Fab Academy requires the creation of a final project to demonstrate the students proficiency in as many of the taught subjects as possible. FabPad
was my third chosen project. The first was too broad and out of the scope of the time offered. The second died from defused interest.
I elected to pursue FabPad because it offered diverse opportunities to build. After all, that’s what this class is about – making.
To almost all, the need and use of FabPad is unknown. I am involved in the education of youth in space sciences and rocketry. The world of mid
and high power rocketry is introduced to the students. In northern Ohio, this means flights to 20,000 feet and rockets as large as 10 feet in
length with powerful engines.
In the last several years, very specialized software has been developed to assist the flyer with flight predications such as max altitude,
accelerations, drift, and projected landing location. FabPad will assist the user by provide live wind data and launch angles. Additionally,
accessory masts are available for such things as photography.
Inspiration for FabPad
Over the last several years, NASA has reconnected it’s primary launch pad for the whatever our next manned space program is. I thought it would
be appropriate to upgrade my own launch facilities as well.
FabPad will become part of a launch system that will help educated students on the effects of environmental conditions and how precise pad adjustments
will assist them in launch predictions.
NASA Launch Pad 39b
FabPad with rocket ready for flight
FabPad Design
Over the last several years, NASA has reconnected it’s primary launch pad for the whatever our next manned space program is. I thought it would
be appropriate to upgrade my own launch facilities as well.
FabPad will become part of a launch system that will help educate students on the effects of environmental conditions and how precise pad adjustments
will assist them in launch predictions.
Superstrucure Construction
The superstructue was designed, modeled, and drafted in both 3D and 2D using AutoCAD. The files were then broke apart
and opened in Aspire. The cut files ewre created using a 1/2" End Mill operating at 1.66 IPS and 12,000 rpm. This proved to be
much more effiecent than a 1/4" bit.
I was extremely happy to have a successful, good quality cut on the first attempt.
The pieces were taken back to my home shop and rough assembly was completed.
Design 2D drafted in Autocad
1/2" signboard in Shop Bot
1/2" Endmill making cuts
Rough assembly
Design Features
To the left you can see various features incorporated into the construction of the
Fab Pad. Note that the pad is designed to fold up onto itself for transportation.
I currently just have a piece of rope trying it together. In the future, a strap would be better.
When untied, the legs dop down to the ground. The user simply graps the center and lifts up to
bring it to position. Note how the legs hit each other in the center.
The red acrylic blast deflecter stand off slides into position. The proper launch rod is selected and screwed into place.
The head base is constructed in two heavy halves connected by a single hinge and two locking hasps. This feature is used to load rockets.
Many time the top of the rod is too high to reach. The head is split open and tilted, the rocket is loaded, then the head returned and locked.
The cool looking composite blast deflector is put into place to protect the pad from flame and heat.
Standoff Design and Construction
The Standoff was design to be removable for travel. It was laser cut from cast acyrilic on the Epilog Matilida Laser cutter.
Settings for the vector cut were 5000freq, 100% power, 6% speed.
Once cut, the assembly was joined with cyanoacrylate (CA) glue. I have small screws to create a physical joint that is less suseptical
to shock.
Design 2D drafted in Autocad
Front of Standoff
Rear of Standoff
Blast Sheild Design and Construction
Every launch pad requires a blast sheild. First off, it stops things from catching on fire. Secondly, itjust sounds cool to say you have one.
I happen to have a couple hundred square feet of spare diamond plate, so it looked like a good material choice for me.
As I'm always one to have a little fun, I decided to have some "messy fab" techniques I learned in the composite section thrown into the project
for good measure. The diamond plate would probably be ok by itself, but I think some extra insulation between the flame and heat and the standoff
would be beneficial. So, looking around the shop I found a nice chunk of 1/2" drywall. That should make for a nice heat sink.
I grabbed my aviation tin snips and cut me a nice shape, then made a couple of bend on the edge of my table saw. I hit the adges with some sand paper to
prevent cuts. Then I cut the drywall to fit. Finally a second piece of diamond plate was cut and shaped to snap onto the standoff.
Now the fun part. I mixed some fiberglass resin from my friends at Bondo. I poured a solid 3/16" layer directly on top of the diamond
plate. Next I wet down the drywall and wrapped into in a layer of fiberglass cloth. I then centered the second plate and encapsulated it with more cloth
and resin. Lastly, I soaked down the entire assembly. I'm glad I was sure to cover all my worksurfaces, wear proper PPE, and use disposable tools.
As I don't have a vacuum bagger, I decided gravity was my friend. I put the assembly flat on some covered asphalt and ballanced 3 concrete landscape
blocks on it. I ended up with a nicely clamped assembly.
I then moved on to other projects. By the end of the night I came back to a rock hard Blast Deflector.
Compass Rose Design and Construction
It's always next to get a chance to spend some quality alone time with your fab instructor. I imagine that
Scott thought my 3 hour and 7 minute laser job was a little much for a Friday night.
I do have to say, even though the engraving time was painfull, the results came out great.
In order for me to have precise readings on the pad, I needed percise guages. I created the artwork for these in AutoCAD, then
after numerous setting tests, engraved the image onto a special markable aluminum called Alumamark. Althought the image came out great, it
took over 3 hours to raster it. Also, the laser cannot cut the material. The settings used was 100% power at 3% speed.
After lasering, hand work had to be done. In truth, I love doing this type of work as my personal shop is really set up for the task. I began
with some snips to cut out the circle. I quickly realized that this was overkill. I substituted some sharp scissors. These did the job very well.
Attention had to be paid to not bend the material as you sheer through it.
Next I took the metal over to my disk sander. It is best to use a sacrificial board tight up to the sandpaper with thin material. I proceeded to
rough sand the stock. I then was very careful to get a small piece of the circle sanded to the exact point.
The machine was turned off. The material was snuged to the sandpaper in my chosen spot. In the exact center of the circle, a screw was driven to
provide a perfect rotational point. Holding on very tightly and carefully, the sander was powered up. The material was rotated a couple
of time yielding a perfect circle. The elevation guage was formed in a similar method.
Although a lot of time was spent on these two pieces, the professional looking results make the whole project stand out.
2D Artwork
Final timeclock on laser
Rough cutting the alumamark
Rough sanding
Precision sanding
Just taking the line off.
Great results
The Anemometer
This piece of the project once perfected will probably be the most useful tool. In addition to knowing the windspeed, it is valuable to read the gusts.
Let's just say launching in a sudden gust is bad......
My anemometer parts were drafted and 3D printed. As a side note, I believe that I've used ever significant machine in the fab lab for this project short of the
scanner and the vacuformer.
I intentionally made the sockets for the connecting rods tight. The assembly is held together with friction fit. So far I have had it in varius temperatures
without an issue. I primed and painted the part. It balanced satisfactorially. A 1/8" dia. all-thread is used as the shaft. A nylon bushing holds everything together.
Initially I wanted to house everything in the 1/2" PVC. This is proving dificult to work with and the PCB isn't fitting correctly.
In intial testing of my mechanism I discovered that the rotational force provided by the wind is exponetially
effected by the turning mass. This means that I need to cut down on any contacts, or phyical generators to provide a reading.
I am going to try to use my hello.reflect board to generate a usable signal. A very light cardstock piece will be attached
to the shaft. It will be placed so that it interfers with the IR LED. When the shaft spins faster, a higher signal will be produced.
All I need to do is modify the existing reflect.py program in the archive to restricted it to my single desired signal.
I downloaded the program and found that it was most easily edited in wordpad. I would normally work in notepad, put it does not
display the format correctly. This makes it much harder to work on.
The program was stripped down of unneeded GUI components. As this is interface is designed to be used out on a field at possibly
a large distance, I enlarged the GUI box. Additionally, I enlarged the font and chose colors with higher contrasts.
Further work that needs to be performed is the calibration. I need to borrow a commercial anemometer to compare and give a multipler to the
proper variable.
Additionally, I am going to further enlarge the GUI to almost full screen. This will allow for easier reading.
Note: More complete documentation for the anemometer can be found in Section 10.
Overall assembly
3D printed movement
3D file
PCB
Component
Interface
Assorted Extras
This page is getting rather long,but I want to quickly point some features that may have been overlooked.
-- The "FabPad" logo was cut in three different colors on the vinyl cutter. It's purpose was only to provide some name recognition.
-- The wind sock was made from lightweight ripstop nylon. It is glued on some 1/8" dia steel stock I bent around a paint can. The
ends are inserted into a bearing and filled with epoxy. The bearing is glued on a 1/2" pvc slip coupling.
-- The Upper and lower mast capture system is constructed of PVC slip couplings that have been threaded to accept thumb screws. Masts are simple
1/2" diameter steel electrical conduit with misc. fittings. The capture system is designed to allow for angled mast placement if desired. In
the event of unusual circumstances, the masts can be driven into the ground to stake down the pad. Always remember to secure the upper arm capture
first or else it will fall on your head when securing the bottom!
-- Interchangable launch rods are rails have been constructed using chrome threaded fittings that screw onto the pipe on the head. the rods were carefully
clamped vertically in the center of the fitting. The bottom half of the fitting was filled with clay to hold it in position. Epoxy was then poured into
the fitting to secure the rods.
-- The Camera Arm is simply a piece of electrical conduit. I cut several different lenghts so various configurations can be put together. The unusual
looking clamp and mount is a Dinkup System Action Pod. This item really filled the need perfectly, and I had a coupon for $20 off! Normal cost is $34.
Distribution Plans:
I am electing to make Fab Pad “Open Source”. Individuals that have the resources are free to use my plans and data to build their own and improve the design.
My dissemination plans are to simply start a thread on the popular interent forum "The Rocketry Forum" introducing Fab Pad and linking back to the Fab Academy archives.
Just some cool Vinyl
Colorful Windsock
Upper Arm Mast Capture
Lower Mast Capture
Interchangable Launch Rods
Camera Arm
Bill of Materials
| Item |
Quantity / Size |
| 1/2" MDO Plywood (Sign Board) |
4'x5' Used |
| Heavy Duty Strap Hinges |
6 |
| Locking Hasp |
1 pair |
| 3 1/2" Hinge |
2 |
| 1/2"x3" axle bolt |
1 |
| 1/2 PVC slip Couplings |
6 |
| 3/16"Thumb Screws |
12 |
| Knurled Knobs |
5 |
| 16"x16" Alumamark |
1 |
| 12"x12" Cast Acrylic |
1 |
| 1/2"x6" Misc metal |
1 |
| Diamond Plate |
20"x20" |
| Bondo Fiberglass Resin |
1 quart |
| Ripstop Nylon |
24"x54" |
| 1/2" Drywall |
12"x12" |
| 1/2" PVC Pipe |
3' |
| 1/8" Steel round stock |
36" |
| 3/16" Allthread |
12" |
| 1/2" Steel Electrical conduit |
40' |
| 1/2" Conduit Couplings |
10 |
| 1/2" Conduit 90 Degree Angles |
6 |
Electronics Bill of Materials
Part Value Device Package Description
C1 1uF CAP-US1206FAB C1206FAB
J1 AVRISPSMD AVRISPSMD 2X03SMD
J3 PINHD-2X2-SMD PINHD-2X2-SMD 2X02SMD
R1 10k RES-US1206FAB R1206FAB Resistor (US Symbol)
R2 1k RES-US1206FAB R1206FAB Resistor (US Symbol)
U$1 LED LED LED1206 LED
U$2 ATTINY45SI ATTINY45SI SOIC8
Note: Individual various fastners shall be provided. This project has been built using thru bolts whenever possible, and as little
as possible screws. No nails were used! T-nuts were employed on all plywood when possible.
In addition to the materials listed, various adhesives, primers, and paints are used.
Thoughts & Conclusions
The purpose of this project was to design a mid and high power launch pad with advanced features. I think what has been
constructed meets these objectives.
In evaluation, two items need direct attention. First, this pad was designed to be strong and durable. It is. But not enough.
Rocket launches take place normally in the worse location possible. Only once in 35 years of rocketry did I launch on a sod farm.
That was paradise. I normall am found in a plowed under farms field with manure, chemicals, mud, and ditches to climb over. The pad needs
to be made more robust.
Secondly, in order to hold typical high power rockets, the head will need to be completely redesigned. The moment exerted on the elevation hinge
and support arm are too great. In truth, most of the head would be better constructed out of steel. This is out of the relm of the typical Fab Lab.
If you made it this far, I thank you for reading! I'd like to give my sincere thanks to Scott, Neil, Anna, and all the staff that made Fab Academy 2015 possible. Well done.
