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Myford Super 7 VFD Controls & Clutch Switch

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Nick Hulme10/05/2018 11:14:22
718 forum posts
37 photos

This is the VFD control box, mounting position is undecided as yet, adding the clutch switch makes position less critical.

controlbox.jpg

This next bit is a temporary kludge with stuff that was lying around but after seeing my friend's M300 it's been niggling me that I have to use a switch to cut motor power.

clutchleverswitchv1.jpg

These show them working -

https://youtu.be/B_OhV-_HI0M

https://youtu.be/rEeI8_0UqD4

- Nick

Pete Rimmer12/05/2018 20:35:04
543 forum posts
24 photos

What is the microswitch for Nick? An electrical interlock for the belt lever?

Neil Lickfold12/05/2018 23:03:32
581 forum posts
102 photos

Hi Nick,

What is making that high pitch noise in the video's ?

Is that why you want the motor turned off ? or is there some other reason for the constant start stop of the motor?

Yeah the forward reverse and the breaking rate control and the acceleration rate control is just great with a VFD, and the programmed settings that can be made really is awesome. Mine is just box on the wall above the lathe, with the original on off forward reverse switch, is just doing the remote feed off the controller. So the original switch does on forwards/ Off/ On Reverse. The variable aspect is on the adjuster pot mounted on the front cover of the box. Then I have a micro switch that I attach with a magnet , that when activated, turns off the forward control. Then when I switch to reverse, it starts up and runs back. I use this for my thread depth stop when screw cutting inside parts. And now also use it for outer threads as well. Takes away the guess of when to stop. I don't run my S7any quicker than the 60hz in low drive top belt, so something like 700 rpm is the max I run. But the spindle is adjusted to give me the lowest possible error of roundness and spindle movement for trimming my pistons.

lathe-vfd-box.jpg

Nick Hulme13/05/2018 20:08:38
718 forum posts
37 photos

Neil,
The whine is just ringing, I'll tune the VFD modulation frequency at some point but it's the camera mic gain making it seem louder than it is.
The reason to have the motor off when the lathe isn't cutting is that most lathes designed as 3 phase machines work that way, the only reason for running a motor for more of the time is if it's a single phase motor with start windings and the associated lower starting torque and risk of start winding overheat with constant starts & stops.
Regards,
Nick

Nick Hulme18/05/2018 14:59:01
718 forum posts
37 photos
Posted by Pete Rimmer on 12/05/2018 20:35:04:

What is the microswitch for Nick? An electrical interlock for the belt lever?

Sorry Pete, I missed that.
No, it's on the clutch lever, it stops the motor at the end of travel just after the clutch is out and starts the motor again as you bring the lever away from it's end of travel just before the clutch is in, there is now an interlock switch on the spindle lock pin though.

Since the video I've also changed the VFD modulation frequency to eliminate the audible ringing.

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