Tips, Tools and Tricks for undercutting balsa core

W

wexcellent

New member
As I scour threads dealing with cleaning wet/rotten core materials through existing holes I see references to routing, using a dremel, etc. but haven't encountered much yet in terms of specifics. I have routers, dremmels, roto zips, etc and I am curious what bits, hand tools and practices people have used to best effect.

With larger holes like the hatches or the gas fill caps I am not so concerned, more the undercutting 1/4" or 1/2" holes in the fiberglass. I have only just started on repairs but already see the need to fabricate some kind of 90 degree hand scraper.

Thanks!
 
For small holes I found the best was to use an allen wrench in a drill. Usually I would cut the short end of the allen wrench a little shorter and then stick it in the hole. This worked pretty well. For the larger areas like lazarette hatches I made a little tool out of 1/4" aluminum:

20210108_213637.jpg
 
I use a Dremel tool, with 1/4" bit head, Often the flexible shaft is a better tool. There are also flexible shafts for the Roto Zip 1/4" shaft tools. and high power vacuum.

For separating foam from hull or balsa, the Fein MultiMaster or copy bay almost every tool company-I have corded by Dremel, and battery powered. The scraping tool, or about 1 1/4 to 1 1/2' wide fine toothed cutting blade--just don't cut thru the bottom of the boat!
 
Thanks guys.

Bob, I am really hoping it doesn't come to breaking out the Fein, finger's crossed. I've never done fiberglass repair and would rather not start, though doing it under the gas tank probably wouldn't be a bad place for my first time since no one will ever see it.

Clay I will definitely be experimenting with the allen wrench idea, I have a whole coffee can of extras to work with. I like the tool you made, I have made similar for a couple of other applications and don't like using them unless absolutely necessary because they can do a lot of damage to materials, clothes and flesh if you aren't really paying attention. I need to look and see what kind of slot cutting router bits I have and maybe pick up a couple more because they should be perfect for the larger openings. Having one with a top mounted bearing and one with a bottom mounted bearing I should be able to quickly and safely prep the openings.[/img]
 
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