I am making a 4 tiered wedding cake, 8", 12", 15" & 18". In regard to the dowels that are supporting the 15" tier, do I need to also place dowels not only around the outer edges but also inward? I hope this makes sense. I have placed 20 1/4" ones. Is that enough or should I use larger dowels? Thanks!
The dowels should be evenly spaced over the whole area, not just around the edges. I personally use larger than 1/4 inch on the bottom tier since it is supporting the most weight. Any decent cake deorating book will have guidelines for doweling.
Or you could throw out all your dowels and use SPS. There are many converts here on CC.
All of the cake books I have seen say to only dowel around the edge of the cake.
I got nervous recently when having to support a 14" layer that was on cardboard. I finally decided (after polling the experts here, and recognizing my time constraints) to just use the wilton plastic dowles around the edge (and only 8 of them) and put the cake on a separator plate. Though the dowels didn't fit into the plate like a regular SPS would, the plate added the rigidity that 14" layer needed so that support only around the edge was adequate.
I think there are many roads to Rome, so it comes down to what method will give you the most confidence and best results.
I have posted a number of times that I use 4 dowels, no matter what the size .... but I think with a cake this size, even *I* would put some in the middle of that bottom tier!
I use 3/16" dowels on the larger cakes, and I would put a few in the center. More is better