View Full Version here: : Mount & Pier

30-01-2016, 08:04 PM
Sounds like a good name for an AstroPub don't it ?

With the on going poor weather over here, high thin cloud and high humidity I decided to bite the bullet and sort out both the mount and my pier construction. The pier is a Heath Robinson thing that grew as I changed my focus and the mount has been doing some weird backlash things.

So the mount came off and went into the workshop. I then ripped off the rat cage from hell and filled the bottom of the pier with rocks to about 3/4 full, sealed that then using the rat cage as a jig filled the rest with concrete almost to the top with the 4 x M8 threaded rods cemented in. The M12 rod to the slab below is in an alum tube so can still move and once the plug of cement is cured it will be pulled down tight again.
The pier now weighs about 3 x what it did previously and there is more to come.

Following astrobabys instructions ( excellent btw) I disassembled the DEC section, reasonably easy to do, just be careful. I checked all the bearings and tested for play in the worm. Found nothing obvious so I washed out all the grease from the worm and the matching wheel with CRC. Picked up a few very small bits of brass in the bottom of the container, swarf or raw edges maybe. No play in the worm bearings end to end so left those alone. Relubed with Lithium Grease ( weird stuff ! ) and re-assembled.

I had a go at attacking the RA section but couldn't budge the locking ring at the bottom of the shaft, Stupid idea, a round 'nut' !! Doesn't even have a slot for a ring spanner. Checked the RA for play and seemed all ok, I'll deal with that when and if the problem re-occurs when I test it.

I did an on bench adjustment of the backlash for DEC and it seems pretty good but will need to be confirmed under power. The grease and condition internally was all good when I opened it up so fingers crossed it may have just been a bit of contamination causing the problem.

Next stage is to setup the mold for the pour for the pier head. I'm adding 260mm to the top of the pier with the 4 x m8 rods encased. The centre will be hollow so I can reach the nut for the M12 rod inside and I'll probably add a side entry so I can bring some of the wiring through.

I'll post some before and after and a few progress pix later.

It's been a good day .... :thumbsup:

31-01-2016, 06:52 PM
Poured the first concrete plug yesterday, now just go to wait while it hardens enough so I can build the mold for the top.

The mount I ran up on power on the bench and did the DEC worm and wheel adjustments. Seems to be running very smoothly, don't know if I have made any improvement. Soon see I guess

01-02-2016, 05:56 PM
Second pour, messy but complete. Didn't bother with a side entry hole to the internal cavity. I'll give it a few days to cure and harden then see if the bucket will just slide off. Otherwise I'll split it. The bits of wood are just holding it down against the pier base pipe.
The clouds can hang on a bit longer yet.

01-02-2016, 06:50 PM
looking forward to seeing the final result Brent

02-02-2016, 06:49 PM
Ok, paint bucket removed and Voila ! :P

Looks a bit rough on top but I've since scraped off a lot of the rough edges and broken the sharp corners. Next is to make a spacer on the lathe to go down over the internal pull down threaded rod at the bottom of the hole. Then tighten it down and finish it off. Should be firm enough by next weekend to load the mount and scope back on.
I'll also mount a bracket at North side to manage all the cables.

And it's a lovely clear night so I'm going to drag the big DOB out for a bit of visual. :D

02-02-2016, 06:56 PM
And just to really embarrass me here's what it looked like before :whistle:

02-02-2016, 09:19 PM
Heath Robinson is your father?

02-02-2016, 09:27 PM
That was more than a rat cage. That was a rat palace. :eyepop:

02-02-2016, 09:38 PM
You should reduce flex quite a bit with that mod

03-02-2016, 06:15 AM
Heath Robinson is your father?

We're just distantly related ..

Actually it was remarkably solid, Basically a clamped squared box. But yeah, this should be something of an improvement for sure. It came about when I switched from carrying the 10" Newt to the Lunt 102 F7 and it needed some height. At least it let me experiment and find the best pier height, there were several varying iterations to that point.

I've killed most of the rats .. :lol:

Clean up the floor and the pier and maybe even a coat of paint next ..

04-02-2016, 06:48 PM
And now cleaned up, tightened down ( it does not move !! ) and topped. Not levelled yet, just had time to turn up a spacer tonight.
Looks like I'll get the mount back up again over the long weekend, rain is predicted for Sat at least. It will probably get a paint job later as well to tidy it up.
Quite pleased with the result, didn't take as long as I expected. :thumbsup:

04-02-2016, 07:55 PM
That's looking like a nice solid pier Brent. Should work well.

08-02-2016, 06:31 PM
OK, re-assembled mostly. Clouds are preventing any alignment tasks ( so what's new !! ) and I've taken the opportunity to reroute some wiring around the mount but basically it's ready to go again. A lot more solid than it was previously, resonance is almost nil. It will get a coat of paint eventually but it needs to cure and dry out a bit first. I'll also make up a back board to mount all the electrics on and tidy up the rear.

20-02-2016, 08:49 PM
And the result just to show you a little maintenance is worth the effort. So a pier rebuild and a strip and lube of the mount with subsequent realignment using PHD2 mostly. Now I've got round stars and more detail and the guiding graph is much better than it was.
6 min 30 secs of exposure at ISO 1600 with the 1200D (18 exposures ) with an almost full moon nearby.
First clear night we've had since I completed the rebuild.