MMX Plastic Screw On Retainers

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TopRamen

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I was recently toying around with the idea of finding a way to make a screw on retainer from Aluminum for 13mm rockets, but one thing led to another, and I ended up with a workable model in plastic that fits MMX motor tubes.
They are made from the plastic caps that you would use on valve stems for tires.
I was not going to post them here, as I knew they would be met by criticism due to adding unnecessary weight, but I have refined the making process so that there is only as much material as is required to efficiently hold the motor, so I hope it will be well received.
I am not saying this is any better than any other method, it simply adds "Something Different" to the MMX idea.
I flew it on my stock Fliskits Teeny Triskellion and it did not impede performance.

Yesterday, I accidentally static tested it, as in I had put a piece of masking tape on the launch lug and rod of one of my MMX models to hold it steady while I carried it out to the pad, but forgot to remove the tape before launch, resulting essentially in a static test, with no damage resulting to either pad or rocket. The only notable damage was my embarrassment at my mistake. :facepalm::blush:

Here is the jig I made from a valve stem, that I chuck in my hand drill to spin them. They are pretty self-explanatory.

MMX Retainer Holding Jig 2016-04-24 004.jpgMMX Retainer Holding Jig 2016-04-24 003.jpgMMX Retainer Holding Jig 2016-04-24 005.jpg
 
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Top,
That's looking fantastic! If I ever started into the world of micro, I for one would certainly trade a little performance for the aesthetic gain. Keep up the strong work, I continue to read these threads with much interest
 
Top,
That's looking fantastic! If I ever started into the world of micro, I for one would certainly trade a little performance for the aesthetic gain. Keep up the strong work, I continue to read these threads with much interest

Thank you.
 
Maybe this is just a brain fart on my side,but what do the modded valve caps/retainers screw onto on a model that small?
 
Maybe this is just a brain fart on my side,but what do the modded valve caps/retainers screw onto on a model that small?

The portion of the motor tube that sticks out the back. It just threads itself right onto the paint, then when you remove it, the threads stay there like magic.
On a future build that I'm working on right now, I'm actually going to get a thread cutting die, and make the threads from JB Weld infused with Fiberglass to lighten it.
I'll drill 4-5 super tiny wire gauge bit holes in the cardboard tube prior to cutting the threads into the JB Weld Epoxy concoction.
As I said, it may not be practical, but that is not the purpose of doing it. I'm doing it because I'm having fun doing it, and it gives me experience working with stuff I don't work with everyday to develop new ideas.
I'de have grown tired of rockets long ago if I did'nt keep trying things that looked silly to other folks that only care about performance.
 
I figured the valve stem was used for the threads. Didn't realize just the cap works. Guessing the neighborhoods of people reading this will experience a mini crime spree as the valve caps disappear from cars at night.
 
I figured the valve stem was used for the threads. Didn't realize just the cap works. Guessing the neighborhoods of people reading this will experience a mini crime spree as the valve caps disappear from cars at night.

I lucked out, as my Son has like 15 bicycles that are in various states of disrepair, plus a few working ones. They just sort of accumulate in my sheds and behind my house.:confused:
He likes to take parts from one and mix it with another, and another, and so on...

I used to have some sweet caps on my Cannon's wheels, but I think my Son stole them for one of his bikes.:(
They were just for show anyhow, as I found it is best to simply fill it's wheels with expanding foam, they being an odd size and all.

I have some cool silver ones on my truck, and they are plastic, but it's my truck, so it's obviously off limits til' I get money to go shop for some new ones.

Walmart has plastic ones that are made to look like metal, for like 2-3 dollars, and I'll hit up the auto parts stores that I frequent too.
There has to be some really perfect ones out there for using as retainers.:)

now that I can just chuck any cap in any drill, there is no reason not to have a wide selection to choose from to suit whatever style of rocket I want.

Metal caps are all too heavy for this size rocket.
 
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I've been reading these MMX and little rocket threads too much. I bought a GMA 13mm research hardware set on here just now. They look really cool at least. Just realized no motor ejection, so if I do use it, I need an altimeter in the little thing (or a saucer with tumble recovery).
 
I've been reading these MMX and little rocket threads too much. I bought a GMA 13mm research hardware set on here just now. They look really cool at least. Just realized no motor ejection, so if I do use it, I need an altimeter in the little thing (or a saucer with tumble recovery).


I noticed that! I always miss the bus on the Green Monkey Research Kits, but one of these days I'll be in the right place at the right time or search one down when I have the funds. I don't have the room right now to set up a mixer and the likes to make sizable batches of composite propellant, so if I ever get into that sort of thing it would have to be on the small scale, batches of 100g. or less.
When and if I ever get a new house and sell this one, it has to have a nice outbuilding that can become a rocket factory.
I was not into rockets again when I bought this place, and it is too small for pretty much anything fun, even though there is 13.5 Acres of woods and logging trails.
My next place needs the rocket factory and a 20+Acre field for flying.:)
 
I noticed that! I always miss the bus on the Green Monkey Research Kits, but one of these days I'll be in the right place at the right time or search one down when I have the funds. I don't have the room right now to set up a mixer and the likes to make sizable batches of composite propellant, so if I ever get into that sort of thing it would have to be on the small scale, batches of 100g. or less.
When and if I ever get a new house and sell this one, it has to have a nice outbuilding that can become a rocket factory.
I was not into rockets again when I bought this place, and it is too small for pretty much anything fun, even though there is 13.5 Acres of woods and logging trails.
My next place needs the rocket factory and a 20+Acre field for flying.:)

I got the outbuilding, no yard for flying. Barely worth having a push mower.

Never mixed smaller than 500g batches. Usually, smaller grains are made from leftovers.
 
Thanks for liking it! I made sure to make it as light as possible to avoid your wrath.:wink:
I actually learn quite a bit from you.

Your welcome:
One question. Did you have to off-set you launch lug to miss the overlapping plastic cap?
I can think of many places where this retainer would be a perfect fit particularly in T-3 and larger main body models. Looks to me like the OD of the Retainer cap is about the some size as our T3 body tubes (.375").

If you'er not haveing any problem with the self-threading on T2+ tube, I think I'd simply thread it, Water thin CA the threads & re-thread the cap. JB Weld is just to heavy an epoxy for just about any use with micros. You might want to try Devcon 2-ton clear(30min) or 5-minute if you really must use epoxy. 2-ton & Devcon 5min. epoxies threads well with standard steel thread cutting Taps and Dies without the extra metal fillers making both a bit lighter overall.
 
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Your welcome:
One question. Did you have to off-set you launch lug to miss the overlapping plastic cap?
I can think of many places where this retainer would be a perfect fit particularly in T-3 and larger main body models. Looks to me like the OD of the Retainer cap is about the some size as our T3 body tubes (.375").

If you'er not haveing any problem with the self-threading on T2+ tube, I think I'd simply thread it, Water thin CA the threads & re-thread the cap. JB Weld is just to heavy an epoxy for just about any use with micros. You might want to try Devcon 2-ton clear(30min) or 5-minute if you really must use epoxy. 2-ton & Devcon 5min. epoxies threads well with standard steel thread cutting Taps and Dies without the extra metal fillers making both a bit lighter overall.

I sanded it down thin enough that it works with the Teeny Triskellion and the scratch built rocket in the pics. I suppose if you tried to use them on a MD bird you would need a riser to make it clear the launch lug.
 
The JB weld threads work, but I used cotton fibers in them as I forgot to get a strand/thread of fiberglass ready, but had Q-tips at hand.
It was tricky wraping the spent motor in Teflon tape, as it is so small, but I got it done and the rivets are there. I used a #58 wire gauge drill bit to make the holes for the epoxy rivets. JB Weld is heat resistant, much more so than other epoxies, so it should hold up, but if it fails I'll let ya'll know and share pics'.
Remember, I don't give a crap how high it goes, as long as it is safe to fly and enjoyable to build. If it reaches an apogee of 25 ft. I'm happy, as long as that motor is held in there with my retainer.
I'm not competing for anything or with anyone, just building to suit my own tastes, and loving every minute of it.
The hardware store was unable to figure out what size threads the valve stems were, as they apparently don't have a thread gauge in the agro bin isle anymore. Thusly, I was unable to acquire a cutting die. I screwed the tightest fitting metal one I had on there, and it left it's threads, but I'm going to cut a slot through it with the rotary tool to make it into a thread cutter.
To make up for adding weight, I made the fins and wings entirely from paper. I have to make batches, then choose the best ones, as it is tricky to tack paper together at this scale.


MMXSPARROWREARFINS 2008-01-09 003.jpg
 
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Oh and I found this for the threads but have no money left to buy a cutting die til' next month:

The standard Schrader valve has the following threads:

External thread

Metric: 7.7 mm OD, thread root diameter is 6.9 mm × 0.794 mm pitch
Imperial: 0.305 in OD, thread root diameter 0.271 in × 32 tpi (threads per inch; thread density)
 
Outstanding! I've earned the official "One Star Stamp of Approval", meaning my idea is truly groundbreaking and a winner!

Thanks One Star Guy! You validate and inspire me to greatness!

I'll have to use more JB Weld on Micro builds from now on!
 
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Outstanding! I've earned the official "One Star Stamp of Approval", meaning my idea is truelly groundbreaking and a winner!

Thanks One Star Guy! You validate and inspire me to greatness!

:lol:

I hope you don't mind if I voted it back up a bit. I'm not into MMX but this is cool.
 
:lol:

I hope you don't mind if I voted it back up a bit. I'm not into MMX but this is cool.

It does'nt matter to me, as the Star thing is kinda' silly, but thank you.
I honestly don't build for anyone but me, unless I'm building something for someone else to help develop a technique.
 
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