Narrowband Imaging
NOTE:  These instructions are for an older version of the retrofit.  
Some of the techniques might apply, but check the Exploradome mail list 
for up to date info.

Retrofit with Aluminum Tracks


I purchased my dome in February of 2010. The dome had to sit in the yard until construction completed the beginning of September.  While the dome was sitting on the black ring both had warped in the heat, but not fatally.  When first installed the dome turned, but scrapped on the wheels and black ring in several places.  The main problem was that the bolts for the horizontal wheels were too long.  Once these were fixed the dome was able to turn , but it turned more freely in some orientations than others. It was clearly out of round.

At the time I was completing construction the track retrofit kit was announced. Since I knew I would benefit from this retrofit (and it would be very disruptive) I decided to delay installing the outside retainer ring.

This entire retrofit operation was done by just myself without removing the dome.


The retrofit and dome rotation kits arrived in early December.  I immediately started installing it.  Anticipating that I would likely bump the scope and mount while installing these I removed the scope and mount from the dome.  I have a Pier Tech pier so I just lowered it to the lowest setting.  This meant I did not have to undo my wiring harnesses.  I also did not remove the computer since it was safely in one corner.

The retrofit kit consists of 5 curved pieces.  I anticipated that this was intentionally long and that at some point I would have to cut the tracks.  They were predrilled, but I also anticipated that these locations were a suggestion and the track would likely have to be redrilled in places to fit.


The holes have to be drilled up from inside the track while the Aluminum pieces are in place.  I bought a right angled bit for my drill, but that required nearly 6" of clearance.  That would have put the bottom of the dome above the ring.  I did not think that was a good idea.  After some shopping I ended up getting these

tools This setup allowed me to perform a minimal lift as I show below.

The Lift

I had lifted the dome before when I was first adjusting the wheels.  At that time the channel was sitting on  10 - 2x6 pieces laid flat.  For the initial raise I put a crowbar under the lip of the track hooking the back of the track.  That allowed me to perform an initial lift so the entire track sat on the 2x6s.  That was not going to be enough so I lifted it again to put a 2x4s inside the ring as shown below

dome raised 1
dome raised 2

outside during lift

This allowed me enough space to get the drill in


One important lesson learned that I need to share is where to start construction.  I started at the slit since that section was rounder and I wanted to force the home closer to true before I tackled the more flattened back section.
Big Mistake

In reality the section opposite the slit is the hardest to install.  That was where the joint was in my single piece channel.  The dome also bulges in over the top of the channel.  I wanted to avoid putting holes through the dome if I could.  By starting at the door and working from both sides toward the back it limited my choices of where I could put bolts in the last section.  As a result I ended up cutting the last setion twice rather than once to insure the piece near the back was positioned for reasonable installation.

Installing the Track

The track sections were about 6 feet each and were very easy to lift.  They were curved to fit the required shape of the dome.  One concern I had was whether I would have to force the dome to be round using 2x6s like I did the black ring.  To be brief I did not have to. 

To install a section you remove the blocks from one part of the dome.  You then slide the first end of the section in.  I was then able to manually warp the plastic track enough to snap the Aluminum section in place.

support trackOnce I got the ring in I clamped it with some C clamps.  Another pair of hands would have helped, but I did the work on my own.

support ringI wanted to make sure the ring segment was flat in the plastic channel so I returned the supporting 2x4 so the weight of the dome pushed the segment into place.

protect dome

The most important thing I did was to place a 2" wide piece of steel above any place I was going to drill a hole.  That way the drill hit steel when I broke trough and not dome.

field modsI anticipated the holes were a suggestion.  To get the holes in a convenient spot (e.g. avoiding brackets) meant fitting, measuring, and redrilling the hole.  I did this at least once per section after the first section.

dont scrapeOne last adjustment.  The main problem I had during the initial install of the dome was that the screws for the horizontal wheels were too long.  The dome was not able to turn at all when first installed.  I had to remove the wheels and cut the bolt several times.

This time I wanted to make sure I would not have a problem.  Unfortunately I cut too aggressively and the horizontal wheel now is just at the bottom of the outside of the channel.

new bracketOne final point.  If you plan to install a rotation kit you need to make sure you have the new (right) rather than old (left) bracket at each channel junction.  The old bracket will prevent the rotor channel from being installed correctly.  Dan had sent me a new bracket kit not remembering whether my configuration was pre or post installing them at the factory.  I had the brackets factory installed, but with the older channel bracket. I swapped it out for the new bracket.


A number of people on the Explora-dome list describe being able to move the dome with three fingers.  That is a good description.  It is not like you give it a little push and it sails around unaided.  You are moving 180+ pounds so there is a a lot of inertia and the wheels are not free of friction.  The dome (and/or the black ring) is still a little out of round.  There are some areas where the dome comes closes to rubbing the black ring. My observation is that, once adjusted, the dome rotates without any scraping noises. That in itself is a vast improvement over before.

When I installed the outside retainer ring it rubbed on the roof at two of the roof joints.  I removed about 1/4" of the horizontal section on one segement and reinstalled it.  It now turns without rubbing.

The dome no longer drifts back and forth across the wheels.  Once adjusted to the center the wheel stays in the center of the track.  That argues it is the black ring that is out of round.

The dome now moves as a unit.  When I was pushing it to center it on the ring the entire dome moved.  Before it used to deform instead.

One of my vertical wheels was making a lot of noise.  After experimenting it looks like it needed some oil.  I sprayed some oil on all the wheels which further eliminated noise while turning.  I looked for casters with real bearings (like used in the horizontal wheels).  They don't seem to be available in these sizes.

I am in the process of installing the rotation.  The rotation motor seems to be able to turn the dome, but the rotation track moves closer and further from the motor.  That argues the dome may still not be centered or is still slightly out of round, but the movement is compensated by the spring on the motor so I will probably not adjust further