Sawdust and Shavings

I did get into the ‘workshop’ as planned, and churned out a couple of ManSpace signs on the CNC machine (one carved, one bas-relief)

_DSC2475

before moving onto what I was actually planning to work on – the start of a rocking horse as recently built by a friend.  He kindly gave me his templates and the plans, so I was able to jump straight into it.

_DSC2478This was about 90 minutes work with a bandsaw and a template copy bit on the router.  Still lots of joining, gluing, shaping and finally finishing to go, but getting to make sawdust and shavings was a palatable relief after so long.

One of the first things I went to do was fire up the generator to try out the 15A tools.  The tablesaw fired up without a problem, but the thicknesser was another story.

It kept tripping the generator out.

Now I am rather confused by this.  The generator is a 6.5KW, so isn’t like it is short of power.  Before the move, the thicknesser was working ok, and I subsequently tried (successfully) to turn it by hand (power disconnected, by pulling on the belts).  So why could the generator not get it up to speed?  It isn’t like the generator wasn’t turning the motor, just extremely slowly under maximum load (with the engine labouring) before the circuit breaker kicked out.

I’m not in a position to be able to test the thicknesser any other way – it is way too heavy to move to somewhere there is 15A available, and I don’t have any currently at the property (at least not accessible (aka oven)). Green steam sucks – anything that needs imaginary numbers to describe how it works is obviously magic. (No, I’m not kidding – you need to understand imaginary numbers to perform some of the multi-dimensional calculations involving frequency and phase-shifts

The voltage in a circuit is 45 + j10 volts and the impedance is 3 + j4 ohms.  What is the current?
Answer:
E = I • Z
45 + j10 = I • (3 + j4)

7 – j6 amps

j represents √-1 (also shown as i in non electrical engineering applications).

See what I mean?! Once upon a time I used to understand this stuff.  Happy to have brain-dumped it after the exams!)

What it all boils down to, is the thicknesser will just have to wait until the new shed, and the subsequent installation of a power supply.  At least the tablesaw is functional again – even if it wasn’t used for the rocking horse (yet).  The steps followed so far were all managed on the bandsaw and router table.

 

Retro Controller revisited

Back in April, I wrote about this coffee table that is also a video game controller.

Nintendo Coffee Table Controller

Nintendo Coffee Table Controller

At the time, I thought the woodworking looked pretty cool, but also achievable.  The electronics to make it work would be beyond most of us to bother with (unless you took a real controller apart and stole the circuit board out of it, but even that poses some problems).

However as it happens, I have stumbled across the perfect solution through another website that I frequent, called Kickstarter.com

Kickstarter is a funding website to give inventors a revenue source to get their projects off the ground, and/or into production.  The inventor writes a proposal then seeks funding for that proposal from anyone who reads Kickstarter.  Donations can be as little as $1, right up to $thousands, but the donations come with a reward.  It could be goodwill, or it could be to fund the purchase of prototypes or first production runs of the item.

One of the projects I funded was called MaKey Makey.

MaKey MaKey

MaKey MaKey

To quote from their site:

MaKey MaKey is a printed circuit board with an ATMega32u4 microcontroller running Arduino Leonardo firmware. It uses the Human Interface Device (HID) protocol to communicate with your computer, and it can send keypresses, mouse clicks, and mouse movements. For sensing closed switches on the digital input pins, we use high resistance switching to make it so you can close a switch even through materials like your skin, leaves, and play-doh.

Doesn’t matter how it does it, but the simplest way to look at it is a USB input device for the computer.  By connecting alligator clips to the board, and to a contact device, you can turn pretty much anything into a computer controller.

Pretty much anything.  Even a banana.  A bunch of bananas can become a piano.

The kit can work with play doh switches, even by drawing a controller on paper with a graphite pencil.

PacMan Controller

PacMan Controller

Given how simple it is to turn so many devices into controllers, the MaKey MaKey is dead easy to incorporate into other items, such as the Nintendo retro controller coffee table.

So if you were interested in creating something like that, and didn’t know how to work out the computer interface, this is the solution!

Want to create a keyboard to reenact Tom Hanks in “Big”?

Big

Big

(Or reenact Homer Simpsons’ reenactment!)

I got the Kickstarter kit with a vague idea that it may be used to create a proximity sensor for the tablesaw or similar.  It could also be used to create a controller for the computer to be able to remotely start and stop the computer recording for podcasting.  There are so many items it could be built into.

I’ll leave it to your imagination!

Warning Signs

Hindsight is so much clearer than precognition I must say.

Back when I got my Nova lathe, I mentioned I was getting some small shocks from it.  Annoyances really.  I raised it with the Australian supplier, and that didn’t raise any warning flags either.  As it happened, I saw some tweets from Teknatool (the manufacturer) recently which promoted me to get in contact again, and they immediately responded. That was pretty impressive.

Back to earlier: in hindsight, I, or the supplier should have taken more notice of those little shocks.  You shouldn’t get shocks from an earthed machine.  I know that.  They should have.  But for some reason, I didn’t, and it went through to the keeper.

So fast forward to the present.  As soon as Teknatool heard, they got straight into contact with me, even to the extent of one of their senior engineers ringing me directly from New Zealand to get more information, and to help problem solve it.  Impressive.

Now back in time again, I had tested just how much current was passing from the lathe to the shed (and therefore what was giving me a jolt).  Now if only I had instead tested the earth at the same time, a big red flag would have gone up.  The machine was not earthed.  It is not a double insulated machine (and many of those don’t even have an earth pin): it needs a functioning earth.

I’m not criticising Teknatool / Nova here.  As I will show in the following photos, it is so easy for it to happen.  Perhaps Teknatool should actually glue the earth wire to the earth pin.  Perhaps the tester in the Chinese plant wasn’t as diligent as he should have been.  Who knows, but at some stage in transportation of the lathe, the connector came off the earth, and the tool became dangerous.

Other manufacturers could just as easily experience exactly the same problem.  And all it takes is a very quick check with a multimeter to ensure there is continuity between the earth pin on the flex, and part of the tool itself.

If it wasn’t for an idiosyncrasy of the DVR motor that caused the slight jolt I was feeling when I happened to touch the lathe and the shed (or another tool), I would never have known to even test if the earth was connected.  In the workplace, we regularly (annually) get everything tested and tagged.  Rare to do that at home!

I happen to have access to an actual megger meter so I was able to take the test one step further than simply testing the earth, and that there is no continuity between active and neutral, active and earth and neutral and earth. (All can be done with a mulitmeter.)

Under the specific guidance of the company engineer, I removed the cover from the lathe.

Before

After

Bit dusty in there!  Before going any further, and it is a bit dusty, check out the awesome indexing wheel! (Sorry about the image quality – iPhone rushed shot)

Once the cover was off, time to work out where the issue is.

Well there’s your problem!  The earth wire from the chassis connection point to the back of the plug is not connected. Once I fitted it, it was obviously tight enough that it shouldn’t have come off easily.  A Chinese Friday on the Superbowl weekend perhaps?

Whatever the reason, this demonstrates that we tend to trust a tool that is new is right, especially when it works without actually checking for ourselves.  I am not condoning opening each new tool to check the wiring inside, but a simple check with a multimeter that the earth is working correctly before plugging it into the shed for the first time is simple, quick, and could potentially highlight a problem easily missed otherwise.

It is a shame basic PATs (portable appliance testers) are so expensive (around $1000).  There is no justification for them to be this much, after all they are not much more than a glorified multimeter, and a basic multimeter can be picked up for $30.  They do test other things – namely the quality of the insulation, but it shouldn’t cost an additional $970 to achieve that!

What I suggest is get yourself a basic multimeter and actually test the earth of your machines.  You may want to consider actually getting one of those testing and tagging guys to visit the shed and test and tag your machines.  Not sure what they charge at street rates – at my work I bring in external companies, and they charge between $2.20/test and $2.80.   If you consider how many tests your shed would represent, that is a pretty small number, and therefore a pretty cheap annual check that everything is still as it should be.

In this case I did have the megger meter, so ran a proper earth and insulation test. 2 ticks, 2 passes.

After all, insulation ages and cracks, rats & mice can eat through insulation, wires inside your cables can flex and break, machines vibrate, and nuts holding earthing straps on can come loose, and we do play with things that can cut cables, or have sharp edges and break a cable pulled over said edge.

Whatever the mode of failure, the older the shed, the longer it has been since things were checked, the higher the chance that something important could have been nicked, cut, snapped, worked free or perished.

Food for thought?

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