# Strength of 1 1/2 inch Red Oak Dowel Rod



## Sanding2day

My first project was that of my "shop bar" and it has long bothered me that I did not have a foot rest. It was my intent to purchase the typical brass bar but have not had the finances which I desired to devote to this and have made due to this point with a stack of my excess 2 by 4s under an old shower curtain rod…

I have recently finished a section of fencing and have an excess of 4 by 4s and a 3' section of Red Oak Dowel and thought I would improve upon this *Wont take much*

My intent is to stain one up with the same Mahogany ish color as the bar, stain the dowel with Golden Oak, drill 2 inches into the base 4 by 4 and through the soon to be foot rest glued and wedged with Walnut in 3 places on the front and 2 place on one side.

Although I am confident this would provide adequate strength for a simple foot rest it is my desire to ensure that a 500 lb man could jump up and down on it and not be likely break the dowels.

I have searched for a testing of dowel strength when used in similar applications and have not found any results and am curious if anyone knows of a test location or simply has experience with use and can assure me that this method will provide more then adequate strength or although fairly committed let me know if this is a poor plan. Will post a picture once completed likely next weekend. Thanks,


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## PaulHWood

What is the dowel diameter and what is the span, wood is very weak in horizontal shear.

see the diameter in the title now, what is span between supports?


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## BroncoBrian

I used a lesser wood on a ladder for our playground. 36" wide with ropes tied at each end. The ladder has been through 2 winters in CO and they are fine. I know a square would be a little stronger than a rounded rod. I just used hard maple for a mobile base to hold a 400 +lb jointer and that also worked (1.5" x 1.5" x 24").

I am thinking you will be fine. Make don't glue it. Just use a pocket screw from below. Then you can swap it out when you need to or if I was way off!


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## PaulHWood

While Oak is harder, it is not stronger in beam use then say southern yellow pine.

Square is almost twice as strong and stiff as round.

I think it will be fine for your use as long as it is supported every few feet and you have your 500 pound friends refrain from jumping on it.


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## Sanding2day

Thank you for the feedback…. Will have 0 span Paul, intent is simply to have additional 3 1/2 to rest feet. Total expanse at base of bar is 79 in and made first cut at 82 1/2 for 45 deg around corner.

Bronco I had not intended to glue to bar and was considering pocket hole screws from underneath, believe that is a good plan to ensure a tight fit…

Paul… Surprised that twice as strong is accurate and really southern pine stronger then oak? Either way materials are here and what Im using, not sure but imagine the 4 by 4 is pine of some type. No 500 lb friends and no jumping but do want it capable of taking it!


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## Sanding2day

Cuts done, time for drinking, sanding, and staining…. Will Attempt drilling calculations and mounting this weekend, been up since 0600 yesterday and back to work tonight through tomorrow so nearing sleepy time!


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## Sanding2day

Did post that on 2nd viewing I caught your strength vs hard distinction Paul… Just didn't go through on my phone… Good point, thanks….


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## Sanding2day

Apparently posed incorrectly regardless. Just measured to ensure appropriate drill bit was ready and it is a 1 1/4 dowel…


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## PaulHWood

Ok, thought 4×4 would be used as bracket like typical foot rest and the dowel would span between.

Generally there is no load on a footrest unless there are kids hanging on it.

Moment of Inertia (stiffness measure) for round bar is 3.14xD^4/64 or .049 D to the fourth
Square stock is d^4/12 or .083 D to the fourth so roughly 70% stiffer


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## firefighterontheside

I'm not sure I understand Dan. How will it have zero span? I'm thinking you can not go more than 16" without support or that 500lb friend of yours will be making firewood.


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## bigblockyeti

Pine is not as strong as oak. Statics, Strength of Materials, Machine Design, and the list goes on, all of these classes will confirm that.


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## Sanding2day

Heading for a few hour nap but allow me to to attempt to clarify intent. The 4 by 4 will be the foot rest and the dowels set about 20 inch (not determined) apart but 3 over 79 inch will b err the joinery along with two/three pocket hole screws from underneath.

The 4 by 4 will run parallel the bottom rung and the dowels will be sraight through and wedged/2 inch into rung.

Thinking in addition ro 3 on long and 2 on short sides and pocket holes I will use 2 1/4 inch dowels to hold sides together…

Sure if that didn't clear it up the pic this weeken. *I hope* will…


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## firefighterontheside

So the dowel will be in short pieces. Then I would say they will be strong enough and the joinery will likely be the weakest point.


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## PaulHWood

Latest edition of the National Design Specification for Wood, table 4A and 4B

Red Oak no 2 Fb=800psi, White Oak no 2 Fb= 850psi

SYP no 2 Fb=1100psi which is actually down from a few years ago it was 1500psi

harder and stronger are two different things.

I have had all of the below classes



> Pine is not as strong as oak. Statics, Strength of Materials, Machine Design, and the list goes on, all of these classes will confirm that.
> 
> - bigblockyeti


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## OSU55

In tension perpendicular to the grain, white oak = 800, red oak = 800, longleaf and loblolly pine = 470; In compression perpendicular to the grain, white oak = 1070, red oak = 1010, longleaf and loblolly pine = 960. It very much depends on the specific loading of the strucural member in question.


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## TheGreatJon

> Pine is not as strong as oak. Statics, Strength of Materials, Machine Design, and the list goes on, all of these classes will confirm that.
> 
> - bigblockyeti


For most materials strength will typically decrease with hardness. Also, did you really talk about materials properties of wood in your engineering classes? I think we may have talked about it for a few minutes in Materials, but I'm pretty sure all the professor said was (imagine a giant of an old man with a walrus mustache and a southern accent) "properties of wood in general will vary widely depending on grain structure."


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## bigblockyeti

We studied several wood species in great depth (and in all of the classes mentioned). Before I switched to manufacturing engineering I was studying in an architectural engineering program derived from civil engineering, but concentrating less on bridge building and more on what can be accomplished with modern home design. A free body diagram would have cleared things up about how the dowel was to be loaded. We also discussed grain structure relative to strength and the variability of results that can be obtained from different sources which can vary significantly.


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## PaulHWood

> In tension perpendicular to the grain, white oak = 800, red oak = 800, longleaf and loblolly pine = 470; In compression perpendicular to the grain, white oak = 1070, red oak = 1010, longleaf and loblolly pine = 960. It very much depends on the specific loading of the strucural member in question.
> 
> - OSU55


Who is using longleaf and loblolly pine? I specifically said SYP. Also, bending and horizontal shear are typical controlling loadings for beam members. Oak also has a lower modulus of elasticity.


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## Sanding2day

Well, as hoped I finished up the foot rest this past weekend… Appreciate your feedback on the strength of the dowel however after realizing that I did not have a 1 1/4" drill bit minus for the brace I changed my plans and went with 1/2" by 6" lags. Not overly classy but am confident they will hold the weight and sticks with the original joinery for the rest of the bar.

Was pretty set on seeing the dowel joinery look so I made caps for lags adding fake wedges *the only actual Mahogany in the Oak/Mahogany bar * Did not have the squared off look that I had in mind but as stated in original posting this is a great improvement from the old shower curtain rod that I was using… Should have been part of the original plan!!


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