Celestron Edge baffle lock nut stuck in the reducer

Applies to: Celestron Edge 11 HD SC telescope, and possibly other Edge sizes.

Situation: As you remove the original 0.7x reducer for say, doing planetary work, the baffle lock nut (the "permanent" adapter for the OTA back) gets loose and remains stuck in the reducer body.

Baffle lock nut finally removed

The above photo shows final success. Notice two bright holes from drilling and fitting a rather big face pin spanner.

Not the first time

I'm a firm believer of dry, clean, undamaged threads. No need to apply lubricant unless having extremely wet conditions that could cause corrosion before you have a chance of cleaning and drying. Dry threads are good as reference for applying bolt tightening torque.
Well, there's a couple of extra condition for my plan to work all the time. The threads has to be well made and the appliance likewise well designed. I think the reducer housing failed in either or both! (getting there)

This situation has of course started with the reducer being stuck to the OTA. Three times. But in the first two cases I was able to take a bicycle tube, cut it at one point, then wrap it very tightly around the reducer body in the direction of unscrewing, to increase diameter, leverage and grip.

So it was this last time that I managed to unscrew the reducer with the baffle lock nut. Despite Celestron claiming their thread-lock agent being used, was of the permanent/heating type.


During one of these situations I had let the OTA completely cool down (much) by leaving it outside, then realized I forgot to bring out the reducer. Wanting to set up while waiting for the final cool-down, I forgot that it was probably not a good idea to have the warm/expanded female reducer body threads outside the cool/contracted baffle lock nut. You get the point, as we head towards thermal equilibrium.

But when I use the FeatherTouch focuser adapter directly to the baffle lock nut, nothing gets stuck.
I really think the reducer's threads and thread length are essential contributions to the problem. Not the best mechanical quality I'd say.

Anyway, this last time I had cooled both items down. Maybe not exactly the same. But having things stuck together at wrong locations felt sort of unfair.


I'd opt for professional service if that would actually make it easier for me.
When buying, I chose vendors based on product availability. I had Teleskop-Service in Germany send the C11HD CGEM-DX home to me in Norway. The .7x Edge reducer from OPT Corp USA. At least at that time, I felt that buying local was not an option.

  • Although trying to help, the bottom line advice from OPT was to "admit defeat".
  • TS could not help directly either (or backed by Baader as German distributor), but advised me to drill two opposing holes in the baffle lock nut, for using a pin spanner wrench.
  • Celestron web support (USA) could not help me with a spare baffle lock nut (to not ruin the best part of the season), or another reducer, as they would be completely empty from any such spare parts in the foreseeable future. They recommended sending the stuck unit to them.

The Celestron Support option did not appeal much as the email I got back after a couple of weeks did not assure me that they actually had a plan. I chose the second option as that was my idea too (yeah, smart guys!), and probably the quickest if it worked.

Expect to pay USD 50-100 for a pin spanner set of sufficient size/quality.

Step by step

Put on the cover for the camera side of the reducer.

Before you start

Put gaffa tape all around the cover. To give some friction/grip and avoid scratches.

Tape bottom

Turn the reducer around.
Apply a strip of very thin oil to the threads that are stuck. Not much, as it would penetrate and maybe reach the glass surface. Leave overnight.

Wrap this end in gaffa tape too, leaving two opposing parts of the baffle lock nut uncovered.

Tape the top

Use a sturdy bench drill to make the two holes. I'd go for 2,5mm or 3mm pins for the spanner.

Drill holes

Of course, you take care not to allow the drill bit to go all the way down to the reducer housing.

Holes drilled

Remove some of the gaffa tape so you can try to unscrew.
Didn't work for me at this stage, so I applied more oil and, waited 3 weeks!

Pin spanner at work

So, 3 weeks later. Still there?
The baffle lock nut was too. So I tried to mount the reducer tight in a workbench and got an extra grip for the spanner to increase leverage. Lots of power, but to no avail! So weird, everything was held and pushed in the right directions without twisting.

But hey, I then I tried knocking just a little with a plastic mallet, and it came loose that easy!!(?)
I have never experienced anything like it, but I'm pretty sure this has something to do with the rather poor threads in the reducer, that gradually seizes before any surfaces makes the stop.

Mount carefully in workbench and KNOCK

Note the holes on the camera side of the baffle lock nut. You will need them for reassembly with the pin spanner.

Original holes for on the back side of the baffle lock nut will be needed later on


Apply threadlock agent generously to the inner baffle lock nut threads (or the threads at the OTA), tighten well onto the OTA back using the pin spanner and leave unused for the time specified on the threadlock bottle.

I used Loxeal 55-03 medium strength but could (should?) have chosen a permanent type that requires heating before removal. Celestron claimed they had used such (I find it hard to believe it though), but they could not confirm any of the product codes that I suggested. I think something close to Loctite 276 should have been a good choice.

I have no guarantee this won't happen again.
But now I do have a good pin spanner and the holes are drilled and ready!