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23-11-2018, 16:03
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#31
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Registered User
Join Date: Jul 2007
Posts: 17
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Re: Bolt Threads in Epoxy
Now for something different. Yes, wet the hole with neet epoxy and fill with a mix of epoxy and West System high strength filler. Then or before go to Home Depot and get some Paulin Sert a Thread kits. https://www.homedepot.ca/en/home/p.p...000162982.html. They go up to 1/4 inch.
These are a sort of like a wall anchor. I first used them for a thin glass liner that had shed some screwed in curtain snaps. This was the only fix. Since then I've used them to make threaded holes in my cabin top to attach dodger parts. Be careful to follow instructions exactly - the hole you drill must be the exact size, not any approximation especially in thicker glass (varies with thickness). You have to find the correct size drill and some are not all that standard but, nevertheless are available.The thread fitting does stand a bit proud of the hole but that is usually in the area of bedding compound thickness. I don't see using furniture fittings, rubber nuts or several other solutions offered. I haven't tried tapping a hole in Fiberglass or casting in threads with a waxed bolt. I do feel cutting threads in glass leads to fracturing that may compromise strength - the method above works but might not be the only way.
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24-11-2018, 05:58
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#32
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Registered User
Join Date: Aug 2018
Location: Back in Alberta, Canada
Posts: 44
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Re: Bolt Threads in Epoxy
There are some great suggestions for various types of hardware and techniques here, but I have to ask...
Is there a reason you couldn't simply fill the holes, drill a new hole and use a bolt/nut/washer? Is the back side not accessible?
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24-11-2018, 06:20
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#33
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Registered User
Join Date: Feb 2011
Location: South-East Australia coast
Boat: 40ft fibreglass sloop
Posts: 201
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Re: Bolt Threads in Epoxy
Quote:
Originally Posted by LaughingWarrior
There are some great suggestions for various types of hardware and techniques here, but I have to ask...
Is there a reason you couldn't simply fill the holes, drill a new hole and use a bolt/nut/washer? Is the back side not accessible?
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Correct, not accessible.
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24-11-2018, 06:25
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#34
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Registered User
Join Date: Feb 2011
Location: South-East Australia coast
Boat: 40ft fibreglass sloop
Posts: 201
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Re: Bolt Threads in Epoxy
Quote:
Originally Posted by MurrayC
Now for something different. Yes, wet the hole with neet epoxy and fill with a mix of epoxy and West System high strength filler. Then or before go to Home Depot and get some Paulin Sert a Thread kits. https://www.homedepot.ca/en/home/p.p...000162982.html. They go up to 1/4 inch.
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Quite keen to see what these look like, but for whatever reason cannot access the homedepot.ca site you link to (tried two browsers; may be a geo-restriction). Can't find them on hpaulin.com web site either, so any chance you could provide a photo or an alternative link to these special inserts ?
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24-11-2018, 06:44
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#35
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Registered User
Join Date: May 2011
Location: Miami Florida
Boat: Ellis Flybridge 28
Posts: 4,057
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Re: Bolt Threads in Epoxy
The inserts recommenced by Murray are excellent. They are also sold under the name Nutsert. I think the 1/4” ones will fit in a 1/2” hole, no filling required. They are commonly available in steel but they are also available in plated brass which is what you want for marine use. They can be hard to find. My old store may still have them.
Another option would be to use Togglers. Again these fit in 1/2” holes, no filling required. You want the ones sold by Garelick for installing pedestal chairs as they are stainless.
Toggler Snaptoggle | Install Toggle Bolts, Toggle bolt installation, Anchor bolt installation
You’ve had three suggestions for blind fasteners that shouldn’t require any filling.
Wellnut, Nutsert, Togglers, anyone of which should work.
I’ve used all three and they work.
__________________
Retired from Hopkins-Carter Marine Supplies
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24-11-2018, 08:06
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#36
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cruiser
Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,317
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Re: Bolt Threads in Epoxy
And PlusNut in my #12, similar origins and design, but which when compressed yields a much wider "cross" for maximum side-holding power and spin resistance.
Designed for holding in thin sheet material, so that needs to be taken into account if proposing bedding in epoxy inside a thicker material
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24-11-2018, 17:20
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#37
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Registered User
Join Date: Feb 2011
Location: South-East Australia coast
Boat: 40ft fibreglass sloop
Posts: 201
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Re: Bolt Threads in Epoxy
Thanks HOPCAR and JOHN61 for clarifying. So those Sert-a-Thread nuts are known as "rivnuts" in my area.
And if using rivnuts specifically with no epoxy, you probably want to match the grip range (ie. rivnut length) with your substrate thickness.
Looking at some rivnut installation videos, I think the Plusnut (and Wellnut) would grip much better on a thin fibreglass wall, whereas the Rivnut would grip well on a harder material like steel.
I've ordered some Wellnuts (for my kayak) and Rivnuts for my toolkit for future use. Could not find Plusnuts in stainless. But for my current application have gone to try out epoxy and glass cloth threads as suggested by Thinwater/Practical Sailor. And, just a reminder that my current application is not structural, so if it fails, I drill it out and try one of the other excellent suggestions in this thread.
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24-11-2018, 17:33
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#38
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cruiser
Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,317
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Re: Bolt Threads in Epoxy
PlusNuts are indeed the way to go for mounting as designed in plastic sheeting. As well IMO for the "drop compressed in a hole full of epoxy" jury rig approach.
Contact the manufacturer and ask for contact info for your local distributor
http://www.bollhoff-usa.com/static/p...version-EN.pdf
My last order placed by phone, arrived within 2 days, got a great value tool at the same time.
SS10p175 was the part #
SS stands for stainless, as opposed to one S for raw steel.
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31-01-2019, 10:04
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#39
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Registered User
Join Date: Apr 2015
Location: Alberta
Boat: Gozzard 36
Posts: 115
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Re: Bolt Threads in Epoxy
RIGHT!! ONLY NOW do I find out about waxing the bolt thread --- too smart, too late -- I put a nut (on a intended throw-away Bolt) in the pre-drilled hole then filled the hole with the intention being that later after the epoxy hardened I could just unscrew the bolt and attach the fitting with the proper length bolt --- of course now I can't undo the bolt!!! (Duhh) Any suggestions on how to get the bolt out other than brute force, drilling and chiselling out the epoxy (Most of my repair problems seem to be self-imposed!!!) :-(
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31-01-2019, 10:10
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#40
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Registered User
Join Date: Mar 2015
Location: Boston's North Shore
Boat: Pearson 10M
Posts: 839
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Re: Bolt Threads in Epoxy
Quote:
Originally Posted by foothillsailor
RIGHT!! ONLY NOW do I find out about waxing the bolt thread --- too smart, too late -- I put a nut (on a intended throw-away Bolt) in the pre-drilled hole then filled the hole with the intention being that later after the epoxy hardened I could just unscrew the bolt and attach the fitting with the proper length bolt --- of course now I can't undo the bolt!!! (Duhh) Any suggestions on how to get the bolt out other than brute force, drilling and chiselling out the epoxy (Most of my repair problems seem to be self-imposed!!!) :-(
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you might be able to use heat to soften the epoxy. The hard part will be heating the bolt without heating the surrounding epoxy too much.
You could try heating an old fashion soldering iron and holding it against the bolt head.
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31-01-2019, 10:13
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#41
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Registered User
Join Date: Jun 2016
Boat: Wauquiez Pretorien 35
Posts: 439
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Re: Bolt Threads in Epoxy
Try heating the bolt slightly with a soldering gun. Just enough to loosen the epoxy bond. My 2 cents
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01-02-2019, 07:26
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#42
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Registered User
Join Date: Apr 2017
Location: Hingham
Boat: Dickerson 37AC
Posts: 665
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Re: Bolt Threads in Epoxy
Use a wet rag against the fiberglass, and cover that with a skirt of aluminum foil. Torch to bolt, should soften right up.
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