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oak-dowel-shear-strength-zipper I did this in the boat yard right at the boat. State of the Stack Q1 Blog Post. Failure Modes of Oak dowel shear strength zipper Dowels Figure 5 shows the individual failure modes representing a given group of test specimens. For these reasons, it was not at all suitable to use plain dowels when bonding, and why grooved dowels e. The first step consists of the preparation of the surface so that the interaction between the adherend and the adhesive can be ensured.

The tighter the tolerance on the dowels the harder it makes any interchangeability of the pump parts. The interchange of the pump housing components requires that the dowels be enlarged and the shaft bores be bused and reground. We have a number of smaller gear pumps that have 2 dowels and they are designed to carry a shear load imposed by very high pressure differential across the gears.

As these dowels are not being used for location the tolerances of the dowel pins are looser. We have almost complete interchange of parts on these pumps. It really depends on what you need the pins to do. The best way is to determine what you need strength wise and work backwards.

Keep with 2 pins if possible. Watch pins near the edge. Watch the pin interference also if near a an edge or hole. RE: shear capacity of dowels Greg, Good question. I was trying to speak from the most general perspective.

I define a dowel pin as an interference fit cylinder that is used to transfer shear forces. Most bolted joints do not contain these, but those that do use the dowel to resist shear forces and screws if any to resist tension forces. Bolted joints usually have three varieties: tension, shear-bearing, and shear-friction. Most joints are shear-friction - screws are used with oversized holes and shear force resistance is provided by the friction force developed by the fastener preload.

Shear-bearing has the fastener in a close fit hole so that the fastener takes shear forces by the hole edge bearing against the screw shank. Perhaps others refer to locating pins as dowels.

These pins are loose fit and provide no force resistance. Then, the joint is one of the three above, usually shear-friction. RE: shear capacity of dowels If you have to calculate shear strength of a dowel pin multiply its cross sectional area by shear stress of material. Typical values for shear stress are: 10, psi for Al. I have designed the joint in the way CoryPad describes however I don't have the strength properties for the material.

If you need more accuracy, you can perform simple testing to obtain the shear strength of the pin. RE: shear capacity of dowels Be sure the material the dowel is pressed into and reacts against across the joint is strong enough to carry those shear forces. We use a lot of gray iron and nodular iron castings. Our dowels are for location only centerlines for shafts and bearings.

To carry shear load into the mating material, sometimes the dowel needs to be larger than what its strength capabilities are to make sure the mating material isn't crushed. I can't immediately see a way to use a dowel effectively in a double shear application. The standard rule is one inch diameter for every ' of waterline. The trennel and the hole need to be a tight fit. The trennel hold by fit and friction, not glue. I use a bit of epoxy on the trennel banging it in because epoxy while wet is a terrific lubricant and that makes driving it home easier.

Also, the epoxy seals the end grain exposed by the hole through the planking and frame. For that reason, I make my trennels with a little 'blood groove' to let both air and epoxy being compressed by hammering the trennel home escape. I would not use the furniture dowls illustrated at 2 because they are likely the wrong wood, the fit is problematic, and their design is glue dependent.

Also they are expensive. If you can't find how to very easily and quickly make trennels of whatever size you want with hand tools you no doubt have right at hand on one of the several existing threads, let me know and I'll go over it again. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Thanks.

Cumaru is really strong and basically does not rot so it is like Locust. These are functioning more like indexing pins side to side locators, not doing any holding in power. There is a lot of wood all around this that holds it in, the keel to rear upright stem boards together. This is some wood left over from my worm shoe replacement. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Guy I know used cumaru to make a cockpit sole grating for his sailboat.

IIRC it was hard, and splintered a lot. He found it a bugger to work with, but it looked nice when finished. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak You are joining a 4x8 to a 4x6 at a 90 degree angle?

I think that is what knees are for. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak I recall Egg Harbor had used plywood as an angled brace on each side and had used two 2x8 nailed together for the upright board.

Most of their transom work when I got the boat was rotten. So I redid it my own way, and it has mostly been fine, except for this area with those SS bolts. They also used plywood under thin Mahogany planks for the transom. The things they did which I discovered when I rebuilt my boat, awful stuff designed for a short life. I am making a knee like design on the inside using that bronze bolt I am making and another piece of white oak on the inside of the upright.

Like a brace, will be screwed and glued to the upright stem board and the new bronze bolt pass through it and the keel. So will have the two wood pins and the interior brace. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Okay , just an alignment thingy. Consider putting a square peg in a round hole , which allows lots of epoxy to lock it up. This is the opposite thinking to Ian's trunnel , but this is not a trunnel , more of a corrosion free drift , if I understand it right.

Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Yes, that is the general idea. It is going to be a loose fit, so lots of epoxy glue to secure it on both sides of the joint. I plan to mix some wood dust into the epoxy. Less likely to run out of the repair.

I will saturate first to let epoxy soak a little. I wont use PL for this. I would use a metal dowel. A bronze or copper one. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak I carved a 2. The sap wood had rotted, but the inner heartwood was in fine shape. Limb started out about 6 to 7 inches wide and I just kept trimming it on the 12 inch blade of the table saw till I got this. This piece will be doubled up and form the inner brace. I know it was white because of the leaves and I have another longer limb saved I need to carve.

This ugly rotten limb became a nice piece of wood. And here is the end of the bronze threaded rod, out of focus camera. And I have this stump but was wondering if it is red or white.

If white I could use some chunks. Easy way to tell is some kind of soak test in a dish? I think I will use the bronze carriage bolts as pins. They came my way, and I likely wont ever use them else-wise. They would just sit in the garage for me to look at while I marveled at how much they cost to buy new.

Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Chapelle's "Boatbuliding" has a page comparing different fastenings including trunnels and what diameter is appropriate for substitute.

Page in my edition that has the copyright renewal. Hate to rain on your parade, but the piece you show that you worked down is the poor part of the log. Hardwood mills that saw for quality discard the center 4"x4" piece at the cener of the log, it is called juvenile wood and is not stabile.

Often used for pallet wood or firewood. Sometimes it is expedient to use it, but in that case it is used as a " boxed heart piece" usually a min. Even then, it will end up with long splits often going right to the heart. Of course, you would know all this stuff if you had read "Boatbuilding" , no disrespect, just sayin'. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak I'm not going to puzzle out that exactly you're up to, and whether it makes sense Are the other members large enough so the THEY don't become the weak link at that point?

Herreshoff The Compleat Cruiser. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Thanks David for that. I know the Cumaru is a very strong wood. I will eventually get more pics in the next day so you can see what I am doing. The wood piece I have cut from the limb feels and looks like good oak wood, it will be sealed including all cracks glued so not exposed to water. Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Just as a guideline - the diameter of a trunnel shouldn't be more than half the thickness of the pieces it pierces.

Re: Strength of wood pin loaded in shear, 1 inch diameter Cumaru stronger then oak Ok, a mockup view using my brace which I will glue together.

I made a paper pattern of the deadrise angle from inside the hull. The long wide mahogany board laying down pretend is the rear upright stem wood. Asked 5 years, 9 months ago. Active 5 years, 9 months ago. Viewed 26k times. Improve this question. Pulsehead Pulsehead 1 1 gold badge 2 2 silver badges 9 9 bronze badges.

Add a comment. Active Oldest Votes. I am assuming that most of these guitars are under 20 lbs. I think most are under 10 lbs. Improve this answer. You are right about the weight. I should probably edit that into the question. Since the OP was asking are you aware of a reference for the lbs weight? Matt no I couldn't find a reference I'll try looking again. The Purdue reference that you cite is irrelevant to the question.

It is for dowels loaded in double shear, not for single shear, not to mention, it starts with 1. Further the mode of failure in question would be from excess moment when the guitar strap gets out towards the end of the dowel.

Katie Kilian Katie Kilian 2, 2 2 gold badges 13 13 silver badges 30 30 bronze badges. That was my rough plan. Essentially drill a "mortise" for the dowel on one side of the base, and drill a countersunk hole on the other side.

I'm not worried about the dowel falling out of the base board, i'm worried about the dowel being too narrow and snapping in half. Oh, yeah. Stain your parts before you assemble and it will turn out beautiful.

Zach Mierzejewski Zach Mierzejewski 1 1 gold badge 2 2 silver badges 8 8 bronze badges. While this will help keep the guitar from falling off, I strongly recommend doing something more.

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