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Late model car brake rotor for Celestron AVX pier adaptor

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#1 Robo1957

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Posted 16 July 2018 - 11:03 PM

I am building a ROR observatory in my backyard.  Budget considerations may mean a home made pier.  My background has me considering a four inch steel schedule 40 pipe welded to two steel flanges bolted to a twelve inch sonotube base.  I have a Celestron AVX mount and have learned that the 1995 Ford Fiesta 1.4 litre front disc rotor has the exact axle hole to provide the female to the AVX male.  All that would remain would be some machine shop work to mate the two flanges.  I have a feeling that a car that old is going to be hard to find.  Has anyone else done this with a late model car?  Please do not give me any feedback on the folly of my quest, I know the peril of my choice.  If the stock of a certain company I used to work for starts to go up, then it is all academic (**** Alberta oil patch!).  Are there any late model cars that match the AVX?

I am hoping somebody else has done this with an AVX.  The engineered metal piers you can buy are pretty awesome and have some pretty sound physics behind them, but Holy Crap, they are expensive. 

I am very new to the hobby and I am building now.  I would like to do astrophotography with my EDGE8.  How solid is solid?  How good is good?  When do you get to a point of diminishing returns when you are constructing or buying a pier for your backyard telescope for your own images that you hope to get pretty good at eventually.

Thanks for any help.


Edited by Robo1957, 16 July 2018 - 11:06 PM.

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#2 Nosky3

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Posted 17 July 2018 - 02:20 AM

I have done it. I used a pair of this brake rotor for my DIY metal pier with a 6.67 in outer diameter.

Look for "blank Centric Disc Brake Rotor 121.40017".

It has a 60mm center hole diameter that fits the bottom of the AVX mount.

 

 

Clear Skies.

 

 

Attached Thumbnails

  • top plate1.jpg
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Edited by Nosky3, 17 July 2018 - 02:32 AM.

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#3 Phil Sherman

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Posted 17 July 2018 - 11:57 AM

When I set up my Atlas mount in the observatory, I used a similar solution for the pier attachment. To avoid any machining, I purchased a pier extension tube which gave me the mount attachment end. The rotor I used for the base plate has a center hole that's a little smaller than 4". A 4" sewer test plug provided two heavy duty washers that could be doubled up to provide support for the bolt that holds the extension tube to the rotor. The extension tube's bottom fitting that has the tab that fits into the mount hole was removed, inverted and reinstalled, making a flat surface to sit on top of the rotor. The only work I needed to do on the rotor was to drill three holes for the bolts that attach it to the mount.



#4 Robo1957

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Posted 17 July 2018 - 03:19 PM

Nosky3!  Can you more clearly describe those brake rotors and where the heck I could buy them?  Please.



#5 roscoe

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Posted 17 July 2018 - 06:09 PM

Just go to an auto parts store and buy a new one!  If you go to the chain-type auto stores, they'll be like $20 each.

 

Just tell 'em you want "a 94 fiesta 1.4 front rotor" .  They may have to get it from the warehouse, so perhaps call and ask if they have one in stock.  You might try a couple of parts dealers to cost-compare.  If there's a choice, the cheap one will work just fine.... it's not like you need to put 60,000 miles on it......

 

And, bring your ruler, if it's not the right size, no big deal, they'll just put it back on the shelf.


Edited by roscoe, 17 July 2018 - 06:11 PM.


#6 Nosky3

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Posted 17 July 2018 - 08:53 PM

Nosky3!  Can you more clearly describe those brake rotors and where the heck I could buy them?  Please.

They are sold at amazon prime for $15.31 each with free shipping ($16.38 with tax) under "Centric Parts 121.40017 C-Tek Standard Brake Rotor".

 

Clear Skies.



#7 denny-o

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Posted 18 July 2018 - 08:06 AM

Nosky3 - what do you have against the innocent little AVX to punish it like that?


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#8 Robo1957

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Posted 18 July 2018 - 01:34 PM

Brilliant!!  I am going to get on that right now.  Thanks Nosky3.  I hope you find a Comet and they name it after you.



#9 Nosky3

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Posted 18 July 2018 - 03:13 PM

Nosky3 - what do you have against the innocent little AVX to punish it like that?

smile.png

Well, when the GoTo's on the avx with that heavy load became "grumble-to's", I had heard loud and clear from the little mule's own mouth. So I downsized the load to just the Edgehd 8 (C8) and the At115EDT for visual, for now.

In fact I just purchased Skywatcher EQ-6R mount as an upgrade during the recent sale.



#10 Nosky3

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Posted 18 July 2018 - 03:28 PM

Brilliant!!  I am going to get on that right now.  Thanks Nosky3.  I hope you find a Comet and they name it after you.

You welcome, Robo1957.   However, most of the credit goes to several trailblazers who had extensively used this brake rotor concept for diy pier plates, a few years back.  

 

I am in the process of adapting yet another one of these brake rotors for a top pier plate for my brand new EQ-6R mount. Like its other cousins and clones (Atlas, CGEM, etc),  the  EQ-6R requires a larger center hole of about 65mm in diameter. 

 

Clear Skies.



#11 Mick G

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Posted 22 July 2018 - 07:30 PM

Anyone have a recommendation for a rotor to use with a CGEM DX?



#12 denny-o

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Posted 10 August 2018 - 02:38 PM

Just re-tripped over this thread.

I'm attaching a pic of my pier adapter - for no socially responsible reason other than shameless showing off  choo-choo.gif 

It is half inch steel plate (except where it is thicker than that) The bottom of the adapter box has four bolt holes matching the studs on the top of the pier. Weighs about 30 pounds.

The devil finds things to do for idle hands.051 Resize.jpg


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#13 Robo1957

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Posted 12 August 2018 - 09:15 PM

Just re-tripped over this thread.

I'm attaching a pic of my pier adapter - for no socially responsible reason other than shameless showing off  choo-choo.gif

It is half inch steel plate (except where it is thicker than that) The bottom of the adapter box has four bolt holes matching the studs on the top of the pier. Weighs about 30 pounds.

The devil finds things to do for idle hands.attachicon.gif 051 Resize.jpg

A thing of beauty.

 

Can you guys tell me please.

 

What is a good height for the pier?  What height should the point of connection of the mount to the adaptor plate be? My SkyShed will have six foot walls and the telescope 8 inch EDGE will be in the centre.  I am going for roboscope astrophotography as a goal.  I am not concerned with low horizon.  Thanks.



#14 denny-o

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Posted 13 August 2018 - 12:57 PM

IMO any declination below 25 degrees is worthless for AP and 35 is a maybe.  My pier and mount adapter plus the CGEM peering over the sidewall puts the lowest angle I can see down around 20 degrees. I did not carefully measure things out. I figured lower was better for wind protection. When I built the pier there was no enclosure yet. I figured the floor would be a foot off the ground and the side walls would be 4 feet tall. I made a wild guess as to the the height of the mount + adapter box and set the sonotube height to work with those numbers. I was pretty close and I'm happy.

 

Edit to add that I used a couple of 2x4 leaning together to give me the roughly 5 foot off the ground side wall and than a yardstick and a foot long torpedo level  clamped to a step ladder and  to scope things out by eye before calling the cement truck. It did prompt me to adjust the sonotube by roughly 6 inches. I did set the pier a foot to the South from the center of the 8x8 platform knowing I spend far more time on the North side of the pier.


Edited by denny-o, 13 August 2018 - 01:06 PM.


#15 ssmith

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Posted 17 September 2018 - 06:42 PM

nosky3 -

 

Wonderful idea,  In regards to the brake rotor top-plate maybe I missed something - what does the center bolt that holds the mount head to the rotor bear against?  

 

How easy is it to drill through this material.  I have a medium size drill press - would this be adequate?


Edited by ssmith, 17 September 2018 - 06:46 PM.


#16 Nosky3

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Posted 18 September 2018 - 05:17 AM

nosky3 -

 

Wonderful idea,  In regards to the brake rotor top-plate maybe I missed something - what does the center bolt that holds the mount head to the rotor bear against?  

 

How easy is it to drill through this material.  I have a medium size drill press - would this be adequate?

ssmith:

 

The center bolt bears against a metal bar that is bolted up just under the top plate. You can see the end of the center bolt support bar right under the top plate in the image of the pier.

 

I have attached a image of the center bolt/support bar combo.

 

We used an old drill press (probably medium size too)  to drill the holes. No precision engineering there. Your drill press should work fine.

Attached Thumbnails

  • center bolt braket2.jpg


#17 ssmith

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Posted 18 September 2018 - 08:28 AM

Ok - I think I see what is going on - the center bolt support bar is being held in place by two of the top rotor leveling bolts & nuts.  Perfect !

 

What diameter bolts did you use for the leveling screws?

 

The short center bolt & knob shown in your picture - is that an after-market item or something that can be picked up readily?

 

thanks,


Edited by ssmith, 18 September 2018 - 05:20 PM.


#18 Tom K

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Posted 21 September 2018 - 08:54 AM

I am in the process of building one of these right now - should have finished pics either later today or tomorrow depending on how much "free" time I get to finish.   The center bolt is a metric M10 1.5 bolt.   I am not using a custom knob - I will be setting this on the pier and not taking it off for a long time so I will just use a wrench...

 

A decent cobalt bit, a small drill press at lowest speed, some 3:1 oil and the holes are easy to drill - just go slow.  Getting the post in the right spot takes a bit of measuring to get it right.   I have a 1/2" bolt in there in the right spot and will be grinding off the threads on two sides after installation to provide flat surfaces for the azimuth adjustment screws.

 

I really appreciate the OP - those rotors are nicely built, heavy, and only $15 each delivered on Amazon!

 

Tom 



#19 Tom K

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Posted 21 September 2018 - 06:37 PM

Here is my version as a work in progress.   These bolts were too long so they went back for shorter bolts....

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#20 ssmith

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Posted 21 September 2018 - 11:18 PM

I received my rotors today and they are very nice.  The central hole couldn’t be a better fit to the mount.

 

Tom - what diameter bolts did you use around the periphery ( 1/2” ?).   I don’t see any need for grinding the post bolt flat on two sides.  I would think that the azimuth screws would bear just fine against a round post and you would only loose a tiny bit of adjustment range by leaving it round (wider).

 

The OEM azimuth post on the tripod is actually quite small.  I may try a 3/8” bolt and work my way up if necessary.


Edited by ssmith, 21 September 2018 - 11:30 PM.


#21 Tom K

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Posted 21 September 2018 - 11:37 PM

Here are some images of the (nearly) finished project.   The bar beneath the upper brake rotor is made out of a concrete form stake ($3).  The trickiest part is getting the holes on center for the center M10 bolt connection to the bottom of the mount.   I was a little bit off at first so I just made the center hole into a slot.   This gave me some room so that the M10 center bolt would go in smoothly.   I bought one that was longer than needed and used washers ( and a 1/2" nut) to get the right amount of threads into the mount without bottoming out.   My local hardware store had 50 mm and 75 mm bolts.   50mm is too short (only a few threads get into the mount) and 75mm is too long.

 

My pier is made of 12" square tube steel as it holds up my fold off enclosure.   There is a 1/2" hole in the middle of the top plate with a 1/2" nut welded to the underside of the plate.   I used a square plate sold at Lowes that is used for anchor bolts to hold the bottom brake rotor down.   It is not going anywhere.

 

This setup is rock solid.   Once you tighten up the bolts everything locks in. 

 

Now I get to spend the next few nights dialing in alignment

 

Tom

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#22 Tom K

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Posted 21 September 2018 - 11:42 PM

Steve - you are right - grinding the sides of the bolt was not really necessary but I have an angle grinder and it took less then two minutes, so....

 

I used 1/2 bolts.   Mine are 4 1/2 " long.  As you can see I needed to clear the wooden bottom of my enclosure.   I could have made it tighter but you still need to be able to fit your hand in there to attach things.  

 

I was getting ready to spend many hundreds on an adapter, so the suggestion for these rotors by the original poster saved me a bunch.   I think I spent less than $50 total on this.    I owe the original poster a beer (or ten)!

 

Tom



#23 Tom K

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Posted 22 September 2018 - 12:19 AM

Those last images were terrible - here are some better ones....

 

Tom

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#24 Tom K

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Posted 22 September 2018 - 12:21 AM

Sorry - I am still getting the hang of this image upload system..

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#25 Tom K

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Posted 22 September 2018 - 12:24 AM

More larger images

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