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Stronger finger joints?

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Forum topic by PWF3 posted 06-07-2020 12:01 PM 462 views 0 times favorited 7 replies Add to Favorites Watch
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PWF3

3 posts in 75 days


06-07-2020 12:01 PM

Topic tags/keywords: finger joints joinery dowel dovetails

A traditional finger joint is strong because of all the glue surface it creates—but here’s a thought. Would it make the joint stronger to drill a hole and run a wooden dowel down through the fingers? or for that matter, what about using a brass rod or a screw? Thought someone out there may have run across this before. Thanks for your thoughts on this.


7 replies so far

View John Smith's profile

John Smith

2501 posts in 962 days


#1 posted 06-07-2020 12:18 PM

wow – talk about overkill.
this depends on what the box is used for:
how big is it ?
what kind of forces will be applied from the inside out and
from the outside in ??
if I needed a box that strong, I would weld some 1/8” steel plate
for the box and veneer it with 1/16” wood.

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

View Madmark2's profile

Madmark2

1451 posts in 1388 days


#2 posted 06-07-2020 12:50 PM

I’ve never seen a finger joint fail without complete destruction of the joint. Its already stronger than the boards, how much stronger does it need to be?

Thinking about it, a pin might actually weaken the joint by breaking the wood fibers near the ends. Thus making the pin more likely to bust the ends – maybe. I’d have to see some experimental data to be sure.

Like yellow glue is stronger than wood, you don’t need anything “stronger”.

Now for pure aesthetics, drilling in for a short brass pin would look nice and nothing wrong with that.

-- The hump with the stump and the pump!

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John Smith

2501 posts in 962 days


#3 posted 06-07-2020 01:04 PM


Now for pure aesthetics, drilling in for a short brass pin would look nice and nothing wrong
with that.

- Madmark2

that was my thought, Mark – just for aesthetics. a 1/4” piece in the end just to give the illusion
of a through brass rod may look neat – depending on the project.
(I mean, who would know differently ?? outside of the fabricator).

.

-- there is no educational alternative to having a front row seat in the School of Hard Knocks. --

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splintergroup

3850 posts in 2022 days


#4 posted 06-07-2020 01:53 PM

I’ve used copper rods (actually rivets) in many of my finger joint boxes and clock frames. These are “coarse” in that they only have a very few number of fingers.

The finger joint is stronger than the material as Mark states, so my idea with the copper is I gain the nice detail plus it allows me to go very lean on glue application and not worry about the joint. In a few cases I applied no glue to there the joint since other elements of the construction and the rivets easily take care of the loaf.
Cleaning glue squeeze out from a box joint is not something I enjoy doing 8^)

View Woodknack's profile

Woodknack

13431 posts in 3180 days


#5 posted 06-07-2020 04:25 PM

Box joints have been around for a long time, are strong and successful, take the win.

-- Rick M, http://thewoodknack.blogspot.com/

View AndyJ1s's profile

AndyJ1s

349 posts in 555 days


#6 posted 06-07-2020 07:08 PM

As long as the glue holds, a dowel would likely only weaken it.

In conditions where the glue may fail (e.g. heat and/or moisture), a dowel might be the only thing to save it.

I am generally not in favor of aesthetic touches that mislead the viewer about the joinery, especially if they indicate the joint is more involved than it actually is. When repairing things, these are what makes one want to pull what little hair they have left out of their scalp.

-- Andy - Arlington TX

View Jimothy's profile

Jimothy

56 posts in 1740 days


#7 posted 07-09-2020 06:27 AM

Yeah honestly I think putting a dowel through all the fingers wouldn’t really make it any stronger.

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