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Progress with my lathe.

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Ash Small

Wed Jun 24 2015, 02:28PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Ok, I've been giving this some more consideration, and I've decided an NVR (no volt release) switch is essential, along with a DPDT (double pole, double throw) switch for reversing.

I think I pretty much have everything covered now. I need to ensure that the Stop button triggers the NVR switch to isolate the supply, so that re-setting the stop button doesn't re-connect power to the motor without operating the NVR switch.

Also, the forward/reverse switch MUST be wired in such a way that the NVR switch isolates if the forward/reverse switch is moved to the intermediate 'off' position, to prevent switching from forward to reverse while the motor is rotating.

I think I'm now ready to draw the circuit.

Mads Barnkob

Fri Jun 26 2015, 01:23PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Have you considered using the most widely used concept for motor reversing, self hold and emergency stop/protection relay there is?

I could only find an example in Danish, but the schematics are drawn in english ;)

Use the drop down box to see them at item 2 and 3.

Ash Small

Fri Jun 26 2015, 01:52PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Mads Barnkob wrote ...

Have you considered using the most widely used concept for motor reversing, self hold and emergency stop/protection relay there is?

I could only find an example in Danish, but the schematics are drawn in english ;)

Use the drop down box to see them at item 2 and 3.

I think this is pretty much what I'm doing. I either need a four pole double throw switch, or a single pole double throw switch (ON-OFF-ON) and four double pole relays.

See related thread here:

(From what I can gather, the Danish link you posted depicts a three phase motor, mine is single phase, But I appreciate that the principle is similar)

Ash Small

Sat Jun 27 2015, 02:10PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

New information, progress so far:

I've started drawing the motor reverse circuit. I've drawn two four pole relays, but I've been offered some three pole relays by Dr Slack which I suppose I could use if I 'hardwire' the neutral 'motor run' connection, and just use the relays to switch the live 'motor run' connection, and the two 'motor start' connections.

The 'motor start' wires are shown in red on the diagram.

The single pole double throw (on-off-on) switch can only switch one relay in at a time.

Also, yet to be drawn, is the NVR (no volt release) switch, which will 'trip out' if the 'forward/reverse' switch is moved from either the forward or reverse position to the 'off' position, which 'should' ensure that the motor can't be switched from forward to reverse while it is turning.

Any comments at this stage will be appreciated. Obviously the circuit needs fuses, etc, and isn't completed yet.

EDIT: I considered using four of the three pole relays wired as double pole, but I feel just using one relay for both run and start windings would avoid the possibility of only one winding being energized in the event of a relay failure, which can't be good for the motor.

I think, as mentioned above, that hardwiring the neutral 'run' wire, and using the three pole relays to switch the live 'run' wire and the two start wires should work ok.

EDIT: Here's the motor reverse circuit using three pole relays:

------------------------------------------------ ------------------------------

EDIT: I've been googling NVR switches and this one has 'live' and 'neutral' in and out, and has a 'jumper' between 'A1' and '24'. This, I think, means it will only 'cut out' if the supply 'before' it is interrupted. From the look of it, if the power is interrupted 'after' it, it stays on.

(I think, if I connect A1 to the 'live' feed into the motor, after the relays, and make sure '23' and '24' are the 'neutral' in and out, then it should 'cut out' if the relays are both 'off', even momentarily. It's just a question of getting the 'circuit logic' right.

Ash Small

Mon Jun 29 2015, 04:32PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Ok, I think this is the correct circuit:

The purple wire connects to terminal 'A1' on the KJD17 NVR switch, pictured above.

The instructions say it should have a jumper to terminal '24' (live out in the schematic), but if it connects directly to the live motor run wire at the motor, it should trip if for any reason, the live feed to the motor is interrupted anywhere before the motor.

If anyone can shed any light on this I'd appreciate it. I've ordered two switches. I'll also try and clean the above post up a bit later.

EDIT: there are still some problems with this circuit, for example, the 'normally open' contact in the 'stop' button won't conduct when closed because the NVR switch will have tripped. I'll sort this later.

hen918

Mon Jun 29 2015, 04:39PM

Registered Member #11591 Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556

Ash Small wrote ...

Ok, I think this is the correct circuit:

This one looks right to me, your previous one had the lathe powered through the relay coil of the NVR.

Ash Small

Mon Jun 29 2015, 04:46PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

hen918 wrote ...

This one looks right to me, your previous one had the lathe powered through the relay coil of the NVR.

Yes, I've deleted that one now, just to save any confusion. It came about by googling the wrong symbol for an NVR switch. I've used what's actually marked on the switch this time.

I've ordered a three position rotary switch as well for forward/reverse. They should be here by the end of the week.

EDIT: Well, the switches arrived this morning, which is excellent service, but the switches aren't wired as per the photo posted above. These. although the part number is the same, have an internal jumper fitted between A1 and 24. I can use one on my pillar drill, where an external jumper would be fitted here anyway, but they are no good for the lathe circuit as posted above.

I've E-mailed the supplier asking if they have any with a separate A1 terminal.

EDIT: Ok, the supplier, Axeminster tools

does stock a five terminal KJD17 NVR awitch, but it isn't presently listed on their website. The part number is BURT001236 and current price is Â£14.26, although I'm certain they only charged me Â£25 inc postage for two.

It was confusing because the four terminal version is on the website, although the accompanying photo shows the five terminal version. I've now pointed this out to them.

Apart from the above confusion, service from Axeminster tools was excellent, and I now have a couple of five terminal NVR switches on the way.

EDIT: They have now updated their website. If you want the five terminal switch you need to quote the above mentioned part number as they only have the four terminal switch on the website.

EDIT: They now have other NVR switches listed with 'four and five terminal versions available'. Looks like they listened. Service was excellent by the way, and they did say to 'contact them if you can't find what you want on the website as they stock some 25,000 items and can't put them all on the website'

Ash Small

Wed Jul 01 2015, 08:11PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Ok, here is pretty much the complete circuit.

There is a revised version of this drawing below

I should probably add some appropriate fuses to the 24V system, but apart from that it's looking fairly complete, I think. I'll probably add a few more 'idiot lights', but all the wiring for them will be contained inside the main control box. I think I've accounted for all wires to and from the main control box.

Any further comments at this stage will be appreciated

I'm just collecting everything together so I can work out what dimensions the main control box needs to be.

klugesmith

Sun Jul 05 2015, 02:32AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Nice lathe you got there, Ash. If it hasn't been abused, a man of your talent ought to be able to turn out (NPI) work as large and as nicely finished as with a modern lathe of that size. Just remember to keep those spindle oilers full, turned on when running, and off when done.

Your motor controls are certainly not 19th century. But can you find room for nice-looking start and stop buttons? Like at

or:

Oops, recent posts show you're way ahead of me there.

Ash Small

Sun Jul 05 2015, 03:04AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

klugesmith wrote ...

Nice lathe you got there, Ash. If it hasn't been abused, a man of your talent ought to be able to turn out (NPI) work as large and as nicely finished as with a modern lathe of that size. Just remember to keep those spindle oilers full, turned on when running, and off when done.

This lathe has earned me thousands over the years. Like a lot of lathes from this era, it was fitted with a single phase motor at some point in the '50's or '60's, with a 13 amp 240V plug, when I bought it over 25 years ago and I (guiltily

) never got around to sorting it out properly until now, although I've hardly used it for 15 years or so. (I was predominantly working 'on site', using the client's fitting shop where necessary since my previous premises was demolished to build luxury flats, until I gave up work five years ago.)

It's been in storage for a while but I'm finally getting my shed sorted out, and almost every project I have underway is waiting for this and some of my other equipment to be 'checked over' and gotten operational again.

I always keep an oil can handy to keep the oilers topped up, even though there is some wear in one of the countershafts that can't be adjusted.

I mostly used this lathe for machining stainless components 'slowly'. These 'old lathes' are so over engineered they are ideal for stuff like this. I've also machined monel on it.

Last time it was accurate to ~1/3 thou, but I think I can probably set it up for greater accuracy now (I was young and impatient then). They don't build 'em like they used to.

I could hardly post details on here without sorting out the wiring properly, could I

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