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Any Interest in an 8" Al Travel Scope group build?

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#26 Arjan

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Posted 20 August 2013 - 02:51 PM

Maybe, but you'd need to R&D anyway to convert it to Aluminium?

#27 kfrederick

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Posted 20 August 2013 - 03:18 PM

The water jet will cut anything .Wood plastic carbon fiber so go wild

#28 bertb

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Posted 20 August 2013 - 04:03 PM

My trusses are made of aluminium, 8mm diameter, there are six, each 4 parts, connected with M7 threatparts.
My telescope holds collimation well. However, the construction is a bit fragile, but does the job well during hollydays.

#29 Dave O

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Posted 20 August 2013 - 08:54 PM

My trusses are made of aluminium, 8mm diameter, there are six, each 4 parts, connected with M7 threatparts.
My telescope holds collimation well. However, the construction is a bit fragile, but does the job well during hollydays.


Ah, thanks for that bit of information bertb. :)

If one threaded cables inside the struts and then put them under tension (compressing the struts) would that stiffen them up, or would high frequency vibrations become an issue? Thinking perhaps some design where the cable is permanantly threaded through the strut segments and when relaxed the segments would 'fold' up into a compact size. Perhaps two struts share one cable with a common tensioning device located between them (at the vertex where the two struts meet).

As Kevin F. mentions, a water-jet can cut most anything, was thinking perhaps some form of carbon fiber honeycomb material? Or aluminum honycomb? I think CF would be more durable ... not sure how to bond the pieces together though, epoxy? Cost may be a big factor as well, no idea of the price or availability of those materials.

#30 Pinbout

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Posted 20 August 2013 - 09:26 PM

The water jet will cut anything .Wood plastic carbon fiber so go wild


the guy I deal with says it will stain the wood. even if you seal it before hand it still will stain the wood.

#31 Chriske

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Posted 21 August 2013 - 01:46 AM

Hi,

I just informed whether we can use a local travelscope here in Belgium to use as a starting point. It's a very nice and small one, only 6" high. I'll keep you informed.
Here at Urania Observatory we have our own design but our travelscope is to high to be used for this project.

@ Danny,
Why not design a completely new one. In my opinion it is more difficult to 'transform' a wooden one into an alu version compared to design a new one.

The trusses could be made in parts. The best option is to connect the trusses' parts using the Manfrotto system. No play at all, very stiff and sturdy.

#32 Pinbout

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Posted 21 August 2013 - 05:35 AM

here's some ideas on compression rings for telescoping poles. $$$$

or clamps for telescoping poles

#33 Chriske

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Posted 21 August 2013 - 06:03 AM

Hi Danny,

Lot of $$$$$ signs there... :shocked:

I was thinking of self-made connection studs. Something like these :

Very simple to make, very stiff, very strong yet very cheap..!

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#34 Pinbout

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Posted 21 August 2013 - 06:09 AM

yeah, that looks like my bogen boom arm connectors, but on my bogen there was a ring around the middle to keep them together and one side had angles starting from the middle and thinner on the edges.

#35 gatorengineer

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Posted 21 August 2013 - 07:20 PM

For the connectors it would be easy to turn some round bar stock to just under, and then tap the center. DJ light connectors.... Wish there were more hours in a day

#36 Chriske

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Posted 22 August 2013 - 02:20 AM

For the connectors it would be easy to turn some round bar stock to just under, and then tap the center. DJ light connectors...


Never seen it ( I think), explain please.. :question:

#37 Ps191

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Posted 22 August 2013 - 11:40 AM

We have some very talented designers and alot of great ideas, any interest in an 8" travel scope group build. Thinking of something that could be waterjetted out of aluminum.. Would need to account for various focal lengths of primaries...

Seeing what people think.


Would I be interested-yes-possible. Would like more information, like estimated size of travel package and planed ease/time of the setup and breakdown.

Here are some general thoughts, in no particular order.
- I would prefer a tool less setup and breakdown.
- If not designed carefully aluminum (in areas like rocker box) has little advantage over wood for a 8" scope, even a travel scope.
- Speaking of rocker boxes why have one? Why not have the poles (truss or otherwise) and altitude bearing fastened directly to the “mirror cell”.
- Are we stuck with using only aluminum? Maybe carbon fiber for truss poles, like the shafts from arrows. Even well designed wood components for a group build travel scope could work as good (or better) then aluminum. Wood may also be cheaper and make it easier to find someone willing to CNC from plywood.
- The big advantage of a 'single pole' design is when the pole becomes big enough, to fit the optics inside :lol:
- I suggest a string secondary holder, or an upper ring that is designed for multiple types of secondary holders so builders can have their choice.
- Dan from crawford machining may be interested in helping build some of the parts. I believe he helped with the SS127 refractor group build. Dennis from dobstuff may be able to help with select components too. (Disclaimer - I have no affiliation, (or even bought products from) the two afore mentioned businesses, but they seem to be willing to help atm’ers)
- I would like to see a design were the poles can fit inside the primary package. Having a ‘cube’ with most of the telescope components and then a separate package that is long, skinny and unwieldy seems to defeat the idea of a travel scope.

Comments/questions? I may have more thoughts and ideas to add later.

#38 Pinbout

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Posted 22 August 2013 - 12:41 PM

- Dan from crawford machining may be interested in helping build some of the parts. I believe he helped with the SS127 refractor group build. Dennis from dobstuff may be able to help with select components too. (Disclaimer - I have no affiliation, (or even bought products from) the two afore mentioned businesses, but they seem to be willing to help atm’ers)



I would not like to see a "professional telescope maker" be involved. :foreheadslap:

#39 Arjan

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Posted 22 August 2013 - 02:05 PM

How about a machining service like this one?
Does anybody know one with a good Q/$ ratio?

#40 Chriske

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Posted 23 August 2013 - 05:05 AM

Hi,

I think it would be logic to first make a 'paper' telescope. Once all parts are drawn and the telescope has passed the collitiontest in a 3D drawing software tool, then you start deciding whether parts will be selfmade or not(we even print some parts these days).
Here at Urania we designed a few scopes and telescopeparts of our owne. In most cases a lot of fellow amateurs came up with good suggestions and ideas to fill in their own needs. Next one or even two people build a prototype, that's the only way to encounter and find solutions for growing-pains. I think thats the way to start such a large project.
While assembling the scope(in your 3D software tool) you have to open two assembly windows. One to work with the actual scope and the other assembly window is the one were the scope is folded down for transport. So you can keep track whether all parts fit in the two 'versions'.

This is one of the scope we've designed at our local observatory. I myself did all the drawing while listening to all remarks from all fellow amateurs involved in this project. It took us a while to overcome all problems. This 10" f/6 scope is completely selfmade, even the focuser is own design(another project were all fellow amateur were involved to give comments and suggestions).
Our scope is way to large for this CN project, it measures 400x400x400mm (16"x16"x16") It was our goal to make a travelscope not to make it as small as possible.

I'm trying to say here such a project needs much more work compared to 'simple' scope. You actually build two projects, one working scope and a collapsed one.

Hope it helps. And I'd like to participate in this project if my willing hands are accepted.

#41 Pinbout

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Posted 23 August 2013 - 08:40 AM

Chriske,
what was the red inline skate wheel for?

#42 Chriske

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Posted 23 August 2013 - 09:07 AM

Danny,

If you look closely (and go back one page in the link) You'll notice 2 of these units in that scope. These are DSC, also selfmade. As encoder we use the internal hardware cannibalized from old MS-mice.

Guy, our Elec-guru even made a small PCB for this project. The software we use is from D. Eck.

The bleu colored parts in these DSC-units are selfmade casted resin 'brackets'. Using selfmade (casted) sprockets our largest error during action is about 0.5°.

#43 Pinbout

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Posted 23 August 2013 - 02:57 PM

I got mine down to 12"x12"x5.5" for an 8in mirror. but in the end I made it a little larger [by 1"] to be safe, to make sure everything fits.

designing the model

the model

the result

#44 davidpitre

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Posted 23 August 2013 - 07:57 PM

I'd sure be interested if it was a 10".

#45 Pinbout

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Posted 23 August 2013 - 09:21 PM

So would I. :grin:

#46 gatorengineer

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Posted 24 August 2013 - 07:04 AM

Danny nice job as usual, is there an easy way to get 2d drawings out of sketchup? Does sketchup have the ability to export in a format to feed a cnc machine? Thanks

#47 Pinbout

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Posted 24 August 2013 - 07:46 AM

I'd have to mod it with the flat artwork included. But you have to mod it again for 1/4"thk mat'l

#48 steveastrouk

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Posted 24 August 2013 - 09:09 AM

Yes, extracting flat surfaces is fairly easy. My son and I built a model from Sketchup here
Instructables

Extracted flat surfaces that ended up as DXF files.

#49 Pinbout

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Posted 24 August 2013 - 09:17 AM

That's an awesome project.

How did you use the led tape?

#50 Chriske

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Posted 24 August 2013 - 10:11 AM

Hi,

This is the travelscope designed by Guy and his crew of University Ghent, the one I was talking about earlier in this thread. As long as its source is always mentioned it can be used freely. This one is a 10". A 12" is also available.

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