Home-made Hollowing Tool

We're putting up a Christmas Tree for the first time in nearly a decade, and I thought it would be fun to make a couple of turned ornaments on the lathe.  I like the ones that are a globe with a finial beneath and a hanger button at the top made out of contrasting wood.  So I made a practice globe out of a piece of cherry firewood, and realized I really needed to hollow it out to prevent it from cracking, and also to reduce the weight so it would hang on the tree nicely.

I drilled a 1/2" hole down the center and used a small spindle gouge to remove as much material as I could reach.  It kind of worked.  I couldn't get to a lot of material just inside the opening with the end of the straight tool.  So I picked up a 5/16" steel rod stock and some brazing rods at the orange borg a couple of days ago, and made a hollowing tool for under $10.

I bent the last few inches of the rod about 20 degrees in a vise.  Then I got an old 3/16" drill bit ("black oxide" no mention of the alloy used) and ground a flat on both the steel rod and the drill bit so they would mate together.  I wrapped a bit of thin steel wire around the assembly to hold it while I brazed them together, which I did with a common propane torch.  I've never brazed before, but it's pretty much the same as soldering, which I've done plenty of.  I didn't use any flux paste, just the stuff that was on the outside of the rod.

I cut the drill bit off about 1/2" long, shaped the tip into a scraper, and did some general cleanup on the grinder.  Then I turned a quick handle out of a scrap of alder and a 1/2" copper plumbing coupler, and epoxied it all together.  I gave it a very quick test-drive, and it seems to work well enough for my purposes.

Quick-n-dirty Home Made Hollower

Failed Braze Joint

Update:  I put it to the test tonight, and it started working well, but the braze failed and the cutting tip fell off after a few minutes.  I can see that the brazing alloy only stuck to a very small part of the joint, which I think is due to the tiny amount of flux used.  Basically, whatever melted off the rod when I was heating the joint is all there was.  I'll get a can of paste flux and try again.

Brazing is pretty easy (2nd time around)

Update 2:  I picked up a can of Harris Stay-Silv flux at a local welding shop and tried again.  That braze seems to be much more thorough.  I successfully hollowed out the previously unreachable spots on a little globe, although my cutter could use a little tuning on the grinder.  I'm a little torn on this brazed construction method, because I could also buy some carbide tips, drill and tap the end of the rod, and have interchangeable cutters that last forever anyway.  I could also drill a 3/16" hole in the end of the rod, insert my cutter, and fix it in by brazing or with a little set screw.

Hollowed Globe for a Christmas Tree Ornament, ~2" dia.