Union Graduate Motor Removal

[BobmanDad]

Hi folks

I'm new to this site and to wood turning. I managed to acquire a Union Graduate with a 3 phase motor. I've been having bother with a 1 phase to 3 phase inverter tripping the power, but the supplier has changed it to a different one which powers up okay. I hope you will indulge me as I haven't actually managed to start the lathe yet and have quite a few questions. I'll not stick them all on now, just the one.

The inverter suppliers instructions begin by instructing that the motor should be configured to the non-variable setting. I can't check what it is currently on without taking out the motor. I found these instructions on this forum:

motor removal is easy just remove the grub screw and lock nut from the pedastal at the end of the motor pivot spindle inboard end...slip the spindle towards the outboard end ( there may be a collar too on the shaft between the motor legs motor then slips out through the door

However, they don't mean a lot to me, photos would be good. Can anyone help?

 

[flh801978]

The motor pivots on a shaft at the back side of the machine

Take the lock nut off the grub screw and then unscrew the grub screw out completely
this screw is at the back side of the pedestal to the left when you are at the back of the machine
Then you can tap the shaft out towards the door
there may be a collar with a grub screw on locating the motor cradle in position

The other side of the cradle is held onto the turnbuckle belt tension adjuster....this just slips out when the motor cradle is loose

Motor is heavy
all screws are imperial

I'm not sure what the inverter suppliers instructions about non-variable means
Generally you connect in delta mode for 240v operation ( instructions on motor plate usually )

 

[deema]

The motor will be wired up for star running if its a dual voltage motor. This will definately be the cause of your problem with the inverter.

The motor removal is a little tricky. Be careful to support the motor to protect the drive pulley from taking a 'ding' when tapping out the shaft. Also, it may be obvious, but keep the door open into the motor compartment.....the for obstructs the shaft being removed and a good tap if you have not noticed can ruin your day.

I would also recommend taking out the actual drive spindle when you have a moment. This is very easy, see Daltons WEB site for a manual if you have not already got one. Occasionally, and my machine gasps this problem, an earlier owner will have had the shaft out and not replaced the metal 'bungs' either side if the bearing correctly. My had the bungs on the wrong side as a consequence the grease point would not push grease into the bearings through the recesses in the 'bungs'. I replaced my bearings with sealed for life bearings. A lot less danger of saw dust getting in and mixing with the grease to create a good palling paste!!

You can get advise and buy the sealed for life bearings from
http://www.woodturninglathes.co.uk/about.html

They also will convert your lathe to a Varium for a fee!!

 

[BobmanDad]

Thanks to both of guys.

I'll let you know how I get on.

 

[BobmanDad]

Thanks everyone. Motor out and wiring changed to delta.

 

[graduate_owner]

Hi Deema,
how can you tell if the metal bungs are fitted the wring way round? I had to remove the spindle part way on mine to fit a new drive belt, and I don't know if I've messed things up. It was a bit noisy when I bought it and the inboard grease cap was missing. I replaced it with a standard grease nipple and pumped in some grease with a gun, and now it's much quieter. However it's the outboard side has been removed. I'm a bit concerned about it now

Edit - sorry, I was reading this all wrong. I was talking about the main spindle not the motor arrangement. Duh.

K

 

[Tim C]

Just had passed on to me an old and very rusty 3 phase Graduate. I'm looking to convert to single phase but can't get the motor out to clean and find out if its dual voltage etc. It's off the swinging spindle and belt tensioner but still on the cradle and won't come out of the door as I was told it should, as the cradle plus the control box on top of the motor make it too wide for the door. Do I have to take it off the cradle (horrible to get at the back mounting bolts) or drop it out of the bottom of the lathe body? Or is there another way?

 

[deema]

The motor really seems to only come out of the bottom of the lathe. It’s almost certain it’s hard wired in star and will need the motor opening up, the star point in the wiring finding cutting out and tails bringing out to allow it to be wired in delta for a ‘cheap’ inverter.

 

[Tim C]

Thanks - got the motor out now and it is dual voltage and looks like it can be wired in delta. Any suggestions about best inverter to go for? I've been in touch with ACDC Drives who recommend either a Parker AC10 or Yaskawa V1000 (do I need STO, whatever that is??). I definitely need a bit of help here - I'm out of my depth.
Thanks!

 

[CHJ]

…..do I need STO, whatever that is??...

Safe Torque Off, a safety feature that prevents a motor moving until STO is removed/deactivated.

It does not mean that the motor is isolated from the power supply.

 

[deema]

I use the following for graduate conversations.
https://inverterdrive.com/group/AC-Inve ... C04P2S220/
You will also need the expansion module 12293350 shown at the bottom of the page. The easy start guide shows you how to program and wire it up. Very easy.
I mount them inside the headstock on the back of the starter tray which is below the motor. All fits nicely.

 

[Tim C]

Thanks - very helpful and much more straightforward than other suggestions. I'm puzzled about the mounting - the motor and cradle are at the base of the headstock and it's not possible to mount anything below that. Also, mounting low down (inside the casing?) would require a remote speed/on/off control wouldn't it?

 

[deema]

At the very bottom of the headstock is a cover over the contactor. Your going to remove and get rid of the contactor. The contactor is mounted within a box. There are 4 bolts holding this into the headstock. Remove the box and mount the inverter on the rear face if it. It fits nicely below the motor. (See photo)

Yes you need to have a remote control. Below is a picture of how I do it. Again I use Weg push buttons and the Weg potentiometer ( only because it’s really good quality IMO) and you can buy it all at once with the inverter. I use a double pole 250V 6A mains switch (illuminated) and a single pole switch for the forward and reverse. It’s a bit of a fiddle, but it all fits in the place of the original on / off switc on a 2mm thick plate.

I like to be able to switch the inverter off and not have to remember to pull out the plug which most people have.

 

[Tim C]

Now I understand! That is so helpful - I'm really grateful for your advice and for the pics and info.

 

[graduate_owner]

Just a quick comment about inverters. The instructions on mine say to mount it in an IP rated enclosure (IP65 I think) so as to exclude moisture and dust. My previous inverter packed in and I suspect the cause was moisture and dust ingress. You can buy inverter in IP enclosures but they are more expensive. I made up an enclosure from an old computer case for mine. Plenty of room for cooling air to circulate.

K

 

[Tim C]

I've now tested the motor, which I'm happy to find works, and have the inverter, and info re wiring plus switches for remote control. The instructions say clearly that the motor control wiring from the inverter needs to be screened, which I now have. Can you please tell me whether the remote control wiring to stop/start, forward/reverse/speed control also needs to be screened? I can't find clear info about that and the guys at inverter.com seem also to be unclear.
Thanks for the info about enclosures - I too will have to improvise something.

 

[Ttrees]

It is best practice for the 4 core wire to be an SY cable from the motor to VFD
The weaved shielding SY cable is un-weaved at the ends, and paired with both earths, bolted to the cabinet, then a single earth wire is going to the VFD terminal.
This SY cable can be used for a few reasons if needed....
It can be helpful for stopping interference from phantom earth leakage, causing your radio to have bad reception,
aswell as reducing the high pitched noise emitted from the VFD.
This becomes worsened the farther away the motor is from the VFD,
You can reduce this interference without having to resort to needing an SY cable if your motor is close to the VFD.
I just found a heavier gauge wire and stripped it to use the insulation...there is no danger of any wires abrading in my setup.

I have a shower hose for protection of the control wire on my bandsaw, as there might be a possible risk of damage, since I have an additional
switch hooked up beneath the table.

I have read about folks stating the cheaper VFD's are no good for lathes, and I can attest to this in my experience from my bandsaw.
The cheap ones need to run at the rated speed, and not bog down or they overheat and die.
They also trip if a pot is installed, so I got rid of the variable speed on my bandsaw.

Look up Bob Minchen's induction motor PDF for more information on VFD's
He dwells on the woodhaven2, you will find the PDF underneath his signature.

Tom

 

[deema]

SY cable offers almost zero EMC screening, You need proper screened cable that will have a metal foil that completely encases the cable. To provide the screening the screen is normally connected only to a screen terminal on the VFD. This will then have chokes and capacitors to filter out the emc. If you connect the earth to the screen you might as well not bother having a screen as the earth connection will instead radiate the EMC.

You don’t need to screen the control cables, a screen is only required on anything with high frequency switching. It’s the high frequency switching that generates the EMC.

 

[Tim C]

One further question: I can't get clear info about whether the remote control (low voltage) cabling for on/of, forward/reverse and speed control potentiometer needs to be screened. Also, the instructions say the cable can be anything from 0.5mm to 1.5mm (20-14AWG) - that seems a huge range. Any guidance?
I understand that the motor to inverter cable is screened (and I have that) but am not clear about the remote stuff.

 

[deema]

Remote / control cables done need to be screened.
The reason for the large range in cable thickness is that it isn’t carrying any load, some of it will also be low voltage as well as low current. Usually the upper limit is determined by by what the VFD terminal will accommodate in cable thickness.