Slicing Out Liners?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Good call with the PVC, scratching a case is poor form especially around sealing areas and a steel splitter is cringeworthy in my opinion.

The splitter is aluminum. I've personally never used it, but it'll likely work.

You need to use a lot of grease. Fill any potential air space in the motor with grease.
 
The splitter is aluminum. I've personally never used it, but it'll likely work.

You need to use a lot of grease. Fill any potential air space in the motor with grease.
Everyone has methods that work for them. I highly recommend not using alot of grease. Grease acts like glue. I stopped greasing my liners and for the most part, they just slide out. But it's really a crap shoot. I have had them get stuck either way. I'm thinking spraying with wd40 or silicone might be best option.
 
I'm thinking spraying with wd40 or silicone might be best option.

I hope you mean following the firing, right?

I recommend a lot of grease not necessarily for ease of disassembly, but in order to occupy all potential places for flame front to travel and to eliminate pressure differentials inside of a motor. If your grease is breaking down and creating "glue," you're using the wrong grease.
 
buy a steel bar, fairly small, slice the end to a point on one side and use it to cut your way down to the bottom. Just be careful no the gouge the case. I use a square bar(I can get photos if you want)

Dan - this is what I was referring to.
 
By geometry, I mean good edges and concentric cores.
Those grains pictures looked pretty ragged....to be kind...
 
Revisiting this...

IMG_0912.jpg
Results of removing a 98/17500 liner last night - again, no easy task and I'm wondering where my issue is. Jim - sent you a PM.

Hammering a Front Closure
Seems to work to get everything started, but not long after, the closure tends to just jam up inside the liner, mushroom the edges, break off pieces, or just crumple things as opposed to actually moving it. I'm wondering if the all-thread system (?) would have these same type of issues?

Splitter
Used PVC as opposed to steel to avoid scratching the case, and this seems to work fairly well, but not the best solution in my experience as I've found one usually needs to split down several sides of the case before it finally pops free.

Boiling Water
I like this one. Will try on my next case.


Other ideas? What gives? This is getting pretty old and I really don't want to do this every time I clean up motors. It is just "nature of the beast" by flying mildly-high aluminum loads in ARR liners?

Chris - what's the trick behind getting liners to "fall out of the case without even touching them?" Some sort of grease or ?
 
Yeah, definitely one of the worst things in rocketry. I'm working on a 98-11000 now (well been months actually). Could there be some type of Teflon spray that could be used on the outside of the liner before install?
 
Revisiting this...

View attachment 284160
Results of removing a 98/17500 liner last night - again, no easy task and I'm wondering where my issue is. Jim - sent you a PM.

Hammering a Front Closure
Seems to work to get everything started, but not long after, the closure tends to just jam up inside the liner, mushroom the edges, break off pieces, or just crumple things as opposed to actually moving it. I'm wondering if the all-thread system (?) would have these same type of issues?

Splitter
Used PVC as opposed to steel to avoid scratching the case, and this seems to work fairly well, but not the best solution in my experience as I've found one usually needs to split down several sides of the case before it finally pops free.

Boiling Water
I like this one. Will try on my next case.


Other ideas? What gives? This is getting pretty old and I really don't want to do this every time I clean up motors. It is just "nature of the beast" by flying mildly-high aluminum loads in ARR liners?

Chris - what's the trick behind getting liners to "fall out of the case without even touching them?" Some sort of grease or ?

No grease for me...they fit nice before the burn as well though.
 
Yeah, definitely one of the worst things in rocketry. I'm working on a 98-11000 now (well been months actually). Could there be some type of Teflon spray that could be used on the outside of the liner before install?
OK, I wonder if it's not just me then... I'm curious about grease as well, though.

No grease for me...they fit nice before the burn as well though.
Are you using ARR liners?
 
I may be out in left field here, but has anybody tried some type of powder instead of grease?
 
Other ideas? What gives? This is getting pretty old and I really don't want to do this every time I clean up motors. It is just "nature of the beast" by flying mildly-high aluminum loads in ARR liners?

Chris - what's the trick behind getting liners to "fall out of the case without even touching them?" Some sort of grease or ?


Good Geometry, no voids.
Don't cook the liners and they come out a lot easier.
 
Other ideas? What gives? This is getting pretty old and I really don't want to do this every time I clean up motors. It is just "nature of the beast" by flying mildly-high aluminum loads in ARR liners?

Chris - what's the trick behind getting liners to "fall out of the case without even touching them?" Some sort of grease or ?


Good Geometry, no voids.
Don't cook the liners and they come out a lot easier.

Barking up the wrong tree... Happens even with commercial loads.
 
Ed's device works great, and if you make it out of depot aluminum it won't even scratch the case.
 
Send me your scrap pile ...:)

You don't want to pay freight on that. Sometimes I go back through the pile when I have time and see what I can save. When it works I either keep it, or if I've replaced it by then, I advertise it as a blow out deal on our specials page. I really don't have much patience for stuck liners if I can machine a new casing in half the time it takes to get the liner out.
 
FWIW, I have a set of Needle nose pliers with different nose lengths, I stick it in the case with the liner in there and open them to expand the nose tips into the liner and twist opposite ways and it comes right out. Might be an option as I have noticed twisting them out works better then pushing them out.
 
Slicing Out Liners?








Quote Originally Posted by FredA View Post

Other ideas? What gives? This is getting pretty old and I really don't want to do this every time I clean up motors. It is just "nature of the beast" by flying mildly-high aluminum loads in ARR liners?

Chris - what's the trick behind getting liners to "fall out of the case without even touching them?" Some sort of grease or ?

Good Geometry, no voids.
Don't cook the liners and they come out a lot easier.
Barking up the wrong tree... Happens even with commercial loads.

OK ... say what you want...
 
I stopped using grease, and if you have a good fitting forward bulkhead, the allthread method works like a charm. Usually I just have to get the liner started and I can pull it out the rest of the way.
 
In thinking more about this and after reading responses here, I think my issues lie with the following. Jim, thank you for the phone call last week - much appreciated.

  • Liner fitting during assembly. I think taking more time to really get liners to fit properly as opposed to just jamming them in as best I can will be a big help in getting them back out. See my thread in the EX forum for more thoughts on this.
  • Geometry. Yes Fred...this would seem to help with not burning up liners, as shown in the photo I posted earlier.
  • High aluminum = high heat. I've heard of guys who have nozzles which have flown for years and show absolutely no signs of wear and tear, thanks to flying low-aluminum propellants. I obviously wouldn't go that route, so again, straight cores seem like they would be a big help with liner/case protection.
You don't want to pay freight on that. Sometimes I go back through the pile when I have time and see what I can save. When it works I either keep it, or if I've replaced it by then, I advertise it as a blow out deal on our specials page. I really don't have much patience for stuck liners if I can machine a new casing in half the time it takes to get the liner out.
See Mike, I think this is one of many reasons why I need to learn how to machine cases myself. ;)


Anyways, I still have a 75/7600 to wrestle with this weekend and I have several (hopefully better) methods to try, so we'll see what happens.
 
Use heat or cold as appropriate. I had a reload case stuck inside a rocket so I threw the booster section in the freezer. After a few hours the motor case just slid right out.

As several people have suggested you want to use heat in this situation. Just remember that metal will expand or shrink more than most materials, so use heat or cold depending on if you need to expand or shrink the metal.
 
Use heat or cold as appropriate. I had a reload case stuck inside a rocket so I threw the booster section in the freezer. After a few hours the motor case just slid right out.

As several people have suggested you want to use heat in this situation. Just remember that metal will expand or shrink more than most materials, so use heat or cold depending on if you need to expand or shrink the metal.
Makes sense - my thought is that boiling water would expand the case AND soften the liner.
 
See Mike, I think this is one of many reasons why I need to learn how to machine cases myself. ;)

You'll be trading one frustration for another. If you go for it, do it because you enjoy machining and all will be well.
 
I use ARR liners & casting tubes for most all my motors, they fall right by following this prep procedure.

1. Spiral wrap your grain stack with FireFox pyro flash tape
2. Treat the inside and outside of your liner with FireFox fire retarder
3. Install your nozzle & forward closure on the liner and spiral wrap the assembly with pyro flash tape
4. Use a razor blade to trim the tape back at the O-ring grooves
5. Install O-rings with a light coat of Dow 111 or SuperLube
6. Apply a coat of CRC HD Silicone spray to inside of case
7. Slide case down over reload and install snap rings
 
I'm trying to find out what happened to Trucore (rocketsaway.com). Their website is down and emails undeliverable.
 
Back
Top