[Newbie] 1980 Bridgeport Series 1 - Vfd Question

AxeMaker

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Hi,

My BP has a 2HP motor. Is there any advantage going with a VFD that is rated higher than 2HP? i.e... a 3HP VFD.
 
In most cases no. If you were going to be operating the machine at full load for extended periods, then maybe. This would be very unusual in a home shop.
 
In most cases no. If you were going to be operating the machine at full load for extended periods, then maybe. This would be very unusual in a home shop.

Okay, I can save the money!

I've been looking at the Hitachi WJ200-015SF for $283. I may go ahead and purchase it unless I find a reputable brand with comparable specs for less this afternoon.
 
Not to hijack this thread, Axemaker, but I'm getting ready to do the exact same thing - use a 2HP motor and need a VFD. I get that I need the VFD but am not clear on what else is needed beyond the basic VFD drive itself.

Jim, when would you choose the GS3 over the GS2? I understand the GS3 uses sensorless vector drive but is that a significant advantage? Beyond the basic drive, are there other components that are necessary to complete the installation? I don't mean to take up your time and I will call Automation Direct but your input would be valuable nonetheless.
 
Jim, when would you choose the GS3 over the GS2? I understand the GS3 uses sensorless vector drive but is that a significant advantage? Beyond the basic drive, are there other components that are necessary to complete the installation? I don't mean to take up your time and I will call Automation Direct but your input would be valuable nonetheless.

Please feel free to ''take up my time'', that's why I joined this forum, to help out where I can. :)

I have both drives and use them based on the application. The GS2 is only Volts/Hertz output, in other words, it reduces the voltage as the frequency decreases. Thus the torque curve is variable and the low speed performance is not as good as a sensorless vector output, the GS3. I'm not going to try to explain how sensorless vector works, because I don't understand it myself :confused:. It's electrical magic. :cautious: But the result is that the VFD has a lot more control over the motor and the torque can be constant from about 10 RPM up to the rated speed of the motor. Great for low speed milling. I just replaced the GS2 on my machine with a GS3 and am very happy with the result.

The GS2 is best used between 30 and 90 Hz. I am running the GS3 on my spindle between 10 and 200 Hz (180-6000 RPM, if I did the math correctly). Note: My motor is rated for 6000 RPM, I would not recommend this on a motor that you don't know the specs on. Running an 1800 RPM motor at 3600 RPM (120 Hz) is probably safe.

As for other components, a braking resistor is almost mandatory for reasonably fast stops. Then you may need a small control panel with Start, Stop, For/Rev switches, and a Speed Control pot.

I mounted the GS2 right on my head in place of the original switch and just ran it from the control pad. I am used to reaching up into that area to run a BP type mill.
upload_2016-8-26_14-59-44.png

When I installed the GS3 I built this panel and installed the VFD on the back of the control cabinet.

Here is the BOM for the control box I built. Automation Direct parts.

Item Code | Unit Price | Quantity

ECX2300-5K $36.50 1
SA110-40SL $13.50 1
GCX1131 $12.50 1
GCX1102 $6.50 1
GCX1300 $9.75 1
E22NS31 $4.50 1
E22NS34 $4.50 1
E22NS38 $4.50 1
ECX2640 $3.50 1

Shipping and Handling : $0.00
Order Total : $95.75

upload_2016-8-26_14-53-7.png
 
Thanks so much, Jim. That is exactly the info I was looking for. I get that the sensorless vector drive allows for maintenance of torque as speed/frequency decreases and that is a useful thing on a milling machine. I also understand that the braking resistor is needed to prevent voltage spikes from damaging the drive. I will go for the GS3 and very likely duplicate your purchasing list above.

I really appreciate it, Jim. You taking your time saved me time, and while I still need to study up and understand the technology before purchasing you made that study much more focused. Thank you!

Mike
 
Okay, I can save the money!

I've been looking at the Hitachi WJ200-015SF for $283. I may go ahead and purchase it unless I find a reputable brand with comparable specs for less this afternoon.

Good Choice. I have the exact same unit on my Bridgeport and it has been working very well. Let me know if you want any help with getting your setup working.
 
I have found that the Chinese stuff is hit or miss. Actually the Taiwanese stuff is pretty good, its the Chinese stuff where you can run into problems.
 
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