Pier designs/plan/measurements.

[K3ny0n]

Hey guys, Has anyone had a pier fabricated from a local company? Basically I don't fancy paying for a purpose built "astro" one. Does anyone have any drawing plans/designs and measurment's I could take to a local company to see if they could knock one up for me? The pier would house a NEQ6.

Thanks.

Rob

[Bizibilder]

You can work out the height you need using the supplied tripod first.  As to materials - I went to my local fabricator and had a look at his "offcuts".  I found a piece of 5.5" OD steel tube with a 1/4" wall and some squares of 12mm steel plate.  A few strips of 6mm x 50mm for the bracing and just asked him to weld them up - I gave him a sketch of what I wanted.  The pier is a little over 1m tall, the base about 12" square and the top plates 7" square.

All the studding and bolts are BZP and have lasted well without rusting.

I had a bit of tube left over so I had the same guy make a second "moveable" pier.  This one is around 1.2m tall:

The total cost for all the metal and the welding was around £150 and that is for two piers.  I supplied all the paint and also took the plates and struts (for the moveable pier) home and cut/filed and drilled them before they were welded.

The only other part you will need is an adapter to take the base of your EQ6.  I believe you can get these commercially or find a "tame" engineers to make one up for you.  If you look in the DIY section here you will find drawings and sketches of the plate needed.

[Tinker1947]

I planted a piece of 6" X 6" oak in the ground 3' 6" of, it used pea shingle (10mm) packed round it, if its required to be moved i can suck the pae shingle out with a industrial hoover and lift the oak out, so depending on the type of scope you want to use, i had 18" out of the ground plus 6" of 16mm studding screwed in to the top of the oak for a reflector a refractor would need a further 3' roughly, requires a 15.5mm drill bit for the holes, this then had another piece of oak with matching holes and the centre milled out to take a NEQ6 plus a 10mm coach screw  so the head became the peg, the cost £40 for the oak 2 pieces of 16mm studding  and 8 nuts and washers £20, bag of shingle £3 that's about it £63.....The roof goes right back and since the picture the scope has changed and the pier made 20" higher.....

[pete_l]

I planted a piece of 6" X 6" oak in the ground 3' 6" of, it used pea shingle (10mm) packed round it,

Brilliant!

[K3ny0n]

Thanks for the write up, made it a lot clearer.

If I was to make my own adapter for the mount, would I be able to re-use the azimuth pin with is on the mount now and use it on the adapter I would make?

Rob.

[Bizibilder]

You can use it if it is a screw in type ( The HEQ5 has a cast pin on the top of the tripod - not sure about the EQ6).  It is not difficult to drill and thread a hole for a suitable pin - quite a few folk just use a suitable bolt with the head sawn off..  The only thing to watch is that it clears the inside of the mount casting.

[Tinker1947]

The NEQ6 has a 8mm thread although any size close to that will do just cut the head off a bolt and file so it had 2 flat sides.....if you were to make one out of wood use a coach screw that goes right through so the excess is cut off on the bottom side...

[SnakeyJ]

I copied Mr Bizibuilders design (with some license on dimensions), which I took along to a local manufacturer and had cut/welded up.   It cost me £ 180, which rather more than Roger paid, but I think a good price for a one off comission and considerably more solid and less money than buying the Synta Pillar mount.    Details, including a bill of materials are posted here - http://stargazerslounge.com/topic/192304-snakeyjs-obsy-build-thread/page-3#entry2061925

[DrRobin]

Hi,

I had a pier made by Graham at Astrotec for an EQ6, it was designed to be semi portable but still weighs around 30Kg.  It is very similar to Roger's (Bizibilder) and is very stable.  I can't remember how much it cost, but think it was sub £200.

A slight coincidence, if all goes well with my obs, the pier will be surplus in late Nov/early Dec, but not sure if you will want to wait that long?

Robin

[K3ny0n]

Does anyone know what the diameter of the EQ6 base? Just been looking at work and I have all the parts to fabricate one myself. I just need to know about the adapter plate.

Thanks.

Rob.

EDIT: Am I correct in thinking the diameter of the EQ6 mount base is 130mm?

[K3ny0n]

Sorry about the questions it is just I don't have the mount to measure for myself.

Rob.

[ollypenrice]

You see lots of piers ending in threaded bar to allow for levelling. Piers don't need to be level for the mount to be perfectly polar aligned, so there's a lot to be said for not having the threaded risers since they compromise the strength of the pier.

There may be an effect on software based polar alignment methods but a simple drift alignment is possible on a non-level pier. Note that Takahashi tripods have no facility for levelling since it isn't necessary - provided you have another way of getting the polarscope reticle to have noon/north at the top. That's all your levelling does on most makes of mount. It just calibrates the polar reticle and in an observatory you won't be relying on a polarscope.

Olly

[Tinker1947]

The top of the tripod is 140mm in diameter, the centre hole is is 30mm wide and  35mm deep, the rebate is 65mm wide and 5mm deep, the centre spindle i think is a 12mm thread and 150mm long, the peg sits 45mm from the centre and is 10mm square and 30mm high, Olly mentioned the mount doesn't need to be level and don't need the threaded rises, but you will need a means of getting to the 12mm centre spindle to make adjustments so leave that up to you i used 16mm studding so leave it up to you how you do this bit,,,,

My wooden one....

 

[K3ny0n]

I see the problem with not having the threaded rises, you can not tighten the mount to the top plate. Would a hole which would be drilled in to the side of the pipe to gain acess to the underneath of the mount be okay? Or would it create more problems along the way?

This way it will do away with the two plates I would of been using and have a more rigid pier with just one top plate welded on to the pier tube.

Rob.

[Gina]

This is quite a common thing to do with a steel pipe as pier and called an "owl hole".  Not so practical with a concrete pier though   That's why I have two plates on mine.

Here is my original mounting for the NEQ6 - two 10mm steel discs and a 5mm aluminium plate to provide the 5mm x 60mm recess for the mount.  The disc removed from the ali plate (with a trepanning tool) made a useful washer to give sufficient depth for the central 30mm projection on the mount.  Using washers rather than nuts between the plates and minimal spacing made the assembly as rigid as possible while still allowing access to the M12 bolt with an open ended spanner.

   

[Gina]

Hmm... looking at this again has shown me that I will need to make up a new top plate for my pier top to take my EQ8 mount when it comes as that wants just a 12mm hole in the middle and my present hole is 30mm.  I'd forgotten about that.  A collar, 30mm OD and 12mm ID would be another option.  What's the chance of sourcuing one of those????   These washers get close (but no cigar) - http://www.ebay.co.uk/itm/8-x-Stainless-Steel-Washers-1mm-x-30mm-OD-x-12-5mm-ID-/221149978339?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item337d90dee3

[DrRobin]

The top of my pier has a removable plate, like a 'puck' that is drilled with a centre hole (for the EQ6 mount) and a threaded hole for the RA alignment post.  The puck then fits in to the top of the pier (it is a tight fit) and is then secured with three (radial) screws.  You will need a lathe to make one like this, but it does work quite well.

The 'owl's nest' appears to be a common solution as well.

For my latest pier (concrete) I set 6 M8 x 500mm studs into the concrete with 100mm showing above the top of the concrete.  I then machined a plate to fit over these 6 studs and the mount attaches to this plate.  The reason I went for 100mm is to allow me to adjust the height slightly (it is going in an obs) and level it.  I know the arguments about studs giving flex, but 6 x M8 SS studs aren't going to flex very much.  I will post a picture later.  This arrangement does at least allow for a single plate to be used and if you change your mount, you just need to make a new plate.

Robin

Robin

[DrRobin]

Gina, ah the benefit of a removable plate, you can always make a new one to fit your new mount.

Robin

[Tinker1947]

Hmm... looking at this again has shown me that I will need to make up a new top plate for my pier top to take my EQ8 mount when it comes as that wants just a 12mm hole in the middle and my present hole is 30mm.  I'd forgotten about that.  A collar, 30mm OD and 12mm ID would be another option.  What's the chance of sourcuing one of those????   These washers get close (but no cigar) - http://www.ebay.co.uk/itm/8-x-Stainless-Steel-Washers-1mm-x-30mm-OD-x-12-5mm-ID-/221149978339?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item337d90dee3

If you were a bit nearer i could make a pretty brass one, i do have various lengths/thicknesses kicking about, i would say if you take this route think about bonding it on the outside edge to make it non-flexing......

[opticalpath]

You see lots of piers ending in threaded bar to allow for levelling. Piers don't need to be level for the mount to be perfectly polar aligned, so there's a lot to be said for not having the threaded risers since they compromise the strength of the pier.

There may be an effect on software based polar alignment methods but a simple drift alignment is possible on a non-level pier. Note that Takahashi tripods have no facility for levelling since it isn't necessary - provided you have another way of getting the polarscope reticle to have noon/north at the top. That's all your levelling does on most makes of mount. It just calibrates the polar reticle and in an observatory you won't be relying on a polarscope.

Olly

Absolutely agree with Olly about no need for a double plate mounted on adjustable 'stilts' .... which to my mind potentially weakens the very rigid basic structure of the pier.  The (fixed) top plate of my pier is 1/2" steel with threaded holes to take the high-tensile socket screws that secure the mount base, so I don't need access underneath to tighten nuts.  I do like the mount base to be level, though, to simplify polar alignment, but it's perfectly feasible to achieve this even if the top plate is a little off horizontal.  I have three load bearing washers in a circle sandwiched between the mount base and pier top plate and I simply added shims to those until the mount base was level - a one time job and it never needs any further adjustment.  It is very solid.

Adrian

[ollypenrice]

These bottom fitting central mount-holding nuts have a lot to answer for! It shouldn't be necessary to get in from below or make owl's nests. We need a campaign!

Olly

[DrRobin]

Quite.  The other problem I find with my portable pier is that the central bolt works loose with polar alignment and needs to be checked and re-tightened from time to time.  In fact, it needs to be slightly slack to allow polar alignment and then once aligned should be tightened to stop any play.

My new mount has a pier plate on to which the mount uses three M8 screws from the top.  Just slacken them slightly to polar align and then tighten once aligned.

Robin

[Gina]

Gina, ah the benefit of a removable plate, you can always make a new one to fit your new mount.

Robin

Probably what I'll do.

[Gina]

If you were a bit nearer i could make a pretty brass one, i do have various lengths/thicknesses kicking about, i would say if you take this route think about bonding it on the outside edge to make it non-flexing......

Nice thought - thank you

[Gina]

Quite.  The other problem I find with my portable pier is that the central bolt works loose with polar alignment and needs to be checked and re-tightened from time to time.  In fact, it needs to be slightly slack to allow polar alignment and then once aligned should be tightened to stop any play.

My new mount has a pier plate on to which the mount uses three M8 screws from the top.  Just slacken them slightly to polar align and then tighten once aligned.

Robin

Yes, I've had that problem even with a fixed pier in my obsy.  At least the EQ8 doesn't rely on the central bolt for azimuth stability once PA has been achieved.  But what a daft arrangement to have a central bolt needing tightening from below and then making a pier/tripod with bevel gears to turn the bolt!!  I guess Heath-Robinson would be delighted but I think it's pathetic   It's a total bodge IMO