Separating overtightened spacers in optical trains?

Tim,

freezer and hot (blow torch, not hot water) is a good idea to begin with - that's how I managed it.

I assume the locked parts are no longer attached to your teleskope or camera, but separate from them?

To get a good grip, you first need to cleen all parts from any grease and sweat from your hands.
For not sratching anything and still being able to use a pipe wrench I have a set of PVC cable insulation pieces.
This is the black outer insulation of large energy calbles (cable w/ aproxx. 50-80mm diameter), intended for installation in earthern cable ducts.

This outer insulation is approx. 3mm thick, quite sticky when cleaned and very durable.
But still you must be very gentle not to deform those thin aluminium spacer rings!

Good luck!
Chris

As long as I can get a grip on the rings with them, these work pretty well for me. I have a couple in my equipment bag.

https://www.amazon.com/Regent-Multi-Purpose-Gripper-Bottle-Opener/dp/B019R5TSYW

The main issue here is that those adapters are way too thin to transmit torque without deforming and thus resulting in a very difficult task in removing them. As most if not all of them in circulation are anodized I suspect that the main issue sits here rather than in oxide binding. More expensive adaptors are thicker and have better control in thread uniformity thus rendering the issue not existent in my experience.  Sadly M48 robust adaptors are very hard to come by.

Many thanks everyone for the useful suggestions.  Using the gas ring I've got one of three stuck assemblages apart - so at least partial success.  Have also ordered some rubber covered wrenches so will see how that goes – I suspect that Andrea is also right with his theory that  they just bend and tighten when too much pressure is applied .

I have tried several alternatives, here are some that worked for me:
1. Bottle or jar openers, use two for opposing torque.
2. Strap wrenches, 2 again in opposite directions
3. When all else failed, I took it to my local machine shop and pleaded with them to separate them and they did manage to do so!

I add fine spacer rings between all connections, think .3 to .5 mm. This prevents the binding of the connections for me.
Everything remains tight for imaging but loose enough that i can manually disconnect everything. Otherwise i have done everything from the pipewrenches to freezer and rubber boots

In addition to all the tools suggested, I also found trying unscrewing it from different angles may help – i.e. if at first I grab the thing with thumb on the north side and can't unscrew it, I will try thumb on the east side, then south etc, you may find there is one angle works best.

After you get them apart, cut slots in each side to allow you to use a straight edge to torque them apart.  Like often machined into photo gear and lens retaining rings.  Should be standard design.  Bad that telescope makers don't do this simple thing.  A hack saw leaves a perfect sized kerf.  Wrenches that try to grab the periphery risk warping the metal.

There are also anti-binding compounds that can be used.  Kind of like a grease with a lot of copper micro particles that physically keep the metal surfaces from coming into direct contact.  And the copper is soft and deformable enough to allow torque rotation

Hi,

like suggested above with shoe soles, I can advice to use small anti gliding pads. These are often used as protectors in parcels or machines. Got mine for free, because they were in the trash.
Put one on top, one below, compress the tube assembly and turn. By compressing them, you reduce the tension and friction in the joints and they move very easily. No need for tools or brute force. No damage is caused.
The last 10 years I have succeeded in loosening all tubes, except 2 only. But the solution: Throw them 10 minutes in the freezer and repeat the procedure.

CS
Rüdiger