40% wastage.

[devonwoody]

Recently purchased a good quality log of sycamore 81mm thick, (75mm ordered) . (kiln dried)

I was able to get 5 boards 10mm thick p.a.r. out of the 81mm thick board, using a 4tpi bandsaw blade and working with a planer/Thicknesser.
Thats nearly 40% wastage.

Does anyone expect to get better results than this?

 

[newt]

Did you plane a face then resaw, plane a face again then resaw, or allow a good margin and resaw all boards in one go, then plane them all. I find the former method a pain but more economical.

 

[MikeG.]

I wonder if the whole principle is wrong to start with? Aren't you likely to run into problems with boards splitting or warping if they are cut from much thicker boards?

Mike

 

[OPJ]

You don't say how wide these boards are but, I'd normally allow 6mm waste for each cut, plus the saw kerf, unless you boards were very wide.

So, 16mm goes... Five times in to 80mm but, that doesn't take in to account the wastage of having to straighten the edge at least once (as Pete mentioned) or straying from the cut...

All in all then, I think you got it about right. :wink:

Mike's got a very valid point as well though... Whenever I do resawing like this, I like to leave the sawn boards for several days before planing them out; just in case they decide to move or split... It's almost inevitable, unless your timber was very well seasoned in the first place. :?

 

[markymark12]

Hi

I recently switched to using tungsten tipped bands made my Lennox. I know everyone will be shouting, but the cost, that is another debate. But back to the point, i can cut to within 1mm or closer if i have to and sand the boards as aginst the risk of pickup through the planer. So at a push i would aim for 6 cutting at 11mm and with the kerf of just under 1.5mm be working at 12.5mm each cut. 5 kerfs works up to 62.5mm leaving the last of at 18mm which allows for a bit of straighting through the process.

I always laminate it up to a backer when doing this.

Anyway food for thought.

Mark

 

[RogerS]

I wonder if the whole principle is wrong to start with? Aren't you likely to run into problems with boards splitting or warping if they are cut from much thicker boards?

Mike

????? Then how does anyone get thinner boards??? :wink: Special trees?

 

[markymark12]

I think the point being that deeping thick stock is always risky, even more so when dealing with Kilned stock.

Conversion of wet timber from the round is completely different. The cells are completely saturated. Which is why good yards will convert and let the timber reach fiber saturation point before kilning. a problem with a lot of timber kilned is the fact that it is not left left enough before kilning leading to allsorts of internal stress's as the free water has not be allowed to drain completely.

Myself i would not risk deeping kilned stock unless i am really pushed, i have seen too many pieces wasted due to problems following.

Fresh sawn or air dried, brought in advance and given time to acclimatize for me.[/quote]

 

[devonwoody]

Did you plane a face then resaw, plane a face again then resaw, or allow a good margin and resaw all boards in one go, then plane them all. I find the former method a pain but more economical.

Yes I do the former but in addition I also thickness the rear side before the first cut on the bandsaw, this means that the last piece sliced off has already got a prepared surface as well.

So if I am continually working with 10mm finished boards, what is the most economic sawn thickness to buy?

BTW anyone know where there is some spalted sycamore for sale? (only a small amount wanted)

 

[OPJ]

I reckon you'd be better off buying 1¼in. thick stock, although 1½in. is going to be more readily available wherever you look. Either thickness should have much less stress than that of which you'd expect to find inside something 3in. thick and so, you're less likely to run in to trouble.

I usually find that these dimensions are nominal with locally grown hardwoods - for example, that 1¼in. (32mm) will be closer to 36mm and, as you discovered, 3in. is generally cut to around 80mm, giving you an extra 5mm for nothing! :wink:

This isn't always the case though... So, with some suppliers, you will need to buy 1½in. stock.

 

[markymark12]

If you are buying log quantities, then can you not buy in advance and have a log cut at 15mm.

I have done this before with quartered oak for drawers and cedar for paneling. Sometimes i will mix up the log with various thicknesses to keep the colour true through the project.

It just seems like making hard work of it all deeping down dimensioned stock, it is okay for the odd bit here at there but if you need quite a bit then it takes up a lot of time which can be spent doing the making.

Just a thought.

 

[devonwoody]

So how does the merchant calculate cubic feet.

I reckon they weigh the consignment and say Sycamore is 32 lbs a cu fit and then do a weigh of the consignment for charging purposes, is that so?

So if you get 36mm you are paying for it?

 

[markymark12]

I am not quite sure what you mean.

Are you refereing to the log yield and how they work out what you will pay?

Some material in large volumes is sold by tonnage. But in a yard if you are dealing with one of logs then a agreed rate for sawing and a hopus measure in the round will give a fairly good indictor for the usable amount contained within and then you can work out if one log will give you what you want. You will be surprised how much wastage there is in a log, sap, shake, etc.

Sycamore needs to be dealt with very quickly. You could not go and buy anything now in the round. It has to be winter felled with the sap down. And then shifted and cut, once it has laid on the ground for a while the sugars get to work and hence the stain you sometimes see.

If you are not used to buying in the round it maybe better to take someone along who has experience or go to a reputable mill who i am sure would be happy to help.

I used to buy a lot in the round each winter and found it the best way to go many years ago.

Hope you find what you are after

 

[devonwoody]

I am not quite sure what you mean.



Mark.

I purchased a length of sawn sycamore the other week that was about 8ft long 81mm thick and had round outside edge. width started at 12 inches and the top widest was 8 inches.

I wondered how the merchant calculated its cubic voluum. So I thought perhaps he weighs it and says ah! 48 pounds, that must be one and a half cubic feet at 32 lbs.per cubic foot

Not making any complaint only trying to learn how calculations on voluum are done.

 

[markymark12]

Sorry

I thought you were looking for large amounts of 10mm board without having to resaw.

I did not realise you were after a calculation method for volume in a board.

There are various methods dependant on if you want to go metric or imperial, for older pippers like me i work in feet and inches. So width in inches x thickness in inches x length in feet divided by 144 gives you your volume. Now you will say but it's different widths. Good yards will take a three point measure average, ie measure at three points of width over the length and also measure out defects large knots, shakes etc. If they will not i don't use them. This is partly why a lot of guys like square edged stock, it is quick to process with minimal wastage. Someone will come along with with the metric for sure, just too many numbers for my liking.

 

[devonwoody]

Thanks Mark. Thats the way I would go, but these days of buying over the telephone and accepting a quote means there should be a stated method of calculation I reckon, so its a level playing field.

 

[MooreToolsPlease]

I would say 40% wastage is fairly average, especially from sawn boards.
I always charge my material out at 40% waste, but its inevitable I will end up with more.
Although the wastage is normally off cuts and not shavings as is your case. So at least I can use the off cuts some time in the future.
What is the the other dimension that you typically use? It might be better off buying material to suit your width, and then running 10mm strips out of the boards width.