Pier metalwork help

[jambouk]

Following on from two other threads, I seem to have solved in my head my pier issue (pier to live outside so concrete construction). Now I need to solve the pier head issue. I want something like the metalwork shown in this image (taken from Google), not the same, but similar, and to eventually take an EQ8.

Is this something I can buy off the shelf to bolt down into threaded bar coming up out of the concrete and then attach an EQ8 puck on the top? Nothing in stock at RVO or FLO, and AA haven't replied to my email, and emails from an astro engineer gone silent.

Thanks for any help.

James

 

[MarkAR]

I think most are custom made/DIY.

Main thing is to draw up a diagram with accurate measurements of what holes and where they have to be. With a bit of careful thought one can be made to take a variety of adapter pucks. 

The two plates shown would be fairly easy to knock up something similar myself, then just add the relevant puck or make one with the right measurements.

[Nigella Bryant]

Custom made but you can buy the metal plates off flebay. I did for my neq6 you just need the right size metal plates to take your mounts puck.

[MarkAR]

Old brake disks are also useful. Got some old MX5 ones somewhere.

[adyj1]

For a DIY job, brake disks are a good solution - I have an old black EQ6 which needed a 65mm centre hole. The investigations were quite lengthy, but I finally bought a

     "Genuine SKODA brake disc 1K0615601AC VW / AUDI / SEAT"   

from eBay for £15. The mount fits like a glove.

It then needs

    a metal plate on the back to bolt the mount to,

   a pin mounted in the top for the alignment screw,

   holes drilled in the disk to mount on the pier

   a coat of paint 

It then replaces the top plate in your first picture.

(Luckily I had a mechanic who owed me a favour, so for me the backplate plate was mounted with bolts and I got it sprayed for nowt 🙂 )

 

 

    

 

 

[jambouk]

My friendly garage had some old disc brakes but they have a gap between the two halves; photo of one disc below. It already has central holes which I could pass threaded bar through from the pier, but then I’d need to drill through the disc itself to pass M18 bolts through to the disc above. Are these suitable?

 

[saac]

2 hours ago, jambouk said:

My friendly garage had some old disc brakes but they have a gap between the two halves; photo of one disc below. It already has central holes which I could pass threaded bar through from the pier, but then I’d need to drill through the disc itself to pass M18 bolts through to the disc above. Are these suitable?

 

 

No reason why the vented discs would not work assuming you can easily drill suitable sized/spaced holes. The garage should have a ready supply of the unvented discs which would give a neater finish.

Jim 

[jambouk]

They feel like they are cast iron; is that a suitable material? 

This is why I wish there was an off the shelf option.

 

[MarkAR]

Yes they're cast iron. In theory vented disks will be a lot more rigid and you have more thickness. I would definitely use them.

When you drill them don't use any oil, cast iron is self lubricating. For 18mm you really need a pillar drill and have it firmly clamped down, start with a smaller 6mm hole and work up to 18mm.

If you don't have a pillar drill ask your friendly garage if he can do it for you.

[jambouk]

Thanks. 
 

How do I then attach the puck to the top brake disc? [I have in my head how the bottom disc would attach to the pier, probably with M12 threaded bar up through the concrete, and got in my head how the top disc would levitate above the bottom one with five M18 bolts leaving about a 10cm gap between to get my hand in for the mount heads central bolt, but no idea how to attach the EQ8 puck to the top disc.]

[MarkAR]

You'll probably have to drill and tap the puck and bolt it on from underneath.

[jambouk]

Would it matter that the outer part of the puck was unsupported? The 8” Altair Astro puck would overhand the raised bit of the disk brake by about an inch all the way around...

https://www.altairastro.com/skywatcher-eq8-pier-adapter-cnc-443-p.asp

[MarkAR]

Should be ok, You'll probably have to drill your own holes in the puck. Or maybe turn the brake disk over and see where the holes lie on the puck.

Shame you're not closer to Guildford, I would be able to help with the machining.

Edited September 20, 2020 by MarkAR

[jambouk]

Thanks. Do any of these holes need to be tapped or can I just get them drilled and then have nuts underneath? 

I’ve seen new brake discs of 300mm in diameter online for £25 so may get these and then just paint them in hammerite once drilled. I still worry about the forces between the two discs by the M18 bolts applying too much lateral pressure on them and cracking the discs. 

James

[MarkAR]

The holes in the disks can just be drilled, use nylock nuts as they usually stay put. As long as you leave a minimum of say 20mm around the edge they should be fine. So for a 300mm disk with 18mm holes the distance from the centre to the middle of each hole is around 120mm or less.

[jambouk]

MarkAR - thanks again. I think a plan is coming together.

How many M18s do you think would be optimum between the two discs? I was thinking five, as it is a number I like and I could still easily get my hands between them, leaving a 100mm gap between the top and bottom plates. Can I use stainless steel threaded bar and cut to desired length with nuts above and below each plate, or is it best to use stainless steel M18 200mm bolts?

James

[MarkAR]

Don't do 5, you'll need to adjust the top disk to get it really level. The ideal is 3 as it's easier to level but 4 would be more stable.

[jambouk]

Thanks. Which is more important, stability or being perfectly level? 
James

[AdeKing]

What mount are you intending to put on it at the moment?

If something like an EQ5/HEQ5 then check whether or not the bottom of the mount will fit into the large hole in the top of the disc.

This is how my Vixen GP and GPD2 fit to the one that I have, then just a piece of metal bar with a 10mm bolt to hold the mount in place.

No need for a fancy puck on top that way.

Obviously I'm not using this at the moment, it came free with a recently acquired GPD2 mount and was on a wooden pier.

I've retained it for when the current moveable pillar mount evolves into a permanent pier but need to get my wife accustomed to it being there before thinking about a permanent pier.

Edited September 20, 2020 by AdeKing

[adyj1]

4 hours ago, jambouk said:

How do I then attach the puck to the top brake disc?

As Ade's pictures show, the point of using a break disk is that the centre well acts as the puck, so no puck required. If you want to use a puck (or perhaps need to because of the dimensions of your mount), you don't need a brake disk... 

I have brake disks for my eq5 and eq6. Different sized disks, of course. 

Ady

 

[MarkAR]

With the EQ8 I would use 4 bolts, almost as easy to level as 3.

[jambouk]

EQ8. If I didn't have the top plate [disc], I'm not sure how I'd attach the puck to the lower plate [disc] with M18 bolts, as the whole of the flat surface of the puck is in contact with the flat surface of the mount. Image below of the Altair Astro puck below and the illustration of it from the FLO website.

 

Edited September 20, 2020 by jambouk

[adyj1]

Ok, so the EQ8 has a flat base, apologies - I should have looked into that 🤔. (I think the comments on using a brake disk have probably come from the picture of an eq6 in the first post, and maybe your comment of 'eventually take an EQ8'.)

Looking at the information provided by FLO, it appears you have all the dimensions you need to fabricate the correct 'top plate' for your mount out of a flat metal plate - without needing a brake disk or pier adapter;

- You don't need the brake disk because the EQ8 mounts on a flat surface, and the purpose of a brake disk is to provide a raised platform with a hole for the pier's central mounting column.

- If you bought the pier adapter, you'd have to fabricate a plate with the necessary mount holes to mount the adapter, which is just as much effort than as making a custom top plate to mount the mount directly.

The following thread shows what I am talking about in terms of a 'top plate' onto which the EQ8 is directly attached (and goes into the level of detail probably required when thinking about mounting the EQ8)

 

Mind you, I'd wait for confirmation from someone more familiar with kit at the more exotic end of the equipment spectrum - if you've forked out for an EQ8 you want it to be as close to perfect as you can, and I'm more at the 'let's see if this works' end of the aforementioned spectrum 😉 

 HTH

Ady

 

PS - I've just noticed from the FLO web page that the EQ8 is delivered on a pallet. wow 😮

Edited September 21, 2020 by adyj1
PS

[AdeKing]

19 hours ago, jambouk said:

EQ8. If I didn't have the top plate [disc], I'm not sure how I'd attach the puck to the lower plate [disc] with M18 bolts, as the whole of the flat surface of the puck is in contact with the flat surface of the mount. Image below of the Altair Astro puck below and the illustration of it from the FLO website.

 

Apologies, for muddying the waters, your original post said that you'd eventually mount an EQ8 on it.

I incorrectly assumed that this meant that you currently had a smaller mount but wanted to future proof and install an EQ8 at a later date.

I didn't realise that you wanted to construct and mount an EQ8 on it now.