[Corvair.Flier]

Gentlemen,

I recently purchased an older Bridgeport (Series 1) with a 1hp motor. I started searching for a 3-Phase Converter and I was told that my converter should match the HP of the machine. In my case I would then be looking for a 1HP 3-Phase converter. But I have not found a converter that is anything less then 3HP. Am I looking in the wrong places, or was my advice incorrect? I am assuming (and I really hate doing that) that a 3HP Converter is what I should be using. I based this assumption on what I have read about other Bridgeport owners and commercial converters.

Corvair.Flier

[ww_kayak]

Well, I'm certainly no expert, but a bigger phase converter can always power a smaller motor. Most of the references you see to matching (or exceeding by 1.5x) HP are related to the bigger machines. If you're sure you only need it for this machine, Look into VFD (variable frequency drives). I used my VFD on my BP and it fit the bill perfectly... until I bought a bigger machine

[lakeside53]

Check out www.driveswarehouse.com

Plenty of different size and featured Hitachi and other VFD drives....

Don't buy the cheapest unit - buy one that has a braking unit INTERNAL.. You will likely need external braking resistor. I have both and L200 1 hp unit, and an SJ200 2 hp unit. Without a brake, flipping the speed down quickly, or just hitting "stop", will likely trip the unit as the motor turns into generator (it does with my 2h motor). I use a 50 ohm 500 watt braking resistor and can stop my 2hp motor in 1 second, from as high as 4000rpm.


If you use a larger vfd to run a smaller motor, be sure to change the various registers that control the max motor current etc.

[Corvair.Flier]

Kayak and Lakeside thanks for the information. I was leaning on the side of the VFD until Kayak asked if my Bridgeport was the only thing I would be using the 3-phase for. It got me thinking, I bought the Bridgeport from a gentleman that also owns a nice lathe. And he said that he may be interested in selling sometime soon and that he would give me the first opportunity at buying it. So now I may be leaning back to the Rotary Converter. SO I will have to think about this a little more. But I really appreciated the information. I had never heard of a VFD before and find it very interesting.

Corvair.Flier

[lakeside53]

If you don't care about the variable speed, braking or other vfd feature.. a rotary converter is an easy solution. You will still need 3 phase motor protection, breakers, switches etc, and this can easily cost more than the VFD approach. Personally, I like what a vfd offers, and have/will fit them to each of my machines.


I have a very nice 1hp (start) rotary converter that is gathering dust...

[cnc Rookie]

I've been running my series 2- 2hp motor off a 10hp rotary converter. It's cnc rated which I believe means it stays plus or minus 3% on the output. With shipping and brand new I have around $500 in it. Very easy to hook up....just had to buy some extra wire. Everything else was prewired and ready to go. Had it hooked up and running in about an hour.
I was told to at least double the converter rating for the motor you want run.
So I could of easily used a 5hp converter but had the same thoughts as you and may hook up another machine to it also. If your interested I can hook you up with the place I got mine. Louisiana, if I remember, is where it shipped from.

[mactec54]

Hi corvair.flier
I have a 7.5 hp that is new & has been used one time for a tryout
it is easy to wire & has a softstart which is important I want $275
plus shipping this has a Baldor motor with rubber feet you can
email me if you are interested they cost way more than this the
unit is made by Gentec & is cnc rated

[ww_kayak]

I'll ditto what lakeside said. I only bought the VFD because I needed 3-phase. I had no idea about the other benefits. BUT now I am so use to using it to slow down my speed ups, speed up my slow downs, and fine tune my speeds, I don't think I'll ever go back. You can make a rough cut then speed it up and make a final pass without ever having to deal with the pulleys. The only reason I can't get away with it on my lathe is because they are pretty expensive for 5+ HP... and because I picked some inexpensive parts to build an RPC . If you get one for the mill you won't be sorry, even if you end up needing a converter later.

[cnc Rookie]

Hi corvair.flier
I have a 7.5 hp that is new & has been used one time for a tryout
it is easy to wire & has a softstart which is important I want $275
plus shipping this has a Baldor motor with rubber feet you can
email me if you are interested they cost way more than this the
unit is made by Gentec & is cnc rated

Smokin deal............where's it located?

[mactec54]

Hi cnc Rookie
30 miles south of Nashville TN

[9 1/2]

If you use this VFD, which I am currently using. Make sure you read my thread on hooking this bad boy up. It had some oddities in naming of terminals.

Owen

[luther]

i made my own 3-Phase Converter for my Bridgeport, pretty easy to and i can not tell the difference look at this link www.metalwebnews.com/howto/ph-conv/ph-conv.html

[Corvair.Flier]

Lakeside, kayak and 9 1/2, I was on the DrivesWearhouse website and was looking at the L200-007NFU2 unit. I noticed that there were three references to the braking.

12.0 Braking
12.1 Dynamic Braking Approx. 100%
12.2 DC Braking "Operating frequency, time and braking force variable"

IS this what you ment by Internal Braking?

As always, thanks for the help!
Corvair.Flier

[mc-motorsports]

I also built my own phase converter, cost about $100 plus my time, 3hp and I run 3 mills off of it daily, 2hp bridgeport, 1hp bridgeport, 2hp excello knee mill, no problems, all at the same time. Now I wouldn't start and or stop all of the spindles at the same time, that would probably be a problem! If I had step heads, I would buy the VHD in a heartbeat. All of my mills are variable speed. Just my 2 cents...

[hot knobs]

I have a home made 5 HP rotary that ran a 3 HP lathe and a 2HP mill I would sell for 150.00 plus shipping and a crate or pickup in Reno. oldcat35o@sbcglobal.net

[lakeside53]

Lakeside, kayak and 9 1/2, I was on the DrivesWearhouse website and was looking at the L200-007NFU2 unit. I noticed that there were three references to the braking.

12.0 Braking
12.1 Dynamic Braking Approx. 100%
12.2 DC Braking "Operating frequency, time and braking force variable"

IS this what you ment by Internal Braking?

As always, thanks for the help!
Corvair.Flier

Check you the wiring diagrams. That unit requires an expensive (more than the vfd) EXTERNAL dynamic braking unit. The SJ200-007NFU has an Internal Braking UNIT - you can just connect an external braking resistor.. yes, it's confusing, and the very first VFD I bought was an L200 and incorrect for my needs..

[ww_kayak]

Basically I can stop mine(no external braking) in about half the time without an error. Which for me is fine, I'm not doing any production work. It all depends on your needs... or wants

[lakeside53]

Yes.. whatever works for your needs.

I use my non-braking unit on a wood lathe - fast stops on that are not advisable!


For others reading this thread... it affects two operations as well as "stop"

Reverse - I like a quick reverse! yes, it's more about "like" than "need".

The second is not so obvious - the "path" to a lower speed - like rapid turning the speed knob down can cause a trip on many motors. I don't want to deal with that. Sure, I can program longer deceleration and have the unit track frequency rate decrease based on the the DC buss, but..

[alex 850]

i purchased mine from msc talk to a tech there and they should be able to help you! the motor on my bridgeport is 2 hp. and works well.

alex