Arch construction help

Hi everyone,
I just wanted to get some advice on the best option for arch construction as a I’ve seen a lot of different options.
My planned model is 175cm arch (1m diameter), 35 bullet pixels 5cm spacing.

I’m not sure what’s best, 20mm pvc conduit 25mm pvc, drilled or cable tie?

My plan was:
20mm conduit, 12mm drilled one side, 14mm back side for guide hole.

My concern is the strength of the pvc when drilled will cause it to buckle (this happened with a few test holes I did, mind you I didn’t place pixels in the holes to improve strength). Alternatively the 25mm pipe is too rigid to bend.

If cable ties are best, I’ll do that, but that’s a lot of cable ties if I’m building 10 arches.

I just don’t want to build every model, push pixels, then find in the Melbourne summer the arch buckles or I can’t bend the pipe enough.

Any recommendations are greatly appreciated!

Cheers,
Paul

If you are only doing a single arch I would reccomend the Air Seeder Pipe. It is quite a bit more expensive, but the Air Seeder Pipe is a much better option for Arches in Aus. The pipe is translucent, so you only have to drill 1 X 12mm hole per bullet pixel, or you can even use strip on the inside. I've built mine using the 32mm pipe, and you can then use Electrical T-Pieces available from Bunnings for the foot pieces.

Depends on what effect your going for. The air seeder pipe is good for the diffused look but is ridiculously expensive if you have to ship it.

Myself, I just made a PVC base similar to others air seeder builds, but used regular old poly pipe and cable tied the pixels to the top (Couple of small holes drilled into the poly either side of where each pixel sits, cable tie through and bobs your mothers brother!). The poly made it easy to maintain an even curve and still worked well with pvc fittings.

I wouldn't be too intimidated by the amount of cable ties, its no more work than drilling the same amount of holes in air seeder tube etc.

I chose the 38mm air seeder tubing route ($125/30m roll from Hoseco - pickup from the store) with strips. I like the diffused lighting it gives (sort of like glowing liquid/plasma).

I have bent 20mm PVC for curved props before and found it a real challenge to get even curves on tight bends (eg 1m diameter). What eventually worked for me was to pre-drill 4mm holes (I use a DIY jig to get even 50mm hole spacing) then very gently bend while heating with a heat gun. I needed to do several passes to gradually tighten the diameter. Once I got close to the correct curvature, I drilled out the 4mm pilot holes to 12mm using a step drill. I don't worry about a 14mm clearance hole preferring to slightly enlarge them with a deburring tool - https://www.altronics.com.au/p/t2370-deburring-external-chamfer-tool/
View attachment 21405Going about it this way prevented the PVC collapsing where the holes were drilled.

Though I personally haven't tried it, I wonder if Blue-Line Poly HDPE irrigation tubing might be suitable? It is available from Bunnings in 20mm x 3m (~$15) and in longer lengths comes in a roll. Thicker wall size may make the Blue-Line tricky to insert pixels?

Cheers
Col

I like the sound of the LDPE translucent pipe but the price is probably a stretch (colliers has it at $16/m)
Sounds like cable ties could be the go to keep the conduit from buckling. Happy to hear from any other prop builders!

I’m building my arches this weekend but my plans as below.
Grab some 25mm conduit for the arch and some harder pvc for the base. Make the base the right size for the bottom and put some T pieces on the ends. Now put the conduit into the t pieces based on the size you want. Then grab some builder strapping (I got 30m for $32 in Bunnings) with holes. Cable tie the pixels to that and then screw into the arch.
Takes ages to cable tie but works for me, spacing is every 3 inches on the strapping. I can take a photo on Sunday once I am done.
After they are done I will put some rebar into the ground and slot the other end of the T piece into them to hold them in place.

I did mine with 38mm air seeder, custom 3d printed foot and fishing line to hold the shape. Stupidly expensive stuff and I did real well to score someone's left overs for a good price.

Col The Hammer said:

I have bent 20mm PVC for curved props before and found it a real challenge to get even curves on tight bends (eg 1m diameter). What eventually worked for me was to pre-

Click to expand...

Hah, I bent 7 pieces of PVC to be about that shape just leaving them lying across the rafters in the shed for a year lol - I imagine they'd be easier to drill straight tho.

I also use 2 " HDPE and my arches have lasted for going on 5 years. I use 1 1/4" PVC inserts for the base. I wish I could claim ownership of the design, but I got this several years from a similar website; I just modified it to fit my use and available materials. See the attached file for details of making the end-pieces.

a. Arch material = 2” (OD) HDPE from MacMaster-Carr
b. 5 meter (16.4 feet) pixel strips from Ray Wu, just slightly shorter than the length of the arches (17’2”) so the end pixels should not be covered up too much. The lights are inside of the HDPE obviously.

NOTES:
a) 1 1/4” PVC pipe inserts fairly well into 2” OD HDPE
b) It is not yet known whether center supports of some type will be needed
c) Shape should be maintained by bases
d) Bases: I have 6 arches, so need 2 end pieces and 5 middle pieces

I was fortunate enough to get air seeder 5-6 years ago when it was cheaper and like the diffused look of strip inside it.
I use electrical conduit pieces for feet and just drilled a hole in the bottom to drive tent pegs through to hold in place. No brace or any kind and the natural curve of the hose being formerly on a roll makes a nice natural arch.

JacksonHo said:

I’m building my arches this weekend but my plans as below.
Grab some 25mm conduit for the arch and some harder pvc for the base. Make the base the right size for the bottom and put some T pieces on the ends. Now put the conduit into the t pieces based on the size you want. Then grab some builder strapping (I got 30m for $32 in Bunnings) with holes. Cable tie the pixels to that and then screw into the arch.
Takes ages to cable tie but works for me, spacing is every 3 inches on the strapping. I can take a photo on Sunday once I am done.
After they are done I will put some rebar into the ground and slot the other end of the T piece into them to hold them in place.

Click to expand...

@JacksonHo did you also use a coro prop Infront of everything? Ie coro prop, strapping, conduit?

I'm looking at buying some 1.2m coro arches and then reinforcing with something similar to what you did..when you are talking conduit do you mean this stuff?

A couple of points on comments made here.
PVC will bend easily into any shape you want if you heat it up enough. To do this my suggestion would be to make a jig to hold it in, heat it up, bung it in the jig and let it cool. I have bent plenty of pvc for weird positions in drains before and the trick is getting enough heat in it so it is pliable (without burning it) then hold it in position long enough to cool down and stay. It takes a while so you have plenty of time when you get it hot enough.
The blueline poly sounds like a good idea, I haven't seen anyone use it... yet... but it is in a coil so bending is not an issue, I only wonder about how rigid it would be once set into position. I have some out the back so I may do some experimenting...

I have the air seeder hose for my smaller arches but can't say I'm a fan of the diffused look as it's the only element in my display that is. For my larger driveway arches I just wrapped pixels around 20mm conduit, zip ties every 10 and then sat them in a treated pine 70x35 base.

My arch's would be the easyest,
star pick each side of the arch, cable tie 20mm pipe to it an bend to other side,
then cable tie strip to it.

Domestos said:

If you are only doing a single arch I would reccomend the Air Seeder Pipe. It is quite a bit more expensive, but the Air Seeder Pipe is a much better option for Arches in Aus. The pipe is translucent, so you only have to drill 1 X 12mm hole per bullet pixel, or you can even use strip on the inside. I've built mine using the 32mm pipe, and you can then use Electrical T-Pieces available from Bunnings for the foot pieces.

Click to expand...

Did you use 32 mm ID / 38 mm OD Air Seeder pipe?
https://www.ebay.com.au/itm/273076766184
or 25 mm ID / 32 mm OD pipe?
https://www.ebay.com.au/itm/281611479072

What sort of LED strips? 30/m or 60/m ? 5V or 12V?
Has anyone tried seed pixel strings at 20/m ?

If I have to buy a whole 30m roll, I might as well do the whole front fence.

32/38 and 30 per m for me. I think domestos was the same as he gave me his version 1s.

jm493 said:

Did you use 32 mm ID / 38 mm OD Air Seeder pipe?
https://www.ebay.com.au/itm/273076766184
or 25 mm ID / 32 mm OD pipe?
https://www.ebay.com.au/itm/281611479072

What sort of LED strips? 30/m or 60/m ? 5V or 12V?
Has anyone tried seed pixel strings at 20/m ?

If I have to buy a whole 30m roll, I might as well do the whole front fence.
View attachment 27611

Click to expand...

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