The Uuni 2S is a great portable outdoor pizza oven that burns wood pellets and reaches temps of 900F and produces great pizzas with no modifications at all, but I missed being able to watch the pizza cook. because of the way the oven works if you dont have the door shut at all times the air flow does not work properly and wonrt work. I had seen other people on the facebook group had done this mod and thought I would give it a go. I also added some hinges so you didnt have to remove and replace the door each time.
Step 1: Cutting the Hole
This is kind of a big step. Cutting a hole into my beloved pizza oven. No going back! I am however a bit of an obsessive so I used Fusion 360 to CAD it up and work out exactly what I was doing before doing anything. (I have included the plans later in the instructable so if you want to copy my mod you have templates for everything).
Step 2: Buying the Glass
Because the oven gets up to some stupid high temperatures you cant use normal glass it would just shatter. I found a great company (replacementstoveglass.co.uk) that will sell special wood burning stove glass in custom sizes that didn't cost the earth. I sent them in a PDF template of the glass size i needed. £30 lighter I had my glass, well it isn't glass it is actually a form of ceramic that looks like glass.
P.S. The guy told me you can use a normal glass wheel cutting tool. It may be cheaper to buy a square and cut of the corners yourself. Another option I learnt about after the fact is a plastic called Mica which you can cut with scissors.
Step 3: Failure Is Always an Option
My first attempt I used some Vitcas Heat Resistant Sealant to stick the glass to the door. This was a mistake! it worked great for about ten minutes but when steel of the door and the stove glass got hot it broke. Because of the different expansion rates for the steel and the glass when they are heated, and the fact that there was no flexibility in the sealant the glass cracked then fell off. Doh! Not good, I have cut a big hole in my oven so no going back now.
Step 4: The Rethink
So after buying a new piece of glass and sitting down and having a good think I decided to go with the system that wood burning stoves use. which is having some ceramic rope gasket around the windows and system to hold the glass gently in place.
I bought a meter of Self Adhesive Glass Gasket from ebay £6
1m of 20mmx2mm steel bar from bnq £5
I bent the steel into some bracket that would hold the glass in and stop it moving about to much. and inserted some M4 Rivnuts (but a couple of nuts might have done the trick (see PDF template later in instructable).
The other option to hold the glass in would have been to use high temp silicone (Envirograf high temp silicone) which I was told by someone who used to make wood burner would have done the job, but after breaking one piece I didnt want to take the chance it wouldn't flex enough.
I also installed the hinges which would pivot the door instead having to take it off and on each time. these were riveted in place
Step 5: Cooking!
This time it worked and was great to see the flames rolling across the top of the oven. and really helps being able to see the correct moment to turn your pizza. I have used it a couple of times and no sign of cracks. I do have to give the glass a wipe with a dirty cloth before each time I light it to remove the worst of the soot buildup.
Step 6: Templates
Here are the templates you will need to copy my mod. if you print them full size you should be able to use them a template (Some are A3 size).
I altered the design slightly reduce the height of the window as the glass was catching slightly on the hinge.