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High Speed Reverse

Toms Wheels

Titanium
Joined
Dec 30, 2005
Location
Jersey Shore
There are a number of lathes that have been built with apron mounted controls, which operate low voltage controls for fwd/rev. Monarch has such a system on the 10EE model, called ELSR. Electric Lead Screw Reverse. I had replaced the OEM drive system, with a VFD and 5hp AC motor.

When threading metric threads it is neccessary to leave the half nuts always engaged, which made for a slow return to the beginning point. Yes I could crank the dial abit faster rpm, they slow it do again when threading. Or let the VFD do it for me. All that was needed was one wire and a switch. The apron controls a microswitch, one for fwd, another for reverse, I teed off the reverse control wire through a SPST switch, to the control post on the VFD set to ADD HZ to whatever the VFD is running at. The on/off switch enables or disables the speed increase programmed into the VFD. Since each VFD is different the parameters of my Hitachi would not be much help.

In operation threading at 200rpm is 7hz on the VFD, when the switch is on, and the control lever moved to reverse, it adds 10 hz to the 7, so about 500 rpm in reverse. Works slick.
 
Hi Tom,

My Monarch 10EE has a spot for a switch next to the coolant pump switch for a reverse speed?

I think this was a Monarch option? I have a DC replacement drive and it is wired to the original speed control pot so I think I am out of luck on a simple solution. This is an area where the flexibility of a modern programmable drive has an edge. I guess I could rig some kind of small variable voltage pot with a dpst relay to the speed input on the drive. That may be a nice project down the road.

Steve
 
Steve, I've read your posts in the Monarch forum, nice lathe there. What you need is the same as Monarch does it for the Wiad drive, a relay the switches in the reostate added to the HSR models. I had thought of doing that to add flexibilty to the reverse, but this was so much simpler. The problem is if using BG when threading, I'd need to change the ADD quantity as 10 hz does not help much when the motor is running at 30. It would only take a couple of minutes to change the Add on.
 
I plan to do this on the automationdirect VFD I have on my lathe. It is a really neat idea I think!

On the ADC drive you can define a seperate speed to run at (well actually up to 7) and select that speed externally on a discrete input. So I am going to have the same input that trips to go reverse also tell the drive to use a different speed.

With braking resistors I can already reverse my drive in under half a second, even at higher speeds.
 








 
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