Some where I have a picture of a box joint sled I use to cut the joints in my 10 frame boxes. Funny how you can't find stuff when you want it. You can goggle box joint jig to find one that will work for you.
To keep the hives square I have 6x6 sq blocks I clamp in the top corner that keeps them square, wellmaybe square isn'tthe right word more like true 90 corners.
As for the size set two frames side by side and measure them. Subtract that mesurement from the size for a 10 frame hive.
found them.
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Al
Garden View Apiaries where the view is as sweet as the honey.
Member SEMBA & MBA