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Posted 10 months ago
Chaotic pendulum Ok this is a little maths based toy I made a good 7 or 8 years ago. I’d been reading some pop science book on maths, and it was mentioned in passing that a pendulum, with a metal weight and 3 magnets will behave chaotically (as in chaos maths). I was intrigued, and thought I would give it a go. The effect is pretty good - I’ll post a video as soon as I can work out how to shrink the video file size. basically the ball bearing swings in a very strange, unnatural and captivating manner. There are three magnets on the base, which make it move strangely. It works even better if you cover the ball bearing in glitter - sparkly! But I didn’t want to cover myself with glitter again, so have missed that out this time. The theory behind it is fairly complex, or at least the maths bit is. if you want to know more, wikipedia is your friend. Basically a small change in input leads to a large change in output. What that means in practice is that it should be impossible to predict how the pendulum will move, as you change the start position/velocity. Also, it’s quite hypnotic. To make your own you will need - some wood or similar material for the base (you need to be able to saw it and shape it), a bit of magnetic material to stick the magnets on - a biscuit tin lid will do, but I used the disc from inside a hard drive - magnets stick to it, it’s the right shape and it’s very very shiny. a ball bearing (large or small is good) 3 magnets (I got mine from maplin, about £1 a piece) some string or wire a metal rod - roughly 25cm long (depends on how big you want to make the pendulum). I bought a metal pot stand from the pound shop, and cut it up to get a piece the right size. 2 small washers superglue epoxy resin first, shape the base. Mine is about 25cm long, maybe 15cm wide. The rod will need to be centred along the long axis of the base, and be at an angle of about 60 degrees. So you need to drill a hole in the base at about 60 degrees, pointing in the right direction. Insert the rod into the hole, and see where the tip ends up. You want it to be above the middle of the base - if it’s a bit wonky, you can always try and expand the hole, and wedge the rod so it’s in the right place. Glue it in place with the epoxy resin. Once that’s done, you want to get the hard disk in place. The centre should be at the centre of the base, directly under the pendulum. Glue it in place with the epoxy resin. Now you need to make the ball bearing attach to the string or wire. Take the two washers. put one in a vice, so that 50% is sticking out of the vice. You are now going to take the bit that’s sticking out of the vice, so it makes a right angle. You’ve now got a washer bent at a right angle - stick that washer to the other one, using super glue. The right angled washer will be the loop you feed the string through. Glue the straight washer to the ballbearing with superglue. When that has set, use some epoxy too - this bit needs to be strong. OK now you have a base, with a rod and metal plate, and a ballbearing with a loop fixed to it. Take the end of the rod, and cut a notch in it with a hack saw. Connect the string/wire to the notch in the end of the rod (might take a bit of faffing to get the length of the string right). Place the magnets on the plate. And now you’re done - enjoy! Zoom

Chaotic pendulum

Ok this is a little maths based toy I made a good 7 or 8 years ago. I’d been reading some pop science book on maths, and it was mentioned in passing that a pendulum, with a metal weight and 3 magnets will behave chaotically (as in chaos maths). I was intrigued, and thought I would give it a go.

The effect is pretty good - I’ll post a video as soon as I can work out how to shrink the video file size. basically the ball bearing swings in a very strange, unnatural and captivating manner. There are three magnets on the base, which make it move strangely. It works even better if you cover the ball bearing in glitter - sparkly! But I didn’t want to cover myself with glitter again, so have missed that out this time.

The theory behind it is fairly complex, or at least the maths bit is. if you want to know more, wikipedia is your friend. Basically a small change in input leads to a large change in output. What that means in practice is that it should be impossible to predict how the pendulum will move, as you change the start position/velocity. Also, it’s quite hypnotic.

To make your own you will need - some wood or similar material for the base (you need to be able to saw it and shape it),
a bit of magnetic material to stick the magnets on - a biscuit tin lid will do, but I used the disc from inside a hard drive - magnets stick to it, it’s the right shape and it’s very very shiny.
a ball bearing (large or small is good)
3 magnets (I got mine from maplin, about £1 a piece)
some string or wire
a metal rod - roughly 25cm long (depends on how big you want to make the pendulum). I bought a metal pot stand from the pound shop, and cut it up to get a piece the right size.
2 small washers
superglue
epoxy resin

first, shape the base. Mine is about 25cm long, maybe 15cm wide. The rod will need to be centred along the long axis of the base, and be at an angle of about 60 degrees. So you need to drill a hole in the base at about 60 degrees, pointing in the right direction.

Insert the rod into the hole, and see where the tip ends up. You want it to be above the middle of the base - if it’s a bit wonky, you can always try and expand the hole, and wedge the rod so it’s in the right place. Glue it in place with the epoxy resin.

Once that’s done, you want to get the hard disk in place. The centre should be at the centre of the base, directly under the pendulum. Glue it in place with the epoxy resin.

Now you need to make the ball bearing attach to the string or wire. Take the two washers. put one in a vice, so that 50% is sticking out of the vice. You are now going to take the bit that’s sticking out of the vice, so it makes a right angle. You’ve now got a washer bent at a right angle - stick that washer to the other one, using super glue. The right angled washer will be the loop you feed the string through. Glue the straight washer to the ballbearing with superglue. When that has set, use some epoxy too - this bit needs to be strong.

OK now you have a base, with a rod and metal plate, and a ballbearing with a loop fixed to it. Take the end of the rod, and cut a notch in it with a hack saw. Connect the string/wire to the notch in the end of the rod (might take a bit of faffing to get the length of the string right). Place the magnets on the plate.

And now you’re done - enjoy!

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Posted 10 months ago
It’s alive! Today I connected the computer to the circuitry, and performed the first full test! And it moved (well sort of). The motors all powered up, and the software seemed to be working ok. I pressed play, to start the test run, and the y axis motor started spinning, pushing the y axis assembly along the rail (thats the horizontal rail in the picure above). The x axis and the z axis didn’t move, so I’ve got some work to do. But to be honest I’m really happy 33% of it worked - I was prepared for a total fail, ranging from “nothing happens” to “machine rips itself into small pieces, bursts into flames and in it’s final moments achieves sentience and tries to take over the world”. What I need to do now is some more testing, to work out why it didn’t all move as it should. First I’ll make sure the motors spin when the software is running. Then, assuming that’s all ok move to the threaded rods. I think the Z axis is likely due to some misaligments - the threaded rod was quite difficut to turn before the test. Not so sure about the x axis, but will get the first phase of testing done and see how it goes. Progress though - it’s lots of fun - and satisfying to see something work, even if only partially. Zoom

It’s alive!
Today I connected the computer to the circuitry, and performed the first full test! And it moved (well sort of).

The motors all powered up, and the software seemed to be working ok. I pressed play, to start the test run, and the y axis motor started spinning, pushing the y axis assembly along the rail (thats the horizontal rail in the picure above). The x axis and the z axis didn’t move, so I’ve got some work to do. But to be honest I’m really happy 33% of it worked - I was prepared for a total fail, ranging from “nothing happens” to “machine rips itself into small pieces, bursts into flames and in it’s final moments achieves sentience and tries to take over the world”.

What I need to do now is some more testing, to work out why it didn’t all move as it should. First I’ll make sure the motors spin when the software is running. Then, assuming that’s all ok move to the threaded rods. I think the Z axis is likely due to some misaligments - the threaded rod was quite difficut to turn before the test. Not so sure about the x axis, but will get the first phase of testing done and see how it goes.

Progress though - it’s lots of fun - and satisfying to see something work, even if only partially.

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Posted 10 months ago
Motors I managed to get some spare time over the last week, and have got the motors mounted to the machine, which you can see in the pictures above. The motors will spin the lead screws, which will move each axis - pretty soon now I can test if the thing works at all. The motors are connected to the electronics, which connnect to the PC. I’ve got the software roughly set up too. I’m using an open source piece of software to drive the thing, a programme called EMC2. It is linux based, so free and open (which is the way I like my software). EMC2 should take a 3d model, and turn it into the instructions for the motors, directing the cutting head in order to cut out the desired shape. Software is not my strong point - so I was not looking forward to getting that sorted out. I got the software very roughly configured, using information on the electronics plans and in the software manual. By the time I had done that I was stumped as to where to go next - and when I pressed play on the software, nothing was happening to the motors (I expected them to spin). I went on the emc forums, and asked for some help, listing what I had, what I had done and “help”. Within half an hour I was on the phone to a local expert who talked me through exactly what I needed to do, and how to configure the software. And pretty soon the motors were spinning! That really felt like progress - for me the electronics/software side of things is a weakness, so getting some semblance of a correct configuration was a major achievement. This is what I love about open source - you can post a question/plea for help, and within minutes have real experts trying to help you, without any expectation of financial gain or recompense. People helping, sharing and cooperating out of a love for what they do. So anyway - massive thanks to the annonymous software genius! I now have the motors in place, and all I need to do is to plug the PC into the electronics, hit play and see if the thing works. It’s going to take a lot of messing around to get it all functioning smoothly, of that I am sure. And I still need to fit the limit switches, get all the cabling in place etc. But all of that will wait for the next week or 6, or until I get any more spare time…. Zoom
Motors

I managed to get some spare time over the last week, and have got the motors mounted to the machine, which you can see in the pictures above. The motors will spin the lead screws, which will move each axis - pretty soon now I can test if the thing works at all. The motors are connected to the electronics, which connnect to the PC.

I’ve got the software roughly set up too. I’m using an open source piece of software to drive the thing, a programme called EMC2. It is linux based, so free and open (which is the way I like my software). EMC2 should take a 3d model, and turn it into the instructions for the motors, directing the cutting head in order to cut out the desired shape. Software is not my strong point - so I was not looking forward to getting that sorted out. I got the software very roughly configured, using information on the electronics plans and in the software manual. By the time I had done that I was stumped as to where to go next - and when I pressed play on the software, nothing was happening to the motors (I expected them to spin).

I went on the emc forums, and asked for some help, listing what I had, what I had done and “help”. Within half an hour I was on the phone to a local expert who talked me through exactly what I needed to do, and how to configure the software. And pretty soon the motors were spinning!

That really felt like progress - for me the electronics/software side of things is a weakness, so getting some semblance of a correct configuration was a major achievement. This is what I love about open source - you can post a question/plea for help, and within minutes have real experts trying to help you, without any expectation of financial gain or recompense. People helping, sharing and cooperating out of a love for what they do. So anyway - massive thanks to the annonymous software genius!

I now have the motors in place, and all I need to do is to plug the PC into the electronics, hit play and see if the thing works. It’s going to take a lot of messing around to get it all functioning smoothly, of that I am sure. And I still need to fit the limit switches, get all the cabling in place etc. But all of that will wait for the next week or 6, or until I get any more spare time….

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Posted 1 year ago

Update

Ok first apologies for the severe lack of posting of late.  No decent excuses really, other than being generally busy. I’ve been working hard, and also doing a bit of making.  The pictures above show the all new reinforced x axis.  I added two lengths of box section steel tubing, which has eliminated nigh on all of the x axis sag, which is ace!  Previously the x axis was sagging by about 20mm at the centre, which was I think quite serious. But no more! 

I also fixed the bent lead screw problem - by getting some more threaded rods.  Total cost about £10, and well worth it - I could have easily spent a couple of days trying to straighten the old ones, and ended up with poor results.  And the threaded rods need to be fairly straight, or there will be trouble later.

I have also got the electronics set up, I think anyway.  I made a (very ugly) box to house them, and what need to do now is test them.  I have just got hold of a PC which can be the brains of the operation, so once I have some software on that I will be able to see if I have wired everything up ok, test the motors etc.  I am going to use EMC2 as the software (http://www.linuxcnc.org/).  This is basically a CNC controller software program, using linux.  It runs on ubuntu, is free and open source (for me open source is the way to go).  I will post some more pictures of the electronics, motors and PC set up as it happens. 

On other news, i have also made a few new creations. Previously I made a small phone stand out of aluminium and sugru. I’ve made a new one of those, which also holds my headphones.  Another post for that one coming soon I promise!

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Posted 1 year ago

These shots show the y axis in a little more detail.  I have run into a problem. The threaded rods are bent, which is not good.  The y axis rod is only out by maybe three or four millimetres in the middle but it’s enough to move the whole y axis frame up and down as the rod rotates.  I now need to work out how to straighten threaded rods - if you have any cunning plans, post them in the comments.

The pictures also show a closer view of the motor mounts, and the nut fixing assembly.  The original design calls for the use of a square nut, which you can then fix to a piece of MDF using a few bolts.  I couldn’t find a square nut at the right size, so had to use a standard hexagonal nut.  To keep this in place requires three or four bolts, which ends up being rather imprecise and also adding weaknesses into the frame.  I decided to make my own, using some offcuts from some aluminium rail.  For each assembly I cut four pieces of aluminium, and cut out a hole that would fit the nut snugly.  I then glued them all together with a bit of araldite, and glued the nut in place (laminated aluminium - strange but it seems to work).  I fixed another piece of aluminium on the top, with a hole drilled to the size of the threaded rod.  Fixing this on the top restricts the movement of the nut, making the whole thing stay in place.  I fixed the first one on the Y axis and it looks like it works well.  Once I’ve straightened the threaded rods I’ll fit the next two nut assemblies, then mount the motors.  Once the motors are mounted I can connect them up to the electronics, and it should be ready to start calibrating - if it all works…

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Posted 1 year ago

CNC Progress

The pictures above show how the CNC router is progressing.  I have made the motor mounts, which are ready to fit to the machine. I’ve also made the nut fitting, for fixing a nut to each axis of the machine. The nut is attached to each lead screw (or threaded rod), so when the lead screw spins, the nut can’t turn. So it has to move along the lead screw. Because the nut is fixed to an axis, it pushes that axis along - and you have movement.

The pictures above show the Y axis nut attached, with the lead screw in position and a fitting on the end of the lead screw, to allow the motor to be attached.  On the table are the motor mounts and the two remaining nut assemblies, and a stepper motor. The shaft of the stepper motor will fit inside the grey fitting on the end of the lead screw. The motor mounts will fix the motor to the frame of the machine.

More pictures on the next post…

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Video 6
Notes
Posted 1 year ago

Magnetic knife holder

I made these magnetic knife holders using sugru, and some magnets. My kitchen is too small, so anything I can do to make more space really helps. The magnetic knife holders give me a little extra storage space. To be honest though, I’ve always thought magnetic knife holders were rather cool - so it’s very satisfying to make my own.

I got the magnets from some toys - two rectangular magnets, and about six small round magnets to make the round holder.  I covered them in sugru (2 sachets each), then pressed them against the wall.  The sugru is very sticky when wet, and when they had dried off the magnets were fixed to the wall.Before they dried I pressed plastic mesh into the sugru, to give it some texture (this really evens out the texture, so instead of lumps and finer prints it’s all a bit more even). 

The results are mixed - the rectangular magnets work really well and are in use all the time.  The holder using the round magnets doesn’t work so well.  The magnets aren’t too strong, so it won’t even hold a potato peeler. Using more magnets would probably help here. When I was fixing it all in place it was really tricky to get the magnets to align properly (three stacks of two magnets, all wanting to link into one big chain). I think that using some cellotape would make it easier - getting the magnets fixed with respect to each other would make the alignment stage much easier, and should allow the magnetic poles to be aligned more easily, which would boost the power of the magnets. 

I got the idea for this one from the sugru website, www.sugru.com. They run a “hack of the month” competition, and I think this kind of thing was a winning entry.  When  saw the idea I knew I had to do it.  Covering magnets in sugru means you can stick magnets anywhere, so you can have magnetic anything - which is going to be very useful!

So - does anyone know how magnets work?

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Video 1
Notes
Posted 1 year ago

Phone Stand

I made this stand for my phone, using a piece of aluminium and some sugru. I’ve been on the train lately, and thought it would come in useful for watching films and so on.

I used some right angle aluminium rail, about 1.5cm per flange. I filed it down to the right shape, sanded the filed edges with some fairly smooth paper, then put some sugru on. I used about half a sachet. To put it on, I first covered my phone in clingfilm (sugru doesn’t stick to clingfilm). Then I rolled the sugru into 2 sausages, and put a large sausage on the bottom flange, and a thinner one on top. Then I pressed my phone into place, making the sugru take the shape of the phone. Once the phone was in position I smoothed the edges of the sugru to make sure it was even, and filled all the gaps. Then I pressed some plastic mesh onto the sugru. This gives it a better texture than my fingers can provide. Once than was done I put four balls of sugru on the base, and pressed down on the aluminium, to make four flat feet on the base (make sure its on clingfilm before you do this or it will stick to your desk). Then I removed the phone and let the whole thing cure for a few hours. I used a small scalpel to straighten up some edges, then let it cure some more.

I’m really happy with the result - small and light, and effective. I listen to YouTube videos when I do the washing up, so using this I can keep an eye on them too. Also train journeys, general travel etc. A very simple creation, but makes my life slightly better. If you are thing about making one of these - do it! Sugru can be found at www.sugru.com, about £12 for a pack of 12 sachets. The aluminium rail you can find at a local hardware shop - it will only cost a few pounds and you’ll have a custom phone stand. I got the idea for this from a kickstarter project for a tripod/stand for an iphone (can’t find the link right now).  That looked like a good product, but so simple that it would be easy to make something with a similar function.

kickstarter.com is worth a look - scheme that allows lots of people to pledge small amounts of money, to kickstart a project or product.  When the goal amount is reached, the project has enough money to start manufacture or production, and finished products can be shipped out to the people who pledged the money.  Crowd sourcing funding - fantastic idea!

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Posted 1 year ago
This is sugru. It’s ace. Sugru is an air curing goo - before it sets, it’s soft, rubbery and sticky, but you can work with it like fimo. It sets to a stiff rubbery consistency, kind of like silicone bath sealant. When set it is tough, waterproof and resistant to hot/cold temperatures. As a result, it is a wonderful thing! It’s great for fixing things, or hacking things so they work better, or using in a new creation. Because it cures in air, you can use it on just about anything (fimo needs to cure in an oven, which restricts its use a lot). I first discovered sugru about a year ago, and since then my house has rarely been without it. I’ve got through three or four packs of 12 packets, and made some really handy things. I’ll post some pictures over the next week. Disclaimer: I have no connection with sugru.com, other than being a big fan. Zoom

This is sugru. It’s ace.

Sugru is an air curing goo - before it sets, it’s soft, rubbery and sticky, but you can work with it like fimo. It sets to a stiff rubbery consistency, kind of like silicone bath sealant. When set it is tough, waterproof and resistant to hot/cold temperatures. As a result, it is a wonderful thing! It’s great for fixing things, or hacking things so they work better, or using in a new creation. Because it cures in air, you can use it on just about anything (fimo needs to cure in an oven, which restricts its use a lot).

I first discovered sugru about a year ago, and since then my house has rarely been without it. I’ve got through three or four packs of 12 packets, and made some really handy things. I’ll post some pictures over the next week.

Disclaimer: I have no connection with sugru.com, other than being a big fan.

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Posted 1 year ago

Update

I am now mostly recovered!  Sadly, the doctor has said I can’t use power tools or do heavy lifting, so I’ve made very little progress on the CNC machine since the start of December.  I’m finding that to be really frustrating.  However, I have managed to do a bit of light sanding and sawing, so I am getting there slowly.  And I should be able to do more towards the end of January. 

The machine itself is taking shape.  I have completed pretty much all of the MDF parts, so the basic structure is 95% complete.  I still need to mount the motors, and make sure the lead screws (long threaded rods) are straight and fit together.  I’m also trying to work out a good way to fix each axis to the threaded rod.  The design provided in the book looks weak and like it will be prone to breaking.  So I have been cutting and filing some spare aluminium to see if I can work out something better. I should be able to get that finished next weekend.  Then I need to wire up the motors, circuit boards, power supply and drivers.  Plus a big red STOP button in case things go wrong.  I also need to source a crappy old laptop to be the brains of the machine. 

I should be able to get most of the physical stuff done this weekend, and then hopefully can start work on the electronics.  I need to make a box for the electronics and power supply - but I have lots of MDF offcuts, so that won’t take long.  Once that is done, it should be ready for testing - I’m looking forward to it!

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