Author Topic: Wooden chassis  (Read 133 times)

RhysN

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Wooden chassis
« on: 23 Mar 22, 06:38 am »
This car has done hundreds of miles, off road expeditions in NZ. Chassis is from scaffold boards. One of Brian Smith's several builds.
We must avoid torturing our brains with false problems, it occupies but it can annoy. In jest!

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RhysN

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Re: Wooden chassis
« Reply #1 on: 23 Mar 22, 06:40 am »
My Kim, somewhere here in the UK. Oak rails, wooden body tub, clad in very thin alloy sheet stuck on with Evostick. Full size car was my Peugeot.
« Last Edit: 23 Mar 22, 06:43 am by RhysN »
We must avoid torturing our brains with false problems, it occupies but it can annoy. In jest!

David F-R

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Re: Wooden chassis
« Reply #2 on: 23 Mar 22, 08:42 am »
Excellent start to the topic.

Oak for the chassis sides? I was wondering about some straight grained pine. It's used extensively for structural work.

(Personally, I do have plenty of oak 'in stock' but \I was thinking about what is readily available and cheap.)
I'm not quite as green as I'm cabbage sounding.

synthpunk

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Re: Wooden chassis
« Reply #3 on: 23 Mar 22, 09:16 am »
Swings and roundabouts?
There are few domestic hardwoods available that are as strong as oak, it has excellent resistance to rot, but it does somewhat lack flexibility. Ash and hickory are similarly long grained (strong) timbers, but have better flex and shock resistance. Which is why it’s good for hammer shafts. Sadly ash is getting much harder to find, due to all the trees suffering from Dieback disease, to the extent that it’s basically getting unobtainable.

We use ash at work, in guitar making. It’s now reserved only for our best guitars, as it’s gotten so difficult to obtain in quality quantities..

Ive used quite a lot of Obeche in my build. It’s similar to balsa, but denser and much stronger. It was used most famously in the dH mosquito. It shrinks and moves quite a bit, so you need to make sure it’s fully seasoned, and it’s full of silica which can be a bit of a bear on cutting tools and lungs, but apart from that it’s really nice.

Coincidentally; ash and Obeche make great sounding guitars, but oak sounds rubbish because there’s no resonance. ;c)

RhysN

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Re: Wooden chassis
« Reply #4 on: 23 Mar 22, 09:38 am »
Excellent start to the topic.

Oak for the chassis sides? I was wondering about some straight grained pine. It's used extensively for structural work.

(Personally, I do have plenty of oak 'in stock' but \I was thinking about what is readily available and cheap.)
It was oak just because the local timber merchants have a place where you can look at "stuff", pieces that have been cut etc. These were in there. No other reason.
For my Morgan re-build I bit the bullet and bought ash. Initially I framed it with selected pallet material so that I didn't make any major mistakes with the ash. In reality the pallet timber, when it was good grain structure was hard to tell from the ash!
I have used whatever is available, including Pawlonia for grille/radiator shells, even nicer than obeche!

There was also the Darracq T700 that Wes Raynor built which was all wood/ply. I believe to be one of the first 3 cyclekarts in GB, the list includes Bill (Giant Tribble) and Geoff May who was first? All 3 built differently from each other.
« Last Edit: 23 Mar 22, 09:47 am by RhysN »
We must avoid torturing our brains with false problems, it occupies but it can annoy. In jest!

Jimr1999

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Re: Wooden chassis
« Reply #5 on: 24 Mar 22, 06:32 am »
For mine, I started with table 1 here... http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2010/Part6/section4/appendix.htm
Which gives spans of joists permissible for building regs for an imposed load of 1.5kn/msq for various joist centres for relatively low grade C16 stress tested whitewood joists (Spruce et al)
I chose a stronger timber with a straight grain with few knots and chose tangentially cut pieces. (my section sizes are smaller than the smallest on the table)
From the table, even the smallest cross section would span our wheelbase, though looking at the state of some of the C16 we get at work I would never risk it.
The weak points on my design have been gusseted with ply and a high strength low creep adhesive that is WBP (weather and boil proof)
As I mentioned on my build page, it has not got a lot of torsional rigidity at the moment which I believe I can address with some bracing between the rails and the bodywork/floor as a joined box with glue blocks (like a classical guitar) and braces under the floor (Like a steel strung guitar top)
... Will it work? Feck knows, but I'm having fun
... You can lead a horse to water, but a pencil must be lead.

David F-R

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Re: Wooden chassis
« Reply #6 on: 24 Mar 22, 09:15 am »
So much useful information - thanks guys.

Following the principles of 'what can anyone get hold of' and 'what can I scrounge', I shall do a bit of looking around.

When I go to diy stores for softwood, I usually rummage through the stock for decent stuff and get very picky. Might try that next time I'm in one. In the meantime, my '34 Riley with box steel frame is first priority (after boat, house, loco and list from the management).

I'm not quite as green as I'm cabbage sounding.