markedly improved in finish.

The next day, another advantage became apparent that I had never considered. I was doing a wide facing cut and realized I could vary the spindle speed as the cutter moved between the outer circumference and center, allowing me to keep that "sweet spot" for cutting speed, resulting in overall improved finish.

Lastly, my lathe doesn't have a manual brake but my dynamic VFD generated braking allows me to stop that spindle very quickly. Something that may be important in the future

Food for thought. I took the time to wire my VFD to the existing lathe fwd/rev motor controls and the emergency/power kill button. As I have become fairly conditioned to the controls on my lathe, which are similar to many other lathes, I wanted to make sure my initial efforts and time went to the "right" controls in case of an emergency.

I wish I had made the change to a VFD sooner.

Fred

MCS
01-31-2009, 05:44 PM
You can fix that. There's a "carrier frequency" parameter in the VFD menu that sets the synthesis frequency of the 3-phase output. It's often defaulted to 3 - 5 Khz, and the harmonics are audible to most people as a high-pitched whine. Most VFD's will allow you to set the carrier frequency up to 10 Khz. I find that 7 Khz will make the VFD harmonics almost silent for most people.

This is up and about the common denominator. I have two different VFD's and they are not the same. But in their parameter settings menu, the parameter setting of a certain feature is at the same "address". So it is a sort of "standarized".

So apart from the commercials, the questions can be like:

"I want to make external wiring for speed, forward and reverse, how can I set this in parameter X or are there more parameters?"

"Is there a parameter in brand X where I can change the switching frequency?"

I can't answer both questions because I filed both books in a place where I could retrieve them instantly. Which means they're somewhere out there.

After solving the choice and wiring there is not 1 good reason not to have a VFD, so it is a serious subject.

Sparky_NY
01-31-2009, 06:11 PM
In the end my last VFD selection was by price: 2HP for $80. Drive has a slight high frequency squeal from it (hey it's cheap,) has a chinglish but readable manual, and has a ton of features. I like the S curve acceleration and braking.

-Matt

$80 for a 2HP is quite a deal! I have to assume its used? Wish I could find a deal like that for my bridgeport.

Ryobiguy
01-31-2009, 07:43 PM
No, it was not used, it was from some guy on ebay who had a stack of a few different types of them. I can't seem to find him anymore, maybe they "fell out of a truck" and they finally caught up to him or something... This is the "Orion" VFD drive from Kimatek.

P.S. This drive switches up to 15khz. I think I tried that carrier frequency but didn't like the pitch as much, must be some lower frequency harmonics if I was still hearing it, that's what I meant by "cheap drive."
-Matt

RancherBill
02-01-2009, 02:06 PM
Thanks for all the information. I'll be reading for a long time.


Here was my original thought. I have a drill press a Jet with a good USA motor. It was not in very good condition when I got it. I cleaned it and replaced all the bearings in the press and the motor. I put a Rohm ball bearing chuck on it and it runs like a new. Encouraged by the renewed performance I went out and bought a set of Silver and Demming drill bits.

According to one drill speed chart drill a 1" hole it should be 191 to 381 RPM. I can change the belts to get 310. The Problem is that the belts slip on the small pulley. I think I have the HP and an 'efficient' drilling mechanism. If i don't have the HP, I have another motor that is 1 or 1.25 hp that I can use. The belts are still going to slip.

So my thought was to set up the belts to use some of the larger pulleys and slow the motor. I'll look today as to the exact pulley sizes, but, my guess is approx 20%. Using the larger diameter pulleys I think will help with the slippage problem.

If I am out to lunch, be kind, I have a sensitive spirit. :) :)

gellfex
02-01-2009, 04:31 PM
Thanks for all the information. I'll be reading for a long time.


Here was my original thought. I have a drill press a Jet with a good USA motor. It was not in very good condition when I got it. I cleaned it and replaced all the bearings in the press and the motor. I put a Rohm ball bearing chuck on it and it runs like a new. Encouraged by the renewed performance I went out and bought a set of Silver and Demming drill bits.

According to one drill speed chart drill a 1" hole it should be 191 to 381 RPM. I can change the belts to get 310. The Problem is that the belts slip on the small pulley. I think I have the HP and an 'efficient' drilling mechanism. If i don't have the HP, I have another motor that is 1 or 1.25 hp that I can use. The belts are still going to slip.

So my thought was to set up the belts to use some of the larger pulleys and slow the motor. I'll look today as to the exact pulley sizes, but, my guess is approx 20%. Using the larger diameter pulleys I think will help with the slippage problem.

If I am out to lunch, be kind, I have a sensitive spirit. :) :)

As a direct approach, more tension and a segmented belt could help.

A vfd can't hurt, though you lose a lot of torque when you use a vfd to bring a motor really down, like under 20hz, so you still want to shift the belt down somewhat. Still, you'll never regret vfd-ing your DP, it's life changing experience. Think of all the times you just drilled at whatever speed the tool was last set at, with a vfd you just dial it in, and easier than even a VS tool. Easy programmed speed reversing is another bonus. You can set the display up to read your actual RPM at your chosen default belt speed. It can also overclock the motor, getting an extra 20% even with old motors, great for those little bits.

waumbek
02-01-2009, 09:55 PM
A couple of VFD thoughts:

1) Some of them come effectively self-enclosed, so you can run conduit right to the unit itself and simply screw it to the wall.

2) Others require an enclosure from a local electrical supply place, not a big deal as a large galvanized box will only set you back about $20 but it is something to be aware of. The VFD gets mounted inside the enclosure and you run conduit to the galvanized box.

3) Make sure you get one with low voltage control inputs. Most seem to have them. This is kind of cool, because you can run thermostat wire from the VFD to whatever large ancient controls your older machine has and make them continue to function however they originally did using a low voltage control circuit.

4) Programming the VFD to slowly bring a machine up to speed over 5 seconds or so is nice for older machinery.

5) Programming VFD's is different from unit to unit and always involves much hair pulling and frustration before discovering how to enter the correct values in a number of sequential menus. Get ready to be frustrated for an hour or two, the result is well worth it.

Cheers, Charles Morrill