Hardware bonding make FWW

Re: Hardware bonding make FWW

Barry Irby

Thanks for posting this. I thought I knew about it but you have expanded on what I knew. It had not occurred to me that the hole could be much larger and give better surface area for the bonding.

He uses 3/8" threaded rod in the article

I was surprised to see it, too

Bruce, a MN Galoot

It was about 15 years ago when I was looking for advice on how to make a particularly difficult and different table base. You advised me to use the hardware bonding technique. That table is still going strong!

Re: Hardware bonding *LINK*

William Duffield

I found two articles in a two decade old EpoxyWorks magazine from West Marine on the subject.

https://www.epoxyworks.com/index.php/hardware-bonding/"

https://www.epoxyworks.com/index.php/more-on-hardware-bonding/

I know that at one time, they published a very useful instruction manual on the subject with more diagrams and more examples. I used to have a copy, but can't find it now and also can't find it on the Web on Gougeon Brothers' website or elsewhere. Does anyone know where one could find it?

Re: Hardware bonding

Clint Searl

https://www.westsystem.com/instruction-2/epoxy-basics/bonding-fasteners-hardware/

Question

Bill Tindall, E.Tn.

I have not seen the article. Is what was demonstrated an alternative to a mortise and tenon joint or did this novel (to furniture) joinery enable some construction that conventional joinery would not accomplish? For the typical table, legs joined with M&T joint is as good as it gets.

(Message Deleted by Poster)

Re: Question

John in NM

That's going to fail. Unless it is forever treated as fancy gallery furniture that no one moves incorrectly or uses the way I've seen furniture used all my life. Novel idea, but not a good one.

BTDT

Mark Mandell - Gone Round In New Jersey

The leg "system on Memsahib's Nakashima-style coffee table had to be stacked. The joints for the top blocks were made using 6" sections of 1/2" tread rod epoxied into 5/8" holes.

rock solid

Re: Hardware bonding

John K Jordan

Interesting. I have often epoxied threaded fasteners into loose holes. I didn't know that had a name.

Re: Hardware bonding

Bill Howatt

I have often used epoxy because the holes were too loose

Bill

Re: BTDT

Dick Coers

Did the epoxy run out below? Looks like a run there of some sort. That's what I hate about epoxy. Tape, tape, and more tape, and some still runs out on the wood.

Nope

Mark Mandell - Gone Round In New Jersey

Just a slightly fuzzy picture. Edges of the joins were sealed with micro-c wax

Re: Question

Bill Tindall, E.Tn.

The picture clarified an application. There must be some way of locating the holes where alignment is assured. What might it be?

I am trying to think my way through what the optimum number of pins would be. It is not obvious to me what the failure point of the pin assembly is.

Re: Thanks, Clint

Re: Hardware bonding

James G. Dillon

Thanks William and Clint for the links and TomD for initiating the thread. Very interesting reading explaining a concept that I was completely unaware of (until reading the FWW article). Jim

Re: Closer to "there isn't one"

TomD

I may not have been the Gougeons who originated the system, but it could be as they had a critical lead in the wood epoxy world due to a friendship with, I think it was, a Dupont.

They tell interesting stories about bonding. One of which was that a cleat was bonded to a 60 foot trimaran, that probably weighed 10K pounds, and that something happened where it ended up suspended from that one cleat, and it held the whole weight. The studs would probably be 1/4". and potted in 3 diameter holes. So the glue in a 3/4" hole had something like K pounds load capability per inch of penetration It ends up being pretty stout.

The would bond led fin keeps to boats by just bonding them into holes in the keel, with zero failures. The would add washers and bolts to the top of the studs because it made the owners feel good, but the bonding was doing all the work.

Gougeons made a lot of early wind turbines, a lot like the high aspect ratio ones that one sees everywhere today, except they made them out of wood, for GE and NASA. There is/was one on display in a park in Bay City, and it is something like 130 feet in diameter, and the root is maybe 24 inches. The whole thing is mounted with 24 1/4" threaded studs, if memory serves. The system yields incredibly good results when you consider the massive loading at a wind turbine hub.

Of course if you don't use oversize holes in the wood, it is nowhere near as strong, but it still works , the wood is just more heavily loaded. The failure will be in the wood, normally, not the fastener, so where possible you want to pot the stud in a goodly amount of epoxy, so the load is spread over a much wider area. But then a coffee table is not terribly heavily loaded.

I have used hardware bonding in a number of projects, but one a really like is for bench parts or beds. Captured nuts have always struck me as inelegant, and fiddly. Just a personal view. I like to mount permanent 1/2" studs about or 4 inches into the end of the beam. These are permanent, and make it much easier to align with holes and neater, as all one sees of the hardware is an acorn nut. It is as if the threaded rods grew in the beam end. For precision I make a jig out of 2x that I can screw, or clamp to the project. It is a dowel jig that in this case uses 2 13 mm holes, these are just the perfect size so that I can mount the studs in the jig with a few turns of masking tape to protect the threads, and they can be suspended inside 3/4" holes where I want to mount the studs. I can also transfer marks, using the jig, for the holes I will have to drill in my stock for the studs, by inserting my 13 mm brad point into the jig holes, and tapping them into the wood for center marks for the 3/4" speed bore drill I will make the holes with. The speed bore drill handles the endgrain in maple well, but is none too accurate, but it does not mater too much as the studs in the jig are merely suspended in the speed bore holes, the epoxy does the rest. The parts will be perfectly mounted and the alignment is not an issue. I know this is a really difficult thing to see without pictures, but I am still at the cottage, riding out the pandemic.

Re: Closer to "there isn't one"

TomD

That should read something like "3K pounds load" for each inch of 3/4" hole New computer has sticky 3. I don't see the hardware breaking if it is a reasonable grade of material.

I don't normally use it unless I am building to an engineering brief, but Gougeons make an additive for their epoxy that is specially formulated for hardware bonding. This would allow the epoxy to be runny enough to penetrate endgrain, while being hard enough to resist deformation from the fastener.

Re: Gaps are your friend

TomD

"Thanks for posting this. I thought I knew about it but you have expanded on what I knew. It had not occurred to me that the hole could be much larger and give better surface area for the bonding. "

Yeah, when using the right epoxy, it will hold the threaded rod far more tenaciously than wood ever can. It is harder, can have additives to make it stronger both in compression and tension. And it will bond to the studs. Sand blasting the studs might help, though it would seem overkill for most applications.

This principle would also apply to a simple wooden dowel, in many instances when dowels pull out they are not broken, they simply shear out of the crossgrain hole. So basically what would be a good idea if you had a typical situation where the failure mode was a dowel pulling out of a 1/4" endgrain hole, but not failing in the 1/4" sidegrain situation is that it needs a bigger hole in the sidegrain, but how do you do that? Well epoxy will hold well in the larger sidegrain hole, and can be cast in place. Fasteners hold better in the epoxy, whether wood or metal. Works great.

I do traditional joinery on furniture, because that is what I do. But there are lots of things around the shop where HB is more practical, say you wanted to mount hardware to your bench, or you need to mount a motor to a wooden base, it can be more elegant or efficient to do it with HB. I made some sewing machine tables, for industrials, and Hb'd the motor mounts. I was able to use oversize tops without worry whether the motors could be hung as trad hardware is too light. I did not have the expense of souring the trad hardware. It is just a tool that solves problems in special situations.

Plus you get the advantage of the epoxy adding stability to the areas that have been saturated, so movement is less likely to occur that would cause a fastening failure, and epoxy thrives on huge tolerance differential, like 1/4" gaps in joinery.

Re: I was surprised to see it, too

TomD

Bruce, that is great to hear!

Re: Hardware bonding

TomD

It becomes a thing when it is done in an intentional way with engineering scenarios in mind. The Gougeons also ran an engineering consultancy. And they spread a method that could be used in very highly loaded scenarios, even without needing engineering advice in every case. Plus, there is a whole epoxy joinery technology, that flows seamlessly together and allows one to make all kinds of interesting tools and machinery. Furniture has been made without these processes for centuries, but these tools can be useful if you are pushing into some new territory, or want something functional like a sink, or stone pond, or machine base or frame.

more questions

Bill Tindall, E.Tn.

I am trying to think my way through what the optimum number of pins would be.

This topic is fascinating from an engineering perspective. While you answered the other questions this one wasn't. Unfortunately our picture was removed so we don't have an example to reference. The leg had 4 equally spaced pins in a leg that could have been 1.75" square.

The physics behind this construction must be that the epoxy is stronger than the wood? In a leg would one large pin be stronger? Is maximizing the surface area of epoxy to wood what needs to be optimized? Well I guess not entirely for at some point the shear strength between epoxy and steel would be the failure point.