Thread: Imperial measurements and Australian timber sizes.

Ok...to start off with, don't get too stuck up on precise sizes.

Wood is a very 'close enough' material. If I was making that, I wouldn't even look at the plans as all you need to know is shown in the pic, the rest is 'yea, about that - four legs at about 20x40x1200, ten rails at about 20x40x450* and a small sheet of 12mm ply for the bigger rails and the curvy bits at the top.

Go to your nearest large hardware store and see what they have. There is a list of 'standard' sizes (pdf file) but the trick is that these sizes may not be stocked by your local suppliers...so while they may be technically available...it's better to use what you can get your hands on without 6 weeks of waiting and delivery of two wrong sizes.

Porta Mouldings are stocked by a number of hardware chains.

Cheapest wood would be pine, followed by Tassie Oak; getting other Australian hardwoods generally requires a timber merchant to cut and dress from what they have (which varies from region to region) OR you could go wild and use some of the hardwood sold for decking (just rip some into narrow strips for the legs and rails (19x40 should be plenty strong enough!)

Personally, as it's painted, I'd use 16mm MDF or ply for the larger rail parts and the base, and whatever was close to 20x40mm for the legs/rails.

I'd also put another rail across to deter kids from trying to climb out by themselves as I'd be worried about it tipping if they decided to try climbing out! (I see they added tip resistant feet after the one in the pic was made!!!)

*Then I might go, 'Nah, 450's too big, lets make it 400'.

Thanks for your reply!

I haven't been to the hardware store yet since my FIL jumped right in and decided to go himself and then declared the project unbuildable. I'm going to go this week and see what they say and see what they have on hand.

Do most hardware stores cut pieces if you give them the dimensions?

I think the reason there isn't another rail is so that the kids can access the kitchen bench easily? I'm not too concerned with my daughter trying to climb over the top since she'll only be in it supervised, but I'll be adding the tip resistant feet to it anyway.

Thanks again for your reply! I've had a frustrating few days thinking about getting this project built after hearing how FIL was calling around to timber importers and such!

What Master Splinter said.

Don't fuss too much about the WxD dimensions; if you go to a Bunnings, for example, you should find "close enough" on the shelves. From a quick look at the URL it's the lengths that'll be the critical part and you'll be cutting them yourself, right?

One point where I disagree with the Splinter: the only part I'd consider Ply (or, shudder, MDF) is for the platform itself, as the best joints for the rails would be mitre & tenon!

The imperial sizes are what is called rough sawn. What you probably will be using is dressed timber which is smaller than the rough sawn size by about 1/4". eg for 1" x 8" you would be using 19 x 190mm or 18 x 189mm. 1" x 2" is 18 or 19 x 45mm. Timber is generally sold in multiples of 300mm, with 900mm minimum from a timber yard.

Depending on your skills and tools, you may want to do the arch from a piece of ply, or MDF rather than trying to accurately cut matching curves. As others have commented, the platform could also be done from ply or MDF.

Wishing you well with your project.

Megera,

Firstly welcome. This forum is a fountain of knowledge.

Timber is sold according to it's undressed dimensions.... i.e a 4" x 2" is just that.... for furniture/cabinet making you require DAR (dressed all round)
and the size reduces. You can get undressed timber greater than you require and dress it down to the size you require...at a cost.


Just stick with the DAR (actual size) and modify the design to accommodate that and you'll be ok.

Just remember we are metric and 19mm is 3/4" .. and go from there...


Best of luck.

as everyone else has said, near enough is good enough basically, but if you got a smart phone (could use google), jump on into the app store or google market place, find your self a conversion app, and set it accordingly, and find the closest match. Extremely useful for drill bits and bolts, ie 3/8 is "generally" considered to be 10mm,

I was more thinking about climbing out in the space between the top curved bits and the first rail at the bottom.

And if you are a first time woodie, I'd be hesitant about doing mortice and tenon joins as doing 20-odd of them is a bit daunting - I'd probably go for some through dowels if you don't have a Kreg jig handy. (the jig allows you to drive the screws into 'long grain' by a recessed screw hole in the rail, rather than driving them through the leg and into the rail so that they end up trying (and failing) to hold in 'end grain'.

Maybe someone in Melbourne who has a domino might want to help this new member, if only to show the FIL what can be done without importing fancy o/seas wood.

I could help with cutting but don't have a domino.


Peter.

Wow, thanks again everyone!
I've printed out a few wiki pages with a conversion chart and I'll make a list of the dimensions I need and take it to Bunnings (or Mitre 10 or whoever) on Thursday. I'm not worried about lengths as much as getting the other dimensions correct (cutting length is the least of my worries).

As nice as mortice and tenon joins would be, it's definitely beyond my skill level at this point! I was just going to go the quick and dirty way and screw everything together (not sure if FIL has a Kreg jig - but if he does I'll definitely use it)! In the plans it's mentioned that the wood split with a certain length of screw, what's the easiest way to avoid splitting?

I'll have to employ FIL to run the saw but hopefully after that things will be pretty straight forward, he is *very* hung up on making sure the measurements are absolutely exact so having the a 1x2 is really 19mmx38mm and not 25.4mmx50.8mm might be... interesting

Thanks again! If anyone has anything else to add, I'm all ears!

Measure every piece before you cut anything. Lumber here is still sold in Imperial sizes such that a planed 1" x 8" comes out of the kiln at 3/4" x 7 1/2".......most of the time. 1x2 and 2x2, the actual dressed size depends on the mill it came from. How about 1 1/2" x 2 1/4"? The next mill sells 1 1/2 x 1 1/2.

I needed 80' of new fence along one side of my back yard. Bought a bunch of 4x4 fence posts. Yup, you betcha = exactly 4" x 4". Went up like a dream with a new grape vine in the middle of each 8' section of fence.

Wood carving = really got lucky in Home Depot. Found 2 almost clear and straight grained western red cedar fenceposts. Maybe 40+rings/inch = fantastic. Sold as 4"x 4", I brought them 220 km home and got stuck into the drawings for a variety of carvings. Cut to length. Tried to lay on/transfer the drawings. The posts weren't even square = possibly 3 1/2" x 3 3/4". . . . . they 'looked' 4x4 in the store!

Never again did I shop for wood without a tape or ruler in my pocket.

Not sure if it is the same . But I like to buy my wood rough sawn and convert it into PAR as it works out cheaper. This is OK if you have the equipment

Originally Posted by Megera

Wow, thanks again everyone!
1x2 is really 19mmx38mm and not 25.4mmx50.8mm might be... interesting

Thanks again! If anyone has anything else to add, I'm all ears!

2 x1 when it is dressed all round will become 42mm x 19mm

The best thing to do with FIL is simply throw the measurements out and work from the picture, based on the wood you find.

Screws should go into predrilled holes to avoid splitting - you want the screw thread to cut its way into the wood, and not have the root of the thread forcing its way in. See - Figuring out the right drill size for screws

You'll note (in possibly yet another offence to your FIL) that drill bit diameters will be another area of 'close enough' unless you are prepared to order from some of the extended size ranges of drill bits with the accompanying conversation along these lines - "No, I just want to buy one drill bit, not a box of 1000.", "Mate, that is the price for just one of those drill bits".

See also: Wood joint strength testing

Originally Posted by Master Splinter

The best thing to do with FIL is simply throw the measurements out and work from the picture, based on the wood you find.