Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

How hard is it to build a telescope?

gooseholla

By gooseholla
in DIY Astronomer

Recommended Posts

  • Replies 542
  • Created
  • Last Reply
gooseholla

gooseholla

Posted
  • Author
Posted

El Goosey's 'Manly' guide to sewing a shroud

1. Put on your best Ray Winstone voice.

2. Tell yourself it is for the betterment of mankind...

3. Go to your manliest manly drawers and pull out some pegs, safety pins, dress makers scissors and dress makers tape measure.

11954604_406100576254808_324778933613200

Now you can try all kinds of hard ways like pegging or pinning the shroud around the scope - but you'll have fun cutting excess material. Do yourself a favour - we're not professionals and this way will give you a nice simple shroud which is easy to do.

First, measure from the top of the bottom cage ring. Measure down to the bottom of a pole block. This is your height. Add an inch or two for folding the material to make a nice straight edge. Then measure around the lower tube ring. This will give you width. Spandex is nice and stretchy so you are going to make a tube the same size at the top and bottom.

12047200_406100586254807_529423751443823

11219083_406100579588141_130592113627894

Cut your material to size. You won't get it nice and straight or perfect. Just look at the 'professional' edges to the material! This is why extra material is left to hem it in.

12011229_406100639588135_119496065349466

Now, take an offcut of spandex to make a sweat band for your head....

12047057_406100726254793_244898523535039

Then sit back while your mum sews it on the sewing machine...

12011405_406100769588122_224166598172635

You need to sew it inside out - that is, with the dull side up and the shiny side down.

12046566_406100736254792_514872961759505

The dull (bottom right) is a slightly bluey grey compared to the black. It is easy to see under a light though.

Fold the ends of the tube together that you want to sew. Use a quite tight stitch and stretch the material as you are sewing. You'll end up with a nice tight yet movable piece of material.

Offer it up to your scope and see how baggy the top is - this method does leave the top a bit baggy. You either need to sew a bit of elastic in or a drawstring. We went for a drawstring. Fold over an inch of material at the top and sew. It is the same for elastic or a drawstring. The other option is to make 'darts', where you fold the material in a few V shapes, sew it so that the top becomes smaller and chop the excess material off.

11221771_406100776254788_865441009061176

Use something like a tent rope as a drawstring and thread it through.

12046647_406100836254782_461683961449711

Turn it so the shiny side is now out and place on your scope, tighten at the top, pull down over the bottom of the pole blocks and marvel at your lovely, quick, easy shroud.

11083836_406100842921448_196577008700817

12037979_406100872921445_118320297190893

Now enjoy light scatter free observing sessions.

You should have a bit of material left over to make pole bags, eyepiece bags, or an end cap for your upper cage.

John

Link to comment
Share on other sites
gooseholla

gooseholla

Posted
  • Author
Posted

Found some shrink wrap. 10 metres of 50mm unshrunk, 1mm walled stuff. £20.98 but because it is over £20 you get 15% off, taking it to £17.83. Everywhere else sells about 5m for £15 - 16, but that isn't enough for me. I need at least 6.4m. Might be of use for some?

http://www.ebay.co.uk/itm/371273085751?var=640397643645

John

Link to comment
Share on other sites
mapstar

mapstar

Posted
Posted

I thought I'd posted a comment but must've got side tracked?

Scope cover looks a damn fine effort John and It should improve contrast which would be a nice comparison for you to write up?

Only thing I'm not sure about is your sweatband just may not be the right colour for you  :grin:

Damian 

Link to comment
Share on other sites
gooseholla

gooseholla

Posted
  • Author
Posted

I've got to look at the moon sometime so I can finish my review of John's mirror - its only fair every kind of object gets a look. I'll have to see how much better contrast is at some point but it looks cloudy for the next few days. But yes, i'll come back at some point and see how much better things are. The real test is going to be the orange glow from streetlights, hopefully that will be cut quite a lot from images.

I was going to sew it myself but mum said she had nothing to do today so why not let the expert sew it.

John

Link to comment
Share on other sites
gooseholla

gooseholla

Posted
  • Author
Posted

Have scope out looking at moon. Addition of shroud cuts out orange glow round images. Can see couple of tweaks to new pole system but nothing major. Happy with new focuser position. Can sit in normal chair to view low down now and standing position is good.

Link to comment
Share on other sites
fireball61

fireball61

Posted
Posted

iv

havent built one that large but the idea will be the same.....i buuilt a 6" dobsonian.....with a coulter mirror...8 or 10
" pvc tube....all mounts and spider home made ....and plywood base......all mucch cheaper than buying one.....worked perfectly.....first buuild....

Link to comment
Share on other sites
mapstar

mapstar

Posted
Posted

JN is as you know a great guy and I have no doubt he will be able to sort your mirror out.  

Fingers crossed. I'm not sure if for now you could mask off the outer area with the shell in but it would reduce the aperture considerably.

Link to comment
Share on other sites
gooseholla

gooseholla

Posted
  • Author
Posted

Yeah, John doesn't think it looks good. But we'll see now I've provided some better measurements. Oh well.

The story is - I was having problems all night with the sling/collimation system. The sling wasn't letting it rest on the triangles for some reason. I loosened it and tightened it, but still no luck. I was going to have a go at readjusting when crash the telescope went over in the soft wet ground. Then the mirror fell, broke one mirror post, slipped out, knocked the top set of triangles, slid under the top bar of the telescope and all I heard was that horrible grinding/crack noise as it contacted the bolt/nut of one of the carriage bolts that holds the tailgate to the mirror box. Nothing I could do. Even if I had caught the scope I think the mirror would still have travelled.

Just happy it wasn't cos I was an idiot, lent over to collimate and something fell out of a pocket, or a spanner being dropped or eyepiece!!! If you're going to break a mirror, at least do it an epicly spectacular way that involves a telescope crashing and taking out half your garden :grin:  :grin: :grin:  
 

John

Link to comment
Share on other sites
mapstar

mapstar

Posted
Posted

It does sound very spectacular John :eek: and I think you're taking it very well to say it's caused that much damage. :icon_salut:  

Hopefully it will be sorted soon. I have a trip to see JN soon myself as mirrors seem to be troublesome beasts even when they are finished some times  :sad:

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.