Reporting back on this issue; I was able to fix the threads with helicoils. It turned out to be a really easy job. I locally bought a kit with ¼-20 helicoils and the tap and threading tool, drilled the holes out, tapped and threaded in the helicoils. I found that they did not feel that tight when screwed in, so added some loctite to the outside before putting them in. Then I used tef-gel on the screw threads. If I had to do this again, I think I would use the threaded inserts that come with outer loctite (https://www.amazon.com/dp/B002QUZNV8/ref=emc_b_5_t), but the helicoils seem fine for now. A valuable lesson learned on how to repair bad threads. Thanks to the group for pointing me in the right direction. Dave
S/V Aries 1990 C&C 34+ New London, CT > On May 14, 2020, at 10:35 PM, Nathan Post via CnC-List > <cnc-list@cnc-list.com> wrote: > > Yes, you drill the hole bigger and tap for the threads on the outside of the > helicoil or thread insert. The other main advantage of using one of these > over just tapping for a larger bolt is in softer base materials (aluminum, > plastic) it will distribute the screw load and prevent it from stripping in > the first place, at least to a point or damaging the threads when the screw > is removed and reinserted. This is especially important if the screw is one > that will be installed and removed every year. I think that there might also > be an advantage in preventing a stainless steel screw from seizing/corroding > as it will tend to do over time in tapped aluminum, at least in a salt water > environment. For that reason, I would tend toward using a solid insert such > as https://www.mcmaster.com/catalog/126/3505 > <https://www.mcmaster.com/catalog/126/3505> rather than a helicoil if putting > a stainless steel screw into threaded aluminum where I want to be sure I can > get them apart again. We had bolt together reusable aluminum frames at my > last job with M16 and M24 bolts and used inserts for threaded holes in the > aluminum - worked great and we never had issues with stripping or galling of > the threads. > > ~~~ > Nathan Post > S/V Wisper > > > On Thu, May 14, 2020 at 10:18 PM Graham Collins via CnC-List > <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: > Hi David > > Yes, allows the use of the original screw, so whatever is fastening to it > doesn't have to be modified. > > Procedure is to drill and tap oversized, and install a helicoil - essentially > a coil of square wire, wound up like a spring. The wire engages in the new > threads and is sized so that the original screw threads inside it. > > Graham Collins > Secret Plans > C&C 35-III #11 > On 2020-05-14 10:50 p.m., David Knecht via CnC-List 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 >> <https://www.paypal.me/stumurray> >> > _______________________________________________ > > 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 > <https://www.paypal.me/stumurray> > > _______________________________________________ > > 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 >
_______________________________________________ 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
