Building a mold 400mm diameter

[Pyrdon]

Hello,

Need to cast a foundation for a flagpole. It should be 1.2m high and 0.4m in diameter. I can't find any casting molds that large. Is it easiest to build one yourself from any kind of wood, or can you shape a plexiglass sheet or some metal plate or similar?

Do you cast 1.2m in one go, or do you do it in stages?

 

[Claes Sörmland]

If you want to make life easier, buy riser pipes or wells in plastic with a diameter of 400 mm. Examples:

https://markgrossen.se/ror-slang/rens-tillsyns-spolbrunn/stigarror-400mm/

https://www.byggmax.se/dagvattenbrunn-utlopp-sandfång-orange-p31380?store=1313&gad_source=1&gclid=Cj0KCQjwv7O0BhDwARIsAC0sjWPz7DXjKmeUAPKbfFhWHA6vtvx4R_F8AWWFKH0p4HI-cGSiU8siVtwaAhnIEALw_wcB

You need 12 bags of coarse concrete to fill the 150 liters, so cast in one go. Don't forget to reinforce.

 

[Pyrdon]

Thank you! I knew I had seen some pipes but they were unreasonably expensive. It was probably these stigarör. I thought I could get away more reasonably...

 

[Claes Sörmland]

If you have free time and extra wood at home, you can certainly build a mold affordably. If you plan to go buy wood for this, the cost is likely to increase even there. It seems like it costs 1500 SEK just looking at the products at the lumberyard.

 

[Claes Sörmland]

Here's the budget version, a plastic trash can from Biltema for 399 SEK.

https://www.biltema.se/fritid/tradgard/bevattning/regntunnor/regntunna-160-l-2000054196

Dig a hole, 1.2 meters deep. Throw down coarse concrete 30 cm at the bottom. Place this barrel on the concrete mixture. Refill around it with macadam. Cut/saw the bottom open. Fill the barrel with concrete. Some granite stones at the barrel's outer edge save concrete. Some reinforcement bars to prevent cracking.

 

[mexitegel]

Check if any vent company has a leftover 400-pipe piece that you can buy maybe?

 

[Claes Sörmland]

Metal and plastic barrels (drums) are otherwise a whole genre on Blocket. If you can handle the used market's troublemakers.

 

[Timmermannen77]

Find cardboard form tubes that are significantly cheaper

 

[Prodigys]

If the ground is reasonably firm, it is also fine to rent a earth auger, so you can skip the form entirely.

 

[Pyrdon]

If it's relatively firm ground, renting an earth drill works well too, so you can skip the form entirely.

I've already dug the hole. Partly with an excavator, partly by hand. It's full of stones so the hole isn't very neat. Additionally, I don't know if there are earth drills wide enough either?

 

[Pyrdon]

Find cardboard form tubes that are considerably cheaper

In that size?

 

[mexitegel]

400 tubes in cardboard, 2.5 meters long, are available at Ahlsells, my price there is 1500 plus VAT.

 

[Zixten]

If you look around a bit, there are some that have paper tubes that are around 400mm. The cheapest I saw now seems to be around 900 SEK for a 2.5 m tube.

https://nasvensson.woody.se/hus-byg...51.1277006346.1720560868-324266727.1720560868

Ahlsell has them too if you know someone with an account there.

https://www.ahlsell.se/products/byg...rmar-ursparningar/pelarformar/295815-e265b94d

Otherwise, a regular plastic barrel should work, usually there are ads on Blocket for 2 - 300 SEK .... But then it will probably be a bit more than 400 mm in diameter..

 

[GoC]

For 300 SEK, you can buy 30m of råspont, which you can easily use to assemble a 40x40 cm casting mold.
If you want to make the final result a bit nicer, you can place a quarter round molding inside the corners of the casting mold.
We learned to build molds when I attended technical school over 40 years ago.

 

[Prodigys]

I've already dug the hole. Partly with an excavator, partly by hand. It's full of stones so the hole isn't very neat. And I don't know if there are earth drills that wide either?

There are earth drills over a meter in diameter but usually mounted on an excavator. 400mm can be managed without a problem with one like this https://www.ramirent.se/hyra/byggma...borrmaskiner/jordborrmaskin-hydraulisk-385733