Futaba 3UCP 3D printed battery cover

Last year I purchased a couple of Futaba 3UCP transmitters on eBay that were missing their battery covers.  Here are pictures of one of them, front and back.

Futaba 3UCP 3 channel 2 stick transmitter (front)

Futaba 3UCP 3 channel 2 stick transmitter (back)

Futaba 3UCP battery compartment

Both transmitters were in good condition with only minor blemishes from usage.  The single major problem with each of them was the missing battery cover.  Apparently, the original owner was using some sort of larger battery pack and misplaced the covers over the years of owning them.  The seller, who seemed to be a clearance house company, searched for them to no avail when asked about them.  Knowing the covers are practically impossible to find, and with no response from Futaba support, I bought the radios anyway at a reduced price due to the missing covers.  The hope was that I'd find some hole-in-the-wall place online or eBay auction with covers for sale at some point.  I knew this would be unlikely, but worst case, these units could be useful as spare parts for my somewhat large collection of 3UCP transmitters if anything ever went wrong with them.

Here is what the original battery cover looks like:

Original Futaba 3UCP battery cover (front)

Original Futaba 3UCP battery cover (back)

After studying the OEM cover in detail, I decided it might be worth trying to see if I could create a 3D model of the battery cover and have it printed in plastic by a company like Shapeways (http://www.shapeways.com).  Having practically no experience in 3D modeling and design, I asked people on the TamiyaClub forum what they use for design software.  One person suggested using Rhino, but the trial version lasts 90 days and the full version was US $1000.  Although I figured I could create the battery cover in under 90 days, I would ultimately be left with nothing to use after that point in case I wanted to create other things for printing and I really didn't want to spend any money if at all possible.  In the end, I used Blender (http://www.blender.org) because it was free and appeared to have a fairly large user base, including many helpful tutorials on Youtube. Blender also seemed to be fairly powerful with many features that could allow my 3D models to become more complex as my skills improved.

After 10 hours of measuring the original battery cover, reading and watching tutorials and playing around on my own, I finally had the first version of the cover ready.

I created an account on Shapeways, uploaded the model and ordered it in strong and flexible plastic dyed black.  After a week and a half, it was delivered to my door.

Incredibly, it fit into place and actually snapped shut with a very nice clicking sound much like the original part!  I had to file down the top two corners because I forgot to round them in the 3D model, but I was amazed that my very first try at 3D printing actually worked and was completely useable.  The printed cover certainly wasn't perfect - it had gaps around the edges and did not contour perfectly with the transmitter back cover, but with some tweaking I was sure I could make it look and function even better.  

For version 2, I added some rounding to the two corners that I had missed and widened it so the door wouldn't show such large gaps on the sides and top.  I also pulled the bottom rear curved part back a little bit to make it larger than a 90 degree angle in order to more closely mimic the original door contour.  I had missed these things during my initial measurements and modelling.  I uploaded version 2 to Shapeways, ordered it, and waited another couple of weeks.  Here is version 2:

The second version functioned better and looked much nicer than version 1 when installed. The width was now perfect and the overall fit was much tighter, but I still wanted to make a couple more minor tweaks to the door in order to get it to fit more closely like the original part.  I increased the size of the rear stubs so the rear part of the door wouldn't lift as much and show a gap, added material to the hook part of the front barb so the door wouldn't pull down as much and leave a gap and finally enlarged the "OPEN" text so the 3D printer could have an easier time with it.  Upload, order, wait.  Here is version 3:

The third version fit very well with the same pleasing "click", but the looks were not quite as "clean" as the second version.  By clean, I mean it didn't quite fit snug at the top and sides like version 2, which had practically no gaps.  I do not know why this happened, because I did not modify those dimensions in version 3.  Also, it looks like a different model or brand of 3D printer created version 3 because the plastic looks and feels slightly different.  This may explain why the fit isn't the same as version 2.

At this point I thought I was playing within the realm of the resolution of the 3D printers themselves, so further attempts at refining the door might result in something that no longer functionally fit depending on which 3D printer created the part.  I decided that version 3 would become the final product.  3D printing is very different from a mold where each part comes out exactly the same.  Some variation is to be expected each time an object is printed, though it is usually very minor.

I created a store on Shapeways and enabled the ability for others to purchase it for themselves.  If you have a Futaba 3UCP transmitter that is missing its battery cover, you can now order a 3D printed one on Shapeways by clicking here.  Please note that the 3UCP battery cover is unique to this model and does not fit any other Futaba transmitter.

The Futaba 3UCP: My Radio System of Choice

I am old school when it comes to radio control systems.  All of the store-bought cars and trucks I had as a kid were controlled by 2-stick transmitters, so when it came time to purchase the radio system to go with my brand new Tamiya Super Champ kit in 1984, I chose a 2-stick system from Futaba.   Back then pistol grip transmitters were unheard of, if in fact they existed at that time (I honestly cannot remember).  

The radio system I got to control the Super Champ was the FP-T2NL Attack with FP-R2GS 2 channel AM receiver and two S28 servos on channel 82 (75.830MHz) in the 75MHz band.  It was a low-end radio system, being AM and only 2 channels, but back then 2.4GHz did not exist, and FM was relegated to the elite few that could afford the higher price of less glitchy control.  I certainly was not one of them.  Having been used to the cheap AM transmitters included in the store-bought cars, the Futaba Attack system was an incredible upgrade in terms of workmanship and feel.  The transmitter felt heavy, especially with the 8 AA batteries installed.  The plastics looked and felt high quality.  The sticks were knurled and machined aluminum.  The gimbals were incredibly smooth and precise.  There was no side-to-side wobble and no stiffness or weird resistance to movement like the cheap toy transmitters I was so used to.  Just precise control.  The sticks felt like they were supported by ball bearings to my inexperienced hands, even though they weren't.  The servos directed the horns exactly where the sticks told them to, every time.  There was even a voltage meter on the front, which, when the radio was turned on, showed the output level of the batteries so you'd know if it was time to replace them.  I had finally made the leap to "hobby grade" radio control, and it was awesome.  I still have that radio system, and it still works fine.  It's old and dirty and it's not mounted in any of my cars any more.  Only one thing could make me retire that system:  A better radio system.

In the early 90's, pistol grip systems were becoming more popular.  The major brands like Airtronics and Futaba were designing some very sophisticated radio systems for cars and boats.  But I was still used to the 2-stick transmitter.  It was what I grew up with.  I mean, I could get used to a pistol grip, but I still had a preference for thumb control.  There were a few reasons to want to upgrade the radio system I was using for my growing fleet of ground and water vehicles.  First, AM was beginning to take a back seat to FM, and then PCM, and the greater precision and resistance to interference was getting more important in my eyes.  Watching one of my vehicles go off on its own into a curb or other immovable object was not something I wanted to see more than once.  Believe me, I had seen it, and it was not pretty.  These cars were not cheap and back then I wanted to drive, not fix broken A-arms.  Second, the trim settings for each vehicle were slightly different, and it was a pain to reset them each time I switched to another vehicle, so multiple model memory was required.  Third, the FCC had just changed the rules for the radio control spectrum, and narrow band was now mandatory for all new radio systems.  The old radios were still allowed for a few more years, but the writing was on the wall for my old system.

Then, I saw the radio system of my dreams:  The Futaba 3UCP Field Force 3.  The 3UCP was a 2-stick, 3 channel radio system that used Futaba's PCM1024 technology, which, at the time, was some of the best technology available.  It came with the R113iP PCM1024 3-channel receiver and two S9301 servos.  It had everything I had ever wanted in a radio system, but the price was way out of my league.  I was still in college at the time, with no job, so there was no way to afford a luxury item like that.  At least not until I graduated and started making money. 

After graduating in 1993 and getting a job later on in the year (there was a small recession back then, remember?), I finally had some money that could be spent on "toys" such as these.  Futaba was still making the 3UCP, so I bought one.  Finally, I got what was the absolute top of the line 2-stick radio system ever made by Futaba for ground-based vehicles at the time.  It was computer controlled, with a large LCD screen, 6 model memory, programmable mixing, throttle exponential, dual rates, sub-trim, 4-wheel steering, tilt, twin servo control, lap timers and more. 

The Futaba 3UCP Field Force 3 PCM1024 transmitter

It was so complicated that it scared me a little.  I had to learn what all of these functions did, and get used to the terminology.   There was ATV, D/R, EXP, and CURV to name a few.

Just some of the display/setup screens on the 3UCP

My only wish about the 3UCP:  A way to program the name of the vehicle, even just 3 or 4 letters, in each memory slot.   As it is, I have to keep a piece of paper with each transmitter to know which model number goes with which vehicle.  It's really the only complaint I have about it.

The 3UCP was never very popular in the United States, mostly because it was a 2-stick design.  Most big-name and club racers were using pistol grip transmitters.  Also, it was very expensive at around $380 in 1994.  This price was significantly more than its pistol grip counterpart at the time, the 3PB Magnum PCM1024, which sold for approximately $290.  Futaba stopped production of the 3UCP sometime in 1996.

Fast forward to today, and I'm still using the 3UCP to control all of my ground-based vehicles.  My fleet of vehicles has grown over the years to around 24 running models and many more still in kit boxes, waiting to be built.  I now own five 3UCP transmitters and 30 R113iP receivers, exactly enough to max out each transmitter's model memory.  Four out of the five sets I have were brand new when I got them, and the 5th was in very good condition and only needed a new FP-TP-FM transmitter module to make it complete.  As it turns out, the TP series of modules are hard to find in 75MHz ground format, but I finally got one.

My "fleet" of 3UCP radios.

I keep all of my 3UCP transmitters in radio cases for protection from dust and damage. 

I have upgraded the batteries in each transmitter using an 8 cell 9.6V NiMH 2200mAh pack from http://www.batteryspace.com.  The battery pack fits in the compartment along with some foam and uses a connector for easy replacement.  I had to open each transmitter in order to solder the connector, but it was very easy to do.  Now there are no more corroded 9V connector tabs and wimpy Futaba 500mAh NiCd battery packs.  The runtime is something like 4 hours.

My next plan was to buy one of Futaba's newest flagship 2-stick radio systems, the 2.4GHz 3VCS, however Futaba recently discontinued it and removed it from all storefronts.  I really wish I had bought one when I had the chance since it is impossible to find now.  The 3VCS seemed like a worthy successor to the 3UCP.  Now I don't know what I will do once I max out the model memory on these.