# Vfd and motor change



## rimfire1903 (Jun 12, 2018)

need help, i would like to have a vfd on my clausing 8520 mill in very good condition, (but) it has a 3/4hp dc. with belt drive with pulley set up, i  am a gunsmith and need to cut dovetails in slides and barrels, and run in a slow speed around  6-700 rpms,, herd i need a 3ph induction motor and a vfd, i dont have 3 ph. home shop 110/220
 so what do i have to do to achieve this i wouldn't mind a 1 hp or even the 3/4hp is ok with me, can you explain exactly what i need to do including motor type and hp,vfd type for the motor i need,, wright i am running 110, i would like to avoid changing belts but if the cost is out of my ball park, i would like to modernize the older we get the lazier  we get,,,, i get,,, please be specific thank you for your time


----------



## TonyRV2 (Jun 12, 2018)

You don't need 3 phase power in the shop.  Part of the job of the VFD is to take your single phase power and convert it to 3 phase.  You can run a 1hp 3 phase motor using your 110V shop power.  You just plug your VFD into a 20A outlet and wire the VFD's 3 phase output to your 3 phase motor.  Its that simple.  You didn't mention what kind of VFD you were looking at, but I strongly recommend the KB Electronics KBAC-27D model.  These are pricey, but come in a nema 4X/IP65 enclosure which is watertight with watertight knob and switches as well. This controller will drive up to a 1.5hp motor on a 110 volt line, and up to a 2hp motor if you wire it to a 220V line.  Alternatively, you can go with a much less expensive Chinese import and build your own enclosure for it.  There are plenty of folks that have done that with apparently decent results.


----------



## CluelessNewB (Jun 12, 2018)

You might want to try and find a 900 or 1200 RPM 3 Phase motor if you are planning to run that slow most of the time.  The problem with running the typical 1800 RPM motor that slow with a VFD is cooling.  Another option may be to add an external fan.  If your mill uses a 56 frame motor, finding a slower motor may be challenging.


----------



## rimfire1903 (Jun 12, 2018)

thank you both for all the help, i don't run slow most of the time just for dovetails thank you for your help, have a great day, does the motor have to be induction motor? or ac


----------



## markba633csi (Jun 12, 2018)

You say you currently have a dc motor?  With speed control or without? Or did you mean ac motor?
Mark


----------



## rimfire1903 (Jun 12, 2018)

dc motor, via belt and pulleys for speed control, not ac motor, dc motor thank


----------



## pacifica (Jun 12, 2018)

You can get a open frame dc drive from automation direct for 136, need an enclosure and potentiometer, good for up to 1 hp at 90vdc.Probably even cheaper deals around.
Keep your present motor.Potential for dynamic braking, forward reverse , etc.
Others can tell you about the torque curve,  ease of use and installation.


----------



## rimfire1903 (Jun 12, 2018)

Thank you very much


----------



## strantor (Jun 12, 2018)

Post details of your existing DC motor. DC motor is variable speed, if you vary the voltage to it. Not sure why your machine would come with a DC motor and fixed DC voltage. DC was the old way to get variable speed, before the proliferation of cheap VFDs. DC is still a good way to go, and if you have a DC motor already then it probably makes more sense to get a cheap DC drive for it and leave the motor alone. 

I'm half-ass suspecting you actually already have a DC drive buried in there somewhere, even if there's no exterior speed control knob, as I can't come up with a reason they would use a DC motor for fixed speed.


----------



## rimfire1903 (Jun 12, 2018)

This is a causing 8520 3/4 hp all there is a on and off switch. Only way to change speed is by changing v belt on several step pulleys.


----------



## strantor (Jun 12, 2018)

So is that a hard "no" on the picture then?


----------



## rimfire1903 (Jun 12, 2018)

Here's some photos


----------



## strantor (Jun 12, 2018)

rimfire1903 said:


> Here's some photos


Thanks. I should have been more specific. I'm looking for a picture of the motor nameplate so that I can suggest an appropriate DC drive.


----------



## rimfire1903 (Jun 12, 2018)

The name plate is covered by motor mount but it is a GE  3/4hp  1750  110  CW and CCW


----------



## markba633csi (Jun 12, 2018)

You must have an ac motor there if you are just plugging it in- a dc motor would require, at the minimum, a bridge rectifier between the wall power and the motor, probably mounted in a little box somewhere on or near the forward/reverse switch (if there is one)
Mark


----------



## rimfire1903 (Jun 12, 2018)

No box. Just plug in and turn on 
It does have a foreword and reverse  and neutral barrel switch on the mill. Reverse dont work. The motor is not original  thank you. What do I need to do


----------



## strantor (Jun 12, 2018)

markba633csi said:


> You must have an ac motor there if you are just plugging it in- a dc motor would require, at the minimum, a bridge rectifier between the wall power and the motor, probably mounted in a little box somewhere on or near the forward/reverse switch (if there is one)
> Mark


Agreed. However a rectifier could be fitted inside the reversing barrel switch. That would be weird, but possible.

Seems to me more likely an A.C. motor. Without pictures to confirm it's DC, I will have to withdraw my (much cheaper and easier) suggestion of installing a DC drive. 

So, you will need to go out and buy a 1hp 3ph motor, 1800rpm 230v, and a VFD 1hp 230V, rated for single phase input. For the motor I would check surpluscenter.com and for the drive, teco or automationdirect.com


----------



## rimfire1903 (Jun 12, 2018)

Thank you for all your help. I appreciate it thank you all . I will give a update  soon I hope


----------



## Briney Eye (Jun 13, 2018)

I did a video overview of the DRO installation on my 8520 but I also show the Fuji VFD that I installed.  I set the VFD to vary the motor speed from 900 to 1800rpm, and it has plenty of low-speed torque, but I can always rearrange the belts if I want to go really slow (or fast).  I added an external braking resistor so that the VFD can stop the spindle quickly and left it hanging in the video, but I cleaned everything up since then.


----------



## rimfire1903 (Jun 13, 2018)

Thanks I will look at that. I liked the dro set up a lot that's next. Thank you


----------



## rimfire1903 (Jun 15, 2018)

strantor said:


> Thanks. I should have been more specific. I'm looking for a picture of the motor nameplate so that I can suggest an appropriate DC drive.


sorry the motor is an ac motor took it off today,


----------



## Bi11Hudson (Jun 15, 2018)

It sounds like you need to use the back gearing to slow down the spindle speed. I don't think any sort of motor will reliablly operate at that slow a speed. Just a thought there. You might also consider my post of just a few minutes ago. On that very subject.
Bill Hudson​


----------



## rimfire1903 (Jun 15, 2018)

Bi11Hudson said:


> It sounds like you need to use the back gearing to slow down the spindle speed. I don't think any sort of motor will reliablly operate at that slow a speed. Just a thought there. You might also consider my post of just a few minutes ago. On that very subject.
> Bill Hudson​


Yes sir. I dropped pulley size from 4in to a 1 3/4  carbide dovetail cutter's stated under 700 rpms  small. 260 to. 500 thank you Mike


----------



## rimfire1903 (Jun 20, 2018)

up date, here is what i did, i found a treadmill they were giving away, the motor was a 2.25hp, i have seen many videos so, i ordered a 8000w s.c.r. with a pot installed,   and a bridge rectifier, china of course, (good/bad) butt hooked it up and blew a fuse 10 amp, short fuse in the scr. tried a new fuse ran the mill in different speeds  turned the mill off and then back on blew another fuse,??????, i'm stubborn and tried another and up and running again, i could adjust the speed no problem, this time i turned off the mill and turned the scr to the off  position, powered up the mill then turned the scr on to ramp up speed needed and works like a charm i don't know for how long this will work, it will give me time to save and get a 3ph motor and a teco vfd, thank you every one for the help


----------

