Help with image train

Gavin1234 · #1 11-12-2019, 07:54 AM

Hi guys, I haven’t been out imaging for a fair while now because I’ve been recovering from back surgery. Not to mention the cloud and now the smoke.

This morning my wife bought me a 2” dual band filter. I have a problem though, I installed the field flattener on my scope when I first bought it and I’ve never taken it off since. Over that time I’ve been taking the camera off and putting it back on again, at the same time this has been tightening the field flattener.

The 2” filters for my setup go in between the flattener and the adapter ring that sits on the back of it. I have been trying all morning but can’t unscrew the adapter ring from the flattener.

Any thoughts on how I can unscrew this? I’ve tried gently tapping it with a hammer etc but it just won’t budge. Obviously I don’t want to damage it in the process.

Atmos (Colin) · #2 11-12-2019, 08:00 AM

You could try putting it in the freezer for a few minutes, causes the metal to shrink a little.
Even go fridge for a few minutes and then the freezer if you’re concerned about thermal shock

VPAstro (Andrew and Cam) · #3 11-12-2019, 08:00 AM

This may sound stupid, but I had the same problem, and my solution was to use a pair of clean thongs. Place the ring and flattener between the two bottoms of the thong, press hard and twist. Unscrewed instantly for me. Hope it works for you too. Please let us know.
Thanks
Andrew...

traveller (Bo) · #4 11-12-2019, 08:06 AM

Cut a section off a bicycle inner tube, rubber on rubber (similar to thongs but more flexible) will give you more friction.
Good luck.
Bo

ChrisV (Chris) · #5 11-12-2019, 08:31 AM

Or get one of those plastic grip sheets. Don't know what they're called. We've got one for the kitchen - help grip and remove the most stubborn lids.

I sound like the sham-wow guy ....

Tinderboxsky (Steve) · #6 11-12-2019, 09:17 AM

Not stupid at all.
This is a an often overlooked crucial step to “undo” very fine threads that are stuck tight. It is all about reducing the pressure on the outer edge of each thread that is created when the item is screwed tight. Releasing this pressure by trying to unscrew the thread becomes harder the finer the thread pitch is.
Your thong solution sounds ideal.

Quote:

Originally Posted by VPAstro

This may sound stupid, but I had the same problem, and my solution was to use a pair of clean thongs. Place the ring and flattener between the two bottoms of the thong, press hard and twist. Unscrewed instantly for me. Hope it works for you too. Please let us know.
Thanks
Andrew...

bojan · #7 11-12-2019, 09:55 AM

Quote:

Originally Posted by ChrisV

Or get one of those plastic grip sheets. Don't know what they're called. We've got one for the kitchen - help grip and remove the most stubborn lids.

I sound like the sham-wow guy ....

Oil filter removal tool

JA · #8 11-12-2019, 09:59 AM

Hello G,

You could try some form of jar opener....https://www.ebay.com.au/itm/Multi-Purpose-Opener-Jar-Lid-Bottle-Cap-3-In-1-Grip-Twister-Rubber-Opener-1998/232321562741?epid=561936923&hash=it em361771b875:g

ncAAOSwiDRd2eTn

or adjustable oil filter wrench of the rubber band type

Given the thinness of the adapter, you will have to fiddle with the location of the tool somewhat.

Good luck

Best
JA

casstony · #9 11-12-2019, 10:05 AM

Once it is apart, I would apply some liquid Teflon to the adapter threads and let it dry before reassembly.

The can of spray with Teflon in it I have is called 'CRC Dry Glide' - I spray a bit in the lid and use a fine paint brush or Q tip to apply.

I have some of those jar openers mentioned above - they work well since you can apply torque and press the parts together at the same time.

rocco57au (Rocky) · #10 11-12-2019, 12:05 PM

Or maybe try this rubber wrench from Bunnings... and cheap too

https://www.bunnings.com.au/haron-10...rench_p4900118

Gavin1234 · #11 11-12-2019, 02:01 PM

Thanks guys. I tried the thong method but it wouldn’t budge so I put it in the freezer for a few hours. After trying 2 types of thongs I finally got it. It’s nice and frosty too..

multiweb (Marc) · #12 11-12-2019, 02:18 PM

Quote:

Originally Posted by Gavin1234

Thanks guys. I tried the thong method but it wouldn’t budge so I put it in the freezer for a few hours. After trying 2 types of thongs I finally got it. It’s nice and frosty too..

Run the tip of a HB crayon on the thread. The graphite will stop them from seizing in future as it acts as a dry lubricant.

Gavin1234 · #13 11-12-2019, 03:00 PM

Thanks again. Will get some lubricant on it.
as usual I fix one problem only to uncover the next. The filter doesn’t fit ito the flattener it’s about 1mm too small.

Now I can’t figure out where to mount the filter. I’ve tried pretty much every join in the image train and none of them work. It will screw in to the end of my spacers but this covers the threads that join the flattener.

My last hope is that it will go in between the two spacers (they are currently in the freezer because they are also stuck together

). Actually these are stuck much worse than the flattener I’ve just pulled them out of the freezer and they still won’t unscrew.

Any other suggestions as to where the filter should go? I don’t have a filter wheel.

The small space in between the spacers (shown in this pic) is where I’m hoping it fits.

casstony · #14 12-12-2019, 02:48 PM

You could incorporate a filter holder in the image train; this is one of the cheaper options: https://www.teleskop-express.de/shop...gth-15-mm.html

There's also another version that's M48 to T2.

AstroApprentice (Jason) · #15 17-12-2019, 12:30 PM

Quote:

Originally Posted by Gavin1234

Thanks guys. I tried the thong method but it wouldn’t budge so I put it in the freezer for a few hours. After trying 2 types of thongs I finally got it. It’s nice and frosty too..

I realise I'm a bit late, but I find the rubber coated cotton gloves from Bunnings are awesome for stuck threads - the ones with a really rough rubber surface are only a couple of $ and work amazingly well...