7
extract
Thu 3rd Apr 2014

My first draft of a circular bodied owl was based on the Owl Box project. The body was a bit on the skinny side - definitely in need of fattening up!

Rather than using a cylinder for the body, I felt a frustum was more appropriate. Luckily I have just the tool for the job...

<---New section added 5th Apr --->

The owl body is made from a cone shape with the top cut off. The mathematical name for this shape is a frustum.


I made up a rough version of the body shape freehand. Cutting out a curve of card, I rolled it round and trimmed it until it was the size and shape that I was looking for.


I then measured it up ready for transfer to the computer. The important measurements are the radius of the bottom circle (r1), the radius of the top circle (r2) and the height of the model (h). I measured these dimensions and noted them down.


I then downloaded the spreadsheet from an earlier blog post here and opened it in Open Office. (It should also work in excel but I no longer have a copy after Microsoft Word and I fell out.)

I typed in the three measurements into the three arrowed boxes. The circled measurements and the angle are all I need now to construct the net of the owl frustum.

<--- end of new section --->

Having decided on the size that I was after, I entered the various numbers into the spread sheet. Using the dimensions given by the spread sheet I constructed the curved part used in the owl's body.

It all fits together rather neatly. I'll be making the finished owl available as a download on his own then as part of the rrvs type 2 mechanism.


Keep up to date: Receive the latest blog post by email

Rate this post:



£2.50
Download RRVS Type 2
Become a Member for free access to this and other files on the site.
See the Membership page for more details.

Already a Member? Log in Here

Turn the handle on the side of the box and the vertical shaft rotates back and forth. Use this mechanism as the starting point for your own character based designs or as a way of learning first hand how mechanisms work.

Look out for the owl model using this mechanism coming soon.


Print out the parts onto thin card. You will also need some normal copier paper to make the paper straps. Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts.


Fold up and glue the side tabs on the box to make right angle triangle tube sections. Fold round and glue down the other side to complete the base.


Glue together the two box sides.


Fit the base into the box


Fold in and glue the four tabs to the inside walls of the box. Make sure everything stays as square as possible.


Assemble the hinged plate as shown.


Make up the two crank ends from double thickness card.


Glue together the push rod and glue on the two crank ends.


Roll round and glue the four paper tubes accurately lining up the edges with the arrows.


Thread the second-to-shortest tube into the crank ends.


Assemble the two crank pieces


Finish up the crank pieces and glue them to the axle.


Fit the shorter of the two remaining axles into the crank gluing them fully home in the square tubes.


Fit the crank into the box using the picture above to help with orientation. (Note especially which way up the push rod is.)


Glue the hinged plate to the back of the box.


Glue the push rod tab to the front of the hinged plate.


Glue the stop to the vertical shaft.


Make the handle in three steps.


Glue the handle to the crank.


Cut two paper strips 5mm x 100mm from ordinary copier paper. Glue them to the grey areas on the vertical shaft.


Wrap the two straps twice each round the shaft, one in each direction.


Add glue to the grey areas on the locater plate.


Place the vertical shaft over the green line on the locater plate. Pull the two straps tight and glue them onto the glued area. Cut off any remaining paper.


Assemble the triangular push rod and glue the back of the locater plate onto it.


Fit the vertical shaft into the hole in the bottom of the box.

Glue the tab on the end of the triangular push rod to the hinged plate.


Complete the model by gluing the box top into place. Once the glue is dry, turn the handle and the vertical shaft will twist back and forth.

Next step, design a character to go with the mechanism.


Keep up to date: Receive the latest blog post by email

Rate this post:



I've completed the parts and layout for the type 2 RRVS mechanism. All the photography is done so I'll probably have it available to download some time tomorrow. In the mean time, to keep you interested in the possibilities of this mechanism, here's a clip of a Rotating Reciprocating Owl from my Instagram feed. Enjoy!




Keep up to date: Receive the latest blog post by email

Rate this post:



1
extract
Mon 31st Mar 2014

Presented here, the final stage prototype of the Rotating Reciprocating Vertical Shaft Type 2 mechanism.

This is the completed mechanism
ready for coloring and photography.

The vertical shaft turns back and forth as the handle is turned, In total the travel is just over three quarters of a turn
each way.

 


Turn the handle to drive the crank...


...which in turn moves the hinged plate back and forth...


...driving the belt and turning the vertical shaft.


Seen below is a video clip of the final prototype in action taken from my Instagram stream


Keep up to date: Receive the latest blog post by email

Rate this post:



0
extract
Sun 30th Mar 2014

There are two main parts to the type 2 Reciprocating Rotating Vertical Shaft mechanism (RRVS-t2) The first part, which I mentioned in the previous post on the subject, is the pair of paper straps wrapped around the vertical shaft that do the actual turning. These straps are glued to a beam which moves back and forth to rotate the shaft clockwise then anti-clockwise.

The second part of the mechanism is the part that drives the beam back and forth. I'm using a crank for this. You can see the first crank I created to the right of this picture. It worked but took up too much space so the vertical shaft didn't fit in the box.

The redesigned crank fitted into the box is about half the width of the first version. Actually probably narrower than it needs to be. The crank connects via a linkage to a hinged plate at the front of the box.

The box is closed and the beam is connected between the vertical shaft and the hinged plate. The individual parts of the mechanism work nicely but I need to work on how everything is lined up. Moving the hinged plate back and forth by hand you can see that the vertical shaft rotates almost a complete revolution in each direction.



Next step line everything up properly and fit it neatly into the box complete with drive handle.


Keep up to date: Receive the latest blog post by email

Rate this post:



2
extract
Wed 26th Mar 2014

Add to Cart to download this kit for free !
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.


Keep up to date: Receive the latest blog post by email

Rate this post:



0
extract
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!


Keep up to date: Receive the latest blog post by email

Rate this post:



6
extract
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!


Keep up to date: Receive the latest blog post by email

Rate this post:



£2.50
Download Disagreeing Dog
Become a Member for free access to this and other files on the site.
See the Membership page for more details.

Already a Member? Log in Here

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.


Keep up to date: Receive the latest blog post by email

Rate this post:



£2.50
Download RRVS
Become a Member for free access to this and other files on the site.
See the Membership page for more details.

Already a Member? Log in Here

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?!


Keep up to date: Receive the latest blog post by email

Rate this post: