The Rocket Powered Oven: how to build your own super-efficient cooker

Hi Fraser;
I'm not sure exactly what you are trying to do, or what the book wants you to do.
But I can tell you how to remove a lid from a barrel.
All you need is a side grinder.
Stand your barrel on end.
Start grinding on the lip. Keep your grinder horizontal.  Go around and around. Staying on the lip. after a little while you will see a fine line/crack forming.
Continue grinding and that crack will follow you all the way around the lip until the lid finally falls inside your barrel.
Very easy , it is rather noisy but it works fast and good.  You end up with a round disk that is a perfect fit inside your barrel.

On A different note.   Your RMH rocks!  It looks great!

Hope this helps , Have a great day!

These are the illustrations.

I think i get it. The "lip" is the flange. I.e the ring at the end of the barrel.

I guess i need to cut as high up the lip as possible.
I cut at the bottom. So the lip does is now not attached in my case.

Luckily i have access to more barrels so i will try again

Thanks thomas for the compliments. Rmh is the gift that keeps on giving

Yes , grind the flange on the very top.   Flat , just keep circling the barrel.  It takes 20 minutes or so but it will come off very nice.

Fraser;  Here is an old post with pictures.
https://permies.com/t/138675/Barrel-Technology

I give this book 10 out of 10 acorns.

I loved this book. I bought the PDF and it was easy to read. There was a certain can do to this book which was great. It really helped me understand using rocket stoves. I built a rocket oven based on this book and it has turned out great. We have had many pizza parties and it has worked as intended.

The book also had information on making black ovens. I made a white oven.

It would be nice if the book had a updated version. As i believe rocket ovens made at WL are made a little bit different.
Illustrations were great. easy and straight forward to built with tims book.