Advice on removing a CTI nozzle holder from a snap-ring case.

[BryRocket]

Hey y’all.

This is a first for me. I have a 7 grain AMW case that I had a CTI M840 in with the assistance of the “hubcap”. This has been an absolute nightmare trying to disassemble. I’ll spare you all the details on how I got the forward closure out. Currently I have the liner, nozzle and nozzle holder still in the case. I’ve put more hours into this than I care to admit. It’s a little embarrassing.

At one point I was able to knock the liner/nozzle/holder down enough to move the holder to where it is now. I believe the Oring is stuck in the snap ring groove. I can knock the nozzle/liner upward and out of the holder so I know the resistance has to be the holder/case interface.

Most recently, after knocking the nozzle away from the holder a little, I ran a piece of 3/8 all thread, attached to a 54mm bulkhead, through the nozzle hole. I then placed a small section of airframe over the aft end of the case, ran the all thread through a board and tried to pull it out with some wrenches. I basically just pulled the nozzle back into the carrier and no more. I’m not ultra strong but I worked this several times until I couldn’t turn the nut anymore. No luck. Then I just whacked at the board w a sledge. No luck. I’ll throw some pics here to maybe help visualize what I’m doing. I’m at a loss at this point. I’ve also tried sticking a long piece of aluminum pipe up to the nozzle from the forward end and ramming it on the ground as hard as I can. Chipped the driveway up good but still, not a budge.

Open to any and all suggestions!

 

[heada]

I had an issue with a nozzle and liner stuck in an AMW 75mm case. I used the forward closure and a 15ton press to push everything out. Highly recommend you heat the case up in an oven to ~200F before pressing as that should help convert any lubricants from acting like a glue to acting like a lubricant again.

 

[BryRocket]

Heat. Not a bad idea. Maybe I'll try some heat on it and then hit it with the above method again. I don't have a press so I'll have to keep whacking it like a caveman. This is unreal how stuck it is.

 

[jimzcatz]

You should try to draw it into a spare case, not a piece of airframe. I have used the method you show here and ALWAYS have had success. You just need to keep plugging away, it will eventually come free.

 

[BryRocket]

Thank you @jimzcatz and @heada for the help! I heated AND pulled into a spare case. Also milled a piece of aluminum instead of the plywood. Took way more effort than I thought but it finally popped out. I then spent another hour or more on the liner. It’s still stuck. Not much progress. I tried putting a bulkhead sans oring in the case and then hammering it down with a piece of wood. Did not work. I also tried to pull the bulkhead through with the all thread etc. Did not work. Almost appears the liner is breaking some and then it’s all just wedged. Took forever to get the bulkhead back out using the same all thread method. Any thoughts on getting the liner out?

The working solution. I just used the airframe to keep things aligned.



The crime scene. What a mess.


On second thought, anyone want to buy a used 7 grain AMW case with a liner stuck in it? PM me with an offer. I’ve fallen out of love with this one.

 

[heada]

For the liner, get a 1 inch diameter oak dowel and cut a very high angle on one end. Take the point of that sharp dowel and put it between the liner and case wall. A few whacks with a hammer should pry the liner away from the wall and you can pull it out in pieces.

 

[jimzcatz]

Heada's method will work, but I have always just pulled it into a spare case, usually takes more than one attempt. The liner will give, it's pure physics. This is exactly why I don't use dow grease on liners, it acts like glue. Not sure what you used, but on liners I use a very light coat of a synthetic tube grease. Good luck and don't sell the case. You will regret it.

 

[AllDigital]

Oh, good times.

My method for stubborn nozzles or liners is twofold:

1. I put the nozzle end of the motor into a bucket of water and fill the top of the motor with hot water. I try and soak the liner and nozzle as long as possible (an hour?). Often refilling the motor with fresh hot water.
2. I have a number of PVC extensions with different size PVC couplers that fit different motor sizes. I use them, along with loving taps from a sledgehammer, to push the nozzle and liner out. I'll cover the PVC end with a soft rag or cloth if I don't want to damage the nozzle.

I then dry the nozzles for at least a week to make sure there is no residual moisture in the nozzle.

 

[Dave A]

Hey y’all.

This is a first for me. I have a 7 grain AMW case that I had a CTI M840 in with the assistance of the “hubcap”. This has been an absolute nightmare trying to disassemble. I’ll spare you all the details on how I got the forward closure out. Currently I have the liner, nozzle and nozzle holder still in the case. I’ve put more hours into this than I care to admit. It’s a little embarrassing.

At one point I was able to knock the liner/nozzle/holder down enough to move the holder to where it is now. I believe the Oring is stuck in the snap ring groove. I can knock the nozzle/liner upward and out of the holder so I know the resistance has to be the holder/case interface.

Most recently, after knocking the nozzle away from the holder a little, I ran a piece of 3/8 all thread, attached to a 54mm bulkhead, through the nozzle hole. I then placed a small section of airframe over the aft end of the case, ran the all thread through a board and tried to pull it out with some wrenches. I basically just pulled the nozzle back into the carrier and no more. I’m not ultra strong but I worked this several times until I couldn’t turn the nut anymore. No luck. Then I just whacked at the board w a sledge. No luck. I’ll throw some pics here to maybe help visualize what I’m doing. I’m at a loss at this point. I’ve also tried sticking a long piece of aluminum pipe up to the nozzle from the forward end and ramming it on the ground as hard as I can. Chipped the driveway up good but still, not a budge.

Open to any and all suggestions!

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1)Did this motor sit for a length of time before you attempted to disassembled it?
2) Nozzle Carriers do not take much misalignment for them to bind.
3) I've flown a lot of AT M loads in snap ring cases. When I assemble them I grease all o-rings and the liner the full length with disk-brake grease from Adv Auto. I use several grain spacers to push everything out the aft end. Never try to push the nozzle carrier all they way to the fwd end.

 

[OverTheTop]

For the liner, get a 1 inch diameter oak dowel and cut a very high angle on one end. Take the point of that sharp dowel and put it between the liner and case wall. A few whacks with a hammer should pry the liner away from the wall and you can pull it out in pieces.

^^^ This.

I have used this method with a stuck liner in a 6GXL 98mm casing. Using wood means it will not scratch the aluminium. It will come out piece by piece and when enough has been released the rest of the liner will pull out easily.

As to the mess you pictured earlier, it looks about right for the job at hand!

 

[BryRocket]

1)Did this motor sit for a length of time before you attempted to disassembled it?
2) Nozzle Carriers do not take much misalignment for them to bind.
3) I've flown a lot of AT M loads in snap ring cases. When I assemble them I grease all o-rings and the liner the full length with disk-brake grease from Adv Auto. I use several grain spacers to push everything out the aft end. Never try to push the nozzle carrier all they way to the fwd end.

1) yes. I returned home from a launch and basically had to leave town immediately for a week. Not ideal.

I used Super Lube Synthetic Grease. It's what I've always used on my liners, O-rings etc.

Going to give the tapered dowel a go tonight. Wish me luck!

 

[BryRocket]

Heck yes!!!





1” dowel for the WIN! Man, thank y’all so much (@heada)! I’ve never known so much joy could come from simply getting a motor unloaded. Case actually seems like it’ll clean up easy enough now.

I’ve learned a lot through this that I’ll remember. Had I just used a few of these techniques initially this would have been done a few weeks ago.

NOW it’s officially on to the next project.