You sharpen the end of the center dowel so that you can hammer it into the cake and the boards (you need to cut it slightly shorter than the height of the entire cake so it is not visible. When you get close to having it all the way in (just a little showing on top) grab another dowel put it directly on top of the dowel going in and continue to hammer until the 1st one is all the way to the bottom. As for size so far I've just used the Wilton dowels I can pick up at Michaels.

Hey xstitcher,

Thanks for the reply. What do you use to sharpen the end? Does it just go through the cardboard between layers? The dowels I've gotten at Michaels were about 12" tall and skinny. Is this the same ones you got or did I just not see bigger ones? Maybe I can get them at Home Depot.

You can just use a sharp blade/knife to sharpen the dowel and yes it will go thru the cardboards or foamcore (whichever you decide to use). I just got the wooden dowels that are at Michaels I do know you can get larger ones (seen them on-line at cake supply stores) but have not needed them yet.
Here's a Wilton tutorial and you can see that the center dowel looks the same size as the dowels that are in the cake supporting the tiers.

http://www.cakecentral.com/article23-Teired-Stacked-Cake-Construction.html

Thanks to everyone for all your wonderful advice! My sis' friend has approved my 3 tier design so I went today to get the necessary supplies to stack my cake.

So I've got:
- one 7" cardboard round 1/8" thick for the top tier
- one 8" cardboard round 1/8" thick for the middle tier
- one 10" cardboard round 1/8" thick for the bottom tier to sit on
- three 14" cardboard rounds 1/8" thick which I plan to glue together and cover with parchment then fondant for the base
- wooden dowels for each tier for support
- bubble tea straws which I will use along with the dowels
- one center dowel to secure all tiers

And also thanks to xstitcher for her wonderful tips & advice on center dowels.

Wish me luck and I'll post my final cake when it's done - thanks again

One quick tip about the 3 cakeboards you're gluing together.

When you glue them, alternate the corrugated lines so that they are not all going in one direction, this will give you a stronger base for your cake.

Good luck!

Good luck with your cake!

Just wanted to add that if your going to cover the cake board with fondant you will not need the parchment underneath 1st. Great advice from dkelly, I totally forgot about that!

Good luck and please post your pic when your done.

Hey everyone,

Just wanted to say thanks for all the GREAT advice! The cake traveled great. I delivered it this morning and it did not budge, lean, shift or bulge or anything! So happy to have this forum to get great ideas from. Couldn't have done it without you guys!

Here is the finished cake...

http://www.cakecentral.com/cake-photo-1359022.html

Thanks again!

WOW, it looks terrific!

BEAUTIFUL! what an adorable cake!

What a great look cake, love your design and the various shades of pink! Glad to hear everything worked out so well for you.

vlin28

Your cake is beautiful!! You should get tons of orders from this cake. I'm so glad that everything went so well for you!

Oh my SHOCKENESS! that is such a beautiful cake. I totally love what you did with the cake board. Oh my this is such an amazing cake! I will dream about this tonight. I bet ya.

The cake is a knock-out!!

Thanks everyone! I was so excited to do this cake and it worked out better than I ever imagined. You guys gave me the confidence to see this through so thanks again and thanks for the awesome compliments!

absolutly gorgeous!! congrats, its really perfect

Try this video: