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Tube Dents @ -78.5 C

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#1 strdst

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Posted 30 July 2014 - 11:59 PM

Quick story.

There is always a story when I post... but QUICK is new. Throughout my illustrious High School years I worked after school and weekends in an ice plant. No not your typical Aizoaceae nor even Ficoidaceae (very small botanical joke here) and actually not so much a plant as it was more of an ice house because we imported the 300# blocks of ice and turned them into packaged consumer products, we started with ice, not with tap water. 15 year old working around gang saws, hammermills @ $1.15 hr. no medical but in the event something got cut off at least it would wind up packed in (you got it) ice ready to take to the hospital :lol: Dropped a 300# block hard on my foot one day. Co-workers got my boot off before my broken foot swelled too much to pull it off and yeah... iced it. What a great place to work!

Sorry not so quick but I am trying... We sold dry ice. There was a pair of insulated rubber gloves to handle it. My real funny joke at the time was when someone called asking if we carried Dry Ice. My answer was "only with gloves!" Actually I stopped wearing gloves and would amaze the patrons as I quickly grabbed a 5# block out of the freezer barehanded and wrapped it in newspaper for them. Hmmm, at that time I was also sketching sun spots using eyepiece sun filters even after one had cracked and kinda cooked my dominant left eye. I held the dry ice gently but it sort of vibrated in my hands... Everyone has to make their mark somehow. Sometimes I wonder why I don't have fingerprints.

Today I read a Yahoo article about like 10 really cool tricks with cars. A very interesting one on how to break into (your own) locked car. But the one that started this "quick" story was about pulling dents out of car bodies by applying dry ice to the ding! I have a few telescopes and a few of them have dents in the tube. has anyone tried this. Any reason why it wouldn't work with aluminum? Would the paint blister?

Last year I removed the bad remaining remnant coatings from a fine eyepiece with ReaLemon. I cleaned up a somewhat more resistant Swift objective with sulphuric acid from my truck battery. I like off the wall solutions. So dry ice and dents any experience here?
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#2 actionhac

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Posted 31 July 2014 - 10:25 AM

Oh thats too bad!
I got a Omaha steak delivery yesterday shipped with a block of dry ice, I could have tried that out.
I have plenty of dents around here, and no shortage of clam chipped lenses but thats another story.
I set the dry ice out in the driveway to melt (evaporate?) I later moved it to the garbage can when I noticed the chickens near it I didn't want the chickens to get stuck to the block and get frost bite.
I'll remember to try the dry ice dent removal next time, interesting idea.

Robert

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#3 bremms

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Posted 31 July 2014 - 11:44 AM

If the metal is deformed probably not, but it's worth a try. We use LN2 at work which is much colder ~ -190C . Could try that I guess.

#4 bremms

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Posted 31 July 2014 - 11:44 AM

If the metal is deformed probably not, but it's worth a try. We use LN2 at work which is much colder ~ -190C . Could try that I guess.

#5 TOM KIEHL

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Posted 31 July 2014 - 08:50 PM

http://en.wikipedia....ess_dent_repair

#6 bremms

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Posted 01 August 2014 - 09:06 AM

Didn't think it would work.. The Liquid nitrogen boiled in the dent..That was it.

#7 apfever

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Posted 01 August 2014 - 09:32 AM

Did the paint survive?

#8 actionhac

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Posted 01 August 2014 - 03:55 PM

Years ago I straightened a bent aluminum cylinder fin on a air cooled gas engine with heat.
I set our kitchen oven (wood-electric Monarch) on broil which is I think is 600degF and placed the cylinder in it.
To my amazement the cast aluminum fin became plastic like and I bent it back with very little effort. At ambient that fin would have snapped like a piece of peanut brittle.

Robert

#9 Astrojensen

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Posted 01 August 2014 - 04:05 PM

An old mechanics trick to straighten out dents in car panels is to heat them with a blowtorch and then rapidly cool them with compressed air. I've heard of this trick from my dad, who is a skilled old-school mechanic, but I haven't tested it myself. I doubt it would work on aluminum. You certainly would have to be extremely careful, as aluminum melts very suddenly and without warning.


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#10 bremms

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Posted 01 August 2014 - 08:42 PM

The tube was bare 0.065 6061 aluminum (not the soft stuff most tubes are made of). Aluminum has a nice plastic zone.

#11 BarrySimon615

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Posted 05 August 2014 - 10:04 AM

The tube was bare 0.065 6061 aluminum (not the soft stuff most tubes are made of). Aluminum has a nice plastic zone.

I checked with a Paintless Dent Removal shop once about removing dents from aluminum tubes and was told that their techniques would not work on an aluminum tube.  I used a tail pipe expander instead to do the job with fairly good results.  I still needed to smooth the tube with a bondo like preparation, I used JB Weld.  This was followed by sanding and repainting.

 

Pa Bear

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#12 BarrySimon615

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Posted 05 August 2014 - 10:13 AM

Tube before use of the tailpipe expander.

 

Pa Bear

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#13 BarrySimon615

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Posted 05 August 2014 - 02:26 PM

Here is a photo of the same area after repair.  Other areas were repaired too (one major additional dent fixed along with numerous small scratches and dings) with the entire tube being repainted.

 

Pa Bear

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#14 TOM KIEHL

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Posted 06 August 2014 - 09:45 AM

 

The tube was bare 0.065 6061 aluminum (not the soft stuff most tubes are made of). Aluminum has a nice plastic zone.

I checked with a Paintless Dent Removal shop once about removing dents from aluminum tubes and was told that their techniques would not work on an aluminum tube.  .

 

Pa Bear

 

Try another Place ,,,,,, Maybe the place you went to just SHINED you on.... My PDR in town did 3 of my Alum. tube scopes ,,, No problem,,,No paint or filler needed,,, Can't even tell....Just Sayin'



#15 Chuck Hards

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Posted 06 August 2014 - 09:58 AM

Generally, any crease or sharp bottom to the dent will make dentless repair not satisfactory.  It works best with gentle, gradual deformations.  Some of the pros can take it right to the extreme, but not many.








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