Building a mold 400mm diameter

[Pyrdon]

There are earth drills over a meter in diameter but usually mounted on an excavator. 400mm can be handled without any problem with one of these [link]

That looked handy. If I had known such a thing existed, I would have gone for it.

 

[z_bumbi]

A sheet of OSB and some scrap wood works. If you want it cheap, go to a flea market and buy the scruffiest deep bookshelves/cabinets etc. made of panel material or look for ads for giveaways, a Billy bookcase should, for example, be enough.

 

[Pyrdon]

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

Good idea. I got hold of a piece of 90x0.4 they had thrown away. Since it is too short, I chose to cast a larger slab underneath and about 10cm up into the pipe. I thought I could remove it later to raise it, but I can't get it loose. Since it's in a deep hole, it's not easy to reach and pry, etc. Are there any issues if I continue to cast there and leave a steel sheet pipe in the ground? Or do I need to try to remove it? Maybe it was also a bad idea to cast in two rounds...

 

[Nickesågen]

Hi,

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

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

Dig a hole and place a square of timber the last 10-15 cm up through the lawn. Cast directly into the ground. It doesn't have to be more complicated than that. Best regards

 

[mexitegel]

Good idea. Got hold of a piece 90x0.4 they had thrown away. Since it's too short, I decided to cast a larger slab underneath and about 10cm up the pipe. Thought I could remove it later to raise it, but I can't get it off. Since it's in a deep hole, it's not so easy to pry and so on. Is there any problem if I continue to cast there and leave a steel plate pipe in the ground? Or do I need to try to get it out? Maybe it was also a stupid idea to cast in two stages...

No, there's no problem leaving it in the ground. It will rust away over time, and you can cut off the part above ground with an angle grinder if appearance is important.

 

[Pyrdon]

Dig a hole and place a square of timber the last 10-15 cm up through the lawn. Cast directly into the ground. Doesn't need to be more complicated than that. Regards

Since it's been dug with a machine and by hand, and the ground is very rocky, the hole is pretty "ugly". It would take a lot of concrete in that case...