When you hollow blocks what  method do you use to hollow the inside of the block?
    Tools, and what ever else you use to do this.
  I am working on a Dixon Cardinal and want to hollow the top block to get it as light as possible.
  I am thinking about using Forestener bits, then Xacto blades and other tools for this.
  Your thoughts, and why do you use this method...
 thanks,

I've been using some gouges that I made myself, some from music wire, some from drill rod, one teeny one (my first) from a bicycle spoke.

Find a good woodworker supply and look into their carving tools -- you'll find lots of stuff, at higher quality than anything that comes from X-Acto.

But if you go that route -- sharpen often, and treat the tool with the delicacy and patience you'd give to a newborn baby.  Balsa wood, particularly the nice soft stuff, wants a scary-sharp tool and wears edges down quick.  So if you believe that a cutting tool is something that you let rattle around in a drawer until you need it, then you pull it out and use it, then you merrily fling it back in when you're done, stick with X-Acto.  If you are willing to take the tool out, sharpen it until it slices things it hasn't touched yet, use it, sharpen it again, and gently restore it to it's place in the leather pouch -- then you're golden.

I don't do anything manually if there is a power tool handy!  For hollowing blocks, just a Dremel and the 80 grit sanding drum works well.  Makes a bunch of sawdust, but at least you don't cut your fingers.

Floyd

Why not mold it instead? Molding has several benefits:

1) The process is very simple and quick. create a buck out of pink foam, glue it on a piece of pine(to have something to hold on to and to prevent warping), soak a balsa sheet in hot water with a little bit of ammonia(my wife likes that after I'm done, the bathtub is very clean :-) ), wrap it around the buck with elastic bandage(like this one http://www.cvs.com/shop/product-detail/CVS-Elastic-Bandage-With-Clips-3-Inches?skuId=160093 ) and let it dry(can be completely dry in 1 hour if left in the sun).

2) has almost no chance for making a mistake or messing up the shape. pink foam is very easy to work with and if you mess up, it's very easy to make another one. A sheet of 2" Owens Coning pink foam board costs less than $20 and will last you for many, many years.

3) The process allows you to creat multiple exact looking parts. This comes in handy when we crash or drop a heavy tool on top of the model(done that) or when a kid wants to experiment with a saw and grabs the top block(yep, that can happen) while you are not watching.

4) the process can be used for creating many parts: top blocks, bottom blocks, wing leading edge, stab leading edge, etc

5) the process allows for creating super strong parts. Just mold two 1/32 sheets with carbon veil in between and you will know what I mean. Just mold one sheet, let it dry, add carbon veil, apply epoxy(the surface will have to look very dry. if it's shiny, you have too much epoxy), and mold the second layer on top. After epoxy dries, take it out of the mold and be prepared to be amazed!

I used to carve top blocks too. It was one of my most favorite activities during model construction. The slow, careful carving was very soothing to me but after seeing the results of molding I to switch. The only place I still get to carve is wingtips and the front part of the engine cowl(the back side is molded too)

Here's the best hollowing tool I've used.  Dremel ball bit.  Cuts like butter.

I been thinking on a new technique to do mouldings.  Involves making a jig.  Will experiment with it on next build sometime this summer, and post it when it pans outs.  Will eliminate the wrapping with the ace bandage which should cut down the drying to something like 4 hours.  Stay tuned.

Keep us posted. Idea of a jig is interesting. not sure about drying time. Leaving the whole thing in the sun usually gets the job done in an hour or so, depending on how hot it is.

Instead of Ace bandages, use strips cut from an old sheet. The cotton will absorb the water and let it evaporate much quicker.  This is what Al Rabe does.   

If Rabe has done that I'm sure it works,  but one of the reasons I got to thinking about another method was to eliminate the wrapping part all together because its kind of clumsy.  If I was going to wrap it I would stay with the Ace bandage because they stretch and I think that makes it easier to get a better fit of the balsa sheet to the form.

I used tools I made. Brass tubing with a loop soldered on the end that is sharpened on both sides. Rough it out with that then use a ball bit in a Dremel to smooth it out. But I agree, most of the time, molded balsa is better. Depends.

Allan,

Interesting.

How long is that lenght of wood?

Charles