About Our Carbon Tubes...
Aerospace Quality Materials
All of our tubes are made from the highest quality PAN based carbon fiber available. Also, we do not use "seconds" or "blems" found at surplus sites on the net. This is first-quality, aerospace certified material direct from the (USA) manufacturer.
The carbon fiber is compression wrapped in a hi-temp epoxy matrix and cured at 160 degrees over a precision mandrel. The OD of the tube is epoxy coated and precision ground before urethane clear-coating and polishing. The tube is cut to length while still on the mandrel to assure squareness. Tube OD tolerance can be held to +/- 0.010" even on our largest diameters. Wall thickness can be held to +/- 0.005".
Our "Solid Wall" Tubes vs. Cored Tubes
There are two basic types of telescope tubes available: solid wall and composite wall.
The competition’s composite tube typically has 2 very thin layers of carbon sandwiching some sort of core material such as foam or honeycomb. A typical composite tube has a wall thickness of 5/8" or more. Composite construction is very advantageous in many applications such as airplanes or boats due to its rigidity and light weight, but NOT in telescope construction. The problem with composites is that you cannot bolt assemblies through a composite wall without some sort of pre-engineered hard-point or insert.
Torquing a bolt of any size through a composite tube will collapse the core and destroy the local integrity of the tube. Without a predetermined hard-point or insert, you can easily drive the head of even a small bolt right through the outside wall of the tube and destroy it. In addition, the ends of the tube or any opening cut into the tube will expose the soft core material and must be sealed and protected somehow. All of these things must be considered before the tube is built, leading to very high engineering and fabrication costs. Once the tube is built, you cannot "change your mind" about length or hole locations.
Our solid wall tubes are many layers of carbon fiber making up the tube wall; there are NO fillers or core. Therefore our tubes can be cut, drilled, slotted, tapered, etc. without the worry of exposing a weak core. You can torque a bolt through our tube as tight as you want without worry. In fact, the bolt will likely snap or strip before our tube shows any compression damage. If you drill your hole a bit off-target, just grab a round file and elongate the hole a bit to make it work.
Axial rigidity is not an issue with either construction method. Radial rigidity is established by the basic telescope components including rear/front cell, spider, etc.
Another advantage of our solid wall tubes is impact resistance. Accidents can and will happen, particularly at 6:00 AM after a long night of imaging. Our tubes can withstand considerable impact without damaging the structural integrity of the tube. A thin wall composite tube is MUCH less forgiving and is easily damaged by impact.
Don't take our word for it, ask us for a sample and we'll send one out to you. Ask the composite core tube guys for a sample of their tube as well and compare for yourself.
Oh, did I mention the beautiful finish of our tubes?
Urethane Clear-Coat Finish
Our Premium carbon fiber tubes are clear-coated with two-part, automotive grade urethane. The clear-coat is baked at 150 degrees to full cure before it is polished to a mirror finish.
The particular clear-coat we use has very good UV blocking agents to greatly reduce the degrading effects that UV radiation has on the epoxy resin.
Be wary of any tube that does not have UV protection, they will begin to yellow very quickly and will eventually begin to degrade.
Ultra Flat Black Tube Interior
We spent a lot of time researching an ultra-flat black paint for our carbon tubes. We have formulated a superb combination of black primer and flat black topcoat that has excellent bonding to carbon and lower reflectivity than any paint we've ever tested. In testing, we've submerged the tubes in water of various temperature for 2 weeks at a time to make sure it holds up. It does! Our special paint treatment is standard on our Celestron replacement tubes and optional on all custom tubes.
Drilling a hole in our carbon tubing takes about 5 seconds with a good drill bit. Knowing exactly where to drill the holes (layout) can take hours. For our standard tubes, such as C-9.25, C-11, C-14, etc. we have reusable drilling patterns so all of these tubes come pre-drilled at no extra charge.
There is an extra charge for drilling custom holes in custom tubes. The alternative is for you to drill the holes while assembling your custom scope. The carbon tubes can be drilled with any sharp bit in any power hand drill. Large holes, like those for focusers, require a good, fine tooth hole saw.
By: Public Missiles Ltd.
Very Large Diameter Carbon Fiber Tubing
From 7.5" to 24" Diameter
About Our Tubes
Below is a list of currently available tube sizes. Choosing one of our existing sizes eliminates tooling cost. We can make other sizes as well but the tooling cost is quite substantial. If at all possible, try to make one of the tubes sizes listed below work for your project.
Standard diameter tubes listed range in price from $800 to $3200, approx. Thicker walled tubes are more costly than thinner walled tubes.
For custom diameter tubes, please tap here.