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Can't unscrew refractor lens cap

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#1 Star-Geeser

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Posted 13 August 2020 - 03:26 PM

I recently received my Explore Scientific ED102 back from repair after 124 days.  Now I cannot get the lens cover to unscrew from the front element.  It is either cross-threaded or on too tight.  Attached is a photo.  Any suggestions or tool/gripper suggestions are welcome.  I have contacted ES customer support and sent pictures.  I will probably have to send it back again.

 

Attached Thumbnails

  • Inkedimg_2927-1_LIsmall.jpg


#2 jpbutler

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Posted 13 August 2020 - 03:31 PM

Get one of those tools for removing an oil filter.

I have one and it has saved my sanity numerous times.

 

https://www.amazon.c...0NsaWNrPXRydWU=


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#3 Doug Culbertson

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Posted 13 August 2020 - 03:36 PM

I was going to suggest one of those rubber pads used to unscrew jar lids,  but that strap wrench above might work better. 


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#4 JGass

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Posted 13 August 2020 - 03:38 PM

I was going to suggest the similar neoprene strap wrench:

https://www.amazon.c...97351034&sr=8-2


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#5 Bowlerhat

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Posted 13 August 2020 - 03:45 PM

Put some rubber bands on side and unscrew it by gripping the sides hard.


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#6 Hawkdl2

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Posted 13 August 2020 - 04:07 PM

Same suggestions as the others, but I have successfully used the rubber pad method for camera lens filters and I would try that first before the oil filter wrench approach.   


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#7 Trillobyte

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Posted 13 August 2020 - 04:37 PM

Paracord or shoelace. I always keep 12’ feet or so to tie down weights or anchor my rig.
Wrap the cord around the hard to grab part two or three times and tie a knot, your making a loop.

Now place a screw driver or stick in the loop and turn to tighten around the part (Not To Tight)

sneak up on it, it’s a friction game. Now use the screw drive as a handle to turn the piece add a turn 

to increase friction. It had worked for me on 1/2” rod (requiring) many wraps to a 2’ pipe. 
and if you protect the end of the screwdriver you won’t scratch the finish. 



#8 Alan French

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Posted 13 August 2020 - 06:14 PM

It it's like it looks, and like the cap on our Lunt solar scope, the cap itself is thin. Not sure some of the wrap around or wrench solutions would be sufficient on the cap itself, but maybe folks are suggesting holding the wider part behind the cap in place. In that case a rubber sheet used to unscrew jar lids might be useful for turning the cap itself. 

 

Clear skies, Alan


Edited by Alan French, 13 August 2020 - 06:26 PM.


#9 paulh83

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Posted 13 August 2020 - 06:34 PM

Get one of those tools for removing an oil filter.

I have one and it has saved my sanity numerous times.

 

https://www.amazon.c...0NsaWNrPXRydWU=

I have one of these at home and one at work (I assume it is still there since I haven't been on-site since March undecided.gif). The ability to grip relatively smooth surfaces is very useful. Yes, that cap looks thin, but you might be able to grip it. 



#10 rexowner

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Posted 13 August 2020 - 08:31 PM

Strap wrench, because you never know when you need to loosen or tighten a big

threaded thing.

 

https://www.homedepo...wE&gclsrc=aw.ds



#11 Kim K

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Posted 13 August 2020 - 09:51 PM

I'd forget the oil filter wrench if I were you as it's pretty coarse for this task. Instead, try laying a kitchen jar opener thingy flat on the front of your lens cap and then use your palm to twist it. Be gentle at first then go harder. Do not grip the scope or dew shield near the stuck lens cap as the pressure can squeeze the threads together tighter and compound the problem.

Kim

#12 rexowner

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Posted 13 August 2020 - 10:36 PM

This is exactly what strap wrenches are meant for.  It isn't "one of those

tools" -- it is not hard to work if you know what you are doing and/or are 

reasonably mechanically adept.

 

Hold the center strongly because you only want to apply torque, and

don't want the center to translate.

 

If you feel uncomfortable, back off and hold it tighter..

 

if you can't remove it with a strap wrench when you are tightly holding the

center, you better send it back.

 

It is a standard Plumber's tool - no big deal.


Edited by rexowner, 13 August 2020 - 10:39 PM.


#13 Star-Geeser

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Posted 14 August 2020 - 12:10 PM

Thanks everyone.  Good suggestions.  I ordered a rubber strap wrench online.  Should be able to give it a go on Sunday.



#14 jp071848

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Posted 14 August 2020 - 12:48 PM

Thanks everyone.  Good suggestions.  I ordered a rubber strap wrench online.  Should be able to give it a go on Sunday.

I have your scope's big brother, the ES127, and have certainly had exactly that problem with that very lens cap in the past. It's amazing how a small fraction of a turn can go from turning freely to completely welded on. The last time I froze the cap on I resorted to a large pipe wrench to unscrew it. I made a few small marks on the thin rim of the cap but I am now careful to not come any where close to fully tightening the cap. When I screw the cap on, the moment I fell any resistance, I stop and back it off a bit,

 

One caution, which I'm sure you're aware of, the "grab-able" amount of aluminum on the edge of the cap is only about 3/16", and from your picture, the cap is hard against the front lens cell.  Please be very careful when using the strap wrench to not capture any of the lens cell when you start to unscrew the cap.

 

Best of luck, pls let us know how you make out



#15 Crow Haven

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Posted 15 August 2020 - 10:22 AM

The other suggestions are good, especially the strap wrench, but I've also had success just by putting on rubber gloves (the type for washing dishes with) and this gave a great grip and allowed me to twist off the item.


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#16 Toddeo

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Posted 15 August 2020 - 11:22 AM

After you get the cover off- apply some "superlube" grease to the threads-should never bind again.


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#17 daquad

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Posted 15 August 2020 - 01:04 PM

After you get the cover off- apply some "superlube" grease to the threads-should never bind again.

You stole my thunder.



#18 jp071848

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Posted 15 August 2020 - 01:19 PM

After you get the cover off- apply some "superlube" grease to the threads-should never bind again.

I would recommend caution on that. Assuming his 102 is the same as my 127, and the photo indicates it is, the outer lens surface is VERY close to the cap, literally a few millimeters, running the risk of contaminating the lens if too much Superlube is used. Be very careful in how much SL is used.


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#19 Celerondon

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Posted 15 August 2020 - 01:24 PM

The strap wrench or any of the enhanced friction solutions may work.  If you want to give it a go before the wrench arrives I have another way.  

 

Heat differential!

 

Is it hot and sunny where you live?  If the sun is bright you can simply leave the telescope in a warm car for a while.  Once the black metal is warm to the touch you can gently try the lens cap.  If it comes off fine!  If not, you can use ice to quickly cool the cap (but only the cap).  Unless they did something horrible to the threads the cooled cap will spin off like magic! 


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