Reducing Waste

cavedave

I make online calculators that make things more efficient. It is a pretty odd hobby and I should probably learn something useful like how to use a hammer.

One type of calculator that I cannot find online is for the 'stock cutting problem". This is where there are long bits of wood (say 10m long boards) sold by shops. People need shorter lengths for their projects (say 5 3m long boards and 3 7m long ones). And the calculator works out the right number of boards to buy and how to cut them to get the least waste.

Before I go off and make something no one needs. Do you have the 'find the right number of boards and the best way to cut them" problem? If so can you give me some examples?

Thanks for the help.

recipio

Yes, it would be great to have an online calculator - as long as its free of course
If you search www.rockler.com they have a 'construction calculator' for $24.99 so somebody has put it on the market. Not quiet the same thing but a pocket calculator would be very helpful going to a timberyard where you don't know the size of the stock beforehand.

North West

Hi Cavedave.
I would find that an interesting hobby. Are you interested in length only of timber. You have a large multiple of sizes available and also species. Most timber merchants carry different lens according to requirements of Diy - builders - etc The standard stock sizes available would be starting at ( these are in metres )
1.8-2.1-2.4-2.7-3.0-3.3-3.6-3.9-4.2-4.5-4.8-5.1-5.4-5.7-6.0-6.6-7.2-7.8
Depending on whats required these are the lens available, but all merchants may only carry a few specific lens where elsewhere you could have a stock of maybe 60% of lens and 40% available to order if required.

Now you could have 12 different board widths available and 7 board thicknesses and this would be only in one species.
Nw

I worked in a timber merchants for 40 years and if I can be of help let me know.

cavedave

Are you interested in length only of timber

Well I am interested in whatever woodworkers are interested in. If thickness is important to them that needs to included in the calculations.

One thing I imagine people want to to be told how many long boards they need to buy. As in if I have the choices you listed it would be nice not to buy extra wood you don't need? Or do you always buy extra as a backup in case a piece splits or something?

North West

Hi
Well I am interested in whatever woodworkers are interested in.

There are thousands of uses for timbers and each use you would use specific dimensions and sizes of wood for projects. You will have to be more specific on what exactly you want to do.
Depending on the projects a woodworker would be working on, would determine what timbers they use.
NW

recipio

Just so you know, most of us with a workshop will start a project by drawing up a cutting list.Dimensions will be rounded up as hardwood is supplied rough and must be planed. eg if we want 20 mm finished boards we shop for 25mm (1") rough stock and so on.
Some people just want to buy finished softwood of course so you would need to factor in finished and unfinished, imperial and metric and a quick tot from the cutting list to get the total amount needed ( most yards still use cubic feet as a price guide ) -its nice to know roughly what a project will cost before arriving at the till.
Those are the kind of basic calculations I'd look for anyway.

cavedave

There are thousands of uses for timbers and each use you would use specific dimensions and sizes of wood for projects. You will have to be more specific on what exactly you want to do.

What I mean is there is how programmers think about a problem. Which tends to be give me these inputs and I will give you the 'right output'.

And there is the much more important how people who use the program thinks about a problem. It is there mental model of a problem that a programs interface has to match.

For example I as a programmer do not really think about species of wood. The idea in my head was just about combining small numbers (needed cuts) into big numbers (available raw boards) in an efficient way. If what woodworkers actually care about is keeping track of thickness' and species that is the important stuff rather then my initial idea about efficient cuts.

Does that make sense? Every time you have to figure out a remote control with 50 buttons of which you use 5. It means someone has used their model of how you should think rather then actually found out how people think.

As an aside I think one of the reasons, I'm told, wood working tools are so pleasant to use is that over time they have evolved to do just what is needed and no more.

recipio

I'm afraid cutting efficiently is the main thing woodworkers think about.!
It would be nice to have one of those CAD programmes that work out how to cut sheet material after entering all the dimensions needed.

cavedave

recipio

It would be nice to have one of those CAD programmes that work out how to cut sheet material after entering all the dimensions needed.

It is a much more complicated problem to cut shapes out of a sheet efficiently. There are commercial programs out there for this. They seem to be for big factories trying to get as many sofas as possible out of thousands of sheets of plywood.

If there was a standard way of describing the shapes needed and ideally a file format people were already using to describe the parts they needed a calculator for the 2d cutting stock problem (as cutting shapes out of a sheet is known) would be doable, if fairly difficult.

Do people here use CAD programs to design their next projects and if so which ones?

recipio

[HTML]Do people here use CAD programs to design their next projects and if so which ones?

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Well, I'm learning how to use Google sketchup. It ain't easy at my age.