Laziness = Danger


This is a fine example of how being lazy, or just trying to do a job quickly, is a Bad Idea (tm).

I recently bought some old Fresnel lanterns (Strand Patt.123), most of which came without the bolts for fixing to the C clamp. Originally these were 3/8 whitworth thread, and wingnuts and bolts of that size are quite hard to find these days.

The majority of my kit uses M10 nuts & bolts, which is just a tad bigger than 3/8 ww. So, I decided to enlarge some of the holes on the Patt 123s to 10mm. I got out the electric drill and a 10mm HSS bit. Then I made my big mistake.

What I should have done was strip the lantern down to remove the yoke, and put it into a suitable vice before attempting to start drilling. But I was too lazy and in too much of a hurry to do this. I thought I knew better. The Patt 123s weigh about 2.5kg (5 lbs) and I thought that it would be fine to put the lantern on the ground, lens down, and grasp it firmly between my feet while drilling out the hole.

Anyone familiar with Wallace & Gromit (especially "A Grand Day Out") will probably have guessed what happened next.

The drilling started fine, and the bit cut through the first 90% without any trouble. Then it jammed. Solid. So what happened - I've got a 240v electric drill attempting to spin at high revs with quite a lot of torque, and a (relatively) lightweight object stuck fast to the end of the bit. To compound the problem, the drill is a few years old and has a button on the side which locks the trigger in the ON position (sensibly newer drills do not seem to have this "feature"). For a quarter of a second nothing moved as the torque built up in the drill.

My feet's grip on the lantern gave way almost immediately and the Fresnel started to rotate rather quickly. On its own this would have been quite bad, but as you might guess, attached to the lantern was a 2' (60cm) tail with a 15A plug on the end. UK 15A plugs used for stage lighting are made from heavy duty rubber, and the three pins are pretty solid - especially when they start thrashing against your legs at the end of a fast moving cord. Ow! As my feet let go the instrument bashed against the side and top of my foot with a certain violence. The jolt as the bit seized in the hole caused me to inadvertantly click the lock button.

Fortunately I was able to unlock the ON button and the rotation stopped almost immediately. To my amazement the lens was still in one piece, despite the fact that the lantern had bashed the ground a few times while whizzing around at high speed. I was even more amazed when I plugged it in and the lamp lit up (these tungsten bulbs are sometimes a lot more robust than we think).

What didn't surprise me was the sharp pain in my leg where the plug had hit me several times, and another dull pain in my foot where it had been battered by the body of the lantern. I also felt very, very stupid. I was exceptionally lucky that I was wearing strong leather shoes and thick denim jeans, otherwise my injuries could have been far more serious.

The moral of this story should be obvious. I have swallowed my pride and posted this in the hope that no one else gets tempted to be as hasty or lazy as I was.
Dim – we have spoken enough off line for me to tell you that I had tears running down my face from laughing at your mishap, without fear of offending you!

As soon as you mentioned the drill I knew exactly what was coming next as I have been there myself before – not like this but I think we have all had an experience of a drill getting stuck before. Even when clamping the yoke, you could easily have the same thing happen but this time the drill would want to continue spinning and only your hands (and the length of the power cord) stand in its way.

Now I do not know enough about Whitworth thread to know the outside diameter of the bolt but I do know that 3/8" Whitworth spanner will not fit a regular 3/8" nut or bolt. Given that there isn’t much between a 3/8" and 10mm hole, I wonder how much metal needed to be removed and if it would have been better to step up the drill sizes rather than do it in one take. Especially given the yoke that comes with these fixtures. Certainly do not see them like that any more. As I said, not sure of the initial hole.

I also have had power tools with the little lock on switch and on most I have removed them because they always seem to lock on only when something goes wrong. Have often thought about making up a foot controller for the times when my hands are busy trying to fend off an out of control power tool. In fact, could have come in handy yesterday when using my Dremel tool to cut some slots in the 2mm steel frames for my QI lights. Using the flexible shaft to get access and the cutting disc bit and kicked, jamming between the cut and part of the fixture. The flexible shaft flexed and twisted as the Dremel tool (which was hanging on a hook above the bench) laboured. Quickly flicked the switch and fixed the problem but often on power tools it isn’t always the easiest thing to find the power switch when such things happen. I remember that in high school all the manual workshops had big red buttons placed around the rooms and on the machinery, which cut power to the entire classroom if pressed.

Hope that you are OK and that the main injury was to your pride. Good lesson for everyone here.
Yep, also knowing what you mean and feeling your pain. Though for more often it's clamped or not the fixture that spins, instead it's the drill that whips itself from my hands. Hmm, 6.6Amps - more power....

Been there, outch, and laughing all the way in calling myself an idiot for method, lack of oil or wrong speed and pressure especially in that last 10% of the drilling.

Kind of adds spice to life as long as it's me doing it and not someone else I'm supposted to be supervising.

The "them's hurts" just adds to a collective memory of at some point and some day really doing what we already know to be smart over what's most easy. Difference between knowing what one is doing and smart enough to do so I suppose.

Good observation.... yep, I know nothing of what you speak on a constant basis.
Well I'm glad I'm not the only one to suffer from this type of incident.

I still have a few more yokes to drill out to 10mm, but for the rest I'll be a lot more careful. I shall remove them from the fixtures, clamp them securely in a vice and drill through carefully, in a few stages allowing the bit to cool down rather than trying to drill all the way through in one go. I shall also use some sensible lubricant to aid cooling and reduce the risk of seizing. I'll use my cordless drill - which has a clutch that *should* slip if things get stuck and does *not* have a locking ON button.

I shall also set up a video camera so that if anything goes wrong as before I can send it in to "You've Been Framed" and claim my £250 (syndicated across five continents, so you might just get to see me). :)

3/8 Whitworth is just a tiny bit smaller than M10 - you can even start screwing an M10 bolt into a 3/8 ww hole, but only a couple of turns as the pitch is slightly different. Originally I wanted to recut an M10 thread in the hole, but there just isn't enough metal to do it.
Funny you should mention clamping in a vise or cordless drill, much less not mention “proper drilling speed.”

My work table measures 35" high, it’s industrial sized vise probably is 8" above that, and I installed a 8x8x4" box vertically inside the vise today. I was using my cordless drill with a 2.1/4" hole saw in it today and the drill had a fairly new battery.

I was in low gear/high torque for the hole saw setting.

Once the drill bit punched thru the pilot hole (stepping or walking up your hole by way of smaller sized drill bits can help or at least save your drill bits from getting dull some in addition to cutting oil), the hole saw dropped down the length of the drill bit. Than the teeth of the hole saw caught on the metal of the box. Them sharp teeth grabbed into the metal box hard. Really hard in a low gear especially with the clutch setting on drill bit setting. Hard enough that the drill whipped itself out of my hands.

I was also drilling into the box a wee bit higher than normal. Normally I will have mounted the box in the vise and drilled into it’s side, but this was “a quick project.” Or in other words, instead of doing a drill press, corded - two hand hold drill or even something so simple as mounting the box so I was drilling into it sideways, I drilled into it from the top.

Drill whipped itself out of my hands and it’s battery smacked me right between the eyes in the fore head. “It’s blood Monday” was my quote of the day in reference to Ash Wednesday. Same spot especially in consideration of the dot of blood on my forehead.

Spent the rest of the day and even now in a sort of drunk, sort of hung over and definite headache like condition, and have some nice cuts and a decent bruise on my forehead. That was all fun for a while as long as I did not climb ladders, but darned me for an idiot, this past topic did come to mind for me. Were it not for a show leaving today and gear I was constructing for it, it will have been a good excuse to make a three day weekend of the injury. Instead, it was just a pain in the .. Not rear, forehead - but a defiant buzz from it. Not that I want to repeat such a injury.
Ouch! I hope your skull is as solid as mine. Concussion is a serious injury. I wonder if you ought to seek medical advice.

Perhaps drill manufacturers ought to start recommending full-body kevlar suits and motorcycle-style full face crash helmets as standard safety gear, rather than just a cheap pair of plastic goggles...
Now I can just see ship sitting there knitting himself a kevlar beanie, or dimwatt knitting himself some kevlar socks :lol:

So - what colour takes your fancy??

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