Woodworking advice please

[JimH]

It seems a fairly varied bunch here so I might get lucky - I'm looking for some advice on material selection. We need to build a lorry cab. However, this is something designed in 1923 so it is more of a shed fixed to a chassis. I've attached a general arrangement of the cab from the Sentinel archive to give an idea of what is going on.

 

 

And this is roughly what the finished item is meant to look like

 

 

You will probably note that the drawing of the roof doesn't tie up with what they actually built. So you will see that the back and sides are made up of boards fixed to a frame. This then sits on three cross members which sit on the chassis rails. A few more bits make up the seats and bunker. It looks (and is) very simple indeed.

 

What I haven't got is

 

1. Any details of what the various types of wood were used originally

2. The first clue about what wood to use for the various parts.

 

Does anyone have any experience of things wooden to guess what wood should be used to make the:

 

1. cross members

2. frame

3. boards used to form the back and sides

 

One thing that is worth noting is that the chassis is extremely flexible and the cab takes a lot of this load. The other thing is that it will get driven on the road so it will need to last.

 

Any ideas?

[artdjones]

The frame would probably have been ash,it's very flexible.

[Mally]

I'd have put this in the main forum, its a vehicle, and very interesting.

[JimH]

I'll put up something more detailled about what we are up to and how we do it to bore the tits off people later.

[sierraman]

I’d possibly panel it with marine ply.

[mitsisigma01]

Just had a quick Google whilst in the reading room and I came up with something from downunder, apparently they restored a Sentinel a while back so they might have some e more information.

 

Melbourne steam traction engine club .

secretary@melbournesteam.com.au

 

Is this the one going onto an LDV chassis? ?

[dozeydustman]

A most commercials used an Ash frame, I'd guess most of the cladding boards would have been pine. Cross-members? Pass.

If you don't need to be period correct, making the frame from a light but strong wood then I think birch or Alder would be a good substitute.

[colnerov]

 Hi, As said frame should be Ash as it's flexible, if it's going to flex too much with the chassis as you say then use tongue and grooved boards, don't use sheet material as it can't flex and so will pull and fret at the fixings and come loose.

 

 Colin

[DSdriver]

I have never looked at how this sort of thing was put together but would think that marine-ply panels would be fine if they are allowed movement, for example slotted in grooves like paneled doors or screwed in place with coach bolts through oversize holes.Tongue and groove also typical of the period, in our house though, the paneling planks were just butted together but did have a bead for decoration down one edge.

[Junkman]

Here, use this: http://www.americansignproducts.com/Di-Noc/Wood_Grain.html

[Dan the van]

Didn't Salvage Squad restore a Sentinal and have to fab a whole new cab?.Might be worth a look.

[DodgeRover]

When you say the chassis is flexible so the cab takes a lot of load, does that mean you want the cab built rigidly to stop flex or you want it to move with the chassis to some extent?

As has been said ash is traditional but wether it would be correct in this application I don't know, obviously if you are having windows then you don't want too much movement.

[Asimo]

Perhaps have a look at the railway preservation world. Lots of work done on heritage railways rebuilding and repairing wooden coaches and wagons. Similar technology and period.

 

One of your difficulties may be that so many timbers that were once readily available for this sort of engineering are now impossible to get, all of such ancient trees having been felled.

[somewhatfoolish]

I was reading the blog of some loon rebuilding a pre-ww1 Dennis and he built a similar cab from scratch, I'll see if I can find it again.

 

edit; here we go!

[DeeJay]

Try asking on here as well.

 

http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/

[scruff]

I would have guessed the frame will be ash to allow a degree of flexibility, the side boards perhaps pitch pine.

[lexi]

It is usually ash frames a la old gypsy caravans Morris minor many aircraft etc. Lorry beds are Keruing which is straight grain, strong and very hard wearing. Some interesting work there!

[Uncle Jimmy]

Yes, ash was used for car bodies in the early days, it's very strong in small sections and cheap and readily available.

However, that was for car bodies, especially cycle cars and the like. I'm not so sure it would have been used for haulage vehicles like your sentinel.

Ash has no durability- hence the age old Morris Minor traveller rot problems.

Back in the day I'd suggest your sentinel frame would have been oak. Now that's going to be very expensive nowadays, especially if required in 3" or more thickness.

Lookingat those plans and photo it's almost all straight lines so I don't think you'd need anything above 2" stock which helps. Really it's a toss up between oak and something like Sapele, Utile or similar west African mahogany. That will resist rot fairly well and is nearly as strong as Ash.

The cladding would have likely been pitch pine originally, durable and stronger than redwood. The load decks and drop sides of such lorries were often made from poplar, it's not at all durable but that wouldn't have been regarded as an issue as the load area would have quickly became very worn if not broken in use; poplar was liked because it doesn't splinter, relevant when all loading was done by hand.

There are some compound curves on the bonnet which would have been steel over the wooden frame originally, it's too early for any aluminium to have been used.

The top of the roof may well have been covered in oil cloth or possibly leather. Areas where boards met would have likely been sealed with bitumen and maintained to keep the water out.

So I think I'd forget ash and go for something more durable. I would avoid plywood of any sort and use solid and cladding, which wouldnt have been tongued and grooved, either butted up or rebated and the joints tarred. Many of the joints at corners would have been bolted together and steel braces used liberally. Rarely were mortice and tenon joints used in although I'd probably be more liberal with them as I am a joiner.

[Christine]

Wanna book?  If not , anyone else?  Postage only

 

 

 

 

 

 

 

 

 

 

[Uncle Jimmy]

Btw, my grandfather was a car body builder in the 20's working for Frazer Nash, after which he built rowing eights and repaired barges on the Thames postwar.

I inherited his tools and templates and indeed lots of bits n bobs of ash. It was a hard trade on the whole and there wasn't much in the way of machinery to speed you along then, a lot of curves to be cut, often by hand and many many holes for bolts; hence he had a half dozen braces and scores of augers and centre bits as well as many compass planes and spokeshaves. There was barely a flat bottomed plane amongst his kit as virtually everything was curved on the cars and later on the boats.

[DodgeRover]

I've actually found oak is very reasonably priced locally - not sure on the kiln dried stuff but green is lovely to work with.

[JimH]

Yes, ash was used for car bodies in the early days, it's very strong in small sections and cheap and readily available.

However, that was for car bodies, especially cycle cars and the like. I'm not so sure it would have been used for haulage vehicles like your sentinel.

Ash has no durability- hence the age old Morris Minor traveller rot problems.

Back in the day I'd suggest your sentinel frame would have been oak. Now that's going to be very expensive nowadays, especially if required in 3" or more thickness.

Lookingat those plans and photo it's almost all straight lines so I don't think you'd need anything above 2" stock which helps. Really it's a toss up between oak and something like Sapele, Utile or similar west African mahogany. That will resist rot fairly well and is nearly as strong as Ash.

The cladding would have likely been pitch pine originally, durable and stronger than redwood. The load decks and drop sides of such lorries were often made from poplar, it's not at all durable but that wouldn't have been regarded as an issue as the load area would have quickly became very worn if not broken in use; poplar was liked because it doesn't splinter, relevant when all loading was done by hand.

There are some compound curves on the bonnet which would have been steel over the wooden frame originally, it's too early for any aluminium to have been used.

The top of the roof may well have been covered in oil cloth or possibly leather. Areas where boards met would have likely been sealed with bitumen and maintained to keep the water out.

So I think I'd forget ash and go for something more durable. I would avoid plywood of any sort and use solid and cladding, which wouldnt have been tongued and grooved, either butted up or rebated and the joints tarred. Many of the joints at corners would have been bolted together and steel braces used liberally. Rarely were mortice and tenon joints used in although I'd probably be more liberal with them as I am a joiner.

 

Thanks for this.

 

The front "bodywork" isn't framed. The front apron is 14 gauge sheet (yes really - 2mm thick bodywork) fixed to 1" angle iron. The curved plates are pressed from the same 14 gauge plate and riveted in place. This is not standard car building practice  . The quality of construction of these things is somewhere near appalling. None of them were built to last long. Even the much later S Type has a cab more like a garden shed than a car. 

 

The use of poplar probably ties up with something I found buried in a book suggesting that the cab back and sides as well as the platform body were made from magnolia. Looking up the wood database it told me that magnolia is sort of kind of like  yellow poplar. There seems to be a few people supplying poplar for not silly money.

 

The thing will live inside all of its life so rot isn't really an issue - if that is the case is it better to use oak or ash for the frame? Neither seem very cheap so it comes down to which is bestest to use.

 

As for the roof that is down as "deal matchboard" which my approximate translator says is something T&G that isn't very expensive. The roof would have been covered with canvas as far as I know.

[JimH]

Wanna book?  If not , anyone else?  Postage only

 

I haven't seen that. Let us know what you want and I'll PP (or whatever) you the money.

[somewhatfoolish]

The roof would have been covered with canvas as far as I know.

Painted canvas was a common low cost waterproof(ish) sheathing used on boat decks in that period.

[New POD]

I'm thinking aluminium extrusions glued together with carbon sheets riveted to it ?

No.

I'll get my coat.

[Uncle Jimmy]

I'm thinking aluminium extrusions glued together with carbon sheets riveted to it ?

No.

I'll get my coat.

That was on the twin turbo supercharged Imawanka version made by Fujitsu heavy industries in 1921.

[Christine]

That's bollox , because aluminium was invented by Land Rover

[Christine]

Message me an address for the book JimH...

[martc]

Back in the day I'd suggest your sentinel frame would have been oak. Now that's going to be very expensive nowadays, especially if required in 3" or more thickness.

 

Can't you go to Oak Furniture Land and buy a couple of tables and cut them up? They're always having a sale, 50% off.

 

(sorry for non-constructive comment, I'll get me coat)

[Justin Case]

These two Sentinel threads are some of the best things that have happened to AS in years . Today was a working day at the museum (Aldridge Transport Museum) so I thought I would see if I could find out anything that might be helpful while they were still fresh in my mind. First port of call was to look through a pile of 'Bus and Coach Preservation' maagzines that were lying around, but the reports of restorations generally went no further than 'the rotten framing was replaced with new wood', before going on to the panelling. I did find out however that the framing for the Duple bodies that were on most Bedford OBs just after the war were of ash, so it was used on more substantial vehicles.

 

Our 1935 Daimler bus that was converted into a lorry in 1947 is being restored and a lot of the framing is exposed. The wheel arches are original and appear to be made of ash, according to our resident* bodywork expert. The only other prewar vehicles are light commercials and either have all-steel bodies or have double panelling so you can't see the frame. We do have a Scammell Mechanical Horse, the front panel and roof are metal, but the back of the cab is quite flimsy, with horizontal 5 1/2" wide T & G which is probably deal and quite thin, with a fairly basic frame of planed 2" x 1" softwood, so it may not be original, but in any case trundling round raiway termini is hardly the same as going over Shap in a blizzard

 

HTH, anyway it was apleasant way of spending an hour and I've learnt quite a lot