Replies

1. 
   UncleDunc | Jul 28, 2004 11:51am | #1

   Click on the Advanced Search button (near the top of the left hand frame) and search for variable frequency drive and VFD. Probably easiest to do it as two separate searches. I've seen them discussed here several times.

2. 
   RickL | Jul 28, 2004 12:39pm | #2

   Have you tried contacting a local motor repair shop? I got a VFD from my local shop to run a bridgeport we set up. It's a bit tricky to program and has more bells and whistles than you need for a jointer. VFD's offer soft start, variable speed and can boost the rated speed of a motor. It's ideal for shapers, bridgeports, drill presses, lathes that have step pulleys and can give push button variable speed for convenience. 5 hp VFD units are quite a bit more in price than a static converter. For a jointer i'd go with a static converter as it's a lot less money and will do the job. A static will give less power as it only starts the machine then kicks out. It has less power because you are only running on two windings so a 5 hp motor is running at about 3 hp but that's more than enough for a 12" jointer especially in a small shop. A rotory is good for running multiple machines and you can always upgrade to a rotary if you get more machines. A VFD is best for single machines as it's too much of a pain to reprogram for other machines. I've used all three types of converters and there's definitely special applications where each has it's merits based on different criteria based on hard starting machines like compressors, CNC, or just a simple grinder. Again I recommend a local motor shop as they should be able to show you the different units. They should even have one in stock so you could look over the manual to see what's involved in programing it and even give you some help but in my opinion and 20 something years experience with three phase a static is perfectly fine for your 12" jointer. There's a lot of companies making them and they are very basic. http://www.phase-a-matic.com/ is one comapny I've used and they have a good solid tech staff to help with your application.

    

   Unless your motor is a built in direct drive it would most likely be cheaper to change the motor than to use a VFD.

   I'm a bit dubious of the electrical advice on a woodworking forum as some of the stuff I've seen is just plain wrong or a bit off base. How do I know that?  I've been a repair tech for many years and have a group of experts I rely on for advice on specific tasks such as motor repair so I have enough of a general knowledge to guide me through the options.

   
   

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   Edited 7/28/2004 7:05 am ET by rick3ddd

   
   

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   Edited 7/28/2004 12:16 pm ET by rick3ddd

3. 
   barry444 | Jul 29, 2004 12:12am | #3

   i just went through a similar situation as yours . i purchased a 3 phase 5hp dewalt radial arm saw . i ended up using a static converter and am very pleased. the machine starts up instantly and is more powerful than i will ever need. the best part is it only cost $100.00 good luck with your restoration.

4. 
   forestgirl | Jul 29, 2004 12:50am | #4

   What's the difference between a VFD and a "phase converter" which is what I usually hear about.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
   Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

1. 
   UncleDunc | Jul 29, 2004 02:13am | #5

   A phase converter converts 60 Hz single phase to 60 Hz three phase. A VFD allows you to control the frequency to control the motor speed. I believe most VFD's are for single phase motors, but it wouldn't surprise me to find out there are systems that do both the single phase to three phase conversion and the variable frequency drive.

1. 
   RickL | Jul 29, 2004 03:17am | #6

   There's four ways to do it and they all have certain things that makes each the best choice for the application.

   VFD - Variable Frequency Driver: This is an electronic circuit - an inverter actually – that converts single phase AC to DC, and then to 3 phase AC. You’ll need one that uses single phase input and provides 3 phase output. VFD’s typically offer forward, reverse and motor speed control as well. These units are sweet but best for smaller motors. A VFD for a 7hp motor costs a fortune ($3,500 or more)! One for a 1.5hp motor is around $200-$250. VFD’s are particularly good for a lathe or drillpress where speed control is important.

   Static Conversion: This method uses capacitors to start the motor which then runs on single phase power. A static converter does the job but you’ll only obtain 70 to 80% of the motor’s normal operating power. If you have a 5 hp 3 ph table saw - you probably won’t notice the difference. Static converters must be balanced to the motor being run. You’ll need a separate converter for each machine you run unless they’re all the same horsepower (and even then you may find variances). A three phase motor will run on 220 single phase once you get it going. The static ones provide the third leg to start it then does nothing. There's enough centrifugal force to keep the armature spinning past the missing leg hence the loss of power but for the most part it's not noticable unless you are really pushing the limits of the machine.

   Rotary Conversion: This method adds another 3 phase motor – an idler – to the static converter providing current in all three phases and while not perfect will allow your motor to run at all or nearly all it’s rated power. A large rotary will let you run many different sizes of machines. The spinning motor actually generates that third leg in three phase so it's close to the real thing.

   Then there's a new fourth method http://www.phaseperfect.com

   Not to be confused with a VFD it's actually digital three phase power. As I understand it so far it won't give the bells and whistles of a VFD but it will run a wide variety of size motors, welders and what have you with the closest true three phase power.

2. 
   forestgirl | Jul 29, 2004 06:35pm | #8

   Thanks Dunc (and Rick too!).forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

5. 
   KeithNewton | Jul 29, 2004 03:19pm | #7

   Pete, You can get a VFD for a 3 HP single phase input from Graingers for about $700. You can buy a new 3 HP single phase motor for about half of that. I don't know why you would ever want to slow the cutter speed on a jointer, so why pay the extra bucks.

   You may be able to use the same starter by just changing the heaters to match the amps of the new motor.

6. 
   RickL | Jul 29, 2004 07:23pm | #9

   You can buy a static phase-converter from Enco for $116 to $160 fot the heavy duty model. Phase-a-matic brand...I'd check the motor specs with them to get the right one. 5 hp on a 12" jointer is more than enough so a static would be fine. I had 3 hp on my Oliver and it never bogged down...of course it was a direct drive, another reason to go with a converter versus changing the motor.  Is yours belted or direct drive. Folks always leave out the important details in posts.

1. 
   pete811 | Jul 30, 2004 05:46am | #10

   rick, direct drive. pete

1. 
   RickL | Jul 30, 2004 06:07am | #11

   Static for sure! More than enough to do the job. Save the money!

1. 
   pete811 | Jul 30, 2004 06:27am | #12

   rick 10.4 and thanks a lot. will keep you posted re: how it goes .  won't be for a while yet lots of other stuff to get through before i can play.  pete

7. 
   Napie | Jul 30, 2004 05:42pm | #13

   VFD’s do not convert single phase to three phase, they are for speed control.  VFD’s are three phase only, single phase motors use speed controllers, similar to a rheostat.  They are available sizes from fractional horsepower to motors of many hundreds of horsepower.

1. 
   RickL | Jul 30, 2004 07:20pm | #14

   http://www.deselectric.com/inverters

   They make them to run three phase motors on single phase.  A local motor shop has a neat baldor inverter on a small drill press that takes 120 volt single phase and converts it to 220 volt three phase and can adjust the speed electronically. I see the term inverter used pretty much interchangably with VFD

   Edited 7/30/2004 2:10 pm ET by rick3ddd

1. 
   Napie | Jul 31, 2004 12:12am | #15

   The inverter is the heart of the VFD, it is what makes AC power “look” like DC to the motor allowing for the speed change.  The price and size of frequency drives has shrunk many times in the past ten years.  When I started in the business a 10 HP drive was the size of a refrigerator and cost $20K.