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Wed 26th Mar 2014

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Download Three Layer Gears

I have a large project to complete for a local museum where I'll be making a series of automata depicting local historical characters. These will be on display in the museum, powered by electric motors operated by a push switch. Hopefully the finished models will be on display for a long time so I need to be able to make repairs when pieces wear out. Obviously wooden dowels axles are out, I'm replacing them with brass tube. The problem remains, how to fit the gear to the axle so that it can be changed if necessary. Through a process of trial and error I think I'm pretty close to the laser cut gears that I want.

I'll add a download file with this post for anyone who wants to try this out.


The gear is made from three main parts in 3mm ply plus two axle parts from 6mm ply. I'll added a little alignment triangle to each of the gear rings mainly so I know which is the front and which is the back.


I've also cut out a small section of rack with the same pitch as the gear teeth. This helps lining up the layers as they are glued together.


One triple thickness gear. Twenty three teeth. That's a prime number that is.


I punched a dent close to the end of the brass axle piece. It might be better if I put a solid filler piece in the tube whilst I do this. I then drilled through one side only with a 1.5mm drill bit.


I drilled a hole into the side of a hub piece. One side only again.


I pushed the hub onto the axle then twisted them round until the holes lined up.


I then inserted the drill into the hole and drilled right the way through and out the other side.


Finally I fitted a split pin through the hub and the axle.


I finished of by threading the axle though the hole in the gear wheel and gluing the hub and gear together. Finished off by gluing a second hub on the back of the gear.


Here it is meshing with a 47 tooth gear. Looking good! If I need to change a gear wheel in a completed model I'll be able to pull out the split pin and slide it off the axle. Perfect.


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Tue 25th Mar 2014

The guard dog and RRVS mechanism are designed to be modified. I'm delighted to see that they have been!

Michael42er has made this delightful spotty dog...


First to the post though was your friend and mine, Mr Cool with this rather grumpy disagreeing robot. Thank you both for your fantastic models!


 

 

Meanwhile, over at the Instructables website the DisplayGears project has reached 24k views. User ThePropsNerd has posted picture of his acrylic Display Gears model. Nice work!

 

Finally, friend of the web site David Wakefield sent in this video of this wooden owl toy. It is part of his range of wooden toys. The owl, which David had designed a while back, uses a similar mechanism to the RRVS. Check out his website here, it is well worth a visit!


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Sun 23rd Mar 2014

In the previous Rotating Reciprocating Vertical Shaft (RRVS) Mechanism the range of movement is limited to around ninety degrees in either direction. It worked well for the Disagreeing Dog and I'm sure it will be suitable for a whole range of other models where a simple side to side movement is needed.

In the world of mechanisms there are always other ways to create the same type of movement. I've been experimenting with a new design that would allow a wider range of back and forth movement. (Up to three sixty degrees and beyond, in both directions) The other property of this mechanism is that the drive is much more accurate. Back and forth movement will be within a predictable, repeatable range. Here the plan:

The yellow shaft is the driven shaft. This will be attached to the character in the model. The ends of the two red strips are glued to the yellow shaft then both are wrapped a couple of times round the shaft, one of them clockwise and the other anti-clockwise.


The ends of the red strips are then glued down to the blue drive bar at opposite ends of the bar. With the shaft fixed but free to rotate, moving the drive bar back and forth rotates the shaft back and forth.


Having fitted the shaft into a box and established that the drive works, my next step will be to create some sort of linkage that can drive the blue bar back and forth.



The whole mechanism works similarly to a rack and pinion drive but is far better suited to paper as both teeth and gears are hard to make accurately.



I'm calling this the RRVS Type 2. Short for Rotating Reciprocating Vertical Shaft. Looking good so far!


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£2.50
Download Disagreeing Dog
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Turn the handle and the Disagreeing Dog disagrees.

Using the Rotating Reciprocating Vertical Shaft mechanism from the previous post the dog shakes his head from side to side.

Members can download the parts file for free from the link, thanks for signing up. Non-members can download the parts for £2.50


Print out the parts onto thin white card (230 micron / 67lb) Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts. The construction of this model is basically the same as the Rotating Reciprocating Vertical Shaft model and the Guard Dog model combined. It is supplied in both coloured and non-coloured versions.


Fold up and glue down the tabs to make right angled triangle tubes.


Glue together the base box. The picture shows it upside down.


Make the two cams from double thickness card.


Slide the two cams onto the longer square shaft lining them up with the grey lines. Notice that they are rotated by one hundred and eighty degrees from each other.


Glue together the two box sides.


Fit the box base into place. Glue the four tabs onto the inside walls of the box.


Assemble the handle in three steps as shown.


Roll round and glue up the axle tubes lining up the edges with the arrows.


Fit the shorter axle into the cam tube.


Glue the drive plate to the shorter square tube, lining it up with the grey line. Slide the square tube onto the longer axle sliding it into place between the two grey lines.


Fit the drive shaft into place in the box.


Drop the vertical shaft into place.


Fit the box lid over the vertical shaft and glue it down.


Finish the box by gluing on the handle. Turn the handle and make sure that the vertcial shaft turns back and forth.


Glue together the body of the dog. Glue the front legs to the grey areas.


Assemble the back legs.


Glue the back legs to the grey circles on the side of the body.


Glue the tail together to make double thickness card then carefully cut it out.


Glue the tail to the body.


Fold over the ears to make double thickness card and cut them out.


Assemble the head and glue on the nose.


Glue the ears onto the back of the head then fold them down to convert the head from a rabbit to a dog. (!)


Fit the support piece to the inside of the head ...


...and glue on the square shaft. This will be used to connect the head to the vertical shaft on the box.


Drop the body onto the box top. Don't glue it down yet.


Fit the head onto the shaft. Turn the handle to shake the head, move the body round to find the best looking position then glue it down.


Turn the handle and watch the Disagreeing Dog disagree with you.

No.


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£2.50
Download RRVS
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Turn the handle on the side of the box and the vertical shaft twists back and forth. Download and print out the Rotating Reciprocating Mechanism and use it as a starting point for your own character designs.

The next project on the blog, the Disagreeing Dog, is centred around this mechanism, have a look to get an idea of how the mechanism might be applied.

Members can download the parts for free, thanks for signing up! Non-members can download the parts for £2.50ukp

Download the parts sheet and print out the pages onto thin card (230 micron / 67lb) I've used pre-coloured card but you can use white card or preprint one of the pattern sheets from here. Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts.


Fold up the tabs on the base to make right angled triangle tube sections.


Fold up and glue down the base parts.


Fold the two cams in half to make double thickness card then cut them out.


Make up the drive plate in the same way.


Roll up the two drive shaft axles and glue them down lining up the edges with the arrows.


Fit the two cams onto the longer of the two square section tubes, lining them up with the two grey lines. Thread the short round axle into place.


Glue the drive plate to the shorter square tube lining it up with the grey line.

Thread the long round axle into place on the square tube so that it is between the two grey lines.


Assemble the handle in three steps.


Glue together the two parts of the box. Fit the box base into place and glue back the four tabs to the inside walls of the box.

Thread the cam axle into the box.

Drop the vertical shaft into the hole in the box base.


Glue the box lid into place.


Complete the model by gluing the handle to the shaft. Now the fun starts! What will you design to go on the top of the box?!


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Turn the handle on the side of this box and the vertical shaft sticking out of the box top twists from side to side. I'm calling it a Rotating Reciprocating Vertical Shaft mechanism or RRVS. Perfect for a shaking head mechanism such as the Disagreeable Sheep or the Watch Mouse. I have a couple of small changes to make then I'll be releasing this as a mechanism as well as using it in a Disagreeable Dog model.


From underneath you can see that the mechanism is a modified version of the Intermittent Rotation mechanism with an extra cam.


Looking at the underside of the box top you can see the two stops which limit the rotation of the vertical shaft.


The drive plate on the vertical shaft has stops on the top side to match with the box top stops.


The drive shaft has two cams. Each has a cut away so that the drive plate on the vertical shaft is turned alternately clockwise then anti-clockwise.


The various parts all fit together in the box and are driven via a handle at the side.


To try out the mechanism I've added a connector to the inside of a guard dog's head. The eight millimetre square tube fits neatly on the circular vertical shaft.


The body sits over the vertical shaft lined up so that the head will be centred over the body.


I'd say it was looking good but if I turned the handle it would only disagree.


I'm also trying out an owl to go with the intermittent rotation mechanim. This one is looking a bit underweight Might be better with a slightly conical body.


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Add to Cart to download this kit for free !
Download Display Gears

Four interlocking gear wheels in a display case. Art and engineering in perfect harmony.

This project is also on Instructables

The parts of this project are cut out from three millimetre plywood using a laser cutter. In this case, an HPCLaser 3050.

The plans for making this project are available for everybody to download for free. As well as the plywood you will also need a piece of dark coloured paper as a background and a sheet of one millimetre thick clear acrylic for the front of the box. One final addition, you will need three pieces of six millimetre wooden dowel. Two of them twenty four millimetres long and one eighteen millimetres long.

 


The parts file is divided into two pages. The file is a pdf. As different laser cutters use different file formats I leave it to you to convert it to a format suitable for your machine.


The HPCLaser in action cutting out the parts.


All the parts apart for the dowel pieces cut out and ready to go. The blue piece is the clear acrylic front with its protective film still attached. Having cut out all the parts follow the instructions below to assemble the gear display.


Glue together the two eighteen teeth gears. Make sure that they are aligned precisely.


Glue the outer ring to the thirty eight tooth gear as well as the centre hub. Again, make sure you are as accurate as possible with your alignment.


Glue the eighteen toothed gear to the hub. Use a spare piece of dowel to make sure the holes are lined up accurately.


Assemble the twenty two toothed gear as shown using the pentagon hub.


The thirty toothed gear has no hub. Carefully glue the secondary gear ring in place making sure that the teeth are accurately lined up.


Glue together the three base pieces and fit the two longer dowels into place tapping them home with a hammer if necessary. They should be a tight fit and should not be free to turn.


Fit the various spacers into place as shown in the picture.


Glue the eighteen millimetre long dowel into the knurled gear as shown. Make sure that it is sitting accurately square as the glue dries.


Glue the dark backing paper into place. This paper provides contrast with the gears making them stand out visually.


Fit the knurled wheel through the remaining hole in the base plate. It should turn easily in the hole. Fit the small gear into place on the dowel so that it just touches the spacer on the base. It should turn easily via the knurled wheel.


Drop the largest gear onto the dowel. Check that it turns freely via the knurled wheel.


Drop the final gear onto the remaining dowel. Fit the remaining ring over it so that it holds the gear down but still allows it to turn.


Fit together the five main pieces of the frame. Use glue if you need too.


Drop the acrylic front into place inside the box. Glue the two stops into place to hold the acrylic in position.


The finished front cover.


Fit the cover over the gear to complete the project.


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Mon 17th Mar 2014
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Edit |*** I've added a downloadable file for paid members to who would like to try out the zip for themselves. The file has a section of curved zip and a straight section. Just a little bit to keep you going. Click the Add to Cart link to download the file. ***|

You may have spotted a picture in my on Instagram stream of a squirrel I'm working on for a client. The design brief is for a simple to make squirrel which needs no glue to assemble. The client will be printing and die-cutting the final design so there is no problem with complex cutting out.

Making the parts slot together so that they are robust but easy to assemble has been an interesting challenge. I've been trying out all sorts of different ideas with varying degrees of success. Last night, just as I was about to fall asleep, I hit upon an idea. I should have got up at that point and sketched it out but instead I lay in bed working out details and modifying the design in my head. It was gone two thirty in the morning before I finally got to sleep only to have to rise again at six. Luckily I have good coffee to hand.

The idea is fairly simple. I'm using a series of
diamond shaped tabs just like those on the back of a stegosaurus.


Here's a sample of one of the layouts created in Illustrator...


...printed out, the parts fit together easily yet hold together firmly without the use of glue.


Ta daa! On the inside of the joint it looks just like a stegosaurus back, from the outside the joint is smooth.


To double check that everything worked properly I put together this glue-less rabbit. The paper zip works a treat. Just need to improve the legs and feet on the rabbit and I'll put the design on the site as a download.

First though, I need to fit a stegosaurus zip to a squirrel.


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£2.50
Download Guard Dog
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Download this fearsome(!) Guard Dog from the link and make either this coloured version or print the uncoloured version onto patterned paper to make your own individual style. This version of the Guard Dog is a static paper toy, look out for future articles where I'll be showing you how to add movement to him to bring him to life.

Paid members can download the parts sheet for free, thanks for signing up! Non members can join in for the small fee of £2.50ukp


Print out the single sheet of parts onto a piece of thin card. (230micron /67lb is ideal) Score along all the dotted and dashed lines before carefully cutting out all the parts.

All the parts cut out and ready for assembly.


Fold over the tail and glue it down making double thickness card. Don't glue the two tabs together. Once the glue is dry carefully cut out the part.


Fold the top of the ears over to make double thickness card then carefully cut them out.


Fold up the head and glue it together as shown.


Glue the completed ears to the back of the head. Fold down the ears at roughly half their height as shown in the animation.

 


Roll round and glue together the body.


Glue the front legs in place on the front of the body using the grey areas.


Glue the back feet and legs together.


Glue the back legs to the body.


Glue the tail to the marked area.


Glue the head to the body. Where you place the head is a matter for personal preference. I moved it slightly off-centre with the head cocked slightly. Glue the semi-circular tab at the back of the head to the body and at least one of the sides of the head.


The finsished guard dog as well as a mono version printed onto heart-patterned paper.


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Fri 14th Mar 2014

I've completed the layout of the guard dog parts. A few small last minute changes including merging the three head parts into a single piece and increasing the overall size by twenty percent.

I printed out a final test version onto love heart pattern paper for #truelove. (Went down a treat :-)

I'm making the downloadable model as a stand alone static paper character (like in the picture). I'll also be making the rotating guard dog model that I had originally planned. The exciting thing, though, is that the character won't be limited to just that mechanism. Over the next few weeks I'm planning on releasing different mechanisms that can be used to make the dog, and a variety of other characters, nod,( ageeable sheep mechanism) shake it's head, (disagreeable sheep) and many others movements. I'm hoping that with a range of mechanisms and a range of characters all sorts of interesting automata will be easy for everyone to design and make!


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