Looking for "kydex" for 18in dob project

[mikey7]

Hi all,

I've completed the upper cage of my 18in dob and was looking for some sort of lightweight light shield. The guys in the US use "kydex" and was wandering if anyone can suggest something similar to buy in Oz. I live in Sydney so anything that is available locally is obviously the way to go.

Cheers
Mike

[Astroman]

you could try http://www.ntap.com.au/ they are in the NT, they may be able to help you.

[ausastronomer]

Hi Mike,

You can use a plastic called HIPS. (High Impact Polystyrene Sheet)

Here is the Materials Data Sheet on it from a company called City Plastics (http://www.cityplastics.com.au/styrene.html)

You could probably buy it from them. I bought it from a company in Chatswood called All Plastics Engineering (http://www.allplastics.com.au/allplastics/machining.htm). It cost me about $15 for a sheet 1.2 metres x 1.2 metres x .7mm thick. Its very strong and light and can be easily attached with self adhesive velcro.

CS-John B

[Blue Skies]

Is the is a similar plastic sheet (that's slightly heavier) but I can never remember it's name! You could also consider a thin foam sheet, I was amazed at the different thicknesses and colours you can get in foam these days the last time I went to get some packing foam from the local foam/rubber shop.

[mikey7]

Thanks for the info everyone, I now have a place to start looking. I used thin ply for the lightshield initially but its heavy.

Cheers
Mike

[iceman]

:welcome: to the forum, Mike!
I look forward to seeing pictures of your 18" dob!

[Satchmo]

Mike

Kydex goes dimply in the Aussie summer :mad2: As in a traditional truss Dob, the plastic sheeting is just a light baffle and does not need to proviode any additional strength to the cage . Neoprene rubber works really well. It is very light , just roll it into a tube and slide it in , and out again to wash the dust off. Clark Rubber sell it in black in different thicknesses, I've seen 5mm work well.

Mark

[mikey7]

G'day Mark

Thats a great idea, I'll check out neoprene.

My next issue now is trying to find a supplier for gearboxes. I have a servo drive system using a Sitech controller. Its taken me months to work out how to impliment the drives onto the alt/az axis but now that the scope is coming together and I have something physical to look at the drive problems are becoming easier to figure out. This build has been great fun.

Thanks for the welcome. I'll post some images soon or a link to my web page.

Cheers
Mike

[Blue Skies]

Neoprene - that's probably what I was thinking of! I'll have to remember that name.

[Darkplague]

For my 16" project I will be using the left over Ebony Star laminate I purchased for my bearings. Seems to Roll very well!

Btw Does anyone know of a good way to cut the laminate?

[mikey7]

Did you get the ebony star in Oz?

[Darkplague]

Yes, Just go to any kitchen/cabinetmaking place and ask if they stock "wilsonart" laminates.

Ive seen some cages made out of this and they look very nice, imo look better than plain black plastic ones.

[mikey7]

Thanks for that mark. what do you use on the base of the mount for the ebony star to ride on?

[astronut]

Hi M7, I needed a light strong flexible material to make a extended dew shield for my LB. I took ausastronomers's advice and contacted All Plastics Engineering. They had a minimum order so I had to purchase 5 sheets, I will only need one.
They work out at $15each. Let me know if you would like one. John.

[Darkplague]

Teflon squares. Teflon and Ebony Star= smoothness!!!

[Satchmo]

Mike, I have a Scitech system too but have given up on th echallenge of finding/building gearbox clutches and will probably spend $800 on a set of Dan's custom made ones. I'm mainly interested in tracking so Drag /n track will be on most of the time. After using a Dob Driver for a few years, the idea of manual clutches doesn't appeal anymore :)

Mark

[mikey7]

John, I will grab a sheet off you for 15 bucks. Might as well try and see how it works. Can you PM me with postage and payment etc. I'm in sydney.

Mark, I was trying to get out of spending the bucks for a couple of gearboxes by hoping to build one if I get the right combination of gears. On sitech site they have a clutched box at US400 each and one that is not clutched for US300 each. Lotsa dosh. Out of interest do you have a link to Dan's site? I would'nt mind having a look at what he has. I'm also starting to think the idea of a DIY gearbox is going to be more pain than its worth. However I wasnt planning a sistem with a clutch so maybe its doable. You got any piccies of your dob?

Darkplague where did you source the teflon squares from? Sorry if it sounds like I'm being slack and not doing the hunting my self but I dont actually live in Oz. The few times I get home per year I'm into building the dob and dont have much time to run around. You info is appreciated.

Cheers all
Mike

[ausastronomer]

Mark,

A couple of ways to cut it, but if you don't use the right tools and also know the technique, you can end up making a horrible mess with splinters and chips out of it everywhere.

The best way IMO is in a table saw with the appropriate fine blade.

Another option is using a router with a thin (eg 1/8") straight cut bit in it, on the highest speed. It also needs to be a good quality Tungsten Carbide Tipped (TCT) bit. A cheap bit will burn out in a few seconds.

If you dont have access to these tools, mark out your laminate and take it to a kitchen refit company and ask them to cut it. It will only take a few minutes and probably cost about $10.

CS-John B

[ausastronomer]

Dayyam,

They were happy to sell me 1 sheet, but that was over a year ago. I also went to the factory and picked it up. I may need another sheet in August if you still have some left then. I will contact you if I need some.

CS-John B

[astronut]

Mike & John, I hope I need only one sheet:lol: :lol: John I'll hang on to one for you. The size is 1.37m X 76cm X 0.75mm. It's matte black on one side, glossy black on the other.:thumbsup:
P.S. They just arrived this evening by courier. I suggest that they be rolled up in a postal tube for protection and delievery. Let me know if you still want them.

[mikey7]

If you can go thru the hasle of sending me one I would love a sheet. I'll pay mailing costs of couse.

Cheers
Mike

[netwolf]

Mikey7,

I have been researching the Sitech for a while now, I was going to motorise my 10" Dob. Plans have changed a bit. As to the gearboxes etc, you could try Lenord at http://www.gototelescope.com/. Alternatively you can check out this installation for some ideas of geting your items, this link is from listed on the sidrealtech site. http://dbpeckham.com/Telescope/CompScope/Index.htm

If you could get someone to make the brackets locally and the flywheels you could save a bit. Also you can shop around for surplus gear reducers. I have seen the ones Don Peckman used come up on Ebay. Pittman motors also come up on ebay for bargain prices. Some come with gear reducers, have seen one with 60:1 gear reducer. Even with the cost of shipping they are bargains to be had. I will PM you one i just found. ;)

Regards
Fahim

[Stevo69]

Hi John, I know it's a long shot, but do you have any spare sheets?

Went to my local art/craft shop today and found some A2-size art folders. They are designed to carry large items of art work in. Th material which they are made from, I believe are a Kydex-type plastic: flexable, about 1mm thick, semi-shiny on one side and a more "matt" finish on the other. It is the same material as the front and back covers of those A4 display books you get from your newsagents. Now I've never seen Kydex before (only what people have descibed), but I think this is the same material. Anyhoo, it will be perfect for the secondary cage, I will have 2 joins 180 degrees apart, but I'll hide it somehow, and I might double it up anyway.

[astronut]

Hi Steve,
I don't have any sheets left, but if you go to www.allplastics.com.au (http://www.allplastics.com.au/home) they have them here.
It's called H.I.P.S. High impact polystyrene sheet. It works brilliantly, though it sounds like the material you've found is similar.
Good luck, John.:)

[Satchmo]

Steve, Yes thats Kydex.

As you are relying on your cage stiffness from the aluminium rods , it doesn't really matter what you use to line the cage. Some of the well known scope makers in Sydney use a black foam Neoprene ( like wetsuit material ) from Clark Rubber. The advantage is you can roll it into a tube, insert it into your cage and it just sits there. Easy to remove and wash when it gets dusty.

[GrahamL]

mark I was looking at that stuff in clark rubber the other week
as I can't find the other sheet up here ...anyway
so do they slit it to slip up the vanes ?

thanks for shareing that:)

[Satchmo]

Yes , just put a slit for the vanes . Roll it into a tube and slide it into the cage. Its got quite a porous texture so easy to paint flat black on one side.

Another way to go is thin aluminium. The first large commercial truss dobs I saw in 1989 by Sky Designs used that.