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If I'm clicking on publish, its coming "Please add at least one image to your introduction." This means what?

I made my first instructable. Then I clicked on publish button. After that it's coming as I mentioned above. Someone please help me with this.

Question by K Gowtham    |  last reply

Where can i get a cheap lenticular print? I only want one and everywhere seems to have a min order of 500!?

I have a budget of £20/$30 ish.Is it possible to make a lenticular poster ?I want this photograph to change from 'perfect' to 'ugly' depending on the angle it is looked at.Thankyou to you lovely people

Question by dalbyman    |  last reply

What kind of switch to operate and bypass motion sensor security light?

I would like to be able to manually operate the light for when I need it to stay on continuously, and then have it operate on the motion sensor when I am away from it. Basically I have a motion sensor light mounted above the entrance to my shed/ workshop, and sometimes I need to set up my sawhorses outside of the shop to do work at night and the light is sufficient, but when I have been still too long, perhaps doing some figuring or whatever, it goes out. I don't want to have to continue to wave my hands about to get it to come on every time it goes off. Do I need a double pole single throw switch, or a single pole double throw, or what(is a three way light switch a SPDT- [single pole double throw] switch)? Is there a way to wire it to a single switch where I could flip it over to one side to operate continuously, and then flip the switch to make the light work off of the motion sensor when I have gone in for the night? Please forgive the ignorance. I just can't envision it in my head. Thanks.

Question by stevecinstrfme    |  last reply

Landscape LED lights

I just bought 4 LED light 15 v / 11.2 w and I need to buy a transformer ,the question is what type a transformer and where can I buy it (online)

Topic by tucargen77    |  last reply


The Electronic Goldmine  has a rare to find component. "Tiny audio optocoupler is about the size of a pencil eraser and has 4 leads. These are used extensively in audio compressors, audio level controls, audio limiters, expanders/noise gates, guitar tremolo effects, guitar amplifiers and music effect boxes. Inside the black epoxy case is a 2 lead photocell (not a photodiode or photo-transistor) and a 2 lead LED. This is why the device finds extensive use in audio applications (photocell instead of photodiode). The LED requires about 10-16mA current and the resistance of the photocell varies from 150K up to megohms when the LED is off to under 400ohms when the LED is on." A

Topic by iceng    |  last reply

Looking to make a Dance Dance Revolution pad but for fingers, any suggestions on the materials?

Hi, as the title says I'm trying to build a finger pad for a custom DDR game I'm doing for a school project. I've already made the game software and connected it through serial to the Arduino Mega 2560. At the moment I'm using a 4x4 matrix keypad for testing purposes, but I'm looking forward to a more presentable, pretty and functional way to do it. I've thought about pressure sensors, but I think someone more specialized could give me some advices on how to do it and what materials to use. Any suggestions? fedloan

Topic by SonilGomes    |  last reply

transistor substitute?

Can i use bd 139 instead of bc 547

Question by jumper1111    |  last reply

I accidentally invented a device to collimate any light source into a concentrated beam... what should I do with it?

I've been umming and ahhing about what to do with this for the couple of weeks since I accidentally invented the thing (I was working on a solar energy device), and I thought you guys may be your usual well-spring of help and advice. Basically I seem to have designed a device which will collimate an extended light source. Any light source. So you could, for example, turn a 100 Watt light bulb into a 100 Watt laser. Or a square meter of sunlight into a kiloWatt. I haven't made it, but simming on the computer gives an optimal blow out rate of about 1/2 meters per kilometer, so over a range of meters or tens of meters it's pretty much as accurate as a normal laser. The only upper limit I can see on how much power you could put through this thing is when the materials start melting, which would probably be pretty high. There's really nothing fancy about it, it's just a shape. You could print it out easily on a 3d printer and fill it with some kind of settable glass for the total-internal-reflection. It would weigh about as much as a 2 litre bottle of water and be about the same size. I was concerned about it being weaponisable, but even at a kiloWatt the lethal range would probably be less than 100 meters, in which case you might as well just get a gun. I don't know if anyone's already done something like this, I can't find anything online, and people kept telling me it was supposed to be impossible. So, um, yeah...

Topic by SolarFlower_org    |  last reply

Self springing wheeled legs

I am trying to build myself a sliding truck bed drawer. There are lots of video or instruction on how to do it..However I am thinking to build it with the intent to use it as a slideout deck, so it easily could be loaded with a good amount of weight... Therefore I am thinking if anyone knows how to add a self-spring leg in the front /middle of the bed? I am talking about something like folding table legs / Gurney's legs (but with wheels.. likely wheels (ex. gate wheel) with self-adjusting spring wheel for height differences). It should spring open and lock in place as bed is extended out of the truck bed. And as the bed goes back in, it should able to hit the legs and allow it to fold back up.What you guys think?

Question by dgupta3    |  last reply

Laser Engraver

I bought a laser engraver from Amazon and it is a Luyeen brand. It's straight from China and honestly, it's a POS. When I put it together, which took 24 hours, I couldn't get the laser to work. I looked on line and I found a forum that had someone that bought the same thing as I did. The wires that were on the connector were backwards. I took the cable to a PC Repair place and they fixed it. Now, the laser has not worked and I contacted the manufacturer and they ASKED ME to have it repaired and they will also give me $100 to compensate me for my time. ARE YOU FREAKIN KIDDING ME? NO!I am returning the whole thing to Amazon for a complete refund. So, here's the question, Folks! Where can I find an AMERICAN made laser engraver that isn't going to empty my wallet and I can afford. I am tired of Chinese places advertising GOOD products and when they arrive, they don't work, they are not as advertised and the directions are worthless. I REALLY would like to get an engraver but I will NOT be buying off of Amazon that deals with foreign manufacturers that sell substandard equipment. Can someone give me some place where I can look?Thanks, David

Question by irishwarrior1958    |  last reply

Problem using LEDs with Arduino Nano

Hi,I am trying to set up some LEDs that light up in a cascading fashion when triggered by a Hall Effect sensor. They are connected to Nano's pins D2 - D12 and A1 - A5 (17 in all). It all works fine when I have a 3.7v battery via a boost to Vin (7.5v) AND a USB cable plugged in. In the non active state the voltage on the LEDs is 1.7v so they are off and get turned on one at a time with a cascade effect, it works fine. However, if I remove the USB cable and only use the battery (Vin is still 7.5v) the non active voltage on the LEDs is now 2.6v so they are lit all the time and the cascade effect is seen as a slight increase in brightness.If I switch off the battery and leave the USB connected it doesn't work at all. Any ideas as to why this only works with both voltage sources connected?

Question by pdp12    |  last reply

Chimes for electronic clock

I had a couple of quartz time switches that had stopped working and a very cheap inaccurate clock in my workshop. I also had a double faced outdoor clock that only worked when it felt like it! My solution to this was to make a driver circuit where the mains frequency was reduced to 0.5Hz to run the stepper motors. The output is from an H-bridge that can deliver up to 800mA so in theory I could have a lot of slave clocks. A switch gives a choice of three outputs, stopped (to put all clocks back), fast forward (to run clocks ten times normal speed) and normal operation. All in all a thoroughly satisfactory operating system.I have now had the crazy notion of creating chimes for the outside clock. I want to have a chime every quarter hour and to strike the hours as well. I do not want an electronically reproduced replica of bells played on a loudspeaker. I have made tubular bells from water pipe and just need to fine tune them. I also have a prototype striker system that operates via small solenoids. I can use my 0.5Hz clock signal and reduce it further to get a trigger every fifteen minutes. I also want to silence the chimes from 11pm to 7am so will have to include timing for this.My dilemma is that I don’t know the best way to get the results I want. I have ideas for electromechanical systems and electronic circuitry to do this. I was wondering about decade counters cascaded and connected via diodes to the relevant solenoids through transistors. The sequence would be interrupted by an output feeding the clock inhibit where necessary and the next quarter hour signal would ground that to restart the chiming. Obviously this will end up with a lot of circuitry and be a bit of a nightmare to assemble - definitely not for the faint hearted! There must be an easier way that my limited knowledge is overlooking but I guess that the answer is not that simple or there would be quartz clocks readily available that did this, albeit with a loudspeaker rather than mechanical chimes.If anyone out there has had the patience to read all this and has any ideas that might help me out then I would gladly be open to suggestions. Thank you, have a great day and keep safe in these challenging times.

Question by NigelL12    |  last reply

ABB robotic Arm Project

HiI have two ABB industrial robotic arms, The CPU/Control units are very old & outdated. The supplier says the programming language has changed and I should throw it away, which I don't want to do.I am hoping that I can use Arduino to get the arms working and I am hoping someone might be interested in getting involved. My knowledge is very limited but I am willing to learn and put some money into the projectKind regardsFerdi

Topic by Ferdi66    |  last reply

Direct-Line Phone over WiFi using Raspberry Pi

Hello, I am new here and new to making in general. I was wondering if anyone has heard of creating a Direct-Line Phone over WiFi using Raspberry Pi? I'm trying to do it and I have two questions : 1. Can I use a WiFi calling app to whitelist contacts and send all other calls to voicemail or auto reject the calls? I know I can put Android OS on my Pi and use WhatsApp for WiFi calling. But it doesn't seem like WhatsApp will allow you to whitelist contacts so you don't get spam calls. Any suggestions on programs that do this?2. Is there a program that will let me use a switch or button to auto dial a number? I would like to set it up so that when a circuit is tripped through a switch or a button, the program autodials the number. I'm only planning on having one number in the system, so this could be an auto-redial program. I know this part is harder and I will probably have to program something myself from scratch. But any input on if this has already been done or even ideas on how to do it with existing programs and codes would be greatly appreciated! Also, suggestions on where to find a cheap reliable switch / button would be helpful. Thanks!!

Question by davecarring    |  last reply

does anyone know how to remove bubbles from the kitchen sink?

Do you know those pesky bubbles in your kitchen sink that always reside after you finish washing up the dishes? well i know them all too well and they never pop however much i poke them or blow on them or hair dryer them :( i had a look online and found a idea that you can tip ground pepper on the suds to pop them efficiently, but all it did was pop a couple of centermeters of the bubble monolith and now my sink smells like pepper :( does anyone have anyone ideas/experience as to how sove my bubbly problem?

Topic by sooie    |  last reply

Arduino / Stepper motor with rotary encoder speed controll > OLED or LED matrix display

The title summarizes it.Here are the details.I want to build an artistic installation project using:- arduino as platform- simple rotary encoder that controlls the speed of a >- > stepper motor ("NEMA17 17HS8401B" 1.7A - that has enough torque to move my project)- the speed set by the encoder (the steps / clicks made by the encoder) must be counted and displayed on something (physical, NOT, on the computer screen), like > - an OLED display (I have several 0.96" SPI - 7 pin), OR > - simply on a LED matrix (I have a few 8x8s), adding / lighting one more LED as I incerment the speed click by click >- > this because there will be 3 (or even 4) such stepper motors and their correlated speed is essential to the project- also, the core of the project is to be able to change the speed of the motors while these are turning, stop/start themThe project would look like this: I turn the 3 encoders right / left (one by one) to set the exact speed I wish for each motor. To know the exact speed I need to see it on OLED or LED matrix (if you have any other idea, I'm open for proposals), while I'm not connected to the computer. Pushing (clicking) the encoder starts the motors, that will turn continuously until I stop them manually. Meantime I need to be able to change the speed of the motors separately.The motors will turn very slow, like one rotation in 2 or 5 seconds (need to test).There might be one OLED / LED matrix for each encoder. Or the three encoders connected to only one OLED, that displays continously on three rows the speeds of the motors. Might be one single switch that starts all the motors after the speeds are set (even better this way). So, there are some open posibilities, but now I'm at the main functionality part.I also have an Arduino CNC shield V3.0 and 4 stepper drivers 8825 (I thought I might use it to controll the motors).I saw different videos that address parts of my project, like connecting a rotary encoder to an arduino, or controlling stepper motors using CNC shield, but they don't do what I want and they're not connected.I'm not an expert. I manage to (kind of) understand the arduino code and modify settings of an existing project to adapt it to my needs, maybe to connect two or more projects, but not able to write code myself.Please, show me a direction of how to put things together, and I'll try to develop / build the details myself.Thank you!

Question by DragosA  

If I mist my condenser while it help cool my house? Answered

Lets say I put a mister on my condenser outside, and when the air conditioning comes on it sprays water mist on the condenser. The idea would be: as the water evaporates on the coil it will remove more heat from the unit and it wont run so much.

Question by BluTiger    |  last reply

how can i drop 1A dc to 500ma dc? Answered

I have an AC-DC power supply with voltages of DC 3 - 4.5 - 6 - 7.5 - 9 - 12V and 1000ma and i want to drop this down to 500ma!

Question by thecookiemonster    |  last reply

There's ducks in my Backyard

So a while back, a duck found the top of a shed a good place for nesting in my backyard. Me and my step dad talked about it and we're thinking of raising the ducklings once they hatch. We're building a pond and whatever else comes to mind that duckings would need. Has anything like this happened to any of you before? I fell dumb for asking , but is this a good idea to raise ducks from the wild as pets? (I've never heard of a story in the news where a duck has harmed a person before so...) Has anyone raised a duck before? What are your thoughts on this? haha, if we really do this, I could probably post an instructable on how to raise ducks if this goes well. Here's some pictures of the duck that's on the shed.

Topic by TZ Inc    |  last reply

Replaceable lid for a tin can Answered

I would like to come up with an easy way to hold a lid on the top of a tin can that I am using as a squirrel feeder. The feed flows out of the bottom of the can, and the top of the can is protected by a removable lid. The lid must be easily removed, but when replaced, won't blow off or get knocked off by birds, squirrels, or other critters. The inside of the can cannot be obstructed because it will be full of sunflower seeds.

Question by wjramsey123    |  last reply

How can I make this book cover look old?

I'm making the Book of the Vishanti from Doctor Strange out of an old textbook, but since it was so clean and well-preserved (as well as the wrong color) I decoupaged some crumpled tissue paper to the cover and painted it with some acrylic paint. Now my problem is that the cover looks a little too much like it was painted, and is really just one flat color. Are there any techniques I can use to make it look more worn and ancient?  Note: in person, the cover looks a lot more drab and consistent in its color.

Question by Numbuh1Nerd    |  last reply

is it needed to use a resistor in a circuit consisting of a 12 volt motor and a 12volt rechargable battery .

I' making a wheel chair run by a 12 volt rechargable  battery connected to a 12volt motor and also a switch.Is a resistor needed,if needed what resistor should be used?Can I use a variable resistor

Question by pvamsi    |  last reply

12VDC to 9VAC - How to do it? Anybody?

Well, I've posted this in numerous places and no one seems to have a clue. Myself being electronically illiterate, still, with all the technology out there, you can't tell me this can't be done. I live off-grid. We all know how inefficient the inverter is. It's a huge drain on my battery bank, won't function when they get below a certain voltage, yet all my peripherals that operate directly from the battery bank, operate fine. That being said, I have been trying to come as close as possible to eliminating the inverters and I have two peripherals left: 1) cordless telephone and 2) modem The problem is that they run from that pesky wall charger/converter from 120VAC to 6.5 and 9VAC respectively. Now, notice these units run on LOW VOLTAGE AC, not DC. That is, they are powered by the AC. My guess is that inside each unit, there sits a rectifier converting it right back into DC. In fact, for the phone, I see no other way because it charges a NiCad battery.  So.... does anyone have an inkling as to an efficient way to convert 12VDCD to low voltage AC. Preferably variable, but not absolutely necessary. There is nothing on the market that I have found. So if you're looking for something to have to break into the electronics market with, here ya go. I'll bet there are hundreds of thousands 'off-gridders' who would want this technology.

Question by basementsong    |  last reply

how can i melt a hole in a glass bottle without breaking it?

I hawe a few normal drill bits and a propane/mapp gas torch.

Question    |  last reply

12V DC to 12V AC? Answered

I have a speaker with an embeded amplifier that uses 12VAC ~ 2.9A and want to connect to a 12VDC in my car, a simple bridge rectifier will do the trick converting the corrent? 

Question by Salazar2    |  last reply

How to make an exoskeleton arm?

Hello everyone, just need an answer to a question I have, I want to make an exoskeleton arm for no reason except that its cool, and i wondered if i could do it for under £50.I need a list of hydraulic or pneumatic parts that are under £50, are verified hopefully and which is better to use?I understand that pneumatic are cheaper, and I don't need to lift 2 tons or anything like that, so is it possible? Thanks

Question by he110w0r1d  

Filament slipping out of extruder

I have a prusa MK3s which i am currently trying to get back on its feet, but cannot solve this issue: the filament will slip out above the idler gear, making it so that the 3d printer can't extrude. Help!

Question by Cheesey125    |  last reply

Portable media build parts question!!

I'm looking to build a portable gaming and media station but I'm stuck on a couple things and am hoping people here might have some suggestions and/or links. Basically, I bought a large aluminum camera case, big enough to hold a 22" led tv in the lid. I am going to mount the tv in the lid, thinking of just drilling the holes and mounting the tv directly to the lid. Any critiques or problems with that would be nice.Second, I'm going to mount a ps3, a portable media player (think Von Haus) which uses flash drives or portable hard drive via US, and a retropie system. Now where I'm running into trouble is two-fold. One is how to mount the items into the case. Foam would normally work well, but I'm worried about heat reduction, less so for the media player and more for the ps3 and retropie. I'm also worried about having it hardmounted onto the case via glue gun because of any shocks it might get while in transport. I also want to dremel out in the front and the back, and put in ports to be able to connect to an outside source as needed. Basically, I need a number of connectors which mount inside with the port leading out. USB 2/3, HDMI, RCA cable connector (RWY). I can find extension cables, but what I'm more looking for is, say for USB, a male lead on one end to connect to the ps3, and a female lead on the other end which sits inside case but is dremel'ed out to be able to connect a USB from the outside, basically a plate which I can just screw in. Something similar to what you'd find inside a console or similar. Anything which anyone can help with on any of these would be greatly appreciated. Thanks.Nox ShowBox Mobdro

Topic by achanakbhayank    |  last reply

LED illumination for Sith wayfinder

Hi all,I've just finished making a reproduction of a Sith wayfinder from the latest Star Wars movie, The Rise of Skywalker. Looks great as it is, but it would be even better if I could light it up, just like in the movie! The problem is, I know almost nothing about electronics.What I'd like to do is have two LEDs - one bright white (or maybe bright green) to provide the main illumination and one red (flashing, to represent the navigational beacon) - connected to a small battery pack to be housed within the wayfinder. I was thinking of using it occasionally like a night-light or display object, and was considering using rechargeable batteries (like Eneloops).Can anyone help me out with a simple circuit?

Question by xoworane    |  last reply

Question about dumpster diving in Tennessee

Anyone know if it's legal in Tennessee? I keep calling the police but they just keep saying no instantally. Best as i can they they are assuming I'm looking to steal ID's or meth supplies (big probs with that here). I don't mind the risk of getting yelled at the the store guys but i don't want to get arrested. Also I'm not dumb enough to dig around in private dumpsters here, I'd sooner get arrested than shot to pieces LOL :P

Topic by Vizth    |  last reply

Leatherman PST

I've been looking at instructables for a long time. I have not seen ONE Leatherman PST! Anyone out there have a Leatherman PST, and use it as frequently as I do? (everyday) Its a discontinued Leatherman, without some very useful features but it still has proved itself daily to me. I also have the leather sheath, not the nylon. Discuss Leathermans, but mostly the Leatherman PST.

Topic by Tape-structable    |  last reply

Smart Phone Projector

My daughter is building the smart phone projector. She used a plastic magnifying glass I had lying around on my desk. It did not work. What magnifying glass do you recommend?Thanks,Carey

Topic by careygister    |  last reply

How can I change file name?

When I change the file name ' to', permission denied error occured. How can I solve this error. Thanks

Question by Htet Yan    |  last reply

I need a good lunch box for a Raspberry Pi alarm clock.

Hi!I'm building an alarm clock out of a Raspberry Pi, using a touchscreen and a Pi 3B.My plan for the end product is to have the screen in a hole in the lunch box, and inside have the Pi, a fan, and a small speaker. I've encountered one problem: Finding the perfect lunch box. I've found a handful of good ones, but I want to find the best one humanly possible.If you know of a cool lunch box, please send me the link!The two I've found are here and here.Thanks!

Topic by CuriousCat618    |  last reply

Epoxy and CNC reaction Answered

I have a burning question I couldn't get the answer online and finally decided to ask here.. is it possible to use a wood cnc on an already made epoxy wood or will it damage the bit? Considering on making it for a table top project.

Question by ndichut    |  last reply

How can I solve "ModuleNotFound" error in Python?

Hello everyone! Although I installed firebase "ModuleNotFoundError: No module named 'firebase' is showing as error msg; How can I fix Thanks

Question by Htet Yan    |  last reply

Controll a 230volt using ir sensor

I have an idea that I would need some help with.Have thought to control a door that opens with an ir sensor.I will need 2 pieces one outside the gate and one inside. I think I can solve that bit myself, the problem is that the motor to the gate is 230 volts. How can I control it via arudion and IR sensor

Question by berntsson88    |  last reply

Carbon bike paste and paint

Hi,my bike orbea orca aero.A piece of stone sprang to the back. The paint was removed. (a small piece)Broken, puncture etc. there is no problem. It's just a paint problem.Color: Pantone bright red C (It is not matte color but glossy.)First version was white in color. I found it from the original color of the bike and painted it inside, but the pit was not filled and roughness remained.problem picture: Turkey, no one knows anything about carbon fiber surfaces.I need help. At least which filler is used for the carbon surface, etc.1. Polyester paste 2. Fiber paste 3. Epoxy paste.It is necessary to fill and paint with these pastes. But these substances damage carbon fiber, and I don't know if these substances stick to carbon fiber.I don't know what to do, should I take it to the car body workshop. That's why I'm afraid to go to car body repairers. Maybe they can make it worse.My last resort is to put a sticker on it.Thanks.

Question by TanerJames    |  last reply

Building a makeshift speed controller

Hi all, I recently posted about issues with my treadmill. I thought I'd fixed it but it has multiple problems. I've decided rather than go down the route of costly replacement boards, to go for a chinese universal treadmill controller.My question is, could I make a makeshift speed controller using the components from the circuit boards? (it may take 4 weeks for the chinese controller to arrive, so would like to continue using the treadmill)I'm guessing I have all the components needed to change the 240v AC to 130v DC, could I then use a potentiometer to vary the speed?I've added a photo of the board, not pictured is the big transformer.Any help greatly appreciated :)

Topic by dimmaz88    |  last reply

I need a bread dough-rising box for temperature control, that I can make myself (I'm not a very handy person). Answered

My house is too cool (temp.) for optimum bread dough rising. I can't heat the whole house just to get bread to rise properly! I'm envisioning a box big enough to hold my bowl with a couple inches' margin all around; foil-lined, with maybe a light bulb on a thermostat to keep the temp. at an even 70 degrees, sort of like farmers do with baby chicks. I don't know how to set that up, can anyone help?

Question by threeoutside    |  last reply

Poison Oak Treatment?

I contracted a case of poison oak about a week ago and it's really got me itching today. I need some relief and I was wondering if the community had any ideas for home remedies and or effective treatments. I've been through the whole course of oral steroids (prednisone), and topical creams (hydrocortisone) with previous outbreaks, but they never seem to work all that well. I'm open to any and all of your suggestions, so let's hear them. Look at the pictures. Feel my itch. Answer my question, and help me return my skin back to its normal, smooth state.

Question by noahw    |  last reply

Anyone Interested In Creating A Video Game?

Hello there, I am currently creating a video game with a really good game engine and I need as much support as I can get! I need a story, characters, settings and someone who is willing to learn how to program and code in the basic level. I'm really just looking for people who are passionate about video games and who want to create one. I will later on open up my own video game company here in London (Yes I have the money for that). I also have publishers who will help in making our game get attention. But of course all this happens after the game is created. Any ideas? Anyone that lives in London? Or anyone who wants to join me online to create an amazing game? Thanks! Send me an email to

Question by Exterm    |  last reply

Neopixels not responding to remote

Hi all, for a project im working on i have 20m of neopixels , divided in 4 limbs, run through an Arduino Due. Next to the Due I have a Uno which is responsible for the remote. At first I had 3 of the 5m neopixel limbs working but this was insufficient of course, so I placed a level shifter between the power, NP and Due. Afterwards I changed the code so it would run the 4 limbs, yet now i have nothing at all.Anybody who could give me some insight here?Attached you can find my code and fritzing file.

Topic by driever    |  last reply

How to fix this python program? Please any advice!

I'm testing 'Arduino and Raspberry Pi Powered Pet Monitoring System'. Now I'm facing error on step 15. Ican't run python program. The error message is attached below. Someone please advice me! Because it's important for me. Thanks

Question by Htet Yan    |  last reply

Work boot making classes?

I'm interested in making boots and shoes, so if anyone can make that happen it would be fantastic!Dịch vụ bảng giá giúp việc theo giờ 2020 uy tín giúp việc theo giờ tại quận 9 giá rẻ Dịch vụ chăm sóc sản phụ sau khi sinh chuyên nghiệp

Question by thelearnlaxi  

Help for ESP-NOW project

I am trying to make a remote control system, for control 12 Relays using ESP-Now, 12 push buttons on master module and 12 Relays on slave module anyone can help me for this project

Question by nirosh1288  

​Questions are a special typ

Questions are a special type of forum topic that allow the community to vote on best answer

Question by thanhle12345  

Assassin's creed Odyssey facts - Can you make Mercenaries your buddies?

I have recently seen a video with someone trying to defeat the Calydonian Boar. He led three Mercenaries to the site, which ended up fighting the rest of the hogs and the legendary animal itself. I wonder if Mercenaries can still fight these entities after selecting the "Pay all Bounties" function while still on the site. It would seem as if you were old friends! 😀🤗😎So, could this happen? 🤔🤨

Question by Prismarine soldier 123456  

Ancient technologies revisited - drilling and machining

In the ruins of our ancient world we often see exceptional accuracy for surfaces but also clear indications of machining work that should have been impossible back then,For quite a few of these impossibilities modern scientists, inventors and people that just like to experiment came up with plausible conclusions.So let's start with a few of them...Core drilling...It is a process were a rather large hole is not actually drilled but cut out.Imagine a piece of pipe you press into some clay - that's what you end up with.A circular, deep hole with a standing core inside, break the core off and you are good to go.Doing this with copper or brass tools as the only available metal tools seems feasable.If it is something soft like sand stone but for things like granite???Ancient texts provided some clues, like that slow spinning tubes were used or that drilling a 2m deep hole did only take a few hours.Appearently it was done in less than half a day - a day being daylight.Modern diamond drilling tools would still struggle to create such a deep hole in that time unless you pay a fortune for a custom made drill bit.One clue that was nagging these people for a long times was how it was possible to reach these high penetration speeds.The marks on core samplesand holes clearly show and almost spiral pattern, indicating the "drill" went deeper by a few mm with just a few rotations of the drill.The calculated pressure required to do this is about equal to having a tank parked on top of your drill....Impossible I know...Hammer drill differences give us another clue here.Take you homedepot drill that can drill in metal and stone - it runs fast and although it does the job the tradesmen tool does it better.Not because it is way more expensive but because it is purpose made by running slower but with a much more powerfull impact for the drill bit.How do you create a massive impact with copper or brass?Those who tried a copper drill will tell you they are no good for anything.Those who tried a copper core drill will tell you the same.Too soft, deforms too quickly, no "teeth" that last for more than a few seconds.But is that really true???These soft metals seem to have a feature that makes them special: They can be "work hardened".Like the top end of your cold chisel "peeling"...Of course the harness levels you can achieve are still very short of being even like soft steel.Every material has a resonant frequency, even hard rock like granite.A technique called sonic drilling utilises this as an advantage.The drill is subjected to an audio signal that is very close or matching a harmonic frequency of the rock in question.There is even nice Youtube videos showing how two stones are flattened against each other just with loudspeakers and some wire to hold them together.The same guy posted videos showing that core drilling is possible this way too.The science behind it is still not a 100% understood though.Several universities did their own experiments here and here are some of the more modern explanations why it works despite being impossible:The vibrations cause surface fractures on contact, a bit like when your dentist cleans your teeth with this screaming thing...The contact surface of the drill actually does not do any impact damage, it simply acts as a transducer horn for the vibrations.In their tests it was even confirmed that steel tools are no good here as the material would mean you need very long tools due to the resonant nodes forming differently in denser material.Most interesting was that these aido drills can be literally of any shape you like.Not hard to create a fancy symbol shape from copper pipe - and then to vibrate it into the surface to create writing....Several ancient cultures show clear tooling marks in their carved symbol creations while others seemed to have "melted" the symbol into the rock - audio only ;)Extreme accuracy for planar faces....Be it the walls of an ancient "coffin", box or chamber, we can find a lot of them with an accuracy that even today we would fail to achieve.A solid granit like block with a perfectly square box cut out of it.Several examples exist where the accuracy couldn't be done with modern tools at all.Less than 0.5% divergence from true parallel walls and corners with a rounded inner edge with a radius of less than 2mm....Audio machining is not feasable for this one.And with literally no surface marks scientists were baffled for decades.Due to the size it would mean that for a tiny error you would have to re-do the entire surface of the affected wall.And with a surface so highly polished that even after a few tausand years it still reflects light....Samples taken showed another conundrum - glacing...Almost as if the stone was melted, pressed flat and then repeated until the entire surface was done.The temperautres required for this however are said to be impossible in ancient times, same for any tools capable of tolerating such heat without melting.So this theory was discarded for a very long time and deemed to be interpretation error - after all they had no chance to do this thausands of years ago.Later it was discovered that you actually can use two identically hard stone surfaces to grind them perfectly flat against each other.And well, using the right, mild abbresives it is even possible to give the surface a nice shine.Yes, the theory is sound but can't explain how one would machine the corners like this....The inside of a square or rectangular box can't be produced like this.Plus the problem of actually removing all the unwanted material first.In recent years the old samples taken were subject to new studies, this time in regards to the possibility that the surface was polished using heat.Surprisingly a mix of high temps and cold water allows for quite accurated destruction of the surface.Relatively easy to remove some bumps by just heating the bump and spraying a mist of cold water over it.Still not possible to create perfect corners but a start.It failed to reproduce the shine and polished surface too.Then, as a last resort you might say, lasers were used on rocks of similar or identical composition.The classic CO2 laser is a brute force tool and although accuracy would be possible you wouldn't get a good surface as it does not melt, it just cracks like glass.Femto second lasers were great here but could not provide any glacing effect either.Problem was always that the stone could not soak up any of the laser energy.It would not heat up evenly, only very locally where the laser was hitting the surface and no depth either.Then they finally got the idea to use tiny samples in a wide laser beam.A wavelength more suited to heat rather than vaporise and energy levels per mm² much, much lower than in a focussed beam.No problem to actually fully melt the sample without create any cracks or to adjust the parameters so the core still remains solid for a true glazing effect.Funny side effect of fully molten samples were their extreme surface hardness - very similar to what we find in ancient leftovers we can't explain.On bigger samples two effects were observed.Firstly that of a flat surface with the sample being rather thick, a too fast cooling down would result in the entire surface that was heated to split off.Secondly that the resulting surface was still extremely flat and even.Sadly we can not find any real evidence that ancient cultures knew about how to use high energy lasers with adjustable focus....And so far no one was able to come up with any theory that explains ALL the features of a perfect stone box with polished surfaced, especially if the surfaced is glaced.The ancient lathe....We can see the evidence of large boulders machined on some gigantic lathe through the ancient world, especially in greece and the middle east.And so far the best archeologists could come up with was that some guy sat there for days hammering the surface until a template provided a perfect fit.What they failed to explain was how this guy did this in a true rotary fashion.But the beauty of archeology is that these guys can claim what they like without being required to provide backing of their claims - not their territory OLIn several places we found leftovers of contraptions deemed to be the remains of some grinding mechanism to make flour or maby fine powder from rocks for mortar.But every mill needs a mlling stone - they were never found anywhere.And if the "mount" that remains clearly indicates it was able to be moved in the X and Y direction it would have been a very strange flour mill indeed.In the real world you would only have to move the grinding stone up and even that is mostly optional.The real clue however is how complicated it would have been to collect the flour.No one wants to use a broom to get it off the floor in a desert environment....With the wearmarks on the bottom stone it would have been impossible to produce flour, so why would it have been used for decades more if the flour was no good anyway?Again, outsiders provided vital clues by creating small models of these ancient "flour mills".The ground around them shows wear marks identical to someone running in a circle since the dawn of time.At quite a distance to the center I might add.If horses or cows were used to go in said circle with a harness you could spin quite some weight - like a round piller stone.And the bottom "pan" could be filled with fine sand or similar to act as a rudimentary bearing.The rounded bottom and indentation on the top of ancient piller stones seems suddenly more plausible to be the result of these "flour mills" - they self centered the block for machining.Push your tool(s) against the surface and make sure they keep the tension, then sit back and watch the animals do the hard work for you.Nothing fancy about it, just a vertical lathe driven by animals instead of a big motor and gear box...Won't explain though how some cultures were able to create perfectly round pillars of 20 or more meters in length in one piece....In many places we can observe impossible fitments, like a lid on a stone box that won't even require a sealant to be perfectly air tight.Or in India and other parts of the east intricate stone figurines that are hollowed out - with carved details on the inside.So not just some holes and simple cavities, more like 3D printed.Several experts of their fields, from artists over stone masons to jewlery makers tried to re-create some of these features using modern tools - they all failed badly.You simply can't use a rotating tool if you need to get around several corners to reach the surface to be machined.So how were the ancient builders and artists able to do the impossible?Some say that ancient texts and images tell us that the stone was melted away, like bee's wax.The glacing effect on these surfaces seems to confirm this but we all know you can't melt rock, especially not in a controlled way to create artwork.Rock is not ice - or is it?High frequency ultrasonic machining allows us to work with very hard rock, like cutting through butter with a hot knife.No sharp tools required either.The only problem is that you need very hard tools with a high tensile strenght and "good acoustics" - like titanium as the prefered option in the industry for ultrasonic horns and amplifiers.They did not have titanium in the ancient world and they certainly did not have power outlet to drive some ultrasonic tools.But they did know their acoustics as the "musical temple" in India shows.Hit a pillar, some plate or even statue and they all produce a very accurate frequency, despite the entire temple being carved out of one solid mountain piece...You can not create this today even if you had a clue how to carve it out of the mountain!!No way to create delicated designs that all have individual but extreme accurate musical notes when hit...Means the ancient builder must have known about the way sound travels through solid materials and how it is reflected inside them - otherwise hitting a statue would also make other things in the temple swing....Imagine that it was known how to produce the required frequencies to basically weaken the crystal structure of a rock exactly where you want it to weaken.You would have a rock-shaver of sorts.You could not use it though as it would be a huge thing.Theory is the ancient builder worked the opposite way instead.Making the entire rock or even mountain swing at a perfectly matched resonant frequency that produces a peak right where you need to work.A bit like going a dentist that no longer uses a rotating and screaming drill on your bad tooth, instead you sit in a fast rotating chair ;)Lab experiments clearly showed it is possible on a small scale with our modern technology.Tungsten-Carbide already in the ancient world?Electron microscopy claims to have found evidence of substances embedded in the machined surface that have similar properties to our modern carbides.Of course every alien theorists jumped right on it and claimed that had help from extra terrestrials.But is it really as simple as someone coming down from the stars to give some ancient builder a more than modern tool?He wouldn't have a clue how to use it, how to power it, he would need a teacher and power source.What some of these alien nut crackers missed is the simple fact that a lot of really hard materials can be created by the most basic means.Thermite is still widely used and produces quite good steel, all you need is iron oxide and aluminium powder.With sand you can even make your own silicium metal is you like on the beach....Where the knowelde for such things and more originated might remain a mystery but we have evidence the ancient guys knew quite a bit about ores and oxides, so why is it so hard to think they accidentially or intentionally tried to melt them into tools or art pieces?And then suddenly something goes up up in flames and some shiny and really metal appears when cooled down....We also know the ancient people knew about several acids and how to make them from scratch, even how to concentrate them.Not soo hard anymore to create some waste products that are of no other use to you than to be used as grinding materials and abbresives....As said, it is unclear where the knowledge or idea come from, all we know they had the know how.Where did the ancient tools go?We can still find tools in the pyramids in tiny and no longer accessible areas - at least no human fits in there anymore.We also found clear indications of iron oxides embedded in stone surfaces, predominantly in holes and such.So they might have had iron or even steel around the same time we though they only had copper and brass, big deal...Well, it kinda is...Especially Japan showed us how metallurgy is carried on as a vital tradion into todays times.From selecting the raw material for the melting, over the entire melting process, down to discarding most of the results by just looking at them - an understanding we modern people no longer have.And the swordsmith again only takes those sample where he can see already how they work together when he heats them up and hammers them.Especially the secret knowledge how to iclude impurities, remove them and what natural and most basic additions need to be added is something even modern science fails at.A bit of leafs from this plant, some dirt from that region, some burnt wood and suddenly the resulting steel won't rust anymore, is more ductile and hard at the same time...But you would need this kind of attention when you create tools.For steel you want a certain hardness, flexibility or ability to flex without breaking quickly to avoid fatigue.In most cases these steels are anything except resistant to corrosion.Most tool steels of the older days needed to be kept well oiled or they would rust away quickly.Chrome and other hard to come by elements gave our modern steel the stainless effect.From the ancinet world we know of iron statues and pillars that produce a protective rust layer of just a few microns but no further rust damage.You wouldn't be able to create this without generations of experts refining the process and observing how well or badly it works out.Would you take your expensive tools that might taken weeks to manufacture at a job site with thausands of slaves? Certainly not, you taken them home with them and slep with them under your pillow....No surprise then that we could never find any "good" tools around ancient ruins.Once a town is build today you won't find the tools of the tradies still sitting around either...Is this evidence?Nope, the failure to find high quality tools from builders does not mean they existed.Finding evidence of modern alloys or steels just in abbrasesion or tool marks is no good either.It could be from someone at a later time simply following these marks with a more modern metal tools, like a steel needle.For every evidence here there is also evidence of where the evidence can't come from.Again science clashes with archeology and history without being able to agree or compromise to provide a conclusion that is acceptable by both sides.Only materials designed and created to last throughout history will survive thausands of years of exposure to the elements.We might find real and undeniable evidence one day in lost cities on the ocean's floors, till then though....

Topic by Downunder35m