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RMS 24/40 Grain Adapter STUCK...

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eugenefl

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Alright...this is my first time using a 24/40 casing and needless to say I am extremely frustrated with it. I carefully followed the directions and assembled the delay portion with no problems. The next step involves inserting the propellant grain, grain adapter, and grain spacer assembly and centered within the casing (without closures). The problem I am having and am now stuck with is that the grain adapter BARELY fits in the casing. To get it to move in an inch I nearly had to put my weight into it. Prior to attempting to insert the grain assembly, I cleaned out the inside walls and LIGHTLY greased the RMS casing. Well, dummy me I used excess force and inserted the grain assembly as far as I could. The grain assembly is now flush with the end of the casing and is covering the threading. Now it's stuck. I can't get the closures on because the cardboard grain adapter is stuck. If anyone has any suggestions, please feel free to submit your ideas now before I lose my mind. I really would like to burn this motor and use it in a rocket as opposed to removing it in pieces.

What's worse it that while I was messing around with the RMS casing I accidentally stepped on my brand new Edmonds Decee Thunder and broke it in about 6-7 places. (Stuff is laying around and being prepped for tomorrow). It was all assembled and ready to go for our Saturday launch. In a fit of rage, angered by the RMS casing and my own stupidity for stepping on the glider, I finished it off by breaking it into tiny balsa pieces. Tempted as I am to chuck the RMS casing as far as I can into the forest, I'm going to set it down and walk away. I guess 2-3am is NOT the time for messing with rocket stuff.

I for one can't stand when things don't fit or work the way they are supposed to. Frustration typically causes us (humans) to start goofing everything else up. It's times like this (or other times - you know you've had them...paint runs, fin sets crooked, you jab your finger with the hobby knife, you step on your body tube, etc.) that really make me hate the wonderful characteristic of being clumsy. Being clumsy has no purpose in life...none.

OFF TO BED I GO....fuming too.
 

KenParker

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Ah, Eugenio, my young friend... the volatile tempestuousness of youth... how I (vaguely... wistfully) remember those heady days. :rolleyes:

I am hoping that with a few hours of sleep that perhaps you have calmed down a bit.

Here is something that you can try. BE VERY CAREFUL DOING THIS, I don't want to read about you burning your fingers trying this. Get your girlfriend's hair dryer - or yours, if you use one. Use it to heat the 24/40 aluminum case. (Aluminum expands a LOT when heated.) You may want to use oven mitts to hold it while you do that, or perhaps a pair of wooden tongs. (everyone has a pair of wooden tongs, right?) You will need to get the casing *quite* warm (read - HOT). If you happen to have a monokote heat gun, that would work even better than a hair dryer, as the monokote heat gun puts out *much* higher heat.

Now, once the casing is *quite* hot, VERY QUICKLY see if you can center the lining in the case. You must do this VERY QUICKLY, as aluminum (I wish I could hear the Brits say "al-u-min-i-um," they should patent the pronunciation of that word), dissipates heat VERY QUICKLY, which means it contracts very quickly.

WARNING: This may or may not work, but at this point, it's probably your only shot at salvaging this situation.

IF... you have to cut the pieces out, and in the process you manage to NOT damage the propellant grain, remember that the liner and spacer pieces are just pieces of body tube. You can find substitute pieces for them. Heck, you may even have stuff that will work in your spare/leftover parts box. (Everyone has one of those, too, right?)

IN THE FUTURE..... always check the fit of your liner pieces BEFORE committing to the assembly of the motor. If the pieces don't slide in fairly easily, PEEL A LAYER OF PAPER OFF OF THE OUTSIDE OF THE LINER... BEFORE inserting the propellant grain.

Hope this worked out for you. Please let me know if it did.

And... Eugenio... remind me to never make you mad. :D :kill: :eek:
 

LaneKG

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Eugene,

My first RMS 24/40 experience was the same. I found out you need to remove a laver of the paper on the grain by picking at the end pulling up a corner and unwrapping the layer from the outside before you insert the grain into the case.

John Stein got the stuck grain out by using something like a broom stick and pushing the stuck grain out. It was not easy. We were at the field at the time.

Thanks,

Greg
 

Juerg

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I wish I could hear the Brits say "al-u-min-i-um,"
Not only the Brits Ken, I guess it is about the whole rest of the world ;)

However I'd suggest not to try to center it "as is" but to take it out and peel off one layer of paper.
If the grain liner cannot move inside the casing when the closures are tightened, there is a big risk that the sealing o-rings get damaged or don't seal resulting in a CATO.

So the hint with the hair dryer is good, but I'd suggest to get a wooden dowel that fits the casing exactly (22mm diameter) and to use this dowel to push the grain out when the casing is hot.

Juerg
 
A

Austin

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Eugene...

What they said! I find myself peeling a layer of paper off most 24mm liners...I don't know if AT switched to a different brand, but they just don't seem to fit very well. If you manage to get the grain out with the liner still stuck, I have FOLDED the liner inward before, removed it, then straightened it out, peeled it and re-used it with no problem. I also put a pretty good coat of grease on the liner before installing, then remove the excess that gets squeegeed off by the case edge while inserting

Carl
 

n3tjm

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A lot of people curse the company for this... but helping out at AMW... I have learned that this kind of thing is not thier fault... When the order cases and tubes, they have to order them by the shipload... and when they do so... the companies wants a certain margine of error... so... what happens if a batch of cases measure on the lower end of the tolerance, and the liners measure on the high end? A lot of sanding. And since the cases and tubes meet tolerance, they can not return them.
 

eugenefl

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Ah yes....the joy of waking up 5 hours later and instantly remembering something was bothering me. LOL! How comforting it is to come back to the forum and find multiple replies. It's certainly a pleasure to have you gentleman in my virtual living room. All I know is that my downstairs neighbor is going to have a few words with me about the "banging". For some reason I thought maybe I was creating an echo every time I banged on my floor. LOL!

Alright, so I ended up tossing the casing on the roof of the apartment next door last night and the first order of business is to get it back.....no, JUST KIDDING! :D See, I'm in a better mood already. ;)

So achieved some success this morning. I ended up taking a small flat tip screwdriver and very carefully lifted one edge of the adapter. Once I got the tip of the scewdriver in there I carefully pushed it in causing the cardboard tube to "dent" inwards along that line. (Grain removed BTW.) Once I had a nice clean lengthwise fold or tunnel, I then grabbed another adapter and gently pushed the "stuck" adapter out. I then reshaped it to its original cylindrical shape and fit the grain back in it. After peeling a layer of shiny paper off and lightly greasing the surface, it slid right in like a champ - nice and snug, but not STUCK.

NEW PROBLEM - (Ok, I've used RMS 29-40/120 multiple times and not experienced everything I am telling here.) Are aft and forward closures supposed to thread ALL the way on? I had a bear of a time getting the aft closure to thread on the end of the casing. Without stripping out the threading, I managed to get it started and held off after a few turns into it so not to "force" anything. How far should the closure end up on the casing? Does it need to be threaded ALL the way on? If so, I have a feeling pliers are going to come into the picture.

Please advise. THANKS!
 

swimmer

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Eugene,

The forward closure screws all the way in, the aft closure is what compressed it all together so there will be some resistance when you get to compressing the o-rings. Use a towel to protect your hand when tightening,or build/buy a tool to tighten the closure. No need for pliers. No need to overtighten. The aft closure will stop before bottoming out, slightly and any further tightening could damage your RMS. If it is tight as you can get it with your hand it should be tight enough. But, please don't use pliers.
 

Juerg

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Eugene, no pliers! Aerotech sells a closure wrench made by Rolf Orell from Sweeden. If you are using AT hobby reloads you will need one of these. One tool for all the range from 18-29 mm and the tool works great to open a beer bottle as well after a day of launching! ;)

You see, a MUST!

Juerg
 

rbeckey

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I often thread the fore closure on part way, then the rear part way, then tighten the front all the way, then the rear as much as possible.
 

eugenefl

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Alright...I used my RMS 24/40 casing for the first time today. I didn't use pliers! ;) Jason (jetra2) came over and gave me a 2nd opinion before I had a chance to check the responses. His was inline with what everyone here said. Hand tighten with a paper towel to protect the fingers.

Today was a bad day for me...lotsa prangs, crashes, and core samples. Quite a few rockets were damaged. I'll post a thread in the event forums in a few minutes.

Thanks for all the feedback and assistance. I'll have to look into that tool.
 
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