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Panel held in by wood screws, but the threads in the wood are stripped


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Like many boats, mine has a wooden board / panel at the nav station which the VHF, plotter, breaker panel and so on are mounted into. That panel is held in place by six wood screws, which screw into a wood flange. Of course four of the six screws don't hold well. The screws are not vertical, of course. My first though was to inject some epoxy into the stripped holes and redrill, but I'm thinking it will run out before it cures. If I thicken it I may not be able to get it into the entire hole.

I'm sure I'm not the first person to have this issue, what are the clever / easy / inexpensive ways to fix this? Maybe just squeeze some epoxy paste in there? I know I could also get some of those barbel nuts and install those, but I'm not very good at getting those to go in square. 

 

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  • George Dewey changed the title to Panel held in by wood screws, but the threads in the wood are stripped

Epoxy tends to crack. Same with glue. Kinda works. A wooden match stick, or two, is the simplest. Perhaps with a tiny bit of wood glue. Longer screws? Otherwise drilling and inserting plugs is best. Not dowel — the grain goes the wrong way. Larger the better.

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29 minutes ago, Borracho said:

Epoxy tends to crack. Same with glue. Kinda works. A wooden match stick, or two, is the simplest. Perhaps with a tiny bit of wood glue. Longer screws? Otherwise drilling and inserting plugs is best. Not dowel — the grain goes the wrong way. Larger the better.

+1 on the match sticks. Put some wood glue on them and insert into the holes, perhaps give them a slight tap with a hammer to ensure they reach the bottom. Let dry and put screws back, they will form new threads will squeezing the stick between the wood and the screw, ensuring a tight and durable fit

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+2 on the sticks - toothpicks work too.

Best setup is to install threaded inserts and use machine screws. That's how I set up my engine box panels and it works great.

INSERTS TYPE SKD

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Just now, SloopJonB said:

+2 on the sticks - toothpicks work too.

Best setup is to install threaded inserts and use machine screws. That's how I set up my engine box panels and it works great.

INSERTS TYPE SKD

Cool. What is the name of your preferred product?

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19 minutes ago, SloopJonB said:

+2 on the sticks - toothpicks work too.

Best setup is to install threaded inserts and use machine screws. That's how I set up my engine box panels and it works great.

INSERTS TYPE SKD

I agree this is a great solution but as I said, I suck at getting these to go in square. Is there a trick to it?

Cool idea on the matchsticks / toothpicks! 

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41 minutes ago, SloopJonB said:

+2 on the sticks - toothpicks work too.

Best setup is to install threaded inserts and use machine screws. That's how I set up my engine box panels and it works great.

INSERTS TYPE SKD

Very elegant and effective solution, but when I tried to find these in stainless steel, I found them to be very expensive...

Around 5 bucks a piece expensive...

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2 hours ago, George Dewey said:

I agree this is a great solution but as I said, I suck at getting these to go in square. Is there a trick to it?

Cool idea on the matchsticks / toothpicks! 

Are you tapping the hole that you're putting them in?

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1 minute ago, Schnappi said:

I use inserts when mounting ski bindings. I always tap the hole. The insert screws right in.

I'll try that, for $5 * 6 pieces it's a much better solution. Thanks!

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4 hours ago, Borracho said:

Cool. What is the name of your preferred product?

Don't have one - they're just hardware store stuff. I first ran across them in IKEA furniture years ago.

Last ones I got were at Rona - Canadian competitor to Home Despot.

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4 hours ago, George Dewey said:

I agree this is a great solution but as I said, I suck at getting these to go in square. Is there a trick to it?

The way I install them is to align the panel I'm attaching - position it exactly how you want it mounted. Then I drill a pilot hole through both pieces to ensure precise alignment of the holes.

Then I remove the panel, drill it through the pilot hole to the shank size of the machine screw - I only use 1/4 X 20 machine screws, usually truss head. Drilling these holes 1/64th over makes things easier.

Then drill the hole for the insert, sized to the minor diameter of the wood screw thread.

I find installing the insert with a T-handle Allen wrench works best.

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4 hours ago, alphafb552 said:

Very elegant and effective solution, but when I tried to find these in stainless steel, I found them to be very expensive...

Around 5 bucks a piece expensive...

I've never used S/S inserts. I think the hardware store ones are zinc - never had a corrosion problem combined with S/S machine screws but I've only used them inside, not on deck.

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Use West System G-flex 655 epoxy. It will not ooze out, it does not ooze it stays in place. Spray the screws with PAM baking spray and a piece of tape on the back of the panel so it does not get stuck. The screws can be removed with  little heat.

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Over size the hole, at least 1.5 times the current dia. Micofibre and epoxy mixed and use a syringe to inject into the hole.

It is best you don't drill out the other side to minimise the chance of the mix passing out the bottom , but if you do no biggy just tape over it .  If there is a small hole through it will help minimise the chance of an air gap. The resin mix should be thick enough that you wont have too much of a problem.

Wait for the resin to cure but still slightly green , drill a pilot hole and you can screw in the screw with out cracking and will have a permanent fix.

I have also coated the screw in vasoline and just pushed it is before cure. Depends on the specific circumstances.

Done it many times over the last 40yrs and never had a problem. The epoxy prevents further water problems with that hole as a bonus. 

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If you fill the holes with epoxy you might consider self tapping screws.  You still need to drill a pilot hole.  I used to use self tappers when designing plastic parts that needed to screw together and I was trying to save pennies by not using inserts.  It worked with 3D printed parts pretty well too, after they figured out how to print good elastic resins.  Lemme know if you want to go that way and I'll send info on pilot hole versus screw size.  The downside is you get fewer insertions with epoxy/self-tappers than you do with a metal insert, they just wear out faster and don't tolerate gorillas on the working end of a screwdriver like the metal ones do.

Alternatively you can always tap the pilot hole and use a machine screw.

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Threaded inserts are available in brass.  Holds up very well in the type of situation you describe.  I used them in my cock[it table.  Corrosion has not been an issue in over 10 years of use.  They don't see much salt, just the occasional spray and they are not exposed, so no problems.

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As I go through my boat, I've been removing every screw I can get my hands on and replacing them with bolts (where possible) with lock nuts.  Where I can't, threaded inserts are my next option.  The toothpick / matchstick option works shocking well, but I still hate screwing something that moves into wood.

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Cutting screws are intended for one use, not for removing and reinstalling on any sort of regular basis. The OP's problem is what happens when that is done.

I use screws for "permanent" (is anything truly permanent on a boat) installations and inserts for things that will need to be removed periodically but not regularly.

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On 7/13/2021 at 7:47 PM, Sunset2 said:

Use West System G-flex 655 epoxy. It will not ooze out, it does not ooze it stays in place. Spray the screws with PAM baking spray and a piece of tape on the back of the panel so it does not get stuck. The screws can be removed with  little heat.

I'm opening this panel every few weeks at least for one reason or another.

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1 hour ago, George Dewey said:

I'm opening this panel every few weeks at least for one reason or another.

Inserts and machine screws - that situation is exactly what I use them for.

I have access doors on my engine box for regular service areas - dipstick, filters etc. When I need to use wrenches the whole thing disassembles in a couple of minutes.

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I've been using helicoil inserts. Agree the solid ones are likely beefier but for handing panels, not really needed. I also used knurled thumbscrews on the e-panels, as I'm in and out with regularity, and I don't need a screwdriver.

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  • 2 weeks later...

I ended up fixing it with these things. I just used a 1/4 inch drill bit to widen the existing hole, pressed these in from behind with a vice grip and problem solved. It was actually very easy. Thanks for all the suggestions!

 

IMG_3254.JPG

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Congratulations on finding a solution. I only found this thread and my solutions are “a day late and $2 short” but maybe somebody else might find them useful.

One issue with blind nuts like those is that it’s possible to knock them out when reinstalling the screw.

If going into material 1/2” or thicker, my pic shows a thing called “All Thread Inserts.”  They are a malleable plastic and come in a range of color-coded sizes for #2 to 1/4” screws.

Drill a hole as per instructions and use CA glue (crazy glue) to glue the insert in place. Then screw in the screw which will cut its own, shockingly-effective threads.

This works with both machine threads and sheet-metal thread screws.

This is not a structural solution, but it works great for things like panels, and other fittings.

Also, if you do eventually mangle the plastic threads, simply drill it out and glue in a new one.

Your mileage may vary, etc, etc, but I find them very convenient when used appropriately.

They can be bought here and also in some hobby shops. (They used to be more generally available in hobby shops, but lots of hobby shops have closed down, as have lots of the shop customers who would actually build stuff and use a product like this.)

http://www.ohio-superstar.com/accessories/2-all-thread

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Solution #2 for making a thread in the edge of a fiberglass panel etc is to use a thing called a RivNut (Rivet + Nut) that is basically a pop-rivet that is threaded.

Compared to the inserts w threads on the outside that were mentioned previously, these are not as strong. They Also leave a ring the thickness of a washer on the surface and CANNOT be installed flush. They are therefore best for panels and thin FG, metal, wood panels rather for solid material where the double-thread inserts would be better.

One advantage is that the hole they require is very small, and because it squeezes in from both sides it helps reinforce the edge of the panel where they’re installed.

The tool from Harbor Freight is very adequate for occasional use. HF also has the inserts available in aluminum. Depending on the application, you may want to splurge on higher-quality inserts (in either aluminum or stainless) from McMaster or others.

https://www.mcmaster.com/rivets/aluminum-twist-resistant-rivet-nuts/

https://www.harborfreight.com/45-piece-threaded-insert-riveter-kit-1210.html

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26EAE857-75C8-46F3-A294-CD55B121D32F.png

image.jpeg

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On 7/25/2021 at 6:39 AM, Gabe_nyc said:

Solution #2 for making a thread in the edge of a fiberglass panel etc is to use a thing called a RivNut (Rivet + Nut) that is basically a pop-rivet that is threaded.

Compared to the inserts w threads on the outside that were mentioned previously, these are not as strong. They Also leave a ring the thickness of a washer on the surface and CANNOT be installed flush. They are therefore best for panels and thin FG, metal, wood panels rather for solid material where the double-thread inserts would be better.

One advantage is that the hole they require is very small, and because it squeezes in from both sides it helps reinforce the edge of the panel where they’re installed.

The tool from Harbor Freight is very adequate for occasional use. HF also has the inserts available in aluminum. Depending on the application, you may want to splurge on higher-quality inserts (in either aluminum or stainless) from McMaster or others.

<snip>

They are very useful, particularly for screwing things into aluminum. 

However, the HF tool will not crush a #8 stainless riv-nut. The riv nut is much stronger than the tool. I've only tried it once, since the first time I tried the tool broke. 

 

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On 7/13/2021 at 11:02 AM, sailthebay26 said:

How about drill the holes bigger and insert a dowel in place with epoxy or wood glue?  Then small pilot hole and install the screws.

That is only 5x the work and 10x the cost of jamming a toothpick or two in the hole. So PERFECT for a boat. 

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3 hours ago, gptyk said:

They are very useful, particularly for screwing things into aluminum. 

However, the HF tool will not crush a #8 stainless riv-nut. The riv nut is much stronger than the tool. I've only tried it once, since the first time I tried the tool broke. 

I confess that I only used it on aluminum riv-nuts. 

My previous boat had wooden panels pop-riveted in place from the factory (w pretty, dainty SS ones). I had to take one off and my only choices to put it back were pop-rivets or riv-nuts and screws.

I was quick to do and worked great.

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On 7/13/2021 at 10:34 PM, The Mad Hatter said:

Over size the hole, at least 1.5 times the current dia. Micofibre and epoxy mixed and use a syringe to inject into the hole.

It is best you don't drill out the other side to minimise the chance of the mix passing out the bottom , but if you do no biggy just tape over it .  If there is a small hole through it will help minimise the chance of an air gap. The resin mix should be thick enough that you wont have too much of a problem.

Wait for the resin to cure but still slightly green , drill a pilot hole and you can screw in the screw with out cracking and will have a permanent fix.

I have also coated the screw in vasoline and just pushed it is before cure. Depends on the specific circumstances.

Done it many times over the last 40yrs and never had a problem. The epoxy prevents further water problems with that hole as a bonus. 

Have done this many times and it works fine.  As long as you use the correct tapered bit for the screw size and wax the screws the first time no issues, and back to the original screws.

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