Mill motor upgrade

[DellParticipant @dell]

I have a Warco mill it’s the smallest one they do WM12 but it’s good enough for what I do & recently the motor was getting very hot quite quickly, I converted it to belt drive some time ago & thought rather than wait until I am half way through a job & the motor go poof I would upgrade to a brushless better motor so I could make the parts now & hope the motor lasts until I have finished the machining ( it did ), it’s all up & running but I need to sort out a couple of problems but not being a wiz with electronic stuff I need to do a bit of research 1st problem is the direction switch works backwards but it has 5 wires so not sure what to swap, the 2nd is the taco display is very faint here is a video of it so if there is anybody on here that is good with electronics any help would be much appreciated.

Dell

[Robert Atkinson 2Participant @robertatkinson2]

Hi,

A picture of the back of the switch would help a lot. Also what model motor and control is it or a link to where you bought it?
Does the tacho display look better if you look at it from below?

By the way theose “aviation” connectors are awful and not suitable for use on mains voltages. They are not used in aviation. The only valid use for them is low voltage and low power. Typical use is for mocophones on two way radios. Additionally you have the male connector on the power side so with the connector unplugged there is voltage on exposed pins.

Robert.

[DellParticipant @dell]

Hi Robert

thanks for replying I have turned the display over is I can see it now I fitted it with the pcb writing the correct way up but now writing upside down but it’s readable now here is a link to the eBay kit I got item number 127319076961 I thought the motor was DC if not what plugs & sockets should I be using ?.

the cam direction switch has blue direct from mains to terminal 9 brown from mains via switch to terminal 10 then a yellow to 1 a white to 3 & a red  to 4

[Robert Atkinson 2Participant @robertatkinson2]

H Dell,

I have to say that the “kit” you linked to looks like a dangerous mess. I don’t think it’s safe based on the photos. It looks like they switch the neutral with the Fwd / Off / Reverse switch which is an issue if the NVT fails.
Is the output DC ? That is the chicken and egg questions for motors. All motors have a reversal of current somewhere in their operation. Even one runninng off an AA cell. If they didn’t they would only rotate half a turn at most. On a conventional low voltage “DC” permanent magnet motor the change of direction if current (change to AC) is made by the comutator and brushes.
On a “Brushless DC” motor the switching is done electronically. for something small like a computer fan the electronics is bulit in so the input is DC and the user can’t “see” tha AC. On your motor tha conversion is on the board so the wires between the driver board and the motor carry AC current. You might ask “as the input is AC mains where does the “DC” come in?” well the incoming 59Hz AC is rectified and smoothed to about 330V DC. This DC is then switched by transistors to produce the AC that motor needs.
Note that this AC is switched to suit the motor which has a permanent magnet motor. It will have Pulse Width Modulation (PWM) as a VFD has but unlike a VFD which uses PWM to generate a sinewave a BLDC driver uses PWM to control the current in the windings.
The electronics in the drive will be very similar, just the control software. Indeed I’m currently playing with a servomotor drive that can run an induction, brushed DC or BLDC motor. You just set the correct parameters when setting it up.

The output that you have on the “aviation” connector is high voltage DC which reverses polarity at a rate proportional to the selected motor speed. It is not isolated from the mains so there is a shock risk from the output to ground.
The correct connector for the motor would be a HAN A 3+1 or similar like this:
https://www.tme.eu/gb/details/10200030002/harting-connectors/harting/
Note you need to swap the inserts over so the female is on the box and male is on the cable.
Not cheap but give  3 connections and a proper make first, break last protective earth contact.
At least use a plastic body connector with female on box and male on cable. Or just a grommet.

Robert

[DellParticipant @dell]

And there was me thinking it was going to be easy.

i used this reference website when selecting the plugs & sockets.

What is the Aviation Connector

[Peter Cook 6Participant @petercook6]

Have to agree with Robert it looks a bit dodgy. However two thoughts. The firs is that you seem to have two NVR emergency stop switches. Isn’t the big red button on the front intended to operate as an emergency stop?

I suspect the reason they have wired the NVR switch neutral through the direction change switch is to ensure that the power is off before changing direction. Switching from one direction to the other with the power on will probably blow the driver board up.

I would have expected that the “yellow to 1 a white to 3 & a red  to 4” will be the direction control and probably operate at low voltage. However I would want to do some (very cautious ) checks with a multimeter to  verify what is going on before changing things over.

[Dell]

On Dell Said:

And there was me thinking it was going to be easy.

i used this reference website when selecting the plugs & sockets.

What is the Aviation Connector

OMG, that is awful and not just the language. None of the connectors shown is waterproof.
Even “proper” aerospace / military metal bodied multipole connectors e.g. MIL-DTL-38999, 5015, Pattern 602, MIL-DTL-26482 etc are NOT suitable for use on mains voltages or other hazardous voltages when accessible without tools. There are special versions with insert (pin) arragements for mains but these are not covered by the basic specification.
I once shut down a production line because someone used a male 38999 connector on a mains lead. I confiscated the lead.

Robert.

[old martParticipant @oldmart]

I used similar connectors for the Tom Senior, all different so as to make it impossible to mix them up accidentilly. The motor one is rated 440V and 10A with five wires possible, the mains one is made for standard three wire 230V at 10A and the remote one for an extra emergency stop is 20V rated at about 1A. They are only similar to aviation stuff which I used to work with many years ago. They could be a nightmare to solder up and get the rubber sleeves over each wire, the crimp type with removable pins were nicer.

I don’t see the need for being waterproof the roof sees to that.

[Robert Atkinson 2Participant @robertatkinson2]

Old Mart,  I can’t comment on the connectors you have used because you haven’t given enough detail or photos. Ther is more to a safe mains connector than a voltage and current rating. Note that the motor output of a VFD or mains BLDC driver is considered mains as far as safety goes.
The current requirements for a mains connector accesible to the user of the equipment are:
1/ Adequate voltage and current ratings INCLUDING surge and transient voltages.
2/ A Protective Earth (PE) contact that makes before and breaks after any other contact. Typically this is alonger pin than the others. Connectors for Class II equipment (no earth) must be an approved type.
3/ If the body of the connector is metallic it must be connected to the PE contact by a design feature of the connector. A wire connection by the instller is NOT acceptable.
4/ There must be an adequate cable grip / strain relief for the cable.
5/ The cover, shell or cable grip must only be able to removed or loosened with the use of a tool.
6/ If the connector is not made to an established standard for mains connectors it is the designer’s / builder’s responsibility to ensure it is safe.

Note that many connectors previously accepable for mains (and possibly still available) are no longer considered safe. These include the round “Bulgin” mains lead connectors with threaded covers and Neutrix XLM (same shell as XLR) connectors.

If you use a unsuitable connector and someone is injured or worse you could face legal action.

As I say so many times, do what you like in your own workshop (assuming others don’t use it) but don’t tell others it’s OK unless you are competent to determine that it is safe and legal. Just because someone else uses it does not make it OK.
The Neutrix XLM is an interesting case. A premium product designed and made by a respected manufacturer (but not of mains products at the time) it was mainly used professionally. This included the BBC. It fails the requirements because the otherwise excellent, collet type, cable grip is held by a a cap that is tightened, and can be loosened, by hand.

EDIT: The waterproof comment was beacse the linked data for the connectors impled they were but the ones pictured were not.

Robert.

[old martParticipant @oldmart]

The type that I chose were vetted by an electrician and all the plugs and sockets are the correct way round according to the power source. Our system is in a museum not in somebodys shed.

[old mart]

On old mart Said:

The type that I chose were vetted by an electrician and all the plugs and sockets are the correct way round according to the power source. Our system is in a museum not in somebodys shed.

As I said before I can’t comment as I don’t know what was used. The only common circular metal bodied connector type that is considered OK for accessible power connectors is the M23 (23mm dia) series IF the contact insert includes a specific PE contact. An example is below:

https://www.mouser.co.uk/ProductDetail/Amphenol-SINE-Systems/MB7CKN0600-S1?qs=SfEue%2FEeSJGZuQ%252BipZoQmA%3D%3D

These connectors are often found on industrial servo motors. I’m not saying anything about the person who gave you advice, but this is industrial equipment design, not an electrical installation. BS7671 18th edition does NOT apply.

Robert.

[old martParticipant @oldmart]

I think Dell’s setup is an improvement on many of the efforts seen on this forum and should be safe enough if he always disconnects the mains input plug before any of those plugs are removed. Waiting about 15 minutes before any work is done just to give the capacitors time to discharge is also recommended.

[Martin of WickParticipant @martinofwick]

Using LV/LC connectors is really not a particularly good idea for something that could pull a kW.

How often will you need to unplug the motor from its driver in reality (if ever)? In that case just replace plug with a suitable screened 3 core cable and grommet, hard wiring board to motor for the UVW output. The 5 pin plug for the Hall sensors can remain as is.

The reversing is likely (and this is a guess without seeing the actual switch and board connections) a LV logic switch using two (or three) wires – make one direction of rotation, break for the other direction rotation. As someone has pointed out, this is wired via the rotary switch having one of the  poles carrying the neutral AC  so the power is cut to the board and the motor is stopped, Ugh! A nasty kludge so you cant instantly flip the motor from 6000 rpm one way to 6000 rpm in reverse. Presumably this is because the control board does not have sufficient built in logic control for a more elegant solution.

One has to ask the question, how often and for what purpose do you need to run your mill in reverse? I had a WM16 for about 15 years and never once needed to reverse the direction (other than for idle curiosity), but I am sure someone will come up with an answer.

Two solutions for this: change the labelling on your switch (easy), or more involved, swap one of the logic leads to the other switch way on the relevant switch pole (careful because at least one of the other poles is carrying mains voltage).This may tale a bit of investigation with a multimeter to confirm the correct switch terminal.

 

 

[southernchapParticipant @southernchap]

One has to ask the question, how often and for what purpose do you need to run your mill in reverse?

Power tapping maybe? Auto reverse tapping heads do take up a fair bit of space.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

The Neutrix XLM is an interesting case. A premium product designed and made by a respected manufacturer (but not of mains products at the time) it was mainly used professionally. This included the BBC. It fails the requirements because the otherwise excellent, collet type, cable grip is held by a a cap that is tightened, and can be loosened, by hand.

……

Robert.

As a complete aside, i used to work in BBC studios with those connectors, we ofter hired in cameras, these used the connectors the other way round to the BBC. As it is 25 years since I saw these, I can’t remember which way round was which, but the puns for L & N were recessed so couldn’t touch them, but the earth was a socket.

Mark.

[DellParticipant @dell]

Thanks for all the comments & I will look into replacing the 3 pin plug & socket for the motor but I need to find something not to large, as for the motor direction switch I have decided to just add labels .

[Robert Atkinson 2Participant @robertatkinson2]

Hi Dell,

Problem is you need 4 connections, 3 power and 1 protective earth. If the motor cable does not include a  protective earth you should add one. I know of nothing suitable that is smaller than the HAN 3 or M23 types. There is not much call for small 3 phase nains connectors.
I’d suggest using a strain relief and making the connections inside the enclosure. If themotor only has 3 power connection then if you use a fixed earth connection / lead between the box and the part of the mill that the mounted too and a earth lead between the motor and the mill you will have at least made it safe.

Robert.

[old martParticipant @oldmart]

I used a five pin plug and bulkhead socket for the motor connection, 3 phases, 1 earth and an extra one for the screened cable, just in case.

It made removing the motor to change to a better belt much easier.

Neither of the mills is set up to enable reverse, the Elliot drill has backgear and the switch for reverse if we ever wanted to get into power tapping.

[old mart]

On old mart Said:

I used a five pin plug and bulkhead socket for the motor connection, 3 phases, 1 earth and an extra one for the screened cable, just in case.

It made removing the motor to change to a better belt much easier.

Neither of the mills is set up to enable reverse, the Elliot drill has backgear and the switch for reverse if we ever wanted to get into power tapping.

Are you going to tell us what type / range / part number you used? 5 pin plug and bulkhead socket covers a huge range.

Robert.

[old martParticipant @oldmart]

I can’t remember the details, I even got the VFD wrong and was surprised when it turned out to be a Schneider.

[DellParticipant @dell]

Hi Robert

when I wired everything up the In coming earth I connected to the cast box along with another earth via a mounting bolt that the original case was mounted with that in turn was threaded into the main mill casting along with another 3 bolts that held the original control box on & are now holding the new cast box on, the motor in turn is bolted to the main mill casting so everything should be ground to the incoming earth, should I add another earth directly from motor to earth ?.

As everything is either cast iron steel or cast aluminium & the incoming earth is connected to it via the mounting bolt I assumed that would be enough.

Dell

[Robert Atkinson 2Participant @robertatkinson2]

Hi Dell,
Ideally you should have an earth wire for the motor. Scenario is motor not working due to short to frame, you unbolt motor to investigate, motor becomes live and you get a shock. If there is an earth lead between motor and body of machine you have to disconnect lead as well to get a shock. If earth is via same connector as power you can’t get a shock because you can’t disconnect earth without disconnecting power. The correct type of plug disconnectes power before earth due to longer earth pin.
If you are the only person using the mll you can determine your own risk level. but I’d want at least a lead to the frame of the mill.

Robert.

[BazyleParticipant @bazyle]

Earthing is so important, especially on plastic battery tools.
https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-cisivis-cordless-drill-sold-via-ebay-2406-0043
https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-cisivis-cordless-drill-sold-via-ebay-2406-0043

“Summary
Product: CISIVIS Cordless Drill sold via eBay

Hazard: The product presents a serious risk of fire as it is inadequately earthed”

[Bazyle]

On Bazyle Said:

Earthing is so important, especially on plastic battery tools.
https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-cisivis-cordless-drill-sold-via-ebay-2406-0043
https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-cisivis-cordless-drill-sold-via-ebay-2406-0043

“Summary
Product: CISIVIS Cordless Drill sold via eBay

Hazard: The product presents a serious risk of fire as it is inadequately earthed”

If you actually read the report you would see that it is the mains powered charger that is dangerous not the drill. Or are you just trolling?
Safety is not a joke.

[Author]

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