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Graham

Test rig. The build.

45 posts in this topic

Hope it goes well Graham and you get clear sky's to test it, keep up with the photo's! 

 

Cheers

Ron

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Solid piece of work Graham, you don't do things by half. 👍 It just looks right!

looking forward to more of the same...

cheers!

 

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It is certainly going to be a bullet proof solid design from the look of that cell. :thumbsup:

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Thanks folks.

I so much admire the Victorians and their philosophy for building things to last.

None of this throw away rubbish we get today.

I always try to build thing to last for generations.

 

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It's a John Deere or Massey Ferguson Diff and axle you are going to need by the looks of it. It's going to be a hell of a grab n' go outfit. :rofl:

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Martyn

It is actually not as heavy as it looks. ;)

 

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It bends light! 

 

Johnnyaardvark and Graham like this

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8 hours ago, Graham said:

Thanks folks.

I so much admire the Victorians and their philosophy for building things to last.

None of this throw away rubbish we get today.

I always try to build thing to last for generations.

 

Those Victorians didn't mess about with lightweight flimsy structures.

 

Brunel did some really big stuff, but you got me thinking of James Nasmyth who built a massively mounted 20" F17.5 cassegrain. He sat on stool which was part of the mount and looked through the eyepiece in the altitude axis. It is now in the science museum...

http://www.millseyspages.com/astro_pages/la_palma/nasmyth.html

 

He also built a massive steam hammer among other things.

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Took advantage of the sunny weather when I got home from work tonight and put the test rig frame together. :facepalm:

This is going to be the actual physical size of my scope's OTA when it is completed.

Apologies for the smug looking old fart but I was just thinking to myself.

I think I am going to need a bigger Dome. :rofl:

 

Test Rig.jpg

 

 

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That's pretty big Graham.

 

By the time you have it on your yoke mount it will be bigger then your dome.

 

Nice job though :thumbsup:

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Brilliant Graham. When you build your next, even bigger, scope you won't obstruct the optical path quite so much. :)

 

You deserve to look smug now it's all coming together. :thumbsup:

 

What diameter is your dome?

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7 minutes ago, Doc said:

That's pretty big Graham.

 

By the time you have it on your yoke mount it will be bigger then your dome.

 

Nice job though :thumbsup:

 

Your not far wrong there Mick.

 

2 minutes ago, Tweedledee said:

Brilliant Graham. When you build your next, even bigger, scope you won't obstruct the optical path quite so much. :)

 

You deserve to look smug now it's all coming together. :thumbsup:

 

What diameter is your dome?

 

Thanks Pete.

Did the collimation bits and pieces last night so that is all ready to go.

Just the Whiffle tree guide rollers and the safety plates to do.

The dome is 2.5 meters 

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1 minute ago, Graham said:

 

Your not far wrong there Mick.

 

 

Thanks Pete.

Did the collimation bits and pieces last night so that is all ready to go.

Just the Whiffle tree guide rollers and the safety plates to do.

The dome is 2.5 meters 

Now, if you'd just been content to stick with your 200mm and the frac....:lol:

 

Looks like a full weekend obsy build project, the speed you crack on. ;)

 

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That's what I want - a scope I can stand inside lol. :laugh2:

 

Fabulous job Graham - can't wait to see the complete scope. :)

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Thanks folks.

 

Been doing a bit more tonight.

Cut and welded in the lower frame.

This will carry the pivot bearings.

The top section will be left open so I can put the mirror in and out without anything being in the way.

 

Test Rig 2.jpg

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That is looking great Graham it reminds me of big Blue that was brought to Kelling

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You are making good progress Graham 👍

Step by careful step you are getting closer to a great result, and it's great for us to be able to follow the processes involved.

Looking forward to seeing you prove the mirror etc.

 

Did you get a 'flat' secondary?

 

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Have you calculated the pivot position accurately, or just arbitrarily which may require balance weights?

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Any reason you have only gone with three trusses and not continued those other two upwards to make five.

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2 hours ago, Smithysteve said:

You are making good progress Graham 👍

Step by careful step you are getting closer to a great result, and it's great for us to be able to follow the processes involved.

Looking forward to seeing you prove the mirror etc.

 

Did you get a 'flat' secondary?

 

 

Thanks.

Yup getting there.

I actually got a couple of flats.

A cheapish one that I will put in this rig the other one which is a scientific grade mirror and cost a load more :facepalm: I will use in the scope.

 

1 hour ago, Tweedledee said:

Have you calculated the pivot position accurately, or just arbitrarily which may require balance weights?

 

I have a couple of plates which will span the sides of the rig with the pivot holes cut in ready.

I will put the rig onto a fulcrum  to find the exact balance point before I weld these plates into place.

 

1 hour ago, Doc said:

Any reason you have only gone with three trusses and not continued those other two upwards to make five.

 

I only need the three to keep the top square.

I am going to mount the focuser onto an adjustable plate that will be fixed to the top rim.

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On 12 June 2016 at 21:02, Tweedledee said:

Those Victorians didn't mess about with lightweight flimsy structures.

 

Brunel did some really big stuff, but you got me thinking of James Nasmyth who built a massively mounted 20" F17.5 cassegrain. He sat on stool which was part of the mount and looked through the eyepiece in the altitude axis. It is now in the science museum...

http://www.millseyspages.com/astro_pages/la_palma/nasmyth.html

 

He also built a massive steam hammer among other things.

 

One further interesting fact... I read that during his latter days as an astronomer he co-wrote a book on the moon. Back then photography was not yet advanced enough to take actual pictures of the Moon, Nasmyth built plaster models based on his visual observations of the Moon and then photographed the models for the book! 

 

I have also had a look at that steam hammer and it was a brilliant design! It had full control over the length and force of its stroke - it could crack an egg or generate enormous force at the will of the operator. We had a similar steam driven hammer in the blacksmiths shop at a colliery i worked at a long time ago. I remember using it and there were no safety devices, guards, Emergency stops at all around or on it. It was a great tool and easy to use 😎

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Managed to water jet the bits I needed for the stand.

Spent and hour this morning assembling the rig.

Here's a few photos of the beast.

 

Test Rig 3.jpg

 

 

 

 

 

Test Rig 4.jpg

 

Test Rig 5.jpg

 

Down the throat.

 

Test Rig 6.jpg

 

The collimation adjusters

 

Test Rig 7.jpg

 

The entrance allowing the fitting and removal of the mirror .

 

Test Rig 8.jpg

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