[johnpost]

concerning electrical pvc conduit

Also a better choice. Its sunlight resistant and 50% cheaper than the white plumbing choice. The only downside is that its just a little floppier than the the white plumbing stuff.

do shop around for the electrical pvc conduit.

some brands are a bit floppy, nice where you could use the play for electrical power installation, over a long run you can skip using offsets.

there is a brand that has about maybe 80% to 90% of the stiffness of plumbing pipe, so good for short length structural use like this.

then only the plumbing fittings (L, T, caps) are subject to greater UV deterioration.

i have painted those plumbing fittings with expensive PVC use primer and paint in the hopes of having it last longer.

 

[johnpost]

Thanks for that, johnpost. Is PVC-primer paint readily available?

I used a spray paint that was listed for substrates that included PVC.

I used a spray primer that I recall was listed for PVC but no longer have can nor recall brand. It was a non-antenna project a couple years ago.

Got both at large home improvement or farm supply store.

 

[johnpost]

the fiberglass rods i've seen

the driveway markers and bike flags have a plastic coating.

the white electric fencing rods are uncoated and very durable. they will have glass slivers especially as they weather.

all will produce glass slivers when cut.

adhesive tape is the best removal method i've found for glass slivers.

 

[johnpost]

i don't think it would make a difference in how likely it is to get struck by lightning. makes no matter to a lightning bolt that just traveled miles through nonconductive air.

i don't think ABS is as strong as PVC. As 300ohm mentioned use electrical PVC that is sunlight resistance. Some brands are stiffer than others so you want to compare before buying.

You would still need to ground your tripod if metallic.

 

[johnpost]

Anyone,

I bought these electrical conduit straps (in the sched. 40 - electrical dept at HD) and glued them together using ABS cement - yellow quality.

Will this hold up outside, and is it UV resistant?

those straps are electrical PVC. The electrical PVC conduit is marked UV resistant. I would think the straps, boxes and fittings are also even if not marked. Mine have lasted a decade and a half OK.

PVC gluing with PVC primer and PVC glue is solvent welding. The glue has solvent and PVC resins which dissolves some PVC and then it reforms new polymer chains fusing the pieces together. ABS glues might include ABS resins and solvents, may not give a long lasting piece for PVC.

Having close bonding surfaces is important to a good joint, that is why with pipe/conduit and fittings you sometimes have to muscle them in with dry fitting, they are made for lots of contact. I would file down some of each strap at the mating point to give maximum surface contact. where the parts touch apply primer, glue and put in contact without movement for a minute. you might use a spring clamp to hold together for that minute, less movement likely than with your hands.

With a good quality PVC joint it will fail somewhere other than the joint when it breaks.

 

[johnpost]

Yes, I sanded the each contact surfaces flat, but this is not easy to get perfectly flat.

try a flat file or sandpaper on a sanding block that might help in generating a flat spot, rather than the tendency to curve. also mounting the strap on a block and orienting the strap horizontal, then you have a view of the tool to the strap and might more easily keep it parallel to the base.

 

[johnpost]

there are universal plastic glues that have solvents and a combination of plastic materials. i don't think it works as good as specific glues which have solvents and that particular plastic; there are glues specific to PVC, CPVC and ABS (also there are variations for pressure ratings and setting time of concern to plumbers, likely only one of each type in general stores).

plastic hardware is strange stuff. some plastics have a property of being deformable, the types used for hardware are. after a nut has come tight it may stretch the bolt a whole lot, a number of turns. also these deformable plastics (if not stretched to the breaking point) can then relax and go back to closer to their original shape. also plastics are slick, often used as a sleeve bearing with metal because of this, can be though of as self lubricating. you can then turn a nut on an assembly tight and keep turning it (as the bolt stretches and with little resistance) and then if you stop before it breaks you can then watch then nut unscrew itself (as the bolt relaxes and shrinks and turns the nut with little resistance). makes you think you have a screw loose (that was punny).

plastic hardware works where it doesn't have to be real tight or you use some thread locking mechanism.

 

[johnpost]

i think CPVC is able to be used for water supply because chemicals don't leach out of it like PVC. depends on local codes on when an if it is allowed.

PVC and ABS are cheaper and used for waste.

 

[johnpost]

Feig

Painting CPVC or PVC can be tricky.

What materials ans process do you use? Why black? How has it worked for you and how long?

 

[johnpost]

Any tips on straightening that #10 wire before making it into a zigzag?

thread

Wire Straightening Tricks For Antenna Builds

is at

http://www.digitalhome.ca/forum/showthread.php?t=100636

 

[johnpost]

Also, going back to PVC-related discussion, my fittings arrived this week. Everything is 1/2". I noticed that when putting conduit into the fittings that it inserts 3/4" when it goes in all the way, as far as it will allow. Is this normal? I remember 300ohm's instructions with 1/2" sch40 pvc fittings said to insert everything 5/16", so maybe one is not supposed to insert things all the way in? And if so, why 5/16" and not some other arbitrary amount?

I do notice that when fitting all the way it sometimes takes effort (and possibly lubrication may be in order). Is this why it's not a good idea to insert the tube all the way into the fittings?

3/4" depth is normal for that size fitting.

300ohm dry fastens with a bolt when finished so all of the strength of the joint isn't from overlap as would be with gluing. leaving some additional depth allows for adjustments if needed during assembly.

the fittings are designed to be glued (solvent welded for these plastics) which requires lots of very close contact, so it is very hard to insert fully sometimes when dry fitting. with glue on it acts as a lubricant and it will slip all the way in most of the time with moderate force and a twist.

if you cut all the pieces to fit with full insertion then if any are not fully inserted or pieces not cut square it will cause that joint to be larger. by the end of a total assembly your outside dimensions, which is where the wire is, may be off. so leaving some play allows adjusting joints for a final good result. as you assemble mark the outside of each piece with pencil to show the insertion depth needed.

using for intended purposes of plumbing or conduit may require full insertion. also often when doing those tasks you measure, cut and glue individual pieces and so adjust as you go along. when making structures like antennas or furniture you have to modify construction methods sometimes.

 

[johnpost]

Some toilet seat bracket nuts/bolts are fairly lengthy and made of nylon, so if you can get used to the backwards threading on some of them I think they'd be a good option for someone needing non-metallic joiners for antenna building. I have no idea if they're UV-resistant though.

nylon is also very slippery (self lubrication) and deformable (it will stretch).

so you may need to use thread locking to count on some degree of tightness. because it might stretch you might never get real tightness before the bolt fractures.

 

[johnpost]

My questions to this would be : if i drilled the reflector holes in the mast to the size or slightly smaller than the 1/4" rods used , eliminating the gromets , is there a certain cement that would adhere a steel mast with aluminum rods ? Would the contact of the reflectors and the mast affect the performance of the reflectors ?

having dissimilar metals touch will cause one of the metals to corrode. you could find a nonmetallic tube/pipe that the elements could fit snugly into (and be glued in place) and drill the mast to accept the nonmetallic tube/pipe.

 

[johnpost]

Today I noticed a black plastic "mesh". Looked pretty sturdy and tough. Approx 1/2" - 3/4" square pitch on the mesh. Maybe came on a 3 or 4 ft wide roll.

It looked designed for outdoor use - probably pretty good lifespan outdoors in the elements and in U.V. light / sunlight.

[ Cause one of my ideas was to use plastic snow fence, the bright orange stuff, to support antenna elements ... but this black stuff is much more useful and aesthetic ... I think ]

plastic fence will last long outside as it is designed to. the wind load for this as an antenna support will be large. metal or plastic tubing would be much stronger and stiffer with a lot less wind load.