Helicoils are just one option to deal with stripped threads. IMO if you can go with a larger bolt then it is a better option. Some applications such as spark plugs have limited "meat" and fixed diameter threads so staying with original size is really probably the only option. In other circumstances (SS fasteners in aluminum) you may actually find a good option is to drill the hole clean and install a "liner" such as a rivnut (rivet-nut). This way you will have stainless on stainless. This is really only an option when the material is relatively thin and has space behind (masts).
As for your furler I imagine that the fasteners failed because of the aluminum to stainless galvanic corrosion? In this case you probably have room to increase the diameter but probably not the depth for a rivnut (or for that matter a Helicoil). I would definitely suggest up sizing for this situation. You will now find that you have options. Standard or metric, and how much larger? I would walk the isle of the hardware store and evaluate availability of fasteners before settling on anything. Particularly difficult to find may be metric set screws in stainless. This is your opportunity to "upgrade" to more available standard sizes in stainless. In the case of set screws, you may want to consider availability of allen wrench. 9/32nds or 17/64ths is relatively less available. Stepping up another fraction might put you in a more conventional size of tool. When you install them, make sure to use a galvanic isolating material, either a lubricant like tef-gel or anti-seize, or a thread locker. Blue or green thread locker would be my choice for 1/8 to 1/4 inch set screws. You'll probably have to plan on bringing a micro torch when to go to remove the screws. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Thu, May 14, 2020, 21:52 David Knecht via CnC-List <cnc-list@cnc-list.com> wrote: > I have seen mention of helicoils several times on this list but I have no > experience with them. I have several stripped screws on my Harken furler > and was thinking they might be useful to repair. What is unclear to me > from what I have read is the reason to use them. I still have threads > there, and I thought the idea was to screw in a helicoil to make the > threads grab again. However, every description I have seen of using them > drills out the hole, taps and then screws in a helicoil. I don’t get the > point. If I am going to drill and tap, why would I use a helicoil instead > of just putting a screw into the newly tapped hole? Is it that you can use > the same size screw as before instead of going to a larger size? Is that > preferable for some reason? Dave > > David Knecht > S/V Aries > 1990 C&C 34+ > New London, CT > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
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