making my Dob lighter

Hi folks

I have an 8" homemade F5 dob. The OTA is a piece of thick9 (7mm) wavin tubing about a metre long and is a little too heavy for my tastes. I would prefer the OTA to be lighter. At present the outside Diameter is about 9.5 inches and I reckon I can stretch this to 10 inches and still fit the spider and have ota fit on mount. my question is.

Does anybody know if there any other material that I can use that is lighter than a piece of wavin piping and still has an outside diameter of between 9 and 10 inches?

Hey
Recently i got a 12" tube from Astronomy Ireland, before this
i had a 12" water pipe (i think 7mm wall) from the county council very heavy but super rigid which was why i went for it first. I decided to change to a 12" waste pipe (i think 4-5mm wall) (those orange pipes for sewage) was alot lighter and still very rigid, it however would be in my opinion suitable for a dob mount because of the balance between weight and how rigid the walls are for supporting the mirror cells.

It was later during the design that i decided i wanted to mount the telescope on a EQ-6 mount, this made the sewage pipe two heavy, so eventually that lead me to Astronomy Ireland who were able to give me an extremely light tube only 1-2mm thickness. Give them a call!

Just to finish up my light-year long reply, my advice would be to consider the cells for the mirrors and how they are attached to the tube, if they are tightened from the side with nuts or bolts, and if the walls are thin the cell will start to collapse the tube and man it makes it a pain to center the mirrors in the center of the tube!!!

Good Luck
Michael

Hi trevor, AI might have something allright. However they really don't do this sort of thing much anymore, since they don't make scopes themselves. I did see some tubing around. Give em a call and see if they have anything. I've seen 12" sized tubes around there but not so sure about 8".

The other option would be rolled aluminium tubing. This is commonly used for commercial producion of scopes. I'm sure a search of the golden pages. The third option would be to build a truss tube design like this;

en.wikipedia.org/wiki/Serrurier_truss

This is really cool too;

www.xmission.com/~alanne/DS3Main.html

Cheers Lads

I migh have a look at the truss design. AI were too expensive. even before shipping.

Try these guys:

www.parallaxinstruments.com/tube.htm

Cheers Lads

I migh have a look at the truss design. AI were too expensive. even before shipping.

It is not hard, I rebuild my dobson 250/1200 in this way and now it have 8 kg and can be transported in luggage