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Old 09-27-2020, 11:13 AM   #1
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Teak deck bung repair: broken bronze screw removal necessary?

I've read through several of the excellent threads on bung repair as I start down this path myself on our side decks. I did a trial run yesterday and replaced three bungs where the screw heads were showing. The teak seemed pretty thick still which is good - maybe 1/2" or 3/8.

In each case I was able to back the bronze screws out, but they were all broken off around 1/2" to 3/4" from the heads (presumably stuck in the GRP).

The challenge of course is that the remaining screw material makes it impossible to countersink a hole with the 3/8" countersink bit I have.

Do you recommend leaving the rest of the screw? It would be very difficult to extract. In that case, using a 3/8" brad point bit seems like it would be necessary to get a plug in deep enough.

One final question: several threads mentioned sealing with epoxy. I found it difficult to do this without making a mess on the deck. I'm considering using 291 or wood glue others suggest so as not to have to pre-mix and deal with the epoxy hardening while I work.
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Old 09-27-2020, 11:58 AM   #2
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bungs should be sealed with varnish. Epoxy is forever.
I have a number of broken screws thanks to PO. Extraction (or should I say excavation) is not feasible. There are enough screws in the deck that a few broken ones won't make a material difference. So there are several very thin bungs. The ones in the cap rail however....
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Old 09-27-2020, 03:11 PM   #3
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bungs should be sealed with varnish. Epoxy is forever.
I have a number of broken screws thanks to PO. Extraction (or should I say excavation) is not feasible. There are enough screws in the deck that a few broken ones won't make a material difference. So there are several very thin bungs. The ones in the cap rail however....
Thanks. How do you drill out the hole with the broken screw still in place?
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Old 09-27-2020, 03:15 PM   #4
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There are some drill bits that are like a mini hole saw so you can drill around the broken screw.
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Old 09-27-2020, 03:23 PM   #5
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Thanks. How do you drill out the hole with the broken screw still in place?
As you have suggested, the screw has broken below its bevel, so using a brad point bit will gain you 1/4" at the minimum, so you can safely leave it in place. The breakage is an indication that it is tight in the FRP. Then if you put sealer, glue, varnish, or epoxy in below the new bung, it should remain water tight.

As long as the new bung is thick enough to be sanded flush, it will remain in place until again worn through. It is unlikely it will be worn through, before the majority of other bungs, as it will no longer have a screw that is too high below it.

I have re-bedded several bungs over sikaflex 291 and am happy with the process and the result. I did a small number with epoxy, and am likewise happy with the result. I have some more to do, as they seem to appear at a constant rate of a few every year.
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Old 09-27-2020, 03:27 PM   #6
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Thanks. How do you drill out the hole with the broken screw still in place?
Since you are doing this for appearance sake, you get yourself a 3/8" spot weld cutter and you cut the whole thing out, broken screw and whatever it is stuck in. With a tapered plug cutter, make an inch-long plug. If you are not planning on sanding the plug and surrounding area flat, use wood glue on the plug, tap it in and use a very sharp chisel to cut it flush. Wiping the area with a wet cloth will remove the glue residue.
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Old 09-27-2020, 03:50 PM   #7
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I’d leave the screw part and re-drill the hole using a 3/8” flat drill bit with a depth stop to just above the screw part. Use a Qtip with epoxy and add some to the bottom of the hole and use a 3/8” teak plug sealed with epoxy. A sharp chisel then to cut the plug flush. You need to be careful that the drill bit doesn’t walk when you drill the hole.

The other option is to drive the screw into the fiberglass, re-drill, seal and plug.
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Old 09-28-2020, 11:09 PM   #8
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I worked in yards and owned one. We didn't think we could just ignore a broken screw. I think bungs pop out when the screw breaks or the screw backs out because of a flexing deck. One less screw would mean more flexing. I drill out the entire screw, fill the hole with thickened epoxy, drill and put in a new screw. I put the epoxy in with a syringe to avoid getting it on the teak.
When I lay a new deck, I epoxy all the screws. That way no leaks, no wet core, etc.
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Old 09-29-2020, 01:23 AM   #9
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I worked in yards and owned one. We didn't think we could just ignore a broken screw. I think bungs pop out when the screw breaks or the screw backs out because of a flexing deck. One less screw would mean more flexing. I drill out the entire screw, fill the hole with thickened epoxy, drill and put in a new screw. I put the epoxy in with a syringe to avoid getting it on the teak.
When I lay a new deck, I epoxy all the screws. That way no leaks, no wet core, etc.
Thanks.

How would you drill out the screw without the bit walking on you and creating an oval hole?
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Old 09-29-2020, 01:40 AM   #10
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Maybe use a hollow screw extractor and drill around the screw, remove it and then fill with thickened epoxy. Drill a hole in a piece of scrap wood then center the hole in the scrap over the broken screw. Use the scrap wood as a guide for the screw extractor to keep it from walking. They have several diameters available. This is what I was referring to in post #4.

Rockler.com


1/4" Diameter Screw Extraction
Item #20794
IN STOCK
$14.99
Each
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Old 09-29-2020, 05:58 AM   #11
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https://www.woodcraft.com/products/s...yABEgJkqPD_BwE
I've used these with good luck on my deck screws.
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Old 09-29-2020, 09:27 AM   #12
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https://www.woodcraft.com/products/s...yABEgJkqPD_BwE
I've used these with good luck on my deck screws.
Many thanks for the link. PO snapped off wood screws in swim platform, cap rail, and decks. I had no idea that a tool existed to remove them. Another new project to add to my list.
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Old 09-29-2020, 11:38 AM   #13
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Be careful, they break easily if you push too hard.
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Old 09-30-2020, 06:00 AM   #14
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When you need to remove a brass screw locate a brass bolt that is the size of the removed plug.

Saw off the threads and shorten the remainder to 3/4 or an inch.

Drill a 1/8 hole down thru the bolt .A drill press helps drilling the hole thru the brass bolt

Tap this guide bolt lightly into the broken screw hole , and drill the screw with the 1/8 bit.

The guide bolt hole will give centering on the broken screw . A pass or two with a larger bit will remove as much as you need.

IF the broken screw is too shallow for rhe bolt to cenrer, a hole the size of the bolt in a piece of wood can create a guide that is 90 deg to the screw.
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Old 09-30-2020, 10:07 AM   #15
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When you need to remove a brass screw locate a brass bolt that is the size of the removed plug.

Saw off the threads and shorten the remainder to 3/4 or an inch.

Drill a 1/8 hole down thru the bolt .A drill press helps drilling the hole thru the brass bolt

Tap this guide bolt lightly into the broken screw hole , and drill the screw with the 1/8 bit.

The guide bolt hole will give centering on the broken screw . A pass or two with a larger bit will remove as much as you need.

IF the broken screw is too shallow for rhe bolt to cenrer, a hole the size of the bolt in a piece of wood can create a guide that is 90 deg to the screw.
Basically you are making a drill bushing.
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Old 09-30-2020, 11:28 AM   #16
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Thanks all. Trying to remove all of the broken screws seems like it would substantially increase the amount of work involved. I think I'm going to move forward with a brad point bit to yield a somewhat thicker plug, and a one-part adhesive of some sort so that I don't have to deal with epoxy hardening while I work.
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Old 09-30-2020, 11:50 AM   #17
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Thanks all. Trying to remove all of the broken screws seems like it would substantially increase the amount of work involved. I think I'm going to move forward with a brad point bit to yield a somewhat thicker plug, and a one-part adhesive of some sort so that I don't have to deal with epoxy hardening while I work.
Most use Titebond III for bungs. I do. Epoxy is uv sensitive and will breakdown over time.
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