Making Plugs to Fill Small Holes from Fasteners

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Repairs/Mods
  Making Plugs to Fill Small Holes from Fasteners

search | FAQ | profile | register | author help

Author Topic:   Making Plugs to Fill Small Holes from Fasteners

jimh posted 09-30-2013 02:00 PM ET (US)
In the transom of my Boston Whaler boat there are three holes that remain after the removal of 1.5-inch-long #10 self-tapping machine screws that passed through the laminate, into the plywood reinforcement, and perhaps beyond into the foam interior. Previously I have used small pieces of soft pine dowel to fill these holes, making tapered plus by sanding the dowel down to a suitable shape, but I have been advised that one ought to use a plug cut from plywood instead. I am willing to heed that advice, but I need help.
The smallest plug cutter I can find for sale locally at a reasonable price cuts plugs of 3/8-inch diameter, which will be larger than the fastener holes. Are plug cutters that can cut smaller plugs available at typical outlets (without having to buy some exotic cabinet-maker set of plug cutters)?
If there are not smaller plug cutters, can a 3/8-inch plug cut from plywood be easily rotated in a drill and shaped to a smaller size without coming bonded?
I am not inclined to increase the hole diameter to fit the plug; I would rather the plug fit the hole.
Would using a wood glue, e.g. Tite-Bond III, to install the wood plug be better than using epoxy? (I will be top-coating with epoxy either way, so ignore the concern for water ingress via the hole outlet.)
I also need advice on selecting the material from which to cut the plugs. Should it be plywood? Marine plywood? Or can a soft pine board suffice?
Tom W Clark posted 09-30-2013 03:34 PM ET (US)
I have hardware store plug cutters down to 1/4" which is about as small as is useful.
Tom W Clark posted 09-30-2013 06:07 PM ET (US)
I would not bother to plug a #10 screw holes. I cannot see the advantage of a wooded plug in there.
However, if you do want a wooden plug in there, enlarge the hole to 1/4" and glue in a 1/4" diameter wooden plug.
A #10 sheetmetal screw has an outside diameter of about 3/16". Usually when they are driven into the fiberglass skin of a Boston Whaler, even if care is taken to drill a pilot hole first, the gel coat around the hole will chip or crack slightly.
It is probable that to eliminate this chipping or cracking the hole would need to be enlarged to 1/4" diameter or more, so why not take the opportunity to make a perfect hole to fill by enlarging it now?
I use Forstner drill bits to cut perfect round holes. Again, this is a hardware store item.
Tom W Clark posted 09-30-2013 06:10 PM ET (US)
http://www.acehardware.com/product/index.jsp?productId=1291676
http://www.acehardware.com/product/index.jsp?productId=1293714
Binkster posted 09-30-2013 06:56 PM ET (US)
You can buy a set of tapered plug cutters 1/4"-5/8" at Harbor Freight Tools for about $6.00. Less with a 20 percent coupon. While you are there pick up a cheap bench drill press for about $50 with another coupon. Don't attemp to drill plugs with a hand drill. The plug can hang up in the wood piece and either spin the wood piece or the drill, which could give you a nasty whack. Forstner bits are also made to be used in a drill press. Unless you are skilled in using one in a hand drill you can screw up the hole, but you probably won't get hurt. Use a spade bit instead for a perfectly round clean hole.
rich
andygere posted 10-01-2013 12:25 AM ET (US)
For occasional use, the $50 Harbor Freight drill press is hard to beat, and for jobs like this a lot safer than a hand drill. As for using Forster bits in a hand drill, I've been doing it for years with great results. I haven't used a spade bit in years.
Regarding this repair, I think a 1/4 in. dia. plug cut out of plywood will probably crumble when you tap it in, if it hasn't already when you cut the plug. Then there's the problem of getting a 1.5" thick scrap of low void plywood to cut the plugs from. Thickened epoxy injected with a large syringe will provide a repair that will be nearly as good if not better.
andygere posted 10-01-2013 12:29 AM ET (US)
I would use epoxy, not Tightbond III if you decide to repair using a plug or dowel. Epoxy will fill gaps with a structural adhesive, and it will bond well to all the materials in your transom. Wood glue is really only good for gluing wood to wood,
A plug of soft wood should work fine,
frontier posted 10-01-2013 12:39 AM ET (US)
Jim - I've got quite a few 1/4" mahogany tapered plugs left over from a job years ago.
Be glad to mail you some.
L H G posted 10-01-2013 12:44 AM ET (US)
I drill out all screw holes 3/8", about 1" deep, and then grind a 45 degree bevel (countersink) to make a tapered surface to receive the resin filler. Then glue 3/8" teak pegs in the wood backing/transom plywood, punched in so the full thickness of the glass skin is revealed. The pegs can be cut or bought already cut.
Then I fill the glass thickness cavity with Evercoat Formula 27 polyester resin filler, skimmed flush with a putty knife. After it sets, I grind out a recess for matching gelcoat.
In my estimation, this restores the area as close as possible to it's original integrity. Larger 1/2" diameter engine bolt holes are done the same way.
jimh posted 10-01-2013 08:52 AM ET (US)
Frontier--To have a few pre-cut 1/4-inch plugs would be great. I will get in contact with you. Thanks.
weekendwarrior posted 10-01-2013 12:16 PM ET (US)
Fill them with marine tex. This worked great for me, very hard durable materal.
Binkster posted 10-01-2013 02:03 PM ET (US)
week-warr.
I think your method may be too simple, (some folks like a project), although in my mind its the easiest and best way. My method is almost as simple. Last winter I filled about a dozen holes in the transom of my 15 footer from the 1'2" motor mount holes to small ones like jimh describes. I didn't use MarineTex I used Sprectram Gel Coat Paste repair kit, on the small holes and marine grade bondo,(available from Automotive body shop and paint stores) Its used in the repair of glass cars such as Corvettes and will stand up to vibration, on the large holes. The motor bolt holes went trough the transom so I had to fill from both sides. I sanded the bondo and the sprectrum flush. As I had no intention of painting or regelcoating the transom, I had to be carful not to go through too much gel coat when sanding. Then I took a nice sharp spade drill bit,(not a forstner bit) just big enough to cover the patch and drilled it just deep enough to the depth of the gelcoat over the patched holes and then troweled the Spectrum over those areas. Then just sanded the spectrum flush with 220 grit, 500 grit, 1000, 2000 and 3000 grit. Then I polished the entire transom and the repaired holes disappeared, except for the slight color differece between the Desert Sand gelcoat hull and the Desert Sand spectrum. Its not really noticable except by myself. I'm very fussy.
rich
picflight posted 01-12-2014 02:53 AM ET (US)
After months of searching and posting some questions on similar repairs, I ended up filling the holes in my transom with West Systems epoxy. Then I read some more and I wanted to do the repair in a way that was harmonious to the Whaler.
I drilled out the epoxy, cleaned as much as possible and decided to go the dowel route. The holes I am dealing with are 9/16" deep and about 3/16" in diameter.
I used 1/4" oak dowel on a hand drill, sand paper in hand and smoothed done to size. The dowel easily slides in and out of the hole. I am planning to dip in polyester resin and place in hole with the laminate layer visible. Next, Chopped fiber in resin and then polyester gelcoat and then wax sprayed. Too much for such small holes, but it will be almost like the original ;-)
This post, with the discussion on plugs versus dowel has made me rethink my repair plan, does it matter if dowels are used for small holes? I do not plan to reuse these holes. Picture below is where my project stands as of today.
http://www.flickr.com/photos/picflight/11901604755/
This is what came out of the hole when I removed the original mounted screws.
http://www.flickr.com/photos/picflight/11901814615/
picflight posted 01-12-2014 08:48 PM ET (US)
I made plugs today!
Got a 1/4" plug cutter (~$8) and hardwood (~$3.50), used a drill, sand paper and chisel, tools I had in my box to trim the plugs to size. It took about 2-3 hours to do the seven plugs trimmed to size for each hole. I was in no hurry and the Whaler was right there watching :-) and I had an adult beverage to keep me company.
Next step is to mix the polyester resin, cut the plugs to size and install them in the 7 holes. Waiting for a warmer day, I think next weekend it will in the mid seventies.
http://www.flickr.com/photos/picflight/sets/72157639677655435/
picflight posted 01-12-2014 08:54 PM ET (US)
My earlier posts are following the methods [jimh said he had used pervoiusly] in his original post, hence my posts to try the methods [using plugs instead of dowels] jimh had intended to do.
Binkster posted 01-12-2014 11:32 PM ET (US)
It took about 2-3 hours to do the seven plugs. I had an adult beverage to keep me company.
Binkster posted 01-14-2014 02:03 PM ET (US)
The reason you would fill holes with wood cut from a drill press and a plug cutter is that this is brightwork that is varnished. So you find a piece of mahogany or teak that matches the surrounding wood, drill out the hole 1/4", 3/8", 3/4", whatever, cut your plugs, glue them in so that a small piece protruds from the hole, cut off the excess with a chisel, sand flush and varnish. Make sure the grain of the plug matches the surrounding wood. If you are going to gelcoat or paint over the repair, don't bother with plugs, use a dowel. Cut it about 3/8" or more short, glue it in with wood glue, epoxy, etc, Then use filler to fill the hole. If the hole is large fill it flush, sand it swmooth, and redrill it with a spade bit just larger then the repair, the depth of the gelcoat, Then fill with gelcoat. If its a small hole use filler just short of the surface, and then fill flush with gelcoat.
This is a very easy project.
rich

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: Making Plugs to Fill Small Holes from Fasteners
jimh	posted 09-30-2013 02:00 PM ET (US) In the transom of my Boston Whaler boat there are three holes that remain after the removal of 1.5-inch-long #10 self-tapping machine screws that passed through the laminate, into the plywood reinforcement, and perhaps beyond into the foam interior. Previously I have used small pieces of soft pine dowel to fill these holes, making tapered plus by sanding the dowel down to a suitable shape, but I have been advised that one ought to use a plug cut from plywood instead. I am willing to heed that advice, but I need help. The smallest plug cutter I can find for sale locally at a reasonable price cuts plugs of 3/8-inch diameter, which will be larger than the fastener holes. Are plug cutters that can cut smaller plugs available at typical outlets (without having to buy some exotic cabinet-maker set of plug cutters)? If there are not smaller plug cutters, can a 3/8-inch plug cut from plywood be easily rotated in a drill and shaped to a smaller size without coming bonded? I am not inclined to increase the hole diameter to fit the plug; I would rather the plug fit the hole. Would using a wood glue, e.g. Tite-Bond III, to install the wood plug be better than using epoxy? (I will be top-coating with epoxy either way, so ignore the concern for water ingress via the hole outlet.) I also need advice on selecting the material from which to cut the plugs. Should it be plywood? Marine plywood? Or can a soft pine board suffice?
Tom W Clark	posted 09-30-2013 03:34 PM ET (US) I have hardware store plug cutters down to 1/4" which is about as small as is useful.
Tom W Clark	posted 09-30-2013 06:07 PM ET (US) I would not bother to plug a #10 screw holes. I cannot see the advantage of a wooded plug in there. However, if you do want a wooden plug in there, enlarge the hole to 1/4" and glue in a 1/4" diameter wooden plug. A #10 sheetmetal screw has an outside diameter of about 3/16". Usually when they are driven into the fiberglass skin of a Boston Whaler, even if care is taken to drill a pilot hole first, the gel coat around the hole will chip or crack slightly. It is probable that to eliminate this chipping or cracking the hole would need to be enlarged to 1/4" diameter or more, so why not take the opportunity to make a perfect hole to fill by enlarging it now? I use Forstner drill bits to cut perfect round holes. Again, this is a hardware store item.
Tom W Clark	posted 09-30-2013 06:10 PM ET (US) http://www.acehardware.com/product/index.jsp?productId=1291676 http://www.acehardware.com/product/index.jsp?productId=1293714
Binkster	posted 09-30-2013 06:56 PM ET (US) You can buy a set of tapered plug cutters 1/4"-5/8" at Harbor Freight Tools for about $6.00. Less with a 20 percent coupon. While you are there pick up a cheap bench drill press for about $50 with another coupon. Don't attemp to drill plugs with a hand drill. The plug can hang up in the wood piece and either spin the wood piece or the drill, which could give you a nasty whack. Forstner bits are also made to be used in a drill press. Unless you are skilled in using one in a hand drill you can screw up the hole, but you probably won't get hurt. Use a spade bit instead for a perfectly round clean hole. rich
andygere	posted 10-01-2013 12:25 AM ET (US) For occasional use, the $50 Harbor Freight drill press is hard to beat, and for jobs like this a lot safer than a hand drill. As for using Forster bits in a hand drill, I've been doing it for years with great results. I haven't used a spade bit in years. Regarding this repair, I think a 1/4 in. dia. plug cut out of plywood will probably crumble when you tap it in, if it hasn't already when you cut the plug. Then there's the problem of getting a 1.5" thick scrap of low void plywood to cut the plugs from. Thickened epoxy injected with a large syringe will provide a repair that will be nearly as good if not better.
andygere	posted 10-01-2013 12:29 AM ET (US) I would use epoxy, not Tightbond III if you decide to repair using a plug or dowel. Epoxy will fill gaps with a structural adhesive, and it will bond well to all the materials in your transom. Wood glue is really only good for gluing wood to wood, A plug of soft wood should work fine,
frontier	posted 10-01-2013 12:39 AM ET (US) Jim - I've got quite a few 1/4" mahogany tapered plugs left over from a job years ago. Be glad to mail you some.
L H G	posted 10-01-2013 12:44 AM ET (US) I drill out all screw holes 3/8", about 1" deep, and then grind a 45 degree bevel (countersink) to make a tapered surface to receive the resin filler. Then glue 3/8" teak pegs in the wood backing/transom plywood, punched in so the full thickness of the glass skin is revealed. The pegs can be cut or bought already cut. Then I fill the glass thickness cavity with Evercoat Formula 27 polyester resin filler, skimmed flush with a putty knife. After it sets, I grind out a recess for matching gelcoat. In my estimation, this restores the area as close as possible to it's original integrity. Larger 1/2" diameter engine bolt holes are done the same way.
jimh	posted 10-01-2013 08:52 AM ET (US) Frontier--To have a few pre-cut 1/4-inch plugs would be great. I will get in contact with you. Thanks.
weekendwarrior	posted 10-01-2013 12:16 PM ET (US) Fill them with marine tex. This worked great for me, very hard durable materal.
Binkster	posted 10-01-2013 02:03 PM ET (US) week-warr. I think your method may be too simple, (some folks like a project), although in my mind its the easiest and best way. My method is almost as simple. Last winter I filled about a dozen holes in the transom of my 15 footer from the 1'2" motor mount holes to small ones like jimh describes. I didn't use MarineTex I used Sprectram Gel Coat Paste repair kit, on the small holes and marine grade bondo,(available from Automotive body shop and paint stores) Its used in the repair of glass cars such as Corvettes and will stand up to vibration, on the large holes. The motor bolt holes went trough the transom so I had to fill from both sides. I sanded the bondo and the sprectrum flush. As I had no intention of painting or regelcoating the transom, I had to be carful not to go through too much gel coat when sanding. Then I took a nice sharp spade drill bit,(not a forstner bit) just big enough to cover the patch and drilled it just deep enough to the depth of the gelcoat over the patched holes and then troweled the Spectrum over those areas. Then just sanded the spectrum flush with 220 grit, 500 grit, 1000, 2000 and 3000 grit. Then I polished the entire transom and the repaired holes disappeared, except for the slight color differece between the Desert Sand gelcoat hull and the Desert Sand spectrum. Its not really noticable except by myself. I'm very fussy. rich
picflight	posted 01-12-2014 02:53 AM ET (US) After months of searching and posting some questions on similar repairs, I ended up filling the holes in my transom with West Systems epoxy. Then I read some more and I wanted to do the repair in a way that was harmonious to the Whaler. I drilled out the epoxy, cleaned as much as possible and decided to go the dowel route. The holes I am dealing with are 9/16" deep and about 3/16" in diameter. I used 1/4" oak dowel on a hand drill, sand paper in hand and smoothed done to size. The dowel easily slides in and out of the hole. I am planning to dip in polyester resin and place in hole with the laminate layer visible. Next, Chopped fiber in resin and then polyester gelcoat and then wax sprayed. Too much for such small holes, but it will be almost like the original ;-) This post, with the discussion on plugs versus dowel has made me rethink my repair plan, does it matter if dowels are used for small holes? I do not plan to reuse these holes. Picture below is where my project stands as of today. http://www.flickr.com/photos/picflight/11901604755/ This is what came out of the hole when I removed the original mounted screws. http://www.flickr.com/photos/picflight/11901814615/
picflight	posted 01-12-2014 08:48 PM ET (US) I made plugs today! Got a 1/4" plug cutter (~$8) and hardwood (~$3.50), used a drill, sand paper and chisel, tools I had in my box to trim the plugs to size. It took about 2-3 hours to do the seven plugs trimmed to size for each hole. I was in no hurry and the Whaler was right there watching :-) and I had an adult beverage to keep me company. Next step is to mix the polyester resin, cut the plugs to size and install them in the 7 holes. Waiting for a warmer day, I think next weekend it will in the mid seventies. http://www.flickr.com/photos/picflight/sets/72157639677655435/
picflight	posted 01-12-2014 08:54 PM ET (US) My earlier posts are following the methods [jimh said he had used pervoiusly] in his original post, hence my posts to try the methods [using plugs instead of dowels] jimh had intended to do.
Binkster	posted 01-12-2014 11:32 PM ET (US) It took about 2-3 hours to do the seven plugs. I had an adult beverage to keep me company.
Binkster	posted 01-14-2014 02:03 PM ET (US) The reason you would fill holes with wood cut from a drill press and a plug cutter is that this is brightwork that is varnished. So you find a piece of mahogany or teak that matches the surrounding wood, drill out the hole 1/4", 3/8", 3/4", whatever, cut your plugs, glue them in so that a small piece protruds from the hole, cut off the excess with a chisel, sand flush and varnish. Make sure the grain of the plug matches the surrounding wood. If you are going to gelcoat or paint over the repair, don't bother with plugs, use a dowel. Cut it about 3/8" or more short, glue it in with wood glue, epoxy, etc, Then use filler to fill the hole. If the hole is large fill it flush, sand it swmooth, and redrill it with a spade bit just larger then the repair, the depth of the gelcoat, Then fill with gelcoat. If its a small hole use filler just short of the surface, and then fill flush with gelcoat. This is a very easy project. rich