Today I decided to install the optics from the RC12 into the new truss that I have taken possession recently. I drove down the observatory and picked up the scope and brought it home for the disassembly and reassembly.
When you look at the truss you will see the rear of the scope has 4 truss blocks screwed onto back plate. Unscrew the screws as shown in the first image. Remember the tension of the screws as you loosen them. (pic 1)
Next unscrew the bolts that hold the dove tails onto the back plate. There are 4 bolts to remove. (pic 2)
Once you have done that the rear assembly including the mirror assembly come away from the truss. (pic 3)
If you intend on using a complete mirror cell from another scope remove the mirror cell by unscrewing the bolts that hold the mirror in place. Those 3 bolts are located in the middle of the mirror back and are used to collimate the primary. The large screws are the ones you want to unscrew. Not the smaller locking screws. (pic 4)
Now remove the old mirror cell from the ali tube of the RC12. (pic 5)
Pull the whole assembly out and be careful of the baffle which is really long. (pic 6)
Remove the mirror cell from the outer casing by undoing the bolts that are used for collimation on that scope. (pic 7)
Sit the new back assembly on a flat surface and then sit the mirror cell with mirror and baffle on top of the new back assembly. (pic 8)
Now make sure to install not only the bolts but the springs that provide tension to make the adjustments to the primary. (pic 9)
Install all three bolts and three springs. Now the primary mirror cell is installed onto the rear assembly. (pic 10)
Now install the out casing (black painted shield). Make sure it fits into the slotted ring in the rear plate. (pic 11)
Next fit the truss back onto the rear assembly and shield. Look out for the slotted ring on the middle support plate. The shield fits into that. (pic 12) Screw all the bolts that hold the truss blocks and the dovetails back into position.
Now remove the secondary assembly from the old scope. Undo the collimation bolts first and then remove the centre bolts with a Phillips screw driver. (pic 13)
Install the secondary onto the truss in the reverse fashion to the removal from the old scope. (pic 14)
Now it is time to collimate the scope. You will need a takahashi collimation scope to perform this task. If you own one of these scopes it is best to have a collimation scope anyway. (pic 15). The trick with this is to roughly centre the primary by using the large screws. Then work on moving the secondary so that the centre spot is centred around the tak spot. Then go back to the primary and get that centred. This needs to be repeated several times until you have it all concentric. It should take you about 15-20 minutes at most. I recommend you take a look at Ken Crawfords site for a video explanation of the procedure.
Pic 16 shows a view through the tak scope of the secondary getting close to being centred.
Once you are totally happy with the collimation with the tak scope (take your time with this, the better you get this the easy the final collimation via star test will be) if you have a laser collimator check the collimation with that. (pic 17). If you have done the first lot of collimation right you will get concentric circles. If not go back to the tak scope and keep going.
Finally, I decided to fit a dew heater to the secondary. Inside secondary assembly there is enough space to fit the dew heater made by Kendrick. I drilled a hole in the holding plate and then ran the wiring through that. Some tape of silicone over the hole holds the wiring in place. Make sure you silicone stick the heater to the secondary mirror itself. (pic 18)
Then tape or fix the wiring neatly along the truss. (pic 19)
So there you go, that is how to remove one set of mirrors and install those into a carbon truss.
Thanks guys. It looks like a real scope now. Very sexy, to which my wife looked at me and shook her head last night. I think she is beginning to wonder.
Yes this will be interesting Rolf. I am hoping that I can finalise any further glitches in the coming weeks and then off imaging each clear night.
I noted that the scope was slightly heavier at the front end than before. I was surprised at this as I had expected it to be heavier at the back end. The scope had to be moved further down the versa plate to compensate.
Wouldn't you know it, we had 40mm in Adelaide today which is a new record for February and tomorrow is supposed to be somewhere between 60-100mm. Yep astronomers curse. Drought averted. Haese buys new truss and heavens open up.
Thanks guys. It looks like a real scope now. Very sexy, to which my wife looked at me and shook her head last night. I think she is beginning to wonder.
My wife stopped wondering ages ago, she's now convinced I'm crazy.
New scope is looking good Paul, can't wait for first light.
