Arch construction help

Pyjamas

New elf
Joined
Apr 27, 2021
Messages
19
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
 

Domestos

Apprentice elf
Joined
Jun 11, 2020
Messages
61
Location
Brisbane
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.
 

KHill9314

New elf
Joined
Nov 4, 2021
Messages
6
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.
 

Col The Hammer

New elf
Joined
Dec 23, 2021
Messages
3
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
 

Pyjamas

New elf
Joined
Apr 27, 2021
Messages
19
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!
 

JacksonHo

New elf
Joined
Oct 17, 2022
Messages
14
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.
 
Last edited:

Freman

Uh Oh Elf
Joined
Aug 9, 2021
Messages
90
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.

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-

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.
 

SanDiegoBob

New elf
Joined
Mar 30, 2017
Messages
1
Location
San Diego, California
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
 

Attachments

  • Arch Overview.pdf
    514.2 KB · Views: 12
Last edited:

djgra79

My name is Graham & I love flashing lights!
Global moderator
Generous elf
Joined
Dec 27, 2011
Messages
1,977
Location
Cranbourne West
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.
 
Top