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the curse of diy... serrurier truss and big dob

Dave_D

By Dave_D
in DIY Astronomer

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Dave_D

Dave_D

Posted
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So in a fit of total insanity, i've started 2 projects, both big, both long-term.

first off is something i've wanted for a loooong time, and that's a serrurier truss scope. i'm going to eventually rehouse the optics out of my orion optics GX250. the optics themselves are excellent (if in need of recoating) but, as the scope is quite old, suffers from orion optics previously 'agricultural quality' in the tube and 'cell' (if you can call it that). 

i want to  basically copy  Raymond Collecutts exquisitly made serrurier newt as shown in this thread

http://stargazerslounge.com/topic/206589-carbon-serrurier-truss-newtonian-10-f4-build/?hl=%2Bserrurier#entry2224689

but adapt it to suit my f4.8 primary. 

the other project, is finally, after having them sat in a box for over 25 years (ok, a crime i know), is to build a collapsible dob using my 14.5" f5.6 optic set.

the dob itself is not an issue as there is (light)bucketloads of info available, but the serrurier truss is giving me a headache finding the required info to calculate strut lengths etc.

oh well.... this is going to be interesting....

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kev

kev

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Good luck with it.

I think i would be tempted to do the dob first so that you always have an operational scope.

14.5 " at 5.6 is going to need a stool to stand on to getvto the eyepeice. Bet the views will be marvelous however. My in 14, f5 gave great views, inc lunar whole disk. The detail. And at lunar eclipese ...

Sent from my iPhone using Tapatalk

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Dave_D

Dave_D

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Has anyone used anything like jb weld or loctite metal? It's maybe a possibility instead of aluminium welding.

Found this little vid on youtube

Best Epoxy Streangth Test , JB Weld, Loctite, Dev…:

Could be a possibility?

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Peter Drew

Peter Drew

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A Serrurier truss shouldn't pose too many problems, for a start the components of a truss are the same length and provided that the tube ends are fitted with right angle brackets at their ends as shown in the link they will fit up accurately. I would recommend making a scale drawing to help with the measurements.The worst mistake is to make them too short. In the past I've had to make many truss tube Newtonians from 14" - 30" with no problem. Go for it. 

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nytecam

nytecam

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My attempt at a serrurier truss 17.5" Newt with 50mm square box aluminium section [to be equat mounted] decades ago was a failure.  I made the top end section and could 'rotate' it with hand pressure probably due to poor engineering.  I knew the serrurier design could 'sag' but this was rediculous.  Perhaps you'll have better luck and I wish you well.  I dedid my project in twin-walled ply tube using diaphram construction and it was extremely rigid bit lightweight thus not a truss design   :grin:

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lardy

lardy

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I would buy a secondhand TIG ... a few on Ebay, learn to Alu weld, it'll take a while to get good results, practise on metal before going on to Alu (if you can pat your head and rub your tummy you'll do fine lol)  .... then sell it on Ebay after the project is finished.

They do use liquid metal to stick super car wheels together .... it's not the stuff you would buy over the counter though.

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lardy

lardy

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It's not a very neat way .. but does fuse the Alu together. When you scratch with the stainless rod to break thought the oxide it leaves a very uneven finish, It works though, think I still have some flux and filler rod in my garage. 

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lardy

lardy

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You scratch though the molten applied  filler to remove the oxide on the parent metal with a SS rod which allows the filler to fuse with the parent metal  .... this leaves the filler "weld" a little untidy. It is like brazing but it's not if you get what I mean ... 

The kits are quite cheap and readily available, I watched a demonstration at a Kit car show, were I brought my kit .. the guy made it look so easy and got quite a good finish.

It did the job for me, a quick repair ...   

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Dave_D

Dave_D

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You scratch though the molten applied  filler to remove the oxide on the parent metal with a SS rod which allows the filler to fuse with the parent metal  .... this leaves the filler "weld" a little untidy. It is like brazing but it's not if you get what I mean ... 

The kits are quite cheap and readily available, I watched a demonstration at a Kit car show, were I brought my kit .. the guy made it look so easy and got quite a good finish.

It did the job for me, a quick repair ...   

oooh what did you built? i was doing a Kudos

kudos_coupe.jpg

had an alfa flat 4 boxer 1500 ti that i totally rebuilt and tuned up (over 300hp/ton in that body) and the company that made the body shell went bust lol

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