Is oak an acceptable substitue for maple for motor mounts crutches etc?

[Dennis Holler]

I suspect the Maple is a little lighter, but am I losing anything if I use some Oak?  Its a matter of I have it laying around and am at the point of needing the wood.  The plane(s) are for my learning purposes too so they may or may not have a short life

[Randy Ryan]

I wouldn't use oak, its obviously a very hard wood, but its also brittle and suseptable to shattering and stress fracturing.

[Dennis Holler]

Thanks Randy, Thats the answer I was looking for.  I'll order some maple!

[Randy Ryan]

Check with Bill Sawyer, he's here on SH

[Randy Powell]

I've used red oak without problems, but it is prone to brittleness. Maple can also shatter, but usually isn't susceptible to checking like oak and will usually last many years as it tolerates vibration really well. Lately, I've been using beech. This is hard but is not brittle. Ash isn't bad either, to doesn't have the surface hardness of maple.

Best overall choice is probably still maple.

[Leo Mehl]

I wouldn't use oak, its obviously a very hard wood, but its also brittle and suseptable to shattering and stress fracturing.

Also because of its makeup it is prone to vibration.

[david beazley]

I think the reason to choose maple over oak is the grain structure rather than the hardness factor.  Maple has a tighter grain and less likely to split where oak has a more defined grain and splits easier. 

[Trostle]

I have not ever tried any kind of oak, but have read somewhere that it epoxy does not adhere to it as well as to maple due to an oily compound in the wood.

Now, maybe some wood workers can verify if there is anything to this because obviously, oak is used in furniture and cabinets and something must be able to bond to it.

Keith

[proparc]

I suspect the Maple is a little lighter, but am I losing anything if I use some Oak?  Its a matter of I have it laying around and am at the point of needing the wood.  The plane(s) are for my learning purposes too so they may or may not have a short life

Ash would seem like the best alternative to maple given it's use in everything from baseball bats, to ax handles, to canoe paddles etc.

[john e. holliday]

I don't beleive it is the bonding as much as it is the compression o the wood when machine screws are tightened.  In early days of F2C we made balsas crutches with the hardwood set so the grain ran parallel with the screws.  Never had one crush down on us.   

[Bill Sawyer]

I saw a demonstration of someone blowing cigarette smoke through a foot long piece of red oak. The reason is the grain has openings that run the same as the grain. In places where the wood comes into contact with wayer it is normally not used because of this ( as in boat building ) because the water rots the wood form the inside as well as the outside. White oak is more stable around water and is used for boat building. Red oak works wonderfully for furniture making.

A test was done on several domestic woods by dropping  a metal ball on the side grain of the woods. The hardness was determined by the amount of denting. Maple was the hardest of the woods tested but even maple will dent when enough pressure is applied. There is a hard maple and a soft maple. What we want to use is the hard variety.

I have done woodworking for years using both hard and soft maple as well as most types of wood available. The two hardest woods are white oak and hard maple. The main difference I have seen is that the oak has more of a tendency to crack than maple.

Below pictures:

Top soft maple

Bottom hard maple

[elizio]

I have a LaGG 3, Brodak kit. Only problems whith maple. In Brasil used a "marfim" wood. No problems.

[pipemakermike]

In the UK Beech is the most often used wood with maple second.  Oak is OK but as it is an acidic wood it can cause corrosion under some circumstances

[Fredvon4]

Bill S. are you sure of this assertion? "The two hardest woods are white oak and hard maple"

I also wood work, and have some small samples of a few exotic wood varieties....

Top 10 hardest woods in the world
Wood, as a material, can have its hardness quantified using the Janka rating; the industry standard rating. With this rating, the resistance of wood samples to denting and wear is measured.  Varying on account of wood grain direction, different woods are tested based on the cut surface of a stump cut from the material. The measure of hardness and strength is pounds-force (lbf).

Here, we list the top 10 hardest woods in the world, and provide a bit of information about each type:

Hardest-Woods-In-The-World
1. Australian Buloke

An ironwood tree that is native to Australia, this wood comes from a species of tree occurring across most of Eastern and Southern Australia. Known as the hardest wood in the world, this particular type has a Janka hardness of 5,060 lbf.

2. Schinopsis brasiliensis

A species of flowering plant in the cashew family, the schinopsis brasiliensis originates in Brazil and creates an extremely tough wood of 4,800 lbf. Due to this immense hardness and strength, this wood is often used in construction.

3. Schinopsis balansae

A hardwood tree, the schinopsis balansae is a tree which makes up large areas of forest in Argentina and Paraguay. Reaching a whopping 24 metres in height at times, the tree’s wood is extremely hard, at 4,570 lbf.

4. Lignum vitae

A trade wood, lignum vitae comes from trees of the genus Guaiacum which are indigenous to the Caribbean as well as the northern coast of South America. This wood has been used since the 16th century, combining strength, density and toughness at an impressive 4,500 lbf in the Janka hardness test.

5. Piptadenia Macrocarpa

This wood has a Janka hardness rating of 3,840 lbf, making it suitable for a variety of construction projects. It comes from a tree native to areas including Argentina, Bolivia and Peru.

6. Snakewood

Snakewood has a Janka rating of 3,800 lbf, and is an exotic hardwood which is particularly prized for the highly figured grain it exhibits. Originating from South America, it is used in  a variety of projects requiring tough, dense wood.

7. Brazilian Olivewood

With a Janka rating of 3,700, this wood is an exotic, attractive choice. Combining its pleasing aesthetic with properties including toughness and strength, exotic household furniture can seriously benefit from its presence.

8. Brazilian Ebony

A dense, heavy wood originating from Paraguay, Argentina and Brazil, this wood has a Janka rating of 3,692. Particularly good for the construction of decking and planking, this wood is not only hard and durable, but shock-resistant, making it an attractive yet extremely practical and cost-effective choice in the long-run.

9. Brazilian Walnut

Originating in Central and South America, this wood has a grain that varies from straight to irregular or interlocked. With a Janka hardness rating of 3,684, this wood can be used for a number of projects, whether indoor or outdoor.

10. African Pearwood

This is species of tree is found in Angola, Cameroon, the Republic of Congo, Gabon and Nigeria. With a natural habitat of tropical moist lowland forests, the wood itself has a Janka hardness rating of 3,680 lbf.

 

Here at Hitchcock and King, we are a leading supplier of building materials to customers around the country. Our business is built on four main principles: stock availability, quality products at competitive prices, fast delivery and great customer service, all of which set us apart from our competitors. For more information about our range of products and services, and what we can do for your space, simply get in touch with our friendly team of experts today. We’ll be happy to help, whatever the enquiry.

[Fredvon4]

I guess it is wise to read the time stamps...arguing with folks who can not respond is a waste of key strokes....OH well thanks Ty

Necro threads always get me.....

[Dennis Toth]

Dennis,
I have situation for my Barnstormer that I am going to use a McCoy 29 rear intake that needs the tank lower than the normal. I need 1" deep mounts. The available maple is only 3/4", I have a piece of 3/8"x 1" walnut. I have used this in the past and I think with CA to seal it should be very strong. I think you could do the same with the Oak.

Best,    DennisT

[Dave Hull]

A couple of prior threads have additional, and related information:

https://stunthanger.com/smf/open-forum/threaded-brass-inserts-for-engine-mounting-good-bad/msg539229/#msg539229

https://stunthanger.com/smf/building-techniques/birch-wood-for-motor-mounts/msg114157/#msg114157

The wood properties table I added at the bottom came from an article I wrote for our club newsletter.


Other comments:

Oak is a very ring-porous wood. The difference in the early and late wood within one growth ring is notable. This is why it is so prone to splitting. As noted in some of the prior threads, eastern maple is the most desireable. Western or bigleaf maple is ok, but does not have the crush strength, so embed a threaded sleeve instead of a T-nut.  Ash is also ring porous.

My second choice is birch. Very dense and uniform. Mills nicely.

Oddly, I have also found tulip poplar as found in Home Depot to be quite good. You can find boards that are light, and you can find others that are heavy. I have made motor mounts for a number of planes. Also used it for stub spar material in various racing planes instead of maple. This is not the same mushy wood that is used to make "poplar lite ply."  Different beast entirely, so don't bother trying to beat that drum.

In the first referenced thread, the use of an "AD" type aircraft rivet as a threaded sleeve seems questionable to me. These are made of 2117-T4 alloy, which is soft enough to buck them. (The "A" type are 1100 and dead soft.) They work harden when driven, making the strength acceptable for full-scale aircraft fasteners. Skipping the bucking process means they are as hard as they are going to get--which isn't very hard, and thus, more prone to stripping. So for a small sport plane that isn't expected to have an extended life, or won't have the engine repeatedly pulled for cleaning and maintenance, go ahead. But there are better materials.

Dave

[Air Ministry .]

Dunno where this fits in , and youd have to fgo a long way to get it . But its ding resitant flooring timber and bl88dy stiff .

Botanical name: Beilschmiedia tawa

Other common names: Tawa

Strength: Tawa is a high density, very strong timber.

Durability: Both the heartwood and sapwood are non-durable.

Finishes: Tawa can be stained and polished readily.

Working properties: Tawa is an excellent finishing timber, and useful for across grain turning. The contrast between white and black colouration can be used to good effect.

Appearance: Logs under 35cm diameter are uniformly white throughout, although logs of greater diameter exhibit an irregular pathological zone of ‘black heart’ in the inner core of the tree, which follows the taper of the tree.