Extruded Plastic Hoops

I wonder if you could cut hoops from plastic (maybe fibreglass) tubing. I'm thinking of the stuff they make flumes for swimming pools with.

Or like the fibre glass poles used in dome tents.

How about PVC pipe (Schd80) reheated and formed around a mandrill. Slide off the mandrill after it cools. You could even but joint the ends together. PE coils would could also be used but would not be as stiff.

In response to Randall, Nigh and Spark

The fiberglass rods or tubes have tremendous strength but they were too flexible and the tent pole rods twisted ( after we assembled the netting over the hoops and there was a load of fish in the nets).

FYI

5 hoops spaced 20" apart support a fish net that catches approx. 100 lbs of fish.

the hoops we use now are spun on a circular template with a % of resin and a % of fiberglass thread or 'glass'. It is messy and time consuming.

I have thought of pvc pipe. sliced into hoops . I may try this as it something we have not done yet.

Thank all of you for the replies.

merci beaucoup

netmaker

Does that have to be 5 separate hoops or could it be an 80" long helix?

The hoops must be separate and the entire net must be able to fold down flat in a boat. the fishermen would carry 20-30 of these in his 16' hull.

Inside the net there are two conical flues which are used to trap the fish inside. the hoops need to be separate so the flues remain tight when deployed.

netmaker

If you try the PVC pipe & it is lacking some strength you could try filling it with another material, maybe an expanding foam, to add rigidity.

Sounds to me like you are looking for "Hula Hoops" or at least a manufacturer which can make hoops of that type. Contact www.ssww.com

I work with plastic pipe all the time. I just thought of another way to make the hoops. PE pipeline sliced into hoops on a table saw. I have a chunk 29" OD, 1" solid wall, 30" long, 150 PSI rated. This pipe is designed for direct burial under roadways so crush strength is not going to be a problem. The pipe is formed by an extrusion process and can be cut to the required width using wood working tools and fixtures. The pipe will hold screws like wood. PE is just slightly lighter than water, so maybe a little extra weight will need to be added to the net.

So what do you think?

All,

The Hula Hoops were tried. The thin wall .12" crushed when the nets were retrieved under a semi full load 15-30kg.

The larger pvc seems plausible.

What kind of band saw would we try?

What type blade would work for pvc and not leave a jagged edge?

Lightness in the hoop is a good thing because some of the researchers work in very sandy river systems where siltation builds up and can actually "trap" the net itself ( just think of a dust storm in the Rub' al Khali desert ....only with water pushing the sand not wind).

I need to get to work in the shop but will check back tonight.

thank you all for the input. this CR4 site is turning out to be a wealth of information with lots of smart folks.

Thank you.

Netmaker

I think PVC might be too brittle to work well for long, and salt water will attack PVC over time. I do have some 3/4" ID Polyethylene (PE) pipe that could be formed into hoops and butt fused the ends together. It would make a very smooth hoop. It carries a pressure rating of 160 PSI and is not anything you would find at a local hardware store. This stuff is used in water desalination plants so I know it will hold up well over time, in any water. It wouldn't be as stiff as say solid PE rings cut from a 30" pipe, but it is tough to kink a 12" piece by hand. This is sold in 500" rolls, scrap will be minimal.

The rings cut offs from 30" pipe might be cut with a band saw but it would need a very deep throat or away to spin the pipe as it is cut. We use a table saw, rollers and spin the pipe as needed. The edges are smoothed by a table router and planer/jointer. The rings would be much stronger than hoops, but would cost more too.