Did you let it settle overnight before putting the fondant on? If you don't let it settle you will get that bump.
How long did you allow your cake to settle after filling? Cakes are going to settle. It's important to allow them to do this before icing. I level, fill and wrap in plastic wrap and let them sit for several hours before crumbcoating and icing. You should also make a dam out of thickened buttercream for your filling. Doing these two things will prevent that dreaded budge.
Thanks for the replies. The cakes are all buttercream, including the filling. No, I didn't let it settle. Guess that's it. I also didn't use the dam. I didn't realize that you should do that when you are using buttercream. I thought you only did that with a fruit filling. Duh!
mamawrobin is always full of helpful info.
If you use a slightly stiffened buttercream as the filling in your cakes, then you do not need to let your cakes sit around before you finish them, and you don't need to use a dam with buttercream as your filling. On some recent Saturdays I've had 35 cakes due and don't have time to let them sit around.
You will find that the millions of people who do cakes a) do things differently; b)change their ways of doing things as they gain experience; and c) half will swear by one method while the other half NEVER do it that way. LOL
Why does it happen if you did let your cake settle? Mine sat overnight and still: the dreaded bulge.
It would seems that your filling was too thin, and letting the cake sit for days on end waiting for it to "settle" won't help one bit. If you were using buttercream, stiffen it up a bit next time.
I've looked at this cake a couple of times and to me I do not see a bulge in the middle of the layers of the bottom tier. Somehow, it looks like the bottom layer of that tier is narrower that the top layer of the bottom tier. How odd. I have no idea how or why.... very strange....
I agree with mommawrobin.
I assume you iced all three tiers the same way. Notice that the top and middle tiers don't have the problem. I'm wondering if the dowels in the bottom cake were too short which would cause more weight on it causing the "waistband".
Since I started using Sugar Shack's method of stacking cakes, I haven't had a problem with waistbands or blow outs. If you can, order her stacking cakes DVD. It's very informative.
Hope you figure it out as I know how frustrating it is. Your cake is beautiful! Don't give up.