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The Simple $86 Do It Yourself Infrared Controlled Lego Lens Sled

post #1 of 36
Thread Starter 
After a few months of tinkering, I thought I would share my simple do-it-yourself infrared controlled lens sled. The commercial lens sleds out there are ridiculously expensive and I thought I could build the same thing for much less.

This is completely controllable by a universal IR remote and doesn’t require any fancy limit switches or a control system. I’m using the HTB Lens.
Total cost of all parts for me was $86:

Lens sled retracted:


Lens sled extended:


The key working parts of this system are some cheap Lego parts. Lego has a category of product called “Technic” which is their more advanced robotics brand. They have motors, IR receivers, transmissions, etc, and the key components can be bought as separate parts on Lego.com.

Here’s the Lego parts you need:

Battery Box $6.49


XL Motor $9.49


IR Receiver $13.99


IR Remote Control $8.99


You’ll also need a shaft, wheel, and tire. These are a little tougher to find, but you can find millions of lego parts on E-bay at many E-bay stores (The Brick Place, FindMyBrick, Finders Keepers Brick Shop, just to name a few). Or you could go to Wal-Mart and buy a small Technics lego kit that has the parts (or steal the parts from your kid)



Picture of the lens sled with the parts labeled:


Attach the motor to four small 90 degree angle brackets using small spring pins (they are hollow and are cut down the length to allow them to be compressed into a smaller diameter for insertion). Would suggest taking the motor to the hardware store to make sure the pins fit. Then attach the motor and bracket assembly to a piece of MDF or wood with wood screws:


It’s a simple concept, just install the Lego tires (I used two wheels stacked against each other) against the drawer slide and then command the lego tires forward and backward with the remote control. I had to attach a piece of aluminum to the drawer slide to get a consistent smooth surface and the right tire height, but you can probably find a better drawer slide than I used if you looked. Glue the shaft into the motor, and glue the wheels onto the shaft. Place some small 90 degree angle brackets where you want your travel stops (you can see in the picture above that I placed a screw in one of these brackets so I can fine-tune the extended stop position). What’s cool about this is that you don’t need any fancy limit switches, just power the motor against the stops and the rubber tire “skids-out” if the remote command is a little too long.



As for providing power, the battery pack requires 6 AA batteries, which ends up supplying 9V to the motor. You could use batteries if you want, but you’d have to turn it off every movie session, or you’ll be replacing batteries every few days. What I did instead was use a 9V DC adapter from E-bay, and then hooked it into the circuit. This way I can leave it on 24/7. To complete the full connection circuit, I used copper wires to simulate the batteries, and glued them in with conductive adhesive and/or solder. (Be careful if you solder, there is a circuit board in the battery box, and I toasted the first box because I can’t solder worth a crap). Here’s one side of the battery box opened. The black and red wire go to the DC adapter:



And here’s the other side of the battery pack (the white wires are the battery “replacements”):



6 AA batteries put out a fair amount of current, so make sure you get at least a 1 amp DC power supply:



I programmed my Harmony 880 remote control to learn the commands from the Lego remote. I velcro’d the IR receiver to the MDF base plate so that it faces the big-screen. This way I can point the remote at the screen, and the IR signal reflects off the screen to command the lens sled.

So, final parts list and cost:

$6.49 -- Battery Box
$9.49 -- XL Motor
$13.99 -- IR Receiver
$8.99 -- IR Remote Control
$13.00 -- 1.0 Amp DC Power Supply
$6.00 -- Drawer Slides
$8.00 -- Misc. Lego Parts (shaft, wheel, rubber tire)
$20.00 -- Misc wood, brackets, screws

About $86 bucks. I’ve been using it solid for two months now, works great.

And finally – I made a video on YouTube showing it work:

http://www.youtube.com/watch?v=oLYWP6lRxoU

So let the Lego fun begin and let’s see if you guys can improve on the design!
post #2 of 36
I've said it before, and I'll say it again
Great job Banshee! You've got me thinking now

(we previously posted that the battery box could perhaps be bypassed with the power going straight to the IR receiver)
post #3 of 36
I was all ready to LOL cuz I thought you made the actual track out of Legos. But, I must say that's a pretty cleaver use of the lego motors.
post #4 of 36
This is brilliant! LOL
post #5 of 36
very nice! you could market this for $1500
post #6 of 36
This is totally the DIY spirit! Kudos.
Sorta reminds me of reading me recently favorite magazine, http://www.makezine.com/
post #7 of 36
Okay, so I have the urge to break out my Legos that have been in storage for years and build a motorized sled. My only suggestion to make it better would be to add some gearing to slow the sled movement down. Also I wonder if the smaller motor would work. Looking at it though it seems mounting it would be more difficult.

post #8 of 36
Thread Starter 
With gearing you can definitely use a motor with lower torque, and I would bet the smaller lego motor would work. The main disadvantage with gearing of course is there are more parts that could break or malfunction. But by all means give it a shot - look forward to seeing it.
post #9 of 36
Banshee, we need more people like you on the forum.

Thanks for the Post and time explaining it!
post #10 of 36
Awesome stuff....

Steve
post #11 of 36
I checked it out on YouTube...WOW Factor!!!

Steve
post #12 of 36
Phenomenal. Time to bond with my son.
post #13 of 36
this thing is soooooo coool...
post #14 of 36
Maybe paint the parts or something...Legos don't look "professional", however, that was one wickedly good idea!
post #15 of 36
This looks fantastic. A brilliant idea. Very nice solution for the people wish to have budget motorised sled. Just wondering about the durability and longevity of Lego components.
post #16 of 36
Thread Starter 
Quote:
Originally Posted by syncguy View Post

This looks fantastic. A brilliant idea. Very nice solution for the people wish to have budget motorised sled. Just wondering about the durability and longevity of Lego components.

Well, even if the lego motor breaks down (again, my lego system has been going strong for almost three months), at $10 a motor, you could buy 200 motors or more for the price of the "professional" sleds out there... it's an easy thing to replace the motor.
post #17 of 36
Great stuff. Love it.
post #18 of 36
Great idea. Why not try a small cheap remote control car and just use a back tire?
post #19 of 36
You know...not that this really is related, but I love Legos...alltime favorite toy. This is like "Legos for adults".
post #20 of 36
this is one of the best DIY work I've ever seen

Good work
post #21 of 36
Awesome! You could have used a gear and glued the a track on too but relying on friction seems better. How is it for precision? Does it place the lens where you want it exactly? I'm sure with some of the new lego stuff you can make this bullet proof for less than 200 dollars.

Your next mission, build retractable screen masking with lego.
post #22 of 36
You beat me to it Raoul. Let's see lego masking!
post #23 of 36
Banshee, don't sweat the sarcastic remarks... We Love Haters its nothin

Steve
post #24 of 36
Thread Starter 
Quote:
Originally Posted by raoul View Post

Awesome! You could have used a gear and glued the a track on too but relying on friction seems better. How is it for precision? Does it place the lens where you want it exactly? I'm sure with some of the new lego stuff you can make this bullet proof for less than 200 dollars.

Your next mission, build retractable screen masking with lego.

Using the hard stops, it's very accurate and moves the lens to the exact same spot every time. I looked into a rack-and-pinion system, but the friction method is much simpler and there are no precision part alignments required.
post #25 of 36
It's really awesome! I've been wondering about this for a while. With Mindstorms you could probably handle a 12v trigger too.
post #26 of 36
This is awesome. Thanks for sharing!
post #27 of 36
thanks a million, billion times for your skill and extension of time to share with the avs gang your project!
post #28 of 36
Wow Banshee,

This is by far one of the most creative DIY projects I have seen in a long time.

I am so doing this! It's a very simple solution to an expensive problem. Now I wounder if I could do something like this for a 2:35 to 16:9 masking system. Hummmmmmm...
post #29 of 36
Nice work. You can lower the gearing by just using a smaller diameter wheel if you can find one. That would mean either spacing the track down (washers?) or moving the motor up. It would also mean putting less strain on the motor increasing it's life span.

This really does have me wondering how cheap I can do a masking system. I can think of at least 4 different ways to do it using mostly the same parts just swapping a couple of things.
post #30 of 36
Thread Starter 
The lego sled has now been going for 9 months solid with no problems!
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