Thread: Maybe I'm on the journey to becoming a real woodworker?

Great thread. Careful where you put the magnet mount on the head stock. I have a memory of Skew saying something about a mysterious problem caused by a magnetic thing put near the pulley or something.

The idea is to put the remote controls away from the headstock , out of the danger zone

Originally Posted by tea lady

a mysterious problem caused by a magnetic thing

Luckily this can all be fixed by the judicious use of a foilie...

Originally Posted by tea lady

Great thread. Careful where you put the magnet mount on the head stock. I have a memory of Skew saying something about a mysterious problem caused by a magnetic thing put near the pulley or something.

Ah, sounds like induction heating. I wonder how close Skew's magnet was to the pulley?

I do very much appreciate all the comments and suggestions. Typical of me, things tend to happen in bursts with quite long lulls in between the bursts.

I think I will go with the remote control panel idea (and I must get my order in - 2 weeks delivery time) and I have a think about how I might set up the extra switches around the lathe, and what type of switches to use. I don't expect I'll get much more done on the lathe this side of Christmas.

Chris

Originally Posted by chrisp

Ah, sounds like induction heating. I wonder how close Skew's magnet was to the pulley?


Chris

I think it was something to do with the magnet pulling something off gradually.

It has been awhile...

Continuing the story, when I last left it, it was essentially a wiring mock up to check that the motor and variable speed drive would work together. Now that I'm happy it is all going to work, it is time to start the real wiring. I've cut all the mock up wiring from the controller, rather than unscrewing it, as the stubs of cable will help to confirm the correct locations for each wire.

The original switch gear is shown in the next two photos

Attachment 106302Attachment 106303

The lathe with the original switch gear removed and the panel removed to show the proposed location for the VSD.

Attachment 106304Attachment 106305

Electronic devices don't like having metal shaving in them, so rather than using the VSD as a template, the mounting hole locations were measured and marked on to masking tape.

Attachment 106306

Screws for mounting the VSD were captivated to the back panel with shake proof washers and nuts. This was done to make it easier to installed and removed the VSD it will be be done many times during the wiring. The VSD will be secured to this screws with another set of nuts later.

Attachment 106307

Check that the mounting screws are in the correct place.

Attachment 106308

The VSD was removed and another hole drilled through the back panel. This hole will become the main earth point.

Attachment 106309

It is very important to remove all the paint around this hole to provide a good earth contact on to the body of the lathe. I used a Dremel type tool with a grinding stone.

Attachment 106310

The earth screw is, in this case, a 4mm screw with a star washer and nut.

Attachment 106311

This are installed to the earth point - with the star washer to the bare metal. These are then tightened up.

Attachment 106312Attachment 106313

All the earth connections of the various parts will brought back to this point. I've shown a few crimp lugs on this terminal so you can start to get an idea of the earthing arrangement.

Attachment 106314Attachment 106315

Looking ahead a bit, some of you maybe wondering how I'd be able to adjust the speed when the VSD is installed. The VSD is capable of being controlled by an external control panel shown here.

Attachment 106316

Back to the earthing. It is very important to be convinced that the earth connection is good. Using a multimeter, I check the resistance between the earth screw and the tail stock. I choose the tail stock as it was about the furthest bit of metal on the lathe. This will be about the worst resistance measurement I should get.

Attachment 106317

The earth resistance reads o.3 ohm (acceptable), but I know the multimeter leads contribute a fair bit of this. Shorting the multimeter leads together gives me a measurement of the lead resistance. In this case it also reads about 0.3 ohm.

Attachment 106318

Therefore, my real earth resistance is about 0 ohm (or about 0.1 ohm give or take). You should be able to achieve earth resistance of 0.5 ohm or lower. If the reading (corrected for the leads) is above 0.5 ohm, you should review the earthing arrangement.

The earth resistance needs to be low so that in the event of a fault, the fault current will be high and trip the circuit breakers, or blow the fuse, promptly.

I'm happy that I've got a good earth contact to the body of the lathe. I've placed a sticker near the earth screw to indicate that this will be the central earth point in this machine.

Attachment 106319

I rewire the motor side of the VSD. Note that the earth is taken to the earth screw.

Attachment 106320

The mains side of the VSD is slightly more complicated. The active and neutral go straight to the VSD. The earth from the cable to connected to a lug. A separate wire is used to connect the earth terminal on the VSD to another lug.

Attachment 106321

These two earths are taken back to the main earth (rather than daisy chained).

Attachment 106322Attachment 106323

It is important to constrain the wiring too. The wiring is constrained with cable ties to prevent the cable coming adrift if the wires break.

Attachment 106324Attachment 106325

So far, the wiring has the mains coming in and going directly to the VSD. We'll need a mains switch as well - and also an earth to the panel on which the switch is mounted. I've added another earth cable from the central earth for this purpose.

Attachment 106326

The loop of yellow cable will be cut and a switch installed. I'm using a industrial switch. As the mounting block doesn't have cable entries in the rear, I'll drill my own and install cable glands.

Attachment 106327Attachment 106328Attachment 106329

I've install the panel back on the lathe. [I'll deal with the extra holes later.]

Attachment 106330

The yellow cable has been cut and fed through the cable glands.

Attachment 106331

The mounting block has been attached to the plate.

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The rear of the plate shows (a) how the glands come though one of the large holes; and (b) the earth connection to this plate. Again, the paint was removed and a star washer used.

EDIT: The front panel is earth using a separate, dedicated, screw rather than doubling up and using, for example, one of the screws holding the switch in place. This is done so that the earth isn't accidentally left unconnected when doing work on the machine, and also, screws though plastic (i.e. the mounting block) can't be relied on to maintain sufficient tension on the screw to maintain a good earth contact.

Attachment 106333

The active and neutral are wired through the switch. Note this is a 3-pole switch intended for 3-phase. I'm only using two poles. Tighten all the screws - including the unused terminals. Very important: DON'T ever switch the earth!

Attachment 106334

The earth connection is tightly twisted together. It is this twisting that makes the main contact between this wires.

Attachment 106335

This twisted joint was folded and a 2-screw BP connector installed. It is important to check that the screw actually presses on the wire. These aren't my preferred type of connector for this type of connection. Screw terminals that have the screw pressing directly on to flex or not the best. Normally I would use a crimp joiner.

Attachment 106336Attachment 106337

Tape up the earth connection and install the switch to the mounting block.

Attachment 106338Attachment 106339

Behind the panel, Tighten the cable glands - these form the cable restraint to prevent the connections from receiving mechanical forces that may be applied to the cable. Cable tie the cables together to keep everything neat and tidy and out of harms way.

Attachment 106340

With the panel installed, check that the cables are well out of harms way. These photos, looking up the past the motor, show the cable sitting well away from the moving parts, and no sign of cables or wiring near the belt.

Attachment 106341Attachment 106342

The bulk of the mains wiring is now done but there are a few things still to be done:

• Cover the holes
• Install the remote control panel
• Install some axillary / emergency stops
• safety test

More soon...

Excellent post. Probably something that only someone with electrical experience should/would attempt, but a very detailed and informative explanation of 415v > 240v conversion, as well as changing bearings etc. Many thanks!
I also have an old Woodfast 415 volt lathe which would benefit from this process, but I think I'll just sell it as it is and point prospective purchasers to this thread.

Wayne

An excellent lathe. I have one I bought in 1981. The bearings and belt are as good as the day I bought it, in spite of a hell of a lot of work. Changing the belt speed is a pita.
Jim