Push-button vs rotary switches (two-wire vs three-wire)

Hey guys,

I'm retrofitting my lathe with a VFD (Yaskawa V1000). I've read the manual a few times, and everything seems pretty clear on how to do it.
The only thing I can't decide is which controls to use to operate the lathe.

Three options in my mind (E-stop button included in all of the options):
1:
- FWD/REV - two-position rotary switch
- Start - green NO push button
- Stop - red NC push button

2:
- FWD/REV - two-position rotary switch
- ON/OFF - two-position rotary switch

3:
- FWD/OFF/REV - three-position rotary switch

The VFD supports all three options, and I have buttons/switches to implement all three as well.
What would be most convenient/safe arrangement? This is a home workshop, I'm the only user.

Thanks!

gene-pavlovsky said:

Hey guys,

I'm retrofitting my lathe with a VFD (Yaskawa V1000). I've read the manual a few times, and everything seems pretty clear on how to do it.
The only thing I can't decide is which controls to use to operate the lathe.

Three options in my mind (E-stop button included in all of the options):
1:
- FWD/REV - two-position rotary switch
- Start - green NO push button
- Stop - red NC push button

2:
- FWD/REV - two-position rotary switch
- ON/OFF - two-position rotary switch

3:
- FWD/OFF/REV - three-position rotary switch

The VFD supports all three options, and I have buttons/switches to implement all three as well.
What would be most convenient/safe arrangement? This is a home workshop, I'm the only user.

Thanks!

Click to expand...

None of the above.

Lever. Long one. Much as once actuated a clutch and brake, "back in the day". My Jaguar has a 'stick shift". But it only moves microswitches for one of the five cornfusers. not rods nor levers. "gas pedal" talks to an electronic bus, not a linkage, too. But it still sits under my right foot.

It's just more "natural". As an "ergonometric man-machine interface" as has become all the rage.

As with motorcars. Motor cycles. Boats. Or aircraft. Or even joysticks for "game boxes".

You can put any sort of switches you need onto a "human friendly" actuator.

Or even USE a game-box "joystick".

Easier to integrate than the massive brass "Engine Order Telegraphs" on the bridge of a major steamship...

Engine order telegraph - Wikipedia

But then again...

You'd have to know "Old Iron" and proud owners, of it?

Grips - Control - Parts

I've got my lathe set up with momentary push buttons - three separate switches - one each for forward, reverse and stop. Then a push toggle switch for enabling/disabling jog and a pot for frequency adjustment. I have two additional "disable/e-stop" switches - one on the standard "rotate to enable, push to disable" switch and another connected to the switch on the spindle footbrake.

thermite, do you have any pictures of lathes set up in a way you described?

eKretz, I think your way can be convenient. But I don't see how my Yaskawa V1000 would allow configuring the inputs like that, at least not without some extra parts to implement this logic I think. It has 2-wire and 3-wire sequence options, using momentary start/stop switches requires using a 3-wire sequence, and in this case the FWD/REV direction is selected by a latching switch.

I have #1 and #3 set up, Bridgeport & ATW lathe are #3, horizontal mill is #1.

Included on the horizontal is a pot for speed control, having that on the same control cluster as the start/stop buttons is very helpful. The speed control pot is located on the back side of the Bridgeport which is a little annoying since I have to walk around the machine to adjust it. I've not bothered to set up a pot for speed control on the lathe- its a 12spd unit, so there is reasonable coverage via the headstock.

I used full size drum switches to act as the rotary switches, which is helpful when you reach for the controls; the lever is easy to grab and a long throw with robust detent avoids mistakes.

Both methods seem to work fine.. drum switches are easier to set up given they latch and have fwd/stop/rev already, just have to wire them. I don't have a jog setup, but I think a momentary button approach would be right control for that.

I'd hesitate to go for #2 for fear of accidentally grabbing the wrong rotary lever/knob.

gene-pavlovsky said:

thermite, do you have any pictures of lathes set up in a way you described?

Click to expand...

My one is the earlier hydraulic controlled one - same colour as here:

Cazeneuve HBX360 Lathe

The later electrically controlled variator is in a PM thread.

You'd have to download the manual to see how the guts of either one work, but both have the same lever on the carriage linked by a rod.

The electrical "side" is whatever the system - VFD in your case - specifies it needs.

Up to you to provide any sort of knob, arm, lever, rod, or such from those to the human hand.

Schaublin had lathes that used a "joystick". Milacron, our PM site founder, explained some of that "Right here, on PM"". It had MANY functions "in one hand".

Same again a dirt-moving "trackhoe" arm, bucket, and swing all in one hand.

Hardinge it was UP/DOWN RPM pushbuttons. HBX its a lever on the carriage, operating a control rod.

And thats much the same place and operator hand movement as a lever at-carriage and a rod to mechanical clutch controls that has been in use since at least the 1920's. It's "natural" to the operater.

And that's the whole point. To put the controls in the most helpful place for comfortable, natural, and safe operation by the human that has to use them.

Faster that way. Less fumbling in an emergency

See also motorcars or motorcycles.

Make your one any way YOU want it!

Well... motion-detector switches where you change direction by leaning one way or the other or go faster by rising up on your tippy-toes, slower by squatting down might be a bit unpredictable.

But yah CAN do that.

gene-pavlovsky said:

thermite, do you have any pictures of lathes set up in a way you described?

eKretz, I think your way can be convenient. But I don't see how my Yaskawa V1000 would allow configuring the inputs like that, at least not without some extra parts to implement this logic I think. It has 2-wire and 3-wire sequence options, using momentary start/stop switches requires using a 3-wire sequence, and in this case the FWD/REV direction is selected by a latching switch.

Click to expand...

It certainly can be set up that way. These drives can usually be set up pretty much however you'd like, just sometimes takes a lot of reading to figure out how. If it was necessary you could use a latching switch, but I believe your drive can use momentary. Here is the relevant section from your drive's technical manual regarding the forward and reverse settings and switch setup. You'll have to look up the rest if you want them. I use jog mainly to help when changing gears but also sometimes for indicating or indexing inserts on a milling cutter, etc.



Oh, and my lathe has plenty of speed range in the headstock gearing too, but I still wanted the pot. For one thing, it's nice to be able to up the speed when facing a large surface to try to keep SFM up once the tool gets closer to center. For another, if chatter ever rears its ugly head, speed changes can be made mid-cut without stopping the spindle. And last, switching from roughing to finishing with the same tool, speed can be changed without stopping the spindle and waiting for the associated deceleration/acceleration.

eKretz said:

I use jog mainly to help when changing gears but also sometimes for indicating or indexing inserts on a milling cutter, etc.

Click to expand...

I had the displeasure of a converted 50 HP DC motor on 50 inch lathe where it was "jog" or go get a tommy-bar. Fixed speed motor, so it was b***y brutal and JOG was the right word, first cousin to smacking the spindle with a pile driver's hammer.

I *think* a VFD can do what I do with the DC Drives instead?

"Creep" or "snail" slowly and smoothly towards a desired position. No drama.

gene-pavlovsky said:

Three options in my mind (E-stop button included in all of the options):

Click to expand...

And a fourth, my approach to life: center off toggle swtich. FWD/OFF/REF.

Fits in a small enclosure with the speed control pot, locate it in a handy place.

eKretz said:

Oh, and my lathe has plenty of speed range in the headstock gearing too, but I still wanted the pot. For one thing, it's nice to be able to up the speed when facing a large surface to try to keep SFM up once the tool gets closer to center. For another, if chatter ever rears its ugly head, speed changes can be made mid-cut without stopping the spindle. And last, switching from roughing to finishing with the same tool, speed can be changed without stopping the spindle and waiting for the associated deceleration/acceleration.

Click to expand...

Yeah thats a good point, I've pretty often had to do some shifting middle of a job. maybe its time to see if I can fit a pot in/on that switch...

Keep the opinions/setups coming, guys!

I'm definitely installing a speed control pot on the control panel. Got an RV4NAYSD202A pot recommended in one of the topics in here. Haven't decided whether or not to put jog controls on the lathe itself. My VFD enclosure will be within arm's reach and I will have a Yaskawa LCD operator panel mounted on the front panel of the enclosure, so jog will be accessible via that one.

Any suggestions for the switches? I have a selection of (cheap) 22mm push-button and rotary switches from eBay. These seem pretty robust, if not super pretty. But I also held in my hands a few brand name (e.g. Schneider Electric) switches and those also have a lot of plastic parts and generally don't feel much nicer than the cheap Chinese ones. Don't know if I should pay rather silly money being asked for brand name industrial switches. Another issue is that Chinese switch comes as a kit while with a brand name you should order separately the operator, panel holder and the contact blocks, got to know their catalogs very well to figure out what goes with what...

I didn't read all the posts in entirety so this may have been touched on, but my question to the OP is, what factory controls does your lathe have now. Most large "professional" type lathes would have an apron lever, foot brake and a jog button. These controls would dictate how you wired the logic of your drive.

The apron lever would be a maintained switch closure, up for FWD and down for REV. The connections are easily achieved on the logic buss of the drive. 'JOG' is merely a FWD command that momentary.

I have a 17" lathe using a Hitachi drive and all the functions utilize the factory controls linked to the logic buss of the drive.

I'm going to guess your lathe may be a small guy with no onboard control features...could be wrong though.

Stuart

Stuart,

The lathe, a little Hobbymat MD65, has setup #2 - a rotary switch for fwd/rev, another one for on/off. I don't particularly like this setup.

Jog is not always just a momentary FWD. If a VFD's input terminal is set up as a jog command, activating that input would make VFD run the motor at a predefined slow speed, rather than the speed set on the pot.

gene-pavlovsky said:

Stuart,

The lathe, a little Hobbymat MD65, has setup #2 - a rotary switch for fwd/rev, another one for on/off. I don't particularly like this setup.

Jog is not always just a momentary FWD. If a VFD's input terminal is set up as a jog command, activating that input would make VFD run the motor at a predefined slow speed, rather than the speed set on the pot.

Click to expand...

Yes..true on the JOG feature, my memory lapsed.

It would seem to me a desirable setup would be something like a drum switch which would offer FWD/REV and of course 'off' in the middle position. Drum switch handles are nice and easy to access as you don't need to grab and twist.

These would be maintained switch closures to the buss that commanded RUN FWD or RUN REV...pretty simple to do and there are drum switches available that are a tad smaller than others.

Stuart

Yes it should be easy to wire a FWD / OFF / REV 3-position switch.
Can you show me what kind of drum switch do you have in mind (the one that is smaller than others)?
I'm not familiar with this type of switch, and a google image search shows really giant things

Well, small might be in the eye of the beholder, but linked is a drum switch I would consider small..smaller than some I've seen. The listing calls out the dimensions which gives you a good idea of the size.

https://www.amazon.com/1-5-Electric-Reversing-Returned-RS-1A-MS/dp/B008BFT7GY

Stuart

This may not be a consideration for everybody, but for me cost was a consideration. For momentary switches on a vfd you can use pretty much anything as long as you keep them clear of coolant. The ones I used were salvaged from a store display - net cost: $0.

Drum switches are pretty common, even the fairly large ones are straightforward to mount, some offer quite a bit of configurability via jumpers etc.








Drum switch on the Nichols controls fwd/rev, the OEM control cluster on top has momentary stop/start buttons, the pot is mounted inside, the shaft and knob projecting out the far side. Since all the wiring is low voltage, it was easy to snake it thru the armored cable after removing the original wires.