Meddings LB2 - views on quality?

[Beanwood]

In my continued struggle of trying to get 'better' tools on a shoe string, I've come across a Medding LB2 for a bargain price.(Under £100)

It's obviously had a hard life and is running 3 phase (Which I don't have), so can this be run from a VFD?

MOST importantly, is a worn Meddings going to be a significant upgrade to my Clarke Metalworker drill, that hasn't done a lot of work?

 

[Agroshield]

It is a current model, so have a sniff around Meddings' website for details. Meddings are reasonably responsive, so might give you a price list for spares. Says made in Germany. That could be the shop in China next to the one with USA on the signboard. As it is a modern machine (and of German origin), it would be unlikely not to have a motor that can be wired for high or low voltage. You would need to organise your own switching arrangement as the existing one will control the motor directly but with a VFD you need to use the VFD's own low voltage control circuit.

 

[Beanwood]

Thanks,

I've pulled the trigger, and collect tomorrow - so I'm off to scout around and see if anyone has explained previously how to rewire it!

 

[Hopefuldave]

Under £100 = you stole it! That's less than the delivery charge on a new one...
It'll have a 2-speed motor, so it could be difficult to rewire for 240v 3-phase, but 240 to 400v VFDs are getting inexpensive if you don't mind buying Chinese, simplest might be to use one set of windings and the VFD in place of switching motor speeds

 

[Beanwood]

Well - I have stolen it - but it's staying in the back of the car until I can work out how to lift 84kg without help!!
It has a single speed switch - but it's on 3 phase - with speed variable at 50 or 60hz.
I don't have 3 phase so will need to get another inverter - but it looks like it's a 220v or 415v motor.

 

[galooph]

it's staying in the back of the car until I can work out how to lift 84kg without help!!

That's a great excuse to buy an engine crane...

 

[Agroshield]

It has a single speed switch...

How many speeds are on the data plate? How many steps on the pulley? The description and brochure for the new ones available today says ten speed, using a two speed motor and five step pulley. Maybe yours was not made to that specification.

The reason I mention this is it would be wise to confirm 100% what you have before purchasing the VFD (take a photo of the motor data plate).

 

[Beanwood]

How many speeds are on the data plate? How many steps on the pulley? The description and brochure for the new ones available today says ten speed, using a two speed motor and five step pulley. Maybe yours was not made to that specification.

The reason I mention this is it would be wise to confirm 100% what you have before purchasing the VFD (take a photo of the motor data plate).

It's a ten speed - with 5 pulleys each side, but the plate states different speeds for 50hz and 60hz.
Definitely a 3 phase motor - my next question - how do I wire it for 240V please?

 

[Richiew]

Sometimes there's a wiring diagram on the underside of the cover that you have removed.

 

[Agroshield]

It's a ten speed - with 5 pulleys each side, but the plate states different speeds for 50hz and 60hz.

The motor data plate indicates single speed, so we need to think very hard about how ten speeds would be possible from that and a five step pulley.

The motor photo you show only has 50Hz on it, so which plate has 60Hz written on it? Can you take a picture of that? Does it have a single belt from motor to spindle or is there an intermediate shaft with two belts?

It may be that the motor is not be original and you could be stuck with five speeds. The good news is that the motor you have photgraphed will work on 230v three phase.

In the photo of the motor wiring, blue, brown and black are the incoming phases. Each of those connects to one end of a motor winding (blue, red and yellow). The top right connection in the photo has three wires (white?, brown, black) all connected together. This is the star point. You need to identify the three motor coil pairings. Disconnect everything and use a continuity meter to pair up blue and (one out of white, brown black), red and (one out of white, brown black) and finally yellow and (one out of white, brown black). That will enable you to connect it up in delta.

As above, there might be a crib sheet inside the terminal box cover.

 

[julianthegypsy]

As far as I remember, they give the speeds for 50 and 60hz because we use 50hz and the septics use 60hz. It's just telling you what speeds it will run at in the UK and USA, it's nothing to do with getting more different speeds out of it.

 

[Hopefuldave]

That's a single-speed 4-pole motor, so it'll give 5 speeds with the 5 pulley combinations - and it says on the label that it's usable on 240v 3-phase so easy enough to get a VFD to suit. You can change speeds on the VFD too, e.g. run it between 25 or 30Hz and 50 or 60Hz - running at half speed will give less power though.
You'll want a VFD that can deliver at least 2.3 Amps (the FLA marked on the motor sticker) and 370w (1/2 HP) continuous, never hurts to go a bit oversize on a VFD so maybe go for a 1HP/ 750w 240 to 240 and rewire the motor as so ably expained by Agroshield, be sure that the incoming 3-phase connects to the same *winding start* wires (red, yellow, blue) to maintain the right polarity on the motor poles, the other end of each coil, the *winding end* connects to the *winding start* of the next phase. If it rotates in the wrong direction, just swap two of the incoming 3-phase to reverse it.

 

[Beanwood]

You guys are ace! Thanks.
I have the wiring diagram exactly where @Richiew suggested it would be, now I've got to try and work out how that relates to what @Agroshield has described. I suspect loking at it again, @julianthegypsy is right, and it just states what would be at different input rates.
I'm not worried about 10 speeds - and of course with a VFD I can alter it a bit.

 

[Richiew]

Yay! I'm not wrong for once.

 

[Agroshield]

I have the wiring diagram exactly where Richiew suggested it would be, now I've got to try and work out how that relates...

As you have the diagram, please ignore everything I wrote above and just follow the diagram (just in case you are not clear, it is the lower one in the picture, labelled MESH, with Red and Brown going to U etc. Mesh is an alternative name for delta.

U, V and W are the incoming phases, and may be labelled as such on the VFD outputs. Alternatively, the VFD might say L1, L2, L3. Same thing, different letters.

If it does turn backwards when you command the VFD to go forwards, you can swap any two wires at the output of the VFD _or_ at the input of the motor. That is what the note on the dfiagram means when it talks of LINE wires.

 

[Beanwood]

As you have the diagram, please ignore everything I wrote above and just follow the diagram (just in case you are not clear, it is the lower one in the picture, labelled MESH, with Red and Brown going to U etc. Mesh is an alternative name for delta.

U, V and W are the incoming phases, and may be labelled as such on the VFD outputs. Alternatively, the VFD might say L1, L2, L3. Same thing, different letters.

If it does turn backwards when you command the VFD to go forwards, you can swap any two wires at the output of the VFD _or_ at the input of the motor. That is what the note on the dfiagram means when it talks of LINE wires.

Not quite s simple as all those other lovely diagrams I see, where there are just a couple of copper jumpers to move.

If I've understood correctly - it literally just means taking off the wires from the motor where they are, and putting them on the 'new' posts, along with the feed wire in from the VFD.

Am I correct - for low voltage - nothing goes to N?

 

[julianthegypsy]

Yay! I'm not wrong for once.

Yay! Me too!

 

[Agroshield]

Not quite s simple as all those other lovely diagrams I see, where there are just a couple of copper jumpers to move.

If I've understood correctly - it literally just means taking off the wires from the motor where they are, and putting them on the 'new' posts, along with the feed wire in from the VFD.

Am I correct - for low voltage - nothing goes to N?

Correct. The jumper-style terminal box is a more modern implementation of what you have. Slower to do (you only have to undo four nuts; in the jumper box it is necessary to undo six nuts) and less nous needed to do it, but not necessarily better.

You can leave the blue, red and yellow motor wires on the posts they are already on and just add white, brown and black to the correct post.

A lazy person would leave the incoming phase cables in place and put the three wires you are moving on top, but better to put the two winding wires as the bottom two of the stack of three wires.

As you say, nothing connected to N.

 

[RichardM]

It's a 5 speed drill, the differing speeds are what the speed should be for differing countries with 50Hz (UK) and 60Hz supplies.

24OV delta - Nothing to neutral post on the motor, that's used for the star point fixing as current set up

 

[Beanwood]

All wired up now thank you all @Agroshield, @Richiew .

The drive belt is a little too tight, so it struggles a little to start. It's also worn out, so I'll kill two birds, and get one that fits, and isn't putting everything under strain.
I now need to invest in another VFD (As specced by @Hopefuldave ), alternatively I'm tempted to just put on a single phase motor instead - is that such a bad idea?