Mine look like the bottom picture. Then I wrap tightly with budding rubbers. I want to close those gaps. After that I cover the scion tightly with Al foil. Parafilm would likely be better than Al foil but I get 80% or so takes.

. The first would be an iffy graft, very little cambium contact. If they don't caliper match shift to one side and get as much direct cambium contact as possible.

The second one is cleaner, but one is pointed the wrong way. The wood and buds are directional.

Good catch, Rob.

Like Fruitnut says above. You can get a near-perfect fit with this, and when just right the graft can disappear beautifully the first season. But don't push them together so tightly that they create a bulge.

I wrap with a rubber and follow with parafilm. Best technique would probably be to wrap parafilm right out to the tip of the scion but I think it's usually sufficient, at least with the easier trees, to just cover the actual graft well and then dab a bit of tar on the cut tip. Of course, I don't get the sun they do elsewhere.

Purely out of curiosity, what would happen if you grafted a scion on upside down? Would it just not grow at all or could it start growing down and then make a U-turn?

I am pretty sure it would just fail, but I have not done it.

I have heard of inversion grafting where a 2-3" section of bark is removed from the entire circumference of the trunk, flipped and then replaced. It is supposed to slow vigorous species down for a few years and help induce fruiting....pretty drastic procedure.

I have tried several times to graft the ends of branches together to reinforce a tree with a split leader instead of using cable....never worked. the union always failed and new growth initiated just before splice.

I've grafted a few upside down just because I was in a hurry. They don't take that way, at least not the ones I tried. I just use black electrical tape. I recently started using wax (the $1.50 toilet bowl ring wax) on larger cuts and cleft and bark grafts. On a situation where I have two different size pieces, I use a bark graft. If it's a really big difference, cleft graft.
Here are some of my pics:

{{gwi:124174}}

{{gwi:124175}}

How are you using wax? Are you melting it first and then using some sort of brush to paint it on?

Quick followup question: Do you usually cut the whip/tongue part by slicing both of those cuts higher up (toward the tip). I think when they slide together, it seemed to be better grafts when the cut on both is 1/3rd from top.

Also do you just have this lil' cut going straight downwards on both sides. (or cut it at an angle)?
I wasnt sure cutting straight down into bark (towards the bottom of the branch) seems to be an easier cut. vs cutting at an angle (maybe an angel on both peices 'hooks' the peices better, i dunno, just thought Id ask. The straight cut is easier).

Here is a video

Here is a link that might be useful: Whip & Tongue Grafting