Video by Phil Tuck HVtesla
and a cartoon by Forlath (thedwm.com) referring to my hat for the day.
Video of my small coils
Flashing Light Prize 2017 second entry
So I had a better idea… and as far as I know there is no restrictions on entering twice.
This time, I needed some thing more impressive. I’d been tinkering with a demonstration of lighting a bulb with a single connection for a while, so I tied it in with that. Unfortunately the only (working) tesla coil that I have that has enough power (actually RMS current at the topload) is the Aetheriser. So that is the coil I had to use.
A quick test with a long filament lamp proved the idea workable, but the free connection got a bit warm (e.g. too hot to touch) so I added a brass ball protection to the free end
The large ball on the other end gives stability and stops the lamp from falling over.
The stills from the video.
and the last one of the failed cap end..
Details for the entry for the 2017 flashing light prize.
The Flashing Light Prize is an informal & fun contest to find the most unusual way of flashing an incandescent light bulb.
So, being me, it had to include high voltage, and It had to use what I had lying around as I’ve been quite short of time recently.
My Wimshurst came to mind, but I wasn’t sure the two laden jars would hold enough energy to light a lamp. A quick test proved that as long as I was using small lamps, there was plenty of power available.
My initial tests failed, as the leads from the bulb made a point source that leaked charge away from the Wimshurst, so it never charged up to enough voltage. This was an easy fix, I attached a 1/2″ brass ball onto the bulb leads, with a 12mm Gap I go a flash rate of ~1Hz and ~40,000V, plenty for a 6v bulb 🙂
I had a few 6V 30ma Grain of wheat bulbs and these flashed really well from the sparks from the Wimshurst. The problem was after about 4 flashes that only just lit the bulb the filament would explode and leave a small arc lamp behind.
My thought was that the thermal shock from having 40,000V dumped into the filaments (rather than 6v) was probably something to do with the failure. I started to look around for a large HV inductance that would limit the inrush.
An Ignition coil secondary was put in series with the bulb and then I had a second thought, use it as a transformer to power the bulb at lower voltages.
So two bulbs were connected across the Ignition coil primary and the secondary was put via a spark gap across the Wimshurst terminals. This flashed really reliably. Power and speed could be varied with the spark gap, although at full separation the bulbs looked excessively bright so the rate was kept quite small.
2017 flashing light entry video
Incredibly, I won with this entry … So Chuffed !
Can’t wait until September to defend the title …
First I do not condone house breaking, unless you own or are permitted to enter the property anyway. But there are instances where house breaking becomes a necessity.
We were working in the garden, our next door neighbour wanted to start strimming. Our Rescue Rottie/Great Dane has issues with hissy whirly noises, so we shut him inside, whilst we continued in the garden.
The strimming started and he jumped up at the door, unfortunately he also turned the key in the lock, locking the door, from the inside with the keys still in the lock, although we had keys they wouldn’t work. Our front door, also had keys still in the lock. Our dog had locked us out of the house 🙁
All other Windows and means of entry were fully secured. Not versed in house breaking, I know a couple of local lock smiths Ill see if they could help. A few phone calls later proved that they were all on holiday 🙁
OK so you hear of people breaking in when keys are in the lock, how hard could it be… Well first obstacle, we had a “high security letter box” that took me less than 10 seconds to remove with a pair of pliers from the outside, I’m glad I spent the extra on that!
The letter hole that was left just allowed me to put my hand into the door, nothing else. Even borrowing a small local kid didn’t help, the hole was too small. Being locked out also gave me a few other issues, all my tools were inside, but finding garden wire etc I tried to make a hook to remove the key.
No, the key needed to turn and be upright to be removed.
I then realised that I was left with assess to the most versatile tool a laser cutter.
I made a key spanner, actually I made two as I dropped the first one through the letter box, the second one had a piece of string attached, just in case. After a little fiddling I managed to turn the key and unlock the door from the inside.
So why have I posted how to break into a house.
Because I couldn’t believe how easy it was. OK, I had a laser cutter, but making a tool like the one above could be done in a couple of minutes with a fret saw, and I’m sure they (or something better) would exist available on the internet. So the take away message is if you want to secure your house
DON’T LEAVE ANY KEYS, ANYWHERE NEAR THE DOOR
The other thing is, I live on a street with a door that opens onto the pavement, I was trying to break into my house for over 30 minutes.
NOT A SINGLE PERSON THAT PASSED QUESTIONED WHAT I WAS DOING 🙂
It occurred to me that this piece of equipment is over 100 years old and over that time it has regularly been used to demonstrate the futility of perpetual motion.
So it has been running, although intermittently, quite consistently for over 150 years, powered purely by presenters and demonstrators demonstrating that it doesn’t continue to run.
It’s therefore powered purely by the fact that it is a perpetual motion machine, and no doubt will continue to do so for hundreds more years.
Continued from Tales of a cheap Chinese Laser Cutter – Bed replacement
The cutter runs fine, but cutting anything away from top left was getting more and more of an issue. One of the biggest problems was the lack of air flow at the other corner (bottom right). This was visible as smoke not being extracted. The smoke from cutting at this end also reduces the available laser light by bing in the unfocussed laser beam meaning that you get incomplete cuts. The other issue is the smoke condenses on the optics, making the cutting worse.
Although adding an air assist would help (I may still do this) the cutting it doesn’t solve the other problems.
The real issue here is the asthmatic extraction fan in the unit. The fan wasn’t designed for laser extraction use, it is a repurposed and not very good, bathroom air ventilation fan.
Luckily, I was at an amateur radio sale and found a 6″ mains cooling fan for £1, for that money its got to be worth a go.
i needed to make an enclosure that would take the fan, fit it to the cutter and to the existing 100mm pipe. Looking at the existing fan I decided to just add in the new one to the large flange and make a new plate to fit to the laser.
Taking off the old fan and the inner plate it looked an easy task, just replace this plate with a new one with the new fan.
So I cut and measured the laser, the fan and the old extractor, found a peice if 6mm acrylic and drilled mounting holes, all I needed to do was to cut two 140mm holes in the two peices of acrylic. Easy I have a Laser cutter…. So I reassembled the laser cutter and cut the circular holes in the mounting peices and then re-disassembled it.
I then mounted the fan on to the old fan.
and a plate to fit the slot on the back of the laser cutter
Slotted it in to place
A quick clean of all of the optics and tried some test peices.
A huge improvement – no smoke to be seen at all.
One of the most popular Gaussfest that I’ve run. Loads of exhibitors and even more HV kit and packed with visitors. A great day, thanks to everyone that attended.
Phillip’s toploads and ring flipper
Tony (Leicester Hack space) Wimshurst and jacob’s ladder
Coil brought to test and get running
General Gaussfest photos.
Video from Chris
Continued from Tales of a cheap Chinese laser cutter – Lasering!
After cutting a large piece I noticed some inconsistency with the quality of the cut from one side of the bed to the other. I’d always intended to replace the silly clamp type bed anyway. Plus It did make me wonder why the cutting sweet spot was 6-8mm above the bed,
so I thought it would be a good time to investigate.
The bed plate obviously wasn’t as flat as I’d would have liked. I suspect this damage was caused by the extractor fan being stowed in/on the bed during transit from China, with no packaging what so ever. Every bump on the journey would have had its toll on the bed.
Luckily the bead is easy to remove with 5 screws. Which sit on 5 standoffs from the bottom of the cutter.
I marked the relative position of all of the holes and set about making a frame.
The frame is constructed from 20mmx15mm Aluminum angle (all I could find at a local DIY store. )
I cut these to length leaving a 10mm overlap from the mounting holes. The corners are reinforced by 4 angle brackets.
A sheet of steel hex mesh (5mm hex, 400x300mm) was cut to fit into the frame. As I didn’t want anything sticking up above the height of the aluminum frame, I sanded (rough) and cleaned the inside of the angle and epoxied the mesh to the inside edge.
The two batteries ensure the mesh sits flat whilst the glue cures.
I laser cut some spacers so I can (with a bit of hassle) increase the height of the bed
Replacement bed fitted.
External Links that I have found useful.
My experiences Tales of a Cheap Chinese Laser cutter – Pre-Checks
Continued from Tales of a cheap Chinese laser cutter – Software
With the laser cutter now talking to my laptop. Time for some actual cutting.
Safety first, now is the time to don your goggles. Luckily, the light from CO2 lasers is absorbed by acrylic (If not it would be useless for cutting acrylic). So a good safety precaution is to use some good acrylic safety specs or goggles. IT WONT PROTECT YOU FROM A DIRECT STRIKE, but for unfocused reflections it will give a good level of protection.
Remember that this laser cutter has no safety lockouts, at all!
If you open the lid whilst the laser is on, you have the equivalent of a small, silent invisible chainsaw, with the safety guards removed.
Power OFF, Lid Open.
Lid Closed, Power On.
One of the reasons I opted for the modifications is mine comes with a physical laser On/OFF switch added, some don’t even have this basic protection.
Under the XY bed of the cutter is the clamp for holding your work to be cut. It has a number of failings. It will only allow a sheet of material 90mm x 200mm, which for an A4 capable laser cutter is a bit mad. Also if you cut anything into pieces with small bits of waste, the spring is strong enough to bend the remaining acrylic so nothing is in the same place anymore, although the cutter keeps cutting. The clamp isn’t at the correct height for the focus of the laser. This took me a time to realise, the cuts I were doing were over 0.5mm wide and it made chocolate bar shaped pieces of acrylic when cutting, it was way out of focus.
This showed that the focus was actually 8-10mm above this clamp.
So adding in a bed of 6mm scrap acrylic on top of the clamp has sorted this for now. But I need to sort out a metal grill bed to replace the ridiculous clamp (apparently these cutters are used in China for making stamps, the clamp holds a stamp at the correct height for engraving the rubber on top of the stamp)
Woohooo, it cuts and is usable….
Those issues fixed temporally I can now actually use the machine as a laser cutter.
Another superb design decision by the makers
Put a hole just under the top left corner (where all cuts start from) for cleaning out the bits that fall out of your cutting. But of course, if the laser goes through the target piece, it cuts a large hole in your table top. Putting this hole anywhere else on the bottom of the laser would have been such a better idea.
Another extra from the standard cutter was the addition of a set of roller wheels rather than feet. I have absolutely no idea why this is a good thing, all it means is the laser slowly moves across the desk when cutting. This does have one good side, which is it will help to even out the burn marks on the table over time.
Ventilation, so, I’m in an outside shed, there is loads of draft, I had the extractor pipe just pointed out into the roof space thinking that this would be enough. After a couple of minutes it definitely wasn’t enough, this pipe needs to go outside. Luckily I have an acrylic window, not a problem 10 mins with a tank cutter.
Ok, so that didn’t go entirely to plan…
But the extractor pipe now fits perfectly, can’t see the join…
Add replacing a window to my list of jobs this laser cutter has created.
Other useful K40 info sites and blogs Tales of a cheap Chinese laser cutter – External info Links