More on John Kent

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I’ve been working on an initial layout of parts and characters for the model of John Kent, the first black police officer in the UK. The plan is that he struggles back and forth with a thief and every so often blows on his whistle to summon help.

Dawn’s research has uncovered some awkward facts. Namely, in the time of John Kent the police didn’t use whistles they used rattles! No problem, here’s a new design featuring a rattle driven via a bevel gear and spring steel wire. I’m sure the whistle will come in for another model in the future.

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John Kent’s Whistle

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Click the Pic to hear the whistle in action.

john-Kent-–-the-First-Black-Police-Officer-1837-John Kent was the first black police officer in the UK. He joined the Carlisle police in 1837. As a notable character from Cumbria’s past he is a perfect subject for the Archive Project. Dawn and I have planned out a model featuring John Kent arresting a criminal. They will struggle back and forth then PC Kent will blow his police whistle. In theory we could probably run a pipe up his body and out of his mouth, then blow air through his mouth and into an actual police whistle. There are all sorts of technical difficulties to this solution so instead we are making the sound separately using a set of bellows and a pair of wooden whistles. These will be mounted in the mechanism part of the model user the baseboard.

Here’s how I put together the prototype whistles. Click on the top image to see and hear the whistle in action.

The whistles are made from six pieces of laser cut plywood and a strip of thick (280gsm) card. Police whistles use two tone for their distinctive sound, I’ve made two pipe, one longer than the other to make the two tone sound.

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The cross piece is glued into place forming the bottom of the air hole.

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The end piece is glued into positionwhistle-a03

Then the spacer is glued under the cross piece

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The parts are clamped up whilst the glue dries.

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Whistles work by blowing directed air across a sharp edge. The whistle top is sanded down to make the edge sharp.

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Finally a strip of card is glued into place leaving an air hole at the front. Air blows up through the hole behind the spacer and out through the air hole. The whistle is glued down onto the top of board making the bottom of the whistle.

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The top plate above the bellows has two small holes in to allow air out. The completed whistle are glued to the top plate so that the air comes up through the hole in the whistle and is blown out across the sharp edge making the whistling sound.

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It works really well, the whistle sounds like a police whistle and is loud! Next step is to connect it up to cam or crank and check that the mechanism can make it sound effectively

Puppetry

Here’s a sneak peek at some of Dawn’s awesome puppetry soon to be brought to life with some fiendish mechanicals!

Lady Guildford – titular resident of the Carlisle Archive building – Lady Guildford was an enthusiastic knitter. In this automata she will be regally perched in her chair knitting furiously whilst her two dogs worry the balls of wool at her feet. puppetry-a02

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So cute!

Here’s the drive mechanism for Lady Guildford. The two small gears on the sides drive the dogs intermittently, Lady Guildford’s knitting is driven via a small gear hidden behind the main gear. The motor drive fits at the front – shown in pink on the picture.

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Master of all he surveys, Joseph Pocklington, will be inspecting his treasures through his telescope.puppetry-a05

His friend Peter Crossthwaite will be dusting his collection of curiosities.

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Here a few of the ‘coming next’ group.

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Making Up Weight

As part of the movement of the Catherine Marshall model the suffragette character raises her head to look at the donkey. I have attached a pull wire at the back of her head. Most of the weight of the head is at the front so the pull wire needs a counter weight to make it work.
weight-11Here’s the bottom end of the pull wire. It is connected to a cam follower (the cam is actually not fitted in this picture) the weight on the end of the cam follower is cast from lead. Here’s how:weight-12

I took two blocks of 2×1 and clamped them together. Right in the middle I drilled a 20mm diameter hole stopping about 10mm short of the far side.weight-01

I made a staple from wire to act as the weight hanger. The ends are 10mm apart.weight-02

On the other side of the block I’ve drilled a 5mm deep 20mm diameter hole then two small holes for the staples then threaded the staple into position.weight-03

From the underside you can see how the staple fits into position.weight-05

In a suitable pan I melted some scrap lead using a blow torch.weight-06

Once melted I poured it into the mold filling it right to the top.weight-07

After leaving it to cool for a few minutes I unscrewed the clamps to reveal the completed weight. Ta daa!weight-08

I made a short Instagram video showing the entire process in just 15 seconds! Click the picture to see it!weight-10

Linkage Design

Catherine Marshall was a suffragist. The suffragists believed in campaigning for women’s votes through peaceful, polite means. By contrast the suffragettes believed in deeds not words. In this model Catherine and a suffragette stand on either side of a donkey trying to get its attention with a carrot and a stick respectively.

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The women’s hands are moved via a cam and cam follower which in turn drives a linkage. I’ve used a heavy gauge wire to make the link. This part is made from a single wire bent into position over a template then fixed into position with a fine brass wire and some epoxy resin.link-01

A small screw fixed to a block on the box top provides a pivot point for the linkage.link-02

Then under the box the linkage is connected to a cam follower. All that remains is to see which is more persuasive; carrot or stick?link-03

Updated Rowlocks

I’m making a few mods to the Mary Chamber model to make sure that the rowing action is a full back and forth movement. First thing to change, the rowlocks. In the current version the oars sit in a simple fixed wooden U shaped cut out, I’m making a new version where the U shaped section is made from a sheet of shaped brass and is free to rotate allowing the oars more movement. The brass section is fixed to the boat, the steel section sits in the brass tube and is free to rotate. The U shaped section is screwed to the top of the steel section.rowlock08

I’ve cut the steel section from a 6mm diameter bolt. First things first, the steel in the bolt is hardened so it needs annealing. I heated it up to red heat with the blow torch.rowlock02I then let it cool down slowly in a bed of sand. I repeated that process a couple more times.

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Here’s the annealed bolt ready to go in the lathe. It will need the head rounding off then a suitable hole drilling and tapping. Finally it will need cutting to length

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Rounding off the head in the lathe.rowlock05

Drilling the centre hole.rowlock06

Tapping the hole ready for the screw.rowlock07

The completed piece ready to fit into the boat. One more to make for the other side of the boat.rowlock01

Rotating Work Table

All round access is vital when working on the Archive Project models. You really need to be able to get to all sides of the model to work on the various mechanisms.
After a chat with a couple of twitter friends @concretedog and @workshopshed we settled on the idea of a Lazy Susan. In my youth I had seen these being used for cake decorating. Next stop eBay.rotate-a04I ordered a Turner’s 350mm diameter turntable which claimed to be able to take loads up to 250kg. Plenty.

I cut a circle from 12mm ply and screwed it the turntable.rotate-a01Flipped over it looks like this and is ready to go. Sorted. Thank @concretedog and @workshopshed

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Lead Weight – First Attempt at Casting

There are a pair of cam followers on the Colonel Rutherford model, one moves his head, the other his writing hand. The Colonel’s head has plenty of weight so it falls back into place on its own but the hand needs extra assistance to move back after the cam has released it.

A cam works in one direction only, the cam will push the cam follower up but something else is needed to pull it back down. I could use springs but I’ve decided to use weights in this model. I’ve collected loads of bits of lead over the years, mainly from wheel balancing weights found on the side of the road. My plan is try melting and casting the lead to form usable weights.

I used brass wire to create a hanger for the top of the weight.lead-a05

 

I then packed a tin can with white sand from the local builder’s merchants and made a hole in the centre with a 20mm dowel.lead-a06I pushed the wire into the bottom of the hole so the the arch of the loop was buried in the sand.lead-a07

I melted lead in a pan in the kitchen (#truelove was out) then #1son captured the moment I poured the molten lead into the mould.lead-a01After cooling for a few minutes I knocked out the sand…lead-a02…then washed off weight to complete.

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lead-a01I’ll probably try again to see if I can make a smoother finish to the weight but it certainly works well as is.
Total weight for this version 240g.

Any tips on smoother casting would be welcomed!

 

 

 

 

 

Laser Cut Wooden Chain and Sprocket

chain-a12The first version of the Colonel Rutherford model used a chain drive to transfer the drive from the motor to a gear rotating an airmail aeroplane above the model. I originally used a plastic snap-together chain that I bought from eBay. It worked well enough but some of the links were a little stiff giving the motion an uneasy, jerky look. Visuals are as important as how well the models work in these automata so I set about making an improved chain drive, this time using laser-cut wood. Here’s a rig showing the end result in action

chain-a01I cut out lots of little pieces on the laser cutter to construct the chain. For simplicity each link of the chain is constructed from four identical pieces.

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Two of these pieces are glued together for each side of each link. A cocktail stick through the small holes is used to ensure everything is lined up properly then the pieces are clamped up and left to dry .

chain-a03Lots of links are needed!

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The cross pieces of the chain are made from 10mm lengths of  9mm dowel. I drilled the dowel through the centre making a pilot hole for the screws. The screws are fitted using appropriate washers and tightened just enough so that the links are flexible.chain-a06

The sprockets are made from three layers of 3mm ply glued together.I sanded the side of the sprockets off to help guide them into the centre of the chain.chain-a07

Here’s one of the finished sprockets showing the tapered teeth.chain-a08

This version of the chain drive is a test bed to ensure that it works properly. I’ve mounted the two sprockets onto an MDF baseboard and added a handle. Looking good!chain-a09

Linking Links

I’ve used quite a few links made from stiff brass wire – approx 1.5mm diameter. You can see one of them highlighted here in the Mary Chambers model. They are quick and easy to use but do have their own problems.
link-05To use the wire links I make a loop at each end with a pair of pliers  I can then thread a screw through the loop and into the model making a rotating joint.

Two problems that I’ve run up against:

First, it is very difficult to make fine changes to the length. Shortening a link can be just about done by adding some bends into the wire or by re-curling the end loop but it is not easy do do accurately.

Second, I’ve run the wire through a hole drilled in the base board, if I need to take the link out for any reason I either have to cut the wire or unfold the loop at one end. Neither of which are very satisfactory.

Here’s my attempt at a solution. I found a three amp connecting block strip in the  shed.

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Cut off one section and cut away the insulation plastic with a pair of side cutters.

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Leaving the brass block and two screws.

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Perfect! Thread the link wire in from each end and tighten the screws. Simply unscrew to make adjustments or to remove the link completely. Ta daa!

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