Frozen Aerotech Case Forward Closure

[Steinerino]

I have a 75MM engine case where the forward closure is frozen. The booster was 'lost' out on the Black Rock desert playa in October of last year and then found this June (miraculous since it was 7 miles from the launch site). The case was in reasonable condition other than corrosion as shown in the picture here. Natural given the salt and calcium in the playa and soaking over the winter.

The rear closure (boat tail) was badly pitted but unscrewed easily (testament to my using SuperLube on both threads generously before launch). Unfortunately, the forward closure is stubbornly frozen. I have been working on the forward closure by: using a blade to clear the corrosion on the outside at the junction, CLR inside/outside the case, Hoppes 9 inside/outside the case, strap wrenches (inexpensive ones purchased from Amazon that then broke), and some heat from our fire table to warm the junction.

Any suggestions?

 

[rfjustin]

I have a 75MM engine case where the forward closure is frozen. The booster was 'lost' out on the Black Rock desert playa in October of last year and then found this June (miraculous since it was 7 miles from the launch site). The case was in reasonable condition other than corrosion as shown in the picture here. Natural given the salt and calcium in the playa and soaking over the winter.

The rear closure (boat tail) was badly pitted but unscrewed easily (testament to my using SuperLube on both threads generously before launch). Unfortunately, the forward closure is stubbornly frozen. I have been working on the forward closure by: using a blade to clear the corrosion on the outside at the junction, CLR inside/outside the case, Hoppes 9 inside/outside the case, strap wrenches (inexpensive ones purchased from Amazon that then broke), and some heat from our fire table to warm the junction.

Any suggestions?

More heat on the junction, and better strap wrenches:
https://www.acehardware.com/departm...Vv5xaBR3BDgKzEAQYCCABEgJyTPD_BwE&gclsrc=aw.ds

 

[3stoogesrocketry]

I have a 75MM engine case where the forward closure is frozen. The booster was 'lost' out on the Black Rock desert playa in October of last year and then found this June (miraculous since it was 7 miles from the launch site). The case was in reasonable condition other than corrosion as shown in the picture here. Natural given the salt and calcium in the playa and soaking over the winter.

The rear closure (boat tail) was badly pitted but unscrewed easily (testament to my using SuperLube on both threads generously before launch). Unfortunately, the forward closure is stubbornly frozen. I have been working on the forward closure by: using a blade to clear the corrosion on the outside at the junction, CLR inside/outside the case, Hoppes 9 inside/outside the case, strap wrenches (inexpensive ones purchased from Amazon that then broke), and some heat from our fire table to warm the junction.

Any suggestions?

Use a plastic mallet to smack the closer into the case. It will only take one or two hits. The threads are locked with corrosion. I would recommend Kroil penetrative oil. Turn the case upside-down, spray in the oil. Let it sit over night . Wack it and unscrew.

 

[KenECoyote]

From my work with cars, I like PB Blaster. I would spray a bunch outside along the seam with it laying flat, spray inside standing, leave overnight.

Then maybe try using the correct size worm gear hose clamp with pieces of rubber (jar opener cloth or cut up bike inner tube with talc washed off) to protect the finish, tighten and use two big wrenches or one wrench while having 2-3 people hold it with rubber gloves.

Get a torch ready if it still won't give.

Good luck!

 

[SolarYellow]

Kroil

Or kraut oil, if you prefer.

 

[Johnly]

If you have an understanding SO, Kroil and several hours in a 300F oven.
Let it cool, then try your strap wrenches.
If the closure is still stuck try putting a bolt in the forward closure with a washer and locking nut, and try an impact driver on the bolt and a strap wrench on the casing.

 

[3stoogesrocketry]

If you have an understanding SO, Kroil and several hours in a 300F oven.
Let it cool, then try your strap wrenches.
If the closure is still stuck try putting a bolt in the forward closure with a washer and locking nut, and try an impact driver on the bolt and a strap wrench on the casing.

Heat will not help as much as one will think in this situation. The forward closure has more mass and will want to absorbe the heat from the case. It will also expand more and will potentially lock the threads harder. Ice it down .

 

[2-0turbo]

The Kroil is a good suggestion, as is the PB blaster. Both are low surface tension fluids that like to creep into tight (capillary) spaces. Alternating the assembly in the freezer and then blasting the case with heat to create a differential could work. But with corrosion, the corrosion products are often larger than the parent materials, creating the jam and possible preventing the two parts from disassembly no matter how hard you try.

If you can't get it free and are completely stuck and want to salvage the case, you could machine the closure out of the case and save the case. If you have the equipment to do this, it would be pretty cost effective or if you have a friend who could help. You don't say the case impulse, so I don't know the street value. Depending on the case impulse, the economics may still work out to pay a machine shop to assist and salvage the case and junk the closure.

 

[KenECoyote]

The Kroil is a good suggestion, as is the PB blaster. Both are low surface tension fluids that like to creep into tight (capillary) spaces. Alternating the assembly in the freezer and then blasting the case with heat to create a differential could work. But with corrosion, the corrosion products are often larger than the parent materials, creating the jam and possible preventing the two parts from disassembly no matter how hard you try.

If you can't get it free and are completely stuck and want to salvage the case, you could machine the closure out of the case and save the case. If you have the equipment to do this, it would be pretty cost effective or if you have a friend who could help. You don't say the case impulse, so I don't know the street value. Depending on the case impulse, the economics may still work out to pay a machine shop to assist and salvage the case and junk the closure.

Good idea! Can also take it a step easier by cutting the case shorter and threading the new end.

 

[troj]

Good idea! Can also take it a step easier by cutting the case shorter and threading the new end.

This can be done, though it turns the case into a research case.

 

[2-0turbo]

Good idea! Can also take it a step easier by cutting the case shorter and threading the new end.

Yes, shortening would also work. That would make it an EX case from now on.

 

[MClark]

Take the eyebolt out.
Go outside and throw in trash can.
Go inside and order new hardware.
I’m sure your time has some value and case is likely junk from corrosion.

 

[2-0turbo]

Take the eyebolt out.
Go outside and throw in trash can.
Go inside and order new hardware.
I’m sure your time has some value and case is likely junk from corrosion.

Mail it to me before you do this. I’ll pay the shipping.

 

[MarsLander]

 

[astronwolf]

ATF-Acetone mix

Add equal portions of ATF-Acetone-Kerosene-Mineral Spirits and you got Ed's Red.

 

[Wrightme43]

View attachment 653168

This is exactly what I was going to say. It works.

 

[Greg Furtman]

I've had Marvel Mystery Oil help loosen some items (especially bearings) with great success. Stand you motor tube on end with the open end up and pour in maybe and inch worth's and let sit for a number of days.

 

[lr64]

Are both the case and the closure aluminum? That might make it tricky to use heat. However, I wonder what would happen if you heated the whole thing to 250 F or so and then dipped the closure (but not the case) in icewater. And, if the first time didn't work, cycling the temperature a few times. Or many times.

I could also see making appropriately sized holes in some boards and gluing them on to get more leverage. You could use some epoxy that softens at a low temperature. Maybe you could use a mallet on the end of one board while the other is in a vice. Unless the temper has been ruined by holding burning rocket fuel, minimize the heat when removing so as not to ruin the temper. 200F? 250F? Probably best to do a test piece on junk first. Chilling the aluminum might help too, as the coefficient of thermal expansion of wood along the grain is much lower than aluminum's. OTOH, across the grain it's the other way around.

https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html

Above is just brainstorming. Haven't tried.

 

[David Schwantz]

Put it in the freezer over night, whole thing. Then take it out and heat just the case with heat gun, hair dryer. This will expand the case and not the closure.

 

[mtnmanak]

Put the closure in a vise and turn the case.

 

[MidOH]

Map gas touch. Available cheap at any Ace or Bei.

See if it'll soak up oil, while hot. Olde farts use a crayon.

Wrap tube with rubber or electrical tape. Use two Rigid pipe wrenches. You'll gall the closure, but hopefully not the tube too much.

I've never had luck with that strappy do thingy.