Warco WM250

[John RuddParticipant @johnrudd16576]

Jason,

When I swapped out the motor on my SPG 2129 ( 290 equivalent ) the new motor was mounted on a swivelling bracket attached to the bed to permit belt tensioning. The bracket carried the original brushed motor and had the right hole spacing for an 80 frame motor…making changeout easy….

I swapped for a 2 pole motor and ran the vfd at 75 hz to give me the same spindle speeds as before…I just bored out the motor pulley to fit the motor shaft…..QED….

[JasonBModerator @jasonb]

Thanks John, so in the low range to get 50rpm spindle speed the motor would be running at about 220rpm which would need 4hz?

[John RuddParticipant @johnrudd16576]

Ahhh, I fibbed…fMax is set to 70hz not 75…..

At 5hz the spindle is doing 75 rpm…..the motor is turning at whatever speed……I'd need to check other parameters on the vfd which is a bit awkward tucked away in the box….

[JasonBModerator @jasonb]

Don't go to any trouble on my account John, I just was not sure how low the motors would run.

Funny enough over the last couple of years my DC motor seems to have speeded up, where as I used to get 45-950 in low range I now seem to get 70-1050 on a warm day, touch less on a cold one..

[Mark P.Participant @markp]

Jason, I’d noticed that with mine, until it went bang last week!!
Mark P.

[Rik ShawParticipant @rikshaw]

Jason – If you want to slow it down a bit there is amongst the mini pots on the speed control board, one which if backed of – anti clock – will do the job. If memory serves it's the bottom left when viewed with the heatsink at the top – but double check I'm right before you do it!

Rik (John will probably correct me if I'm wrong)

[Les Jones 1Participant @lesjones1]

Hi Jason,
I wonder if the magnets in the motor are becoming weaker which would cause the motor to run faster on the same voltage ?

Les.

 

Edited By Les Jones 1 on 14/02/2017 15:45:10

[John RuddParticipant @johnrudd16576]

Quite possible Les, especially if the motor has been worked hard and got warm ( hot? ) I've no idea what the Curie point is of the magnetic material that is used in these Chinese motors…..One of the reasons to use an extra fan to aid cooling, not just to keep the comm cool, but also the magnets….So imagine if the casing of the motor is quite warm, how hot are the magnets?

I did notice the body of my mini mill motor was rather warm ( hot ) running flat out with a 2mm carbide cutter in cutting aluminium and I wasn' t pushing it either, but could smell 'that electrical warm smell' so I added a small fan to the nde of the motor to help cool things down…..( didnt help coz the motor is toast now!…..think it needs new brushes I hope….lots of sparks around the comm at high speeds….      )

 

Edited By John Rudd on 14/02/2017 16:17:43

Edited By John Rudd on 14/02/2017 16:26:32

[Cabinet EnforcerParticipant @cabinetenforcer]

Posted by JasonB on 14/02/2017 12:23:05:

Cabinet Enforcer, can I ask what spindle speeds you are able to get with that setup and are they pullys two sizes giving you a high and low range? Also is it a 2 pole or 4 pole motor.

I will have to have a look in the back of my 280 to see if teh bed is tapped.

Thanks, Jason

The pulleys are doubles as the belt calcs for the full 1.1Kw say there should be two belts, nothing so fancy as two sizes Of course the pulleys don't line up perfectly so two belts can't be used, if I had a working lathe I could machine a new spacer for the spindle, maybe I will get a round tuit now I remeber it needs doing.

Pulleys are 71mm and 106mm, this gives speeds from 60 to 2000. There isn't huge amounts of torque left at 60 though, and I suspect it could do with both belts on at lower speeds too as slip can start to be an issue if you push it hard. Motor is 4-pole.

In retrospect I would not have chosen these sizes and now would probably go with a 60mm or 56mm and a 125mm to get the low end more usable, and have an alternate set in the cupboard with maybe a 2500 top end.

Getting the pulley ratio yet lower would require an intermediate pulley, or perhaps looking at alternate belt/pulley types, this wasn't possible when I did mine as it was the first lathe I bought and it was broken when I bought it.

[DustyParticipant @dusty]

Hopefully my new motor and other gubbins will arrive tomorrow. I will however spend most of the day at Hospital arranging for my cataract operation. I hope that when done I will be able to see clearly again. I spent today taking the rest of the headstock end apart. Those naughty orientals do hide screws in funny places that are very difficult to get at. I did discover that the WM250 does not have tapped holes in the bed. A fact that I am rather glad of, having ordered a face mount motor. It looks like it may be the weekend before I am able to make any progress, due to other (family) commitments. Once I have the VFD and a wiring diagram for it I will hopefully come back for more advice.

[DustyParticipant @dusty]

Well the motor and VFD have arrived. I have been machining the motor mount in order that I can fit the motor to it. I am afraid that the boss stopped me as it was making too much noise, which I had to agree. I think I will screw it to a piece of MDF in an effort to stop the vibrations. For those interested the motor is a TEC, 71 frame 1hp with face mount. If the bed had been tapped then a foot mount would have worked. The VFD is an Invertek optidrive. Over the next few days I will hopefully cut and carve the sheet metal of the lathe to accept the motor. Then the fun will start connecting everything up.

[Mark P.Participant @markp]

Wish I’d gone the VFD route, would have saved myself a lot of cash.😭
Mark P.

[DustyParticipant @dusty]

Hi Mark

I costed it before I started,and as you know replacement DC motor and control board £300, 3ph motor and VFD £230 I suspect I will need to purchase some bits and pieces to complete the set up but not £70 worth.

[DustyParticipant @dusty]

Well I have now managed to complete the metal bashing part of the conversion. I must admit I have been side tracked more than I would like but that's life. The next step is wiring everything up, which I need to do so that I can complete the installation as the motor is upside down in order to fit it in, this means the junction box is inaccessible with the motor installed. I now need help, I feel confident in my ability to make the connections but I need to ensure I make the right connections. Where do I go from here.

[John RuddParticipant @johnrudd16576]

Dusty,

I assume you bought an Invertek vfd?

I'll try and keep this simple….

You need for wiring the motor…..

2 x 20mm stuffing glands, one for the motor and one to go into the control for the motor cable.

1 metre of 1.5 mm 4 core cable ( 3 phase and earth). Some would say it needs to be screened, but for the length between the motor and vfd, I wouldnt bother. ( I didnt when I did mine, dont suffer from any kind of radiation or from any knd of spurious trips)

Remove the motor terminal cover and make the connections as per the diagram called Delta, by moving the metal straps so they are all in a row vertically.

Next, screw the 20 mm gland into the motor terminal housing. Strip the cable back and ideally use crimp lugs, secure the three phase wires to the terminals marked U,V and W. Connect the earth wire to the earth connection in the box.

Mount the inverter inside the control box, I used a short piece of din rail rivetted to the back.

Fit the other 20mm gland, feed the motor cable into the box, strip back the free end and again with crimp lugs, terminate into the U,V and W terminals on the inverter. Connect the earth wire to the terminal marked PE.

The Mains wiring that went to the two connectors marked L on the old speed control board now need to go to the respective terminals on the inverter…( I am assuming you havent stripped out any of the original wiring), marked L1/L and L2/N.

You should connect a seperate Earth lead from the control box GND to the terminal marked PE on the inverter.

Do not omit the above step!

That concludes the 'mains ' wiring side of things.

You can test the motor rotation now, add a wire link to terminals 1 and 2 on the inverter, switch on your lathe, press the Start button in the keypad on the inverter and using the Up and Down arrow keys the motor should speed up and slow down…Check the motor runs clockwise when viewing the motor shaft…..If it doesnt, post up on here…

I think thats enough for now for you to be getting on with….

Switch everything off and have a cup of tea/glass of wine/ shot of tequila whatever you drink….and toast your success!

 

Edited By John Rudd on 05/03/2017 18:42:43

Edited By John Rudd on 05/03/2017 18:43:45

[DustyParticipant @dusty]

John Thanks for that, I only have one question, what do you mean by control box?

[John RuddParticipant @johnrudd16576]

I was referring to the box that housed the speed controller/ the nvr switch and the reversing switch.

[DustyParticipant @dusty]

Thanks John I told you I were an idjut.

[John RuddParticipant @johnrudd16576]

You're smart enough to ask questions when not sure………

We'll continue the wiring when you are ready….

The important thing is not to rush the job….

[DustyParticipant @dusty]

Ah a small problem or rather 3 First the VFD will not fit into the control box and if it did I would not be able to access the buttons. I am unable to see a PE terminal on VFD. I did strip the wiring as I needed to get the control box assembly from the lathe to cut the motor hole or rather I removed the Control board and filter. The wires from thee pot are still in position as are the wires from speed reader and display. The screened cable from the pot has three wires I have some screened cable on order to replace this as I suspect I will need to place the VFD on the wall near the lathe?

[DustyParticipant @dusty]

I am slowly getting there, acquired some 4 core cable, it is 2.5 which is a bit heavy but I believe in using what you have. This is now wired into the motor and crimp terminals are in position on the other end ready to connect to the VFD I have now located the PE terminal. I do have a question, the speed control pot on the lathe is, it appears only 4k. I have another (new one) rated at 10k which is going to be the best to use? If my memory is right the terminals on the pot are the outside ones are the track and the centre one is the moving contact, but 50yrs could have dulled my memory, like everything else.

Edited By Dusty on 09/03/2017 19:10:13

[John RuddParticipant @johnrudd16576]

10 k is fine…..

Yes, the terminals are as you described…..looking at the front, the left tag goes to gnd…..

[DustyParticipant @dusty]

Everything connected as per instructions, switch on lo and behold the drive shows signs of life. Now for the exiting bit press the up button nothing dead, lifeless, motor not running. I have checked all connections as far as possible, what have I done wrong? I have given the pot a twiddle and that had no impact on the lack of rotation.

Edited By Dusty on 12/03/2017 14:37:50

[John RuddParticipant @johnrudd16576]

1) have you got the link in place between terminals 1 & 2 ?

2) Did you press the Green 'go' button?

What is the lcd display telling you? Any text on there?

The default settings on the inverter sre set so that with the link in place, pressing the Green 'go' button then using the up and down arrows for speed control. That is why the pot isnt having any effect.

Once you have got this far, the vfd needs programming to use the remote controls….

[DustyParticipant @dusty]

Turn on and it shows 'stop', press 'go' button = nothing. Pressing stop button only shows cycles, amps, rpm etc but as the motor is not running it is of no relevance. Turn the whole thing off at the socket and it shows stop after a few seconds U-uol E flashes on for a second before shutting down.

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