Well, I figured I would post this information out there for the up and coming or perhaps the veteran G0704 owners who are looking for an upgraded spindle motor and may be overwhelmed by the options and particulars of choosing, I know I was when I started investigating all the options.

I have made enough mistakes along the way to help educate those who would prefer to stand on the shoulders of my failed attempts and get it right the first time. I'm sure some will think they are immune to my misfortunes and the norm doesn't pertain to them and that is fine, some people must make their own path and learn through trial and error.. I was one of those people who saw the thread about the treadmill motors and dove in head first. Granted back then there was very little information available as to the longevity of the motors in this application and Hoss was still in the early stages of testing. My findings are treadmill motors don't last very long before brush deterioration occurs and smoke and arcing begins.

Next up I tried the 2.2kw BLDC setup and while this last much longer, the motor and driver failed to deliver any appreciable stable torque. It would recover but often times the part finish would suffer from the dip in rpm. They also had some reliability issues and were very expensive to have these issues in my opinion. I spent alot of money replacing drivers and always felt disappointed in its performance.

Finally my BLDC gave up the ghost again and with a quote for $300 to replace the motor this time i finally said enough is enough. It's time to go with something that will perform and last.

So I have been doing a ton of research and have determined by far the easiest thing to get and trust with tons of power is an AC 3ph and VFD. While this isn't new knowledge, it does come with a severe lack of information and what is available is very scattered and jumbled with other uses so its hard to trust if it will work for your application.

Through my research and lengthy time discussing this ad nauseum with the experienced engineers at a variety of drive and Motor supplier companies. I finally felt confident enough to pull the trigger on a setup.



I opted for a good drive and cheap motor because its the holidays and fun money was tight so I grabbed the 2hp iron horse series motor from Automation Direct. This motor is a general purpose motor with an F insulation class rating which is acceptable for inverter duty. Through my discussions, it was determined that the BEST motor would be their Inverter Duty Rated Micro Max 1.5hp Y366. It has 1000:1 constant torque so pretty much from zero rpm to 1800rpm you have full torque and can be over driven via the VFD 2 times the rates speed to 3600rpm with full Horse power. I found this model motor new for $305 here from Electric Motor Wharehouse.. (I may have bought it had I found it before placing my Automation Direct order. They listed the motor for $389 I believe.)

145THTR5329 MARATHON Y366

This is a true insulation class H inverter duty rated motor and when used with the GS3 Durapulse drive in feedback vector mode could be controlled the same as a VMC spindle with indexing and rigid tapping no problem. The frame size is 145T, ( this was an area of great confusion for me, as I had been looking strictly for 56c motor frame sizes). The 145T dimensions are the same as the 56C general purpose motor I purchased according to the drawing spec sheet. Being an 1800rpm motor, it would require an over drive pulley setup, you could go 1:2 and have over 7000rpm and the 1000:1constant torque would still allow a ton of low end grunt down to 3rpm.

For the Durapulse GS3 22P0 AC Drive I was informed of many precautionary measures I should employ. The information is below.

You will want to grab an input side single phase line reactor and output side 3 phase line reactor to smooth the wave form and promote cooler running of the motor at lower rpm and an EMI filter, RF Filter and fuse block. All available and easy to select for the specific drive. This will help keep all your electronics running without a hiccup and protect your home service from feedback. I didn't k ow this but most power companies require you to have a line reactor before the AC Drive.. (I know very few people use them. But I figured with my luck I better play it safe)

By far this is the BEST setup for this mill for full RPM low to high performance with all the extras, prepare to spend about $850-900 but it will be 1 and done and you will never look back.. Between the treadmill motors I tried, the BLDC setup and replacement components to fix it unsuccessfully, and all the time and material and components purchased on the first attempts, I have about $1700 invested in failed motor setups and now spending $680 on top of that to be where I should have been in the first place.

To recap for any readers, below are the parts recommended by all the people in the know for the G0704...

From Automation Direct:

GS3-22P0 Durapulse 1.5hp 1ph input 3ph output AC Drive (contact Automation Direct they will ensure you get the correct peripherals)

LR-22P0 output Line Reactor

LR-22P0-1PH Input Line Reactor

20DRT1W3S EMI input line filter

RF220X00A Zero phase RF Filter

GS-22P0-FKIT-1P Fuse Kit


From Electric Motor Wholesale:

Marathon Micro Max 1.5hp Y366 3ph AC Motor insulation Class H Inverter duty 1000:1 constant torque 1800rpm motor.

That is a recipe I received from Automation Direct for this application.. The peripherals some do without, but I decided no more shortcuts I don't want to hurt this nice equipment or deal with RF interference. I also wanted to help the motor run as cool as possible with the line reactors and not worry with feedback into anything in my home shop electrical system... So to anyone looking for the best bang for the buck. This is relatively cheap for what you are buying and its performance capabilities.. The only drawback is the same with any AC motor VFD setup and that is the motors are large and require new mounting.

So anyone running stock motor.. I recommend designing and making parts for this conversion as one of the first things you do once cnc'd. Even if you Don't upgrade the motor. Have the parts made and ready for when you kill the stocker.. Cause it will eventually happen.

I hope this helps those who are as confused as I was going into this endeavor!!

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