Pro75 4g - Cleaning the case issues...?

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DAllen

DAllen

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Not sure if this is an issue or not but I loaded and flew a L1115 this weekend with the ND Rocket team with a brand spanking new Pro75 4g and after cleaning out the case I noticed these white markings on the inside. Motor fired just fine as far as I could tell and I cleaned it out like I've done with other cases - warm soapy water and a toilet brush. Also, on the forward closure I can't seem to get these stupid black marks off. So are these two issues I need to worry about? While I've flown lots of Loki 75mm motors before this was a new experience for me. Had no real issues assembling it other than the instructions leave a bit to be desired.

https://drive.google.com/file/d/1boGji9yJjfC72CZSDHGdvhRSYmiyXHeO/view?usp=sharing

https://drive.google.com/file/d/1rlSxJggVLS6XzMJ2Rw9mpi1X3YTi_fPw/view?usp=sharing

-Dave
 
Certain chemicals, minerals etc. especially when combined with heat just plain old like to discolor aluminum. Rocket propellant would be one of those. Simply cosmetic nothing more. Here's a couple pics. of my AMW 640 case, very discolored yet smooth as a babies behind inside. I used 7or 8 Skidmarks in it, they had no grain liners, just casting tubes. Heck to clean up but loved the motors. Had to soak em in vinegar for 2 hours first, then washed with soap and water with a bottle brush.

amw 1.JPGamw 2.JPG
 
rcktnut said:
Certain chemicals, minerals etc. especially when combined with heat just plain old like to discolor aluminum. Rocket propellant would be one of those. Simply cosmetic nothing more. Here's a couple pics. of my AMW 640 case, very discolored yet smooth as a babies behind inside. I used 7or 8 Skidmarks in it, they had no grain liners, just casting tubes. Heck to clean up but loved the motors. Had to soak em in vinegar for 2 hours first, then washed with soap and water with a bottle brush.

View attachment 340389View attachment 340390
Click to expand...

Awesome. That makes me feel better. This isn't my case technically so I just want to make sure I do it right.
 
My two cents - the white discoloration in the case could be just that - discoloration. If the surfaces feel smooth, then I would not worry about it.

The black crud in the forward closure is different. That looks like black crud. I use Break-Free to soften that stuff, and you can scrub it out with a 3M scrubby pad.

Clean up is easier if you use some sort of lube in the cases before building the motor. My L3CC turned me on to aerosol Teflon lube -- sprays on wet, dries out immediately and seems to make clean-up easier.
 
Last edited by a moderator:
DAllen said:
Not sure if this is an issue or not but I loaded and flew a L1115 this weekend with the ND Rocket team with a brand spanking new Pro75 4g and after cleaning out the case I noticed these white markings on the inside. Motor fired just fine as far as I could tell and I cleaned it out like I've done with other cases - warm soapy water and a toilet brush. Also, on the forward closure I can't seem to get these stupid black marks off. So are these two issues I need to worry about? While I've flown lots of Loki 75mm motors before this was a new experience for me. Had no real issues assembling it other than the instructions leave a bit to be desired.

https://drive.google.com/file/d/1boGji9yJjfC72CZSDHGdvhRSYmiyXHeO/view?usp=sharing

https://drive.google.com/file/d/1rlSxJggVLS6XzMJ2Rw9mpi1X3YTi_fPw/view?usp=sharing

-Dave
Click to expand...

Scrub them with a scotchbrite pad. I’ll bet they go away. Blue scotchbrite won’t hurt aluminum. Green is slightly abrasive on aluminum but I’ve never hurt a case while using it.
 
Steve Shannon said:
Scrub them with a scotchbrite pad. I’ll bet they go away. Blue scotchbrite won’t hurt aluminum. Green is slightly abrasive on aluminum but I’ve never hurt a case while using it.
Click to expand...

Good to know. I bought a P98 1G casing from Wildman that had been sitting with a liner in it for a while. It was a bear to get out. Thank goodness it was just 1 grain. It left a white residue that has dimension and I need to get rid of it. I was trying to think of the best thing to use for scrubbing. Hoppes #9 didn't really do the trick with no abrasive. It does scrape off but I want to avoid damaging the case. I sure as heck will not leave a liner in it for any length of time. I got a great deal on it and it was worth the effort for sure.
 
I've never used anything other than vinegar, then dish soap and water to clean cases and closures. A little soak in vinegar always removed the black residue(crusty stuff). I clean up my stainless blast plate by laying a paper towel on it and soaking it with vinegar for an hour or so and then take a scotchbrite pad and scrub it good. It gets nice and clean after being very black and crusty. I put vinegar in a spray bottle for my launch rails spray them down and also use a scotchbrite pad to clean them up followed by a good rinse with water. I know Dr. Rocket used to have hardware cleaning instructions and recommended vinegar.
 

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