What timber to choose for this project?

[Nick]

A pal has asked me to replace some aged timber in the cab of his 1956 Scammell heavy haulage tractor. The timber is 7ft x 4 x 3ins and supports the back of the cab. The weight of the cab has bent the timber at both ends and also broken it at one end I can't tell what timber it is (yet) but think it may be an imported hardwood. Appears to be red in colour. Certainly not oak, ash or beech. Pic can be seen here, sorry about file size:

apologies for file size.

The outer ends support the weight of the cab which is not inconsiderable, also subject to a great deal of vibration and temperature change. There is some simple jointing, lap joints, halving and a couple of birdsmouth. I'm inclined to go for oak but would appreciate any other recommendations.

Many thanks, Nick.

[Bob Minchin]

Oak and steel don't mix. The tannin in oak corrodes steel.

Ash was used on Morris travellers etc and I think the chassis of Morgan

3 wheelers is made from ash too.

Bob

[The Natural Philosopher]

Hmm. Ash has been mentioned, and its a great light weight springy wood. Not sure its ideal here though.

Ok..no not for this. I'd be looking at a good quality pine frankly. Or spruce. Should be good for another 54 years..

Beech is a really dense hard wood too. Rock maple is also a contender.

have a look here.

like pitch pine is probably what you have there.

[Simon C.]

I have absolutely no idea, but 10 out of 10 for an interesting and original question. Gems like this make this group a great read :)

[Cicero]

==============================================================================

The red colour suggests it might be mahogany.

Cic.

[The Natural Philosopher]

Nah. Not with that grain.

Its a classic red pine of some sort.

extensively used for truck building.

Mahogany is only really good in one sense,. very fine even grain and good stability.

Otherwise its expensive and not that good structurally.

Old railway sleepers would be ideal...to machine up.

[Jules Richardson]

Agreed. Plus, I used to go to a number of steam fairs and the like, purely to see the Scammells. There's just something about old heavy haulage gear....

[mark]

size:

My apologies for file size.

You could ask the question here.Loads of guys restoring cabs.

[Nick]

Thanks Bob,

ash was, and is, the material of choice of coachmakers and other vehicle body builders for its strength, longevity and propensity for bending easily. The timber I need must not bend easily due to the design of the original construction. I am well aware of the reaction between oak and steel. Fortunately, the main timber I have to replace has only 4 fixings. These can easily be done with non-ferrous items. Any suggestion for a more suitable timber would be welcomed.

Nick.

[Nick]

also thanks to all that have responded. I appreciate it greatly.

Nick.

[Nick]

Thanks Mark,

looks a V interesting site. I'll register & pop a message up there, also trawl through some threads.

Nick.

[Nick]

Jules,

this old Scammell was purchased new in 1956 (or thereabouts) by the father of a chap that I have worked with for nearly 40 years. His father removed the 6 pot Gardner 180 (I think, but may have been another make) and replaced it with a new straight 8 Gardner 240 coupled to a military gearbox. The chassis was extended to accomodate this conversion. A prop shaft driven Gardner military winch 15T line pull (as opposed to the civilian 5T line pull) was then fitted and a ballast box made. Bonnet and front wings were remade to suit. It did sterling service in the fleet but was eventually sold, possibly when the owner passed away. Unfortunately the new owner had to re-register the vehicle with the authorities as it was modified to such a degree that the original spec bore no resemblance. In this process the original registration number was lost and sadly most of the vehicle's early history cannot now be traced. I have been in the heavy haulage business for over 50 years and still love it. Something different every day. Bloody electronic vehicles are getting me down though. Perhaps time to bow out gracefully. Wooden ships and iron men perhaps. Nick.

[Frank Erskine]

Wearing an anorak?

8-)

[Roberts]

Nice interesting note. As an exArmy Scammell driver I still love them. I remember while abroad being told that the wood in the cab was a special type because of insect damage in various foreign parts of the world Also nice to see Scammell spelt correctly>

[Bob Minchin]

Somewhere else in the thread there was a reference to railway sleepers. Many UK ones were made from oak but from bitter experience, I know these have lots of embedded grit in them and very quickly wreck cutting tools. However that started me thinking about other woods used for sleeper than you might be able to buy as new wood. One such is Jarrah.

Thrade sources for jarrah here

guys might be able to help with Jarrah or almost certainly new untreated sleepers make from Euro oak that supply rustic timber framed buildings should be able to do you quality English oak beams.

Good Luck

Bob

[Bolted]

Non-durable so not really very suitable here.

ditto

Looks tropical to me but it's a bit hard to tell.

Ipe would be ideal as both very durable and very high bending strength, but I'm not sure how widely available it is in that sort of section (most commonly available as decking). Iroko might be easier to obtain in the size you need, is very durable but lower bending strength (still better than softwood though).

Looks like you could also up the depth by a couple of inches or more to help reduce future sagging, unless that is too inauthentic (and/or add more bracing, which might be more effective vertical but I haven't really thought that through so may be talking out of my fundament there).

[The Natural Philosopher]

I really don't think so. Quality pine was THE mid 20th century coachbuilding material of choice.

Ash was used for horse drawn, because its light.

But Pine was the material for any sort of tough boring use where the surface finish was not important.

A quick chisel into it and a sniff should tell if its a resiny sort of pine or not. The resiny smell will be musty, but still detectable.

Good pine is streets ahead of most common structural timer in the BM's today, but the specialist suppliers like the John Boddy site I posted, can do it.

Nah. It ain't tropical hardwood. No point in that.

Tropical hardwoods are used for fine high tolerance work, because of the even grain and stability. No one would have used them for a truck frame. FAR too expensive, even then. Teak is the only possible contender but the colour is all wrong..its a red pine of some sort for sure.

[stuart noble]

Lathams might be worth a call. They're pretty big in softwoods, including Douglas Fir, Hemlock etc, and are pretty knowledgeable.

[Bolted]

Fine high tolerance work like all those harbour walls, railway sleepers, lock gates, etc, you mean?

[The Natural Philosopher]

nice site.

Bookmarked.