I've done a few round cake in the past and i can't keep the sides from bulding out. I don't over fill and I stack the layers bottoms up. (I've done the bottoms down too and i get the same thing) What can I do to prevent this from happening. I have my first wedding cake coming up and they want round so I need to fix it!! I know I could trimm the sides but I've never done that so I'm not sure how!
Any suggestions PLEEEEEEEEASE!!!!!

I make my butter cream thicker and put it into pastry bag and make a dam around the cake and then fill in the rest with my filling. I refrigerate it a few hours to have it settle before I put on the fondant. That seems to work for me.

We'll need some more information to try to help figure out what the problem is.
is it the cake itself that is bulging out?
or the filling between the layers?
Are you using a dam around your filling?
Are you leveling each of your layers?

When stacking your layers the bottom one should be top up, and the top one should be bottom up (so the top of each layer is toward each other in the middle of the cake)

You say this is on round cake... have you done the same process with square (or other shapes) and not had a buldge?

What pans are you using? Can they be stacked inside each other?

I find the biggest thing to keep a cake from bulging is keeping it cold and solid.I place a cutting board ontop of my cakes when I assemble them and let it sit in the fridge for a day or so to settle and then all the excess filling has a chance to bulge and extend.Then I go around and scrape the excess icing off and cover..This helps tremendously!!

this

http://cakecentral.com/cake-decorating-ftopict-633571-latest.html+trick

Cakes will not settle properly in the fridge. They will look lovely - until they come to room temp at the venue probably after you've left.

I'm not covering the cake in fondant. I only put about 1/4in of filling in between layers. It does seem to be the cake that is bulging. Kind like it fanning out where i torted it. So when i stack them them i get a bow in the middle of the cake. I have a picture of a Christmas cake I did and you can really see it. The pans I use do not fit inside of each other. I think I may be too impatient and I'm not waiting long enough for them to settle. I did a square cake last week and hadrly any bulg at all if any. That is the Chicago Bears cake in my photos. I covered the side with fondant so I don't know if that helped or not. I will try the tile trick next time. I'd really like to have a "sure thing" before next Saturday. I have a 3 tiered wedding cake!! I've never done 3 tieres or a wedding cake!!! I'm freaking out right now!!!

I'm not covering the cake in fondant. I only put about 1/4in of filling in between layers. It does seem to be the cake that is bulging. Kind like it fanning out where i torted it. So when i stack them them i get a bow in the middle of the cake. I have a picture of a Christmas cake I did and you can really see it. The pans I use do not fit inside of each other. I think I may be too impatient and I'm not waiting long enough for them to settle. I did a square cake last week and hadrly any bulg at all if any. That is the Chicago Bears cake in my photos. I covered the side with fondant so I don't know if that helped or not. I will try the tile trick next time. I'd really like to have a "sure thing" before next Saturday. I have a 3 tiered wedding cake!! I've never done 3 tieres or a wedding cake!!! I'm freaking out right now!!!

I had bulging round cakes already when I just started off. It was caused by 2 things:
Thick and uneven layer / application of frosting (buttercream) and
How I stacked my round layer cakes

I dealt with both issues by 1st:
Carving the round cake sides. A round cardboard the same size of the cake placed on top and take a long carving knife perpendicular to the cake board and in an up and down motion ensure the stacked layers of cake are trimmed neatly to match the cardboard shape. When I did this I was shocked at how uneven my cake was on all sides!

Then I used the largest tip for putting on flat icing as the crum coat. Repeat but ensure you have an even application of icing.

You'll get a beautiful cake in the end.

I put my cakes in the refrigerator for a while first, than cut and thicken my icing and put a dam. than i fill it and dirty ice and put in the freezer for at least 10 min. this process cools the icing as soon as you put it on and it stays like that you shouldn't have any trouble. After i dirty ice i put in the freezer again for an other 10 min and than get it out and ice it. works GREAT!
Your cakes need to be strong too! if they are not cooked enough the sides just won't have the support needed.