Harry Potter Decoy Detonator

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ATL Kenobi

Sr Member
This thread is open to anyone building a replica of a Harry Potter Decoy Detonator, so please feel free to share any related ideas, concepts, found parts, images, or such.

In another thread , EZBSVS, woozelmom, and others sparked my interest in building a Decoy Detonator (DD). After looking for the large air horn, I saw the possibilities, and started collecting parts to build my own; Some of the parts I have so far are:


The little black cones are those dispossable black things that doctors use to look in your ears. I snagged a couple during a recent 2 night stay at a local medical facility. There's a small black solid-plastic knob I'm using in place of the small rubber bulb which I haven't been able to find. The felt pads are for the hi-hat cymbal assembly. Also shown are various metal tubes, the bent one will connect the the two small "horns" together.



The cymbals and the bell are right off of Amazon.com. The long brass horn came from eBay, but the rubber bulb that came with it was huge, so I also got a bicycle horn and the bulb from it is much more in scale. The small brass pieces are valve seats used in plumbing. They'll be used in conjuncion with the large horn.

I also bought one of the robot pencil sharpeners, It's a little small for the scale that the rest of my DD is turning out to be, so I'm intending on making the "feet" out of wood. Styrene would be a good choice too.

I'll probably turn the small whistle on a lathe. I can't find a real whistle anything like the one pictured on the DD artwork.

Using a stepped drill bit, I've enlarged the hole in the top of the desk bell. Pictures to follow.

This will be a static (non-moving) replica. When I finish putting it all together, I'm planning to paint it all gloss black, except for the rubber bulb(s).

ATL
 

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Trooper_trent

Master Member
RPF PREMIUM MEMBER
Subscribed! I absolutely love creative thinking, obscure props, and hardware builds. You just scratched all three itches. :lol
 

woozelmom

Sr Member
Love the inventiveness you are showing!!! I am planning on making one myself but it is going to be much smaller and I am hoping to be able to use mostly found objects. Yours is much more detailed so I take my hat off to you :thumbsup
I am hoping to have a wind up feature as well :) When I get the chance I will take pics of the parts I have found so far but I am in the middle of some very large projects and this one will be taking a back seat for a while but I am so happy to be able to follow along with your process. Exciting!!!!!
 

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ATL Kenobi

Sr Member
It's easy to see this thing's going to be very top heavy, so it's important that all the parts sort of balance each other out. It makes the horn a little longer than I wanted it to be.



Here's the bell with the enlarged hole. I used a piece of insulation from some 20 AWG black wire slit longways as a grommet strip. I'm making the center piece that holds the bell and what the "legs" will attach to out of wood. This is a piece of fir dowel that I believe was a closet hanger rod. I drilled a 5/8' hole through the center of it and then inserted a 5/8" wood dowel as a mandrel.


The top of this wood piece will be squared off using a router.

ATL
 

lukeforester1

Well-Known Member
This is very cool, I've been wanting a decoy detonator for a long time! I hope that you will either share where you got your parts or put finished ones on the JY! Wouldn't it be SOO cool if you made it a wind up so it could run around? That'd probably be really hard to do though... :/
I'll try and drop in to see how progress is coming! I really liked this prop in the movie!
 

ATL Kenobi

Sr Member
This is very cool, I've been wanting a decoy detonator for a long time! I hope that you will either share where you got your parts or put finished ones on the JY! Wouldn't it be SOO cool if you made it a wind up so it could run around? That'd probably be really hard to do though... :/
I'll try and drop in to see how progress is coming! I really liked this prop in the movie!
lukeforester1 - I doubt that I'll make more than 1, but I have no problem sharing where I got the parts.

I believe it's an RPF rule not to post live auctions, but if one were to go to a popular auction site and search on terms such as Marx Brothers Taxi Horn, I believe you may find the big horn I used. As mentioned, the bulb was huge so I also got this HORN. The BELL and CYMBALS are from the same source. The other parts are brass and aluminum, tubing and rod from a local hardware store plus other odds and ends that I found there.

I notice my wife's eye cream container and asked her if I can I have it. I added a Weasley "W" made from electrical tape, and added a couple of coats of gloss black lacquer. She now calls it the Baby DD.:lol



I'll post an update on the adult DD soon.

ATL
 

EZBSVS

Active Member
Haha, this is awesome! You've done a far better job than I have on yours, it looks great ALT! Can't wait to see how it continues :)
 

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EZBSVS

Active Member
Also, meant to add, for your weight issue on the back, have you considered weighing the bulb with sand or something? So that it counterbalances while being closer to the center? I know it'd cause issues from trying to have a working horn, but just a thought for appearance sake...
 

ATL Kenobi

Sr Member
Also, meant to add, for your weight issue on the back, have you considered weighing the bulb with sand or something? So that it counterbalances while being closer to the center? I know it'd cause issues from trying to have a working horn, but just a thought for appearance sake...
EZBSVS - I had given that some thought - actually lead shot and silcone RTV - but, as you suggest, I am hoping to be able to have a working horn. Since the box artwork is drawn isometrically and in perspective, I'm hoping that the length won't be too big an issue. Thanks for the suggestion!

I attached a square piece of wood to the end of the "lower body" as an index, and ran many passes through the router using a mortising bit.


Two more flat places were added - this will be where the "legs" will attach. The wood mandrel was removed and the "upper body" (5/8" dia brass tube) was put in place. The bell sits on this.



Starting on the feet/legs. That's 3/16" wood dowel rounded off on one end. The connecting piece was shaped using a Dremel tool.



Several other pieces of wood will make up the legs. I'm mostly using a table saw and a drill press.


ATL
 

ATL Kenobi

Sr Member
The different pieces of the feet all fit together. Just have to trim them, round off the edges, drill the slots for the mounting holes, sand, prime, sand, prime, sand, paint, sand, paint, and attach. :lol


Worked on the small horns too. The one shown on the left is finished. The other pieces shown are a piece of 5/32" brass tubing bent to an inside radius of about 0.8", and two 5/32" ID collars (used to hold the wheels on RC airplanes - from Hobby Town)


ATL
 

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PotionMistress

Sr Member
WOW! What a delightful-looking piece this is going to be! I think you are inspiring me to make my own too...somewhere down the line. Thanks for sharing your tips and techniques!:thumbsup
 

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