# VFD added to HF 8x12 lathe



## AllThumbs (Apr 9, 2008)

Here are a couple pictures of the VFD installation. I can now do about 200 RPM to 2000 without a belt change. If I need torque for heavy cutting at low speeds, I will still need to change the belt position. The belt is set for the old 420 RPM position. Old motor was 3/4 HP, 1750 RPM, new motor is 3/4 HP, 3450 RPM. VFD is set for 0-120 Hz so thats 0 - 6900 RPM at the motor. Sings pretty good.

New motor was C flange (face) mount, so a bracket had to be made. Old motor had "feet".

E


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## BobWarfield (Apr 9, 2008)

Sweet!

I've been wishing for more HP and sometimes RPM on my 9x30. I've got a DC treadmill motor that's nice, but despite the 1 HP label, there is just no way it has that much.

Best,

BW

PS That lathe would make a fine CNC platform!


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## Bogstandard (Apr 10, 2008)

Bob,

It is always nice to have a lot of power, and overmotoring is usually the way to go. But it can cause some major damage to your iron if you try to use it in the wrong way.

I actually changed to a smaller motor on my old Atlas, to prevent any overstressing damage if I took some silly cuts. My machine now lets me know if I am 'pushing' it to its limits by slowing down slightly, rather than damaging almost irreplaceable parts.

As E rightly says, belt changes are required so that the machine is not trying to drive thru the wrong settings for the machine.

John


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## AllThumbs (Apr 10, 2008)

I have not changed the overall HP of the machine. I have simply allowed for more speed variations without belt changes (I hate belt changes), and also can now tune the speed to the workpiece more closely, since I went from 8 spindle speed options to infinite. Actually, if I include belt changes I could go from 0-10,000 rpm on this lathe now. I just don't know about the spindle bearings at those kinds of speeds.

E


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## Alphawolf45 (Apr 10, 2008)

The question that comes to my mind -- You changed from the original single phase to a 3 phase motor?...I am under the impression that VFDs only work with 3 phase motors and if that isnt right I want to hear otherwise..
.
 I second what BobWarfield said, that lathe would make excellent conversion to cnc and with the VFD you've moved partway there already...There many times a little cnc lathe would be just what the doctor ordered..


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## AllThumbs (Apr 10, 2008)

Alphawolf45  said:
			
		

> The question that comes to my mind -- You changed from the original single phase to a 3 phase motor?...I am under the impression that VFDs only work with 3 phase motors and if that isnt right I want to hear otherwise...



Yes, VFD's require a 3 phase motor. Most will allow for single phase or 3 phase input, 3 phase output. The VFD needs to be derated by 30% if operated on single phase input. My VFD is 1 HP, running a 3/4 HP motor. Not quite as derated as it should be.



			
				Alphawolf45  said:
			
		

> I second what BobWarfield said, that lathe would make excellent conversion to cnc and with the VFD you've moved partway there already...There many times a little cnc lathe would be just what the doctor ordered..



I have a CNC converted mill, and have toyed with converting this lathe, but will probably leave it manual. If I had two lathes, I might convert one. Sometimes I think an electronic gear box arrangement would be handy for threading, since I hate changing the gears. Not for now though.

E


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## BobWarfield (Apr 10, 2008)

Bogstandard  said:
			
		

> Bob,
> 
> It is always nice to have a lot of power, and overmotoring is usually the way to go. But it can cause some major damage to your iron if you try to use it in the wrong way.
> 
> ...



Well then you shall simply have to use it in the right way! LOL

These kind of machines have very replaceable parts, so no worries.

That 3-phase is rumored to be a path to nicer surface finish. Hope it works out that way for you.

Cheers,

BW


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## Bogstandard (Apr 10, 2008)

Bob and everyone else, 

I wasn't trying to decry anyone for doing whatever you want to do.

I was just making a statement that sometimes increasing the power to your lathe can have dire consequences. I am sure you all have the knowledge and know how to upgrade your machines. If you don't, I am sure someone on here has already done it, and is quite willing to share the info.

John


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## mrt1723 (Apr 11, 2008)

I have a DC motor I was going to put on my 8x12 but I like your VFD idea a lot better. Can you tell me a little more on what motor you used and what VFD you used ( I can see that the VFD was a Allen Bradley but what model? Also the price would be nice on the motor and VFD.
I plan to CNC my lathe soon. 
I was hoping to get more ideas from Bob's web site but he seems to be dragging his feet a little.


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## Hilmar (Apr 11, 2008)

> Yes, VFD's require a 3 phase motor. Most will allow for single phase or 3 phase input, 3 phase output. The VFD needs to be derated by 30% if operated on single phase input. My VFD is 1 HP, running a 3/4 HP motor. Not quite as derated as it should be.



  I also have a VFD, a FM50, 1 HP,115 AC in single phase, out 240VAC three phase out.
No where in the manual is it written to derate the unit if you have a 
115 AC in and 220 AC out.
 It has Auto Stall Prevention and also Output Short - Circuit Protection.

Hilmar


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## Charlie J (Apr 11, 2008)

Although I read every post, every day I seldom contribute (shy) I have to contribute on this topic. I installed a 220V VFD and 3PH motor on my 14X40 lathe a couple of years ago. What a difference!! It worked so well that as I was saving for a new 6X26 mill to supplement my 30 year old mill/drill the VFD had to be part of the package. An addition you may also want to consider is a tachometer. The tach will take all the guessing of "what speed am I really "running out of the equation. I purchased a "tachulator" from LMS and installed it on the new mill. The tachulator allows you to either read RPM's or you can input cutter diameter and read SFM. I now find myself taking the extra two seconds to match the SFM of the cutter to the material being machined. The net result is no more burned cutters,far less chatter, better surface finishes etc. In other words, no more guessing or the inability to fine tune the cutter speed. The elimination of those types of frustration for a home shop guy...PRICELESS!!!


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## AllThumbs (Apr 11, 2008)

Charlie J  said:
			
		

> Although I read every post, every day I seldom contribute (shy) I have to contribute on this topic. I installed a 220V VFD and 3PH motor on my 14X40 lathe a couple of years ago. What a difference!! It worked so well that as I was saving for a new 6X26 mill to supplement my 30 year old mill/drill the VFD had to be part of the package. An addition you may also want to consider is a tachometer. The tach will take all the guessing of "what speed am I really "running out of the equation. I purchased a "tachulator" from LMS and installed it on the new mill. The tachulator allows you to either read RPM's or you can input cutter diameter and read SFM. I now find myself taking the extra two seconds to match the SFM of the cutter to the material being machined. The net result is no more burned cutters,far less chatter, better surface finishes etc. In other words, no more guessing or the inability to fine tune the cutter speed. The elimination of those types of frustration for a home shop guy...PRICELESS!!!




My VFD has a "User" parameter that allows you to multiply the Hz (or any other parameter) by a user defined number. I multipy by the gear ratio so the drive displays the spindle speed when running. Very handy.

More on where I got my drive and motor soon. No time right now.

E


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## AllThumbs (Apr 12, 2008)

Hilmar  said:
			
		

> I also have a VFD, a FM50, 1 HP,115 AC in single phase, out 240VAC three phase out.
> No where in the manual is it written to derate the unit if you have a
> 115 AC in and 220 AC out.
> It has Auto Stall Prevention and also Output Short - Circuit Protection.
> ...



Only VFD's that are 3 phase input but run on single phase need to be derated. Since your drive is designed to be single phase input you can run it at it's rated output.

E


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## AllThumbs (Apr 12, 2008)

mrt1723  said:
			
		

> I have a DC motor I was going to put on my 8x12 but I like your VFD idea a lot better. Can you tell me a little more on what motor you used and what VFD you used ( I can see that the VFD was a Allen Bradley but what model? Also the price would be nice on the motor and VFD.
> I plan to CNC my lathe soon.
> I was hoping to get more ideas from Bob's web site but he seems to be dragging his feet a little.



The VFD is an allen bradley 1305 VFD. It's an older one. The motor is just a standard 208 V 3 phase motor. 

The beauty of the VFD over DC motors is the speed regulation over a wide range of loads. A dc motor at low speed will slow badly when loaded up (no torque). An AC motor, while it produces less than full torque at the lower speeds, still has a fairly constant speed from no load to full load. VFD's can also be programmed to compensate for loss of speed due to load so if you want 400 RPM at the spindle, thats (roughly) what you get regardless of depth of cut etc.
Basically the speed of the motor is tied directly to the frequency of the output of the VFD, regardless of the load.

I teach electrical at a college. Industry donates a lot of thier surplus equipment to the college. Some of it is used to build demos itc, but sometimes there is just too much stuff to use. This VFD and motor was available, so I asked for it. In return I plan on building an "open" electric DC motor from scratch for demonstration use at the college. Large enough so it's possible to see what's going on as it operates. That is my next project but I wanted the lathe updated first to make the build easier.

VFD's can be had on ebay, so can 3 ph motors. Just make sure they are compatible in HP and voltage, and if 3 phase input, make sure it can also be run on single phase. Ideally, if run on single phase, the drive should be rated 150% of the motor HP. This is not a must, but be aware that if you run a 3/4 HP motor on a 3/4 HP drive that's run on single phase input instead of 3 phase input, you will only get 1/2 HP out of that 3/4 HP motor.

Hope that helps.

Eric

Eric


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## AllThumbs (Apr 12, 2008)

Hewre is one on ebay. Exactly what I have:

http://cgi.ebay.com/VFD-motor-Drive...ryZ42894QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## AllThumbs (Apr 15, 2008)

Here is the finished control panel. I could not use the original. E-stop and speed dial. The old one is sitting there so you can see it. It had stop, start buttons and for/rev toggle.


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## gunboatbay (May 17, 2008)

John Pitkin authored an excellent article on converting his 9x20 lathe to a VFD system; lots of detail. One could easily adapt this article to just about any size lathe. If anyone's interested in the article (pfd format) let me know and I'll email it to them.


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## BobWarfield (May 18, 2008)

mrt1723  said:
			
		

> I plan to CNC my lathe soon.
> I was hoping to get more ideas from Bob's web site but he seems to be dragging his feet a little.



LOL, dragging my feet? Heck, I fell into a sinkhole and haven't been seen since!

Work on the lathe will resume eventually, meanwhile, the Team Build is first up on priorities, followed by mill CNC conversion, and interspersed with much needed shop reorganization. On the latter, I've realized I could buy more machines if I reorganized, so that provides motivation!

One thing some of you may be interested in on this VFD topic. A real VFD and an AC motor works better than the treadmill setup, though it is more expensive. Likewise, there is a VFD step up called a vector drive. Vectors are more money, but they're not incredibly more money. The neat thing about a vector is much broader torque range. So, that means even less likelihood you'd have to change a belt to run slowly. Most of the drive sellers (like driveswarehouse.com) have them listed, and they come up on eBay too.

Cheers,

BW


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