Monarch 10EE rebuild 10Hp VFD no backgear

[Karl_T]

Yep, machining the existing stop pin for a limit switch AND then finding one that would work looked difficult to me.

Here's my solution. Put an AL plate over stop pin to hold it out when running. Put it over the Estop button when in use. Not idiot proof, but should stop my absent minded starting the machine with pin engaged.

 

[Nightshift]

Nightshift
Mine is a ‘64. Looks like they milled through the casing to mount the limit switch, right between the two diagonal bolts that hold the assembly onto the headstock. Vintagemachinery.org has parts diagrams for a 1965 model IIRC. You could check those for details. Not sure how much they show for this.

Thanks Rabler. I checked that out but not much luck. The 65 manual you mentioned does have a blueprint drawing of the electric lockout for the spindle lock but not enough detail to understand. The bolt mounting is vertical also compared to yours a year earlier. Cross section N-N shows what appears to be a plunger-type micro switch that is NC when extended (lockout pin retracted). Bill

 

[rabler]

Thanks Rabler. I checked that out but not much luck. The 65 manual you mentioned does have a blueprint drawing of the electric lockout for the spindle lock but not enough detail to understand. The bolt mounting is vertical also compared to yours a year earlier. Cross section N-N shows what appears to be a plunger-type micro switch that is NC when extended (lockout pin retracted). Bill

I haven't disassembled mine but that diagram looks to match mine in every detail. I'm not sure what you mean about bolt mounting, but it does look like the mounting bolts are both on the spindle side with the pins being farther away, whereas yours the bolts and pins are in diagonal corners.

There is a microswitch mounted on the casting for the lockout. It is on the side farthest away from the vertical face of the headstock. There is a sheet metal shroud covering the switch. I would assume the shroud is there because the switch terminals are line voltage in the Monarch implementation. The wires from the switch run in a small tube/conduit, over the top of the spindle and down the back side of the headstock.

I'd think with a low voltage VFD switch, you could drill a small hole in the casting for a plunger type microswitch, going in from the face farthest from the headstock. Then drill two small blind holes and tap to something like #4 screws on either side of that hole to retain a switch. You can get pretty small switches for low voltage. Then you'd have to figure a way to get a ramp onto the actual spindle lock shaft.

 

[Karl_T]

FWIW, the best idea i had on this was to add a cam on the knob on the outside of the lathe. The knob has to be rotated for the pin to stay locked in. Then add a small roller detent limit switch mounted on the outside surface

didn't like this idea that well. if you build something that works, let me now.

 

[Nightshift]

Thanks Rabler. I will pull mine apart and see if I can modify to add a low voltage switch.

Karl, I agree I don't like the idea of mounting a switch on the outside as it would detract from the excellent vintage lines of these machines. So if I can come up with something, it will be on the inside hidden from view like Monarch did it. Bill

 

[Briney Eye]

I completely agree with your decision. I've done VFD conversions on several lathes. No need for backgear. Interestingly, I noticed an article about a new motor company turntide. They have a great motor comparison chart. I wish the new motors were already available. I'd consider one. For now I'm doing a 5hp motor and VFD

Turntide is doing switched reluctance motors, which have been around a long time. Turntide is just taking the old "sell the sizzle, not the steak" approach and emphasizing how "smart" their motors are.

I did some work with variable reluctance motors in Robotics many years ago, trying to smooth the torque ripple. Commutation is the challenge, but the same cheap microcontrollers that are making brushless DC motors ubiquitous in cordless tools will make switched reluctance motors more common in the future. They are mechanically and electrically simple, have no magnets, and can generate lots of torque at low speed. They've been waiting for more computing power to make them run smoother, and it looks like they're just about there. I was using lookup tables, but digital signal processors can do it on the fly now.

 

[will.mcray]

Great write up? Do you have an final pictures of the VFD location and access to power on?


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[Karl_T]

There's a pic of the VFD on page 2. It sits under the tailstock where the MGset was. I re-used the on/estop button in the standard 10EE location low on the machine left side. From outside the machine you cannot tell its not a standard machine.