30" Cast Scotland

[Gulf]

+1 on the reinforcement. I think that you really need it. I'm not sure if the aggregate was the problem. But, for a reverse concrete form you can make the bottom of the form the front. Placing already smooth surfaces toward the bottom will make polishing the face much easier. I broke and used the smooth side of some already broken colored glass panels that I got free from a glass company. I placed (glued) them in the form where wanted. With that you can use what ever type conrcete and aggregate you want for strength.

[Mullster]

So sorry to see that mate - perhaps it was the aggregate like you said. At least you can make another one though.
I used some reinforcement in mine and just put the decorative on the very front (set in) and used normal pea gravel in the mix.

[Daveholdn]

Ah gutted, even left my arch for a couple of days longer just in case. I think the problem is I used my decorative glass as my gravel for the mix, it's really smooth stuff so I don't think it binded. My mix was 1 cement:2sand:3gravel(decorative aggregate). Has anyone had anything like this, or should I have put rebar through it?
Cheers again.

@david s, thanks for the flue advice there, it does rota te so all good to go, just gotta get this arch sorted first

[david s]

If you can rotate the pipe within the casting reasonably easily then it'll be ok.

[Daveholdn]

No, fit it that way, you’re good to go. Just make sure the pipe is not a really tight fit, so there’s a little room to allow it’s expansion within the casting.

This is the way I do it, but there are plenty of other solutions no doubt.

Aye that's what worried me a little david s, I did pack cardboard around my 150mm flue mold at casting stage as thought it would leave it a little loose for the expansion, but my flue is actually quite a tight fit unfortunately, would you recommend trying to lightly sand the inside of the flue cast a little to try and make it less of a tight fit?

Cheers again

[david s]

No, fit it that way, you’re good to go. Just make sure the pipe is not a really tight fit, so there’s a little room to allow it’s expansion within the casting.

This is the way I do it, but there are plenty of other solutions no doubt.

[Daveholdn]

I could be wrong, but I think that end is designed to be at the top to take either a weather cowl or an extension pipe to go taller.

Hi david s, cheers for replying, I've attached another pic, so the cowel goes on the opposite end as I've tried both ways and doesn't fit into the end with the ridge. I've also attached a pic of it in the flue gallery. Would this do the trick or would you still recommend the tabs?
Cheers mate.

[david s]

I could be wrong, but I think that end is designed to be at the top to take either a weather cowl or an extension pipe to go taller.

[Daveholdn]

Cheers Mullster , just trying not to jump steps and get ahead of myself.
In regards to the flue pipe, mines has come and has quite a large ridge as shown in the pic. It fits perfect and the ridge would defo stop it falling through or tipping, can ask would this negate the need for tabs or do these do another job for the flue?

Cheers again, almost time for blanket and vermiculite layers.

[Mullster]

Daveholdn wow!! Your casting looks so good. Really smooth inside (mine looks like the face of a pensioner in comparison) and I like the triangle shape on the front too! Go steady now - I don’t want to hear anything about cracks from drying too quick!

[david s]

I only do 3 tabs, but you could do 4. Yes, the pipe can be packed around the joint with some 5:1 vermicrete around 150mm high, which is enough to hold it in place when the render over the top of the vermicrete surrounds the pipe higher up, with some high temp silicon between the render and the pipe. This method avoids drilling and fixing into the refractory, of which both can lead to cracking. It also avoids having to purchase an expensive anchor plate.

[Daveholdn]

If you’ve only just removed the damp sand, it would be prudent to allow the casting to dry in the sun and wind for around a week before covering with the blanket.
Maybe you can sort out the flue pipe attachment in the meantime

Cheers David, I'll let it dry out and crack on with the flue pipe then, as I understand in one of your previous posts, cut 4 tabs out and bend them up so they sit on the rim of the flue cast? Do you screw these in at all to secure or is the blanket vermiculite and render layers enough to secure?

Thanks.

[david s]

If you’ve only just removed the damp sand, it would be prudent to allow the casting to dry in the sun and wind for around a week before covering with the blanket.
Maybe you can sort out the flue pipe attachment in the meantime

[Daveholdn]

So back yesterday, straight onto the oven to check she was OK the gallery form came away without too much work, 6mm spacers defo worked a treat as it dropped down with a few gentle taps. Having a little problem with the flue but it is only siliconed together so I don't see it causing to much of a problem.
Taking the sand out, Mullster was right, I was getting excited seeing an actual oven inside. Very happy as not too many voids, only a small hairline void where I think my second batch was a little less moist than the first and I didn't ease into place as much when applying. It's been filled with a small batch of homebrew, like david s explaine , sived the sand to make it a little more refined.
Next is countertop and then blanket layer. Should I hold off on the vermiculite layer or go straight into it?

Holiday was great but couldn't wait to get back to her lol

Cheers, Dave

[seannieboy71]

Your oven is looking great. You are likely in the middle of your 6 day getaway. Hopefully everything is in good shape when you return.