Aluminium or Thinwalled Steel tubing for OTA Tube

[Glenhuon (Bill)]

I've been Googling for a supplier of tubing to build my 102mm SurplusShed refractor. I looked at PVC again but nothing in the standard sizes will fit and I'm a bit dubious about using it for a 900mm FL as its inclined to sag with a bit of heat. Only supplier I found in Aus only had 80mm ID Aluminium tubing. Can anyone suggest a place I could get something nearer 100mm.

Bill

[Omaroo (Chris Malikoff)]

Try here Bill

http://www.onesteel.com/products.asp...Name=Aluminium

[Garyh]

How about Baroques Galore or someone that deals in fireplaces or potbellies? I know you can get flue pipe from 5" and up in about 1m lengths in S/S or gal?
Worth a call?
cheers

[mrsnipey]

Hi Glenhuon,
My 80mm lens from SurplusShed is 900mm focal length and I made the tube out of PVC with no problems at all. There is very little flex (if any) and the view is fantastic. By far my favourite telescope.
I went on holidays for a few days and forgot to put the telescope away . I was busy packing and forgot about it - didn't remember until the next night.
It was on one of those really hot weekends and my telescope is painted black but if it has made a difference, I can't tell. Still fantastic views and no warping of the PVC.

I was going to get one of the 102mm lenses from SS but they sold out before I could raise the cash. Will be watching with interest.
Would love to see some pictures as you go.
Good luck,
Denis.

Originally Posted by Glenhuon

I've been Googling for a supplier of tubing to build my 102mm SurplusShed refractor. I looked at PVC again but nothing in the standard sizes will fit and I'm a bit dubious about using it for a 900mm FL as its inclined to sag with a bit of heat. Only supplier I found in Aus only had 80mm ID Aluminium tubing. Can anyone suggest a place I could get something nearer 100mm.

Bill

[Glenhuon (Bill)]

Thanks for the link Chris, I've bookmarked it until the Objective turns up and can run the vernier over it and get exact size requirements.
I'll have a look at BBQ's Galore Gary, but I think the pipes are rolled and have a seam.

Both Chris and I have made the 80mm x 400FL scopes and they perform very well Denis. 90mm PVC is just a nice fit for the 80mm cells but there doesn't seem to be a standard PVC pipe to fit the 102's, I'll check that again when the lense arrives. I was just thinking back on previous experience with PVC water pipes that took a decided bend over time with the heat but the OTA shouldn't have as much loading on it and might be OK.
I'll keep y'all posted on progress.

Cheers
Bill

[netwolf]

You could try the chap who made Bird's Aluminium OTA.

http://acquerra.com.au/astro/equipment/13/

Regards
Fahim

[GrahamL]

bill is your objective 102 mm or is its cell ?
Some of the older class 12 pvc had an id of 101.7 mm from memory
It won't bend I promise the older stuff had a flared end which would allow you to mount whatever you liked in it .. but it all comes back to your objectives od ?.. as you probably know the next step up is usually 150 mm .