Building a Back-to-the-Future Hoverboard Replica - and a Charger

Hoverboard

The Hoverboard from "Back to the Future Part 2" is one of the most recognizable movie props. That means, I want to have one. 

Quite a few people have done this before, so there is plenty of information that can be found on the web. In particular, there is one thread at "therpf.com", which is just about building BTTF Hoverboard replicas which has a lot of information. A lot of examples can also be found on YouTube. I found the video from the DIY prop shop very helpful, especially since they also provided images of the decals for the front and back sides at dropbox.

These are the ones that I use. Using the open source desktop publishing software Scribus, I converted the original decals into three letter-sized sheets for each, the front and the back side of the board. For copyright reasons, the original decals are missing the brand name "MATTEL" at two places on the front side of the board. I added these in Scribus using the Arial font (make sure to adjust the spacing between the letters, to connect the two Ts). My modified decals are printed on letter-sized cardstock (which is easier to glue to wood, as compared to thin paper).

At different places, one can find slightly different information on the measures of the board. Some suggest a size of 28" x 8" x 1" with the back piece at an angle of 25 degrees. I found that with a thickness of 1", a wooden board would be much too heavy, so I decided to make it 3/4" thick. My printouts of the decals has a total size of 24 1/2" x 7", so when adding 1/2" all around, I get a total size 25 1/2" x 8" x 3/4". The back piece (3" = 2 1/2" decal + 1/2" border) is mounted at an angle of 22 degrees. This is achieved by cutting the full board with a cut at 11 degrees angle and flipping the back piece. The two pieces are glued using E6000 using the following setup.

The edges of the board are sanded to get a nice curvature and smaller details are smoothed using wood filler. The outer 1" area of the board is then painted red (I love the acrylic paints from Apple Barrel, here I used their Bright Red).

Then the decals are glued to the board. I used a credit card to distribute the fast drying "Tacky Glue" in a thin layer evenly over the cardstock. 

The pieces for the bottom side and the rotating disk on the top are made from 3/16" plywood using a laser cutter. On the bottom, the original movie prop has two cylindrical disks. I approximate these using three layers of round disks of 6", 5 1/4", and 4 1/2". The rotating disk for the top side is made of two layers of plywood, with cutouts that allow to mount the strap. Everything is then painted, and sealed using Mod Podge.

The result looks great. Of course, it should always be carried together with Grays Sport Almanac and Marty's color-changing cap.

Hoverboard Charger

In the movie we do not see how the Hoverboard is charged. But since I needed a stand, I decided to design it as a charging station, with a little Arduino-based electronics. The pieces are cut from 3/16" plywood using a laser cutter.

At the bottom, there is a microswitch which detects when the board is placed on the charger. 

In that case, the 10-bar LED battery level display cycles through four different patters. This is seen in the video in the top of this blog.

Related

My other blog posts on BTTF-related props and pieces:
   - Building a Flux Capacitor
   - Building the Time Circuits
   - Building BTTF clocks
   - Building a BTTF Brick Stage (featuring the smallest Flux Capacitor)

Building Back-to-the-Future Clocks

 

Today I am sharing how I built two clocks, related to "Back to the Future"

Introduction

The final scenes in "Back to the Future" when Doc Brown is hanging from the clock tower are a reference to Harold Lloyd's movie "Safety Last".

This is already foreshadowed in the opening sequence in Doc's garage, with one of the clocks showing Harold Lloyd hanging from the minute hand (at 30 sec. in this video clip).

Fun fact: This clock was also used in the background in one of the Seinfeld episodes.

Another clock is seen in BTTF part 3, in the photo that shows Doc and Marty in 1885 in front the clock that is being built for the clock tower.

Some creative person in the forums at therpf.com had photoshopped this image and removed the hands of the clock, so that it can be used for building an actual clock.

So, these are two good ideas, resulting in two nice projects.

Doc & Marty Clock

The "Doc & Marty" clock is built into a wooden 8" x 10" picture frame that I found at a thrift store. I removed the glass and the back panel and cut new 8" x 10" back panel from 3/16" plywood. I started with an image of Doc & Marty that someone had posted at therpf.com, which I cropped (to fit 8" x 10") and which I photoshopped (or, actually "gimp-ed") to remove minor jpeg artifacts in the white area. Here is my version of the photo, in case you would like to create your own clock:

I ordered a clock movement with hands that roughly match the style of the tower clock with a 2" minute hand and a 1 1/2" hour hand. 

The 8" x 10" photo is glued to the backing board using Liquitex Gel Medium. This works well, as it gives you enough time to adjust the photo before it dries. Make sure you apply only a thin layer of Gel Medium, cover the image with wax paper, and remove all the air bubbles. I also strongly recommend to cover the photo with a layer of wax paper and use e.g. a stack of heavy books to add pressure while it dries over night.

Then I drilled a 5/16" hole to screw in the clock movement, and added a hanger piece that I made with a laser cutter (four layers of 3/16" plywood)

The last step is to clip-off the second hand (which does not belong on a clock tower), so that I could use the center piece. Then the whole piece is fixed in the picture frame - and that's it!

Here is my clock:

Harold Lloyd Clock

To build the Harold Lloyd clock, I used another image that was posted in post #28 in this forum. That image is, however, rather small (682x1024 pixels), and it has significant jpeg artifacts. Using Gimp, I scaled it up to 2024x1348 pixels and used Gaussian blur to carefully remove all noise and jpeg artifacts. Then I inserted the image in a new image file with a size of 2100x1650 pixels. When the latter is printed on 11" x 14" cardstock, the clock face has a size of 8 5/8" x 13 1/8" - when adding a 5/16" border, the clock has a total size of 9 1/4" x 13 3/4" which is very close to the original clock. At the bottom of this page is the (150 dpi) image that I used for printing on 11"x14".

The Harold Lloyd figure should be printed on cardstock, such that its height is 3.7".

A piece of plywood was cut to 9 1/4" x 13 3/4", the corners sanded, and the border was painted light gray before thecardstock was glued with Liquitex gel medium (again: add a layer of wax paper, remove the air bubbles, and apply pressure over night as it dries). A 5/16" hole is then drilled for the clock movement.

I ordered a clock movement with simple, wide rectangular hands which are much longer than what I needed. This enabled me to cut the hands exactly at the desired length, and use the remaining pieces to practice gluing the holder for the Harold Lloyd figure. The hands can easily be cut using household scissors.

This was one piece where I had to become a little creative: How to build a holder for the figure, so it can freely rotate. And: the holder has to be very lightweight, so it does not damage the clock movement. I decided to use a tiny piece of a wooden dowel, painted black with a permanent marker. In one side, I drill a hole for a M1.7mm screw and the other side is glued to the minute hand. It turns out that the UHU glue does a reasonable job in glueing the wooden dowel to the metallic minute hand: I could tear it apart if I wanted, but it is strong enough for all practical purposes. 

The hanger on the backside was made using the same pieces that I used for the Marty&Doc clock (see the image above).
That's it! It's fun to watch little Harold moving in circles... 

More BTTF Clocks/Watches

Some time, after building these clocks, I built a replica of the "Twin Pines Mall" sign, with a functioning clock - and I wrote code to display BTTF watchfaces on the cheap LiliyGo T-Watch 2020.

Related

My other blog posts on BTTF-related props and pieces:
   - Building a Flux Capacitor
   - Building the Time Circuits
   - Building a Hoverboard and Charger
   - Building a BTTF Brick Stage (featuring the smallest Flux Capacitor)

   - Back-to-the-Future Watchfaces for the LilyGo T-Watch 2020

   - Building the Twin Pines Mall Clock from "Back to the Future"

Here is the image in full resolution