Made a pier for my telescope mounts, I made it so i can use 3 different mounts on it, a Skywatcher AZ-EQ6 a iOptron Pro Cube and a FTX Alt-Az mount.
Also made a PVC cap to cover it from the elements.
Got sick of setting up the tripod and having to level it etc. most times when i wanted to view or photograph something i found it was to much trouble so i would give it a miss, now i have no excuse.
Nice pier, but you really need scrap the three leveling bolts.
There is absolutely no requirement to level the mounts.
They will polar align perfectly without being level. The bolts simply reduce the the rigidity of your large diameter pier by around an order of magnitude....in engineering terms the weakest link applies, hence we have gone from bolting your EQ head(s) to a twig, instead of a tree trunk.
Nice pier, but you really need scrap the three leveling bolts.
There is absolutely no requirement to level the mounts.
They will polar align perfectly without being level.
Ok I wasn’t aware that the mount didn’t have to be level, I was taught to level the mount first.
The amount of work I put into making it I think it will stay but thanks for your input.
Hi Alan,
Great to have a pier, as others said, makes the whole set up process a whole lot easier. I can get it going in 10-20 mins.
Anyway, if you want to do away with the rate cage as peter said, you can get a half pillar extension and do what I did. You may need more plate adapters for other mounts. http://www.iceinspace.com.au/forum/s...d.php?t=136618
Cheers
Bo
I've got one of those "leveling" plates on my pier but its more so I can get my hand underneath to do up the mounting bolt. That's a lot easier than cutting a massive hole in the side of the pier. Those 3 bolts are a lot more stable than a tripod anyway so that's a big upgrade by it self. The only thing you might find is that the pier might "ring" when knocked, I filled mine with fine sand and it now has a dull thud.
I can get my hand underneath to do up the mounting bolt.
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That's a lot easier than cutting a massive hole in the side of the pier.
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I filled mine with fine sand and it now has a dull thud.
Rick
Yeah that is one reason using 3 different mounts.
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The pier has been galvanised so I won’t be doing that.
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Might do that thanks.
Ok I wasn’t aware that the mount didn’t have to be level, I was taught to level the mount first.
The amount of work I put into making it I think it will stay but thanks for your input.
Al
For circular sections the moment of inertia is proportinal to the diameter to the 4th power. If my arithemetic is correct you have reduced the stiffness of the pier by about 6000x by using 10mm bolt(s) instead of the full diameter of the pier (150mm and say 4mm wall).....hence my comment.
I use a 10” steel pier with 1/2”walls. doesn’t move much
I use a 10” steel pier with 1/2”walls. doesn’t move much
Bit of overkill for an EQ6.
Also, there are myriad threads on pier vibrations/stiffness.
Unless there is something to create vibrations, it is all moot.
If there are vibrations present, you probably need to do a proper analysis, as designing to suppress them is not as simple as add mass/stiffness.
Accidentally hitting a mount ( or wind on the OTA ) is the worst normal scenario, and in this case, the OTA and mount are normally far weaker than the pier, so you will lose the subs, no matter what.
Also, there are myriad threads on pier vibrations/stiffness.
Unless there is something to create vibrations, it is all moot.
If there are vibrations present, you probably need to do a proper analysis, as designing to suppress them is not as simple as add mass/stiffness.
Accidentally hitting a mount ( or wind on the OTA ) is the worst normal scenario, and in this case, the OTA and mount are normally far weaker than the pier, so you will lose the subs, no matter what.
Andrew
Indeed, ideally you want low mass and high moment of inertia, so any perturbation will have a low amplitude (eg immune to small breeze) and decay quickly. That said even an EQ6 probably deserves better than a 8-10mm diameter bolt...the attached diagram from my old engineering text don’t lie.
Gday Peter
The strength/stiffness/deflection calcs are only part of it.
Deflection is very rarely ever the controlling factor in a pier.
ie take an identical tuning fork design ( ie same moments of area etc )
Make one from tuning fork steel and one from bog std Mild steel.
Totally different end results :-)
And again i put it that if the knock/vibration is induced via the mount or OTA, then no amount of pier strength will save you.
Andrew
( also did Mech engineering incl vibration analysis )
Gday Peter
The strength/stiffness/deflection calcs are only part of it.
Deflection is very rarely ever the controlling factor in a pier.
ie take an identical tuning fork design ( ie same moments of area etc )
Make one from tuning fork steel and one from bog std Mild steel.
Totally different end results :-)
And again i put it that if the knock/vibration is induced via the mount or OTA, then no amount of pier strength will save you.
Andrew
( also did Mech engineering incl vibration analysis )
Not sure where you are going with this...but surely not to suggest 3x stainless steel bolts at the top is the best to preserve the stiffness of the lower section of Al’s beaut pier.
Other than in the Hubble, small perturbations can and do go un-noticed in many a telescope...I’ve bumped my head occasionally on the 50kg of counterweights on my mount...and often exclaimed “gosh” or “golly” . ....anyway, the post-concussion subexposure was fine.
Last edited by Peter Ward; 02-09-2018 at 05:55 PM.
Reason: clarification by Al on bolt type
I’ve bumped my head occasionally on the 50kg of counterweights on my mount...and often exclaimed “gosh” or “golly” . ....anyway, the post-concussion subexposure was fine.
