wastage again

[devonwoody]

This is the second time this season I have cleared out the sawdust from under the tablesaw cabinet.
I reckon about 2ft long by 4" high by 12" wide. so that is an estimate of one and a half cubic feet of hardwood gone in the bin. Most probably 40% waste from each board.

 

[OPJ]

That does seem like a lot of waste... Have you considered buying a blade with a thinner saw kerf?

 

[StevieB]

A cubic ft is 12" x 12" x 12". You describe 12" x 24" x 4" which is 2/3rds of a cubic ft. Secondly, sawdust is less dense than the timber it was cut from. As a consequence your sawdust is actually alot less than 2/3rds of a cu ft in timber terms. Thus your 40% wastage is a bit high I would be more concerned about why you dust extraction pipe is missing that amount of dust.....

Steve

 

[Chems]

Yes I was thinking the same as Stevie. Other thing is, with your box making you are doing a lot of cuts to rip things into strips where as when making other things you may only just dimension the wood.

 

[maltrout512]

The only way that I can see of getting an idea of saw dust waste is to find the weight of a given size of the timber. You can then workout how much a cubic metre is. Then weigh the saw dust and work off the figures that you have from the solid wood.
May be (barking) up the wrong tree no!!!!

 

[devonwoody]

SteveB, it was the second time so double your figure?
Yes the dust exraction is very inefficient.

 

[Richard Findley]

Hi DW,

Maths isn't my strong point but you MUST have your sums wrong somewhere there.... 40% Wastage on saw cuts? Your blade is what 3mm/3.5mm wide, to get 40% wastage just from that your board must only have been 5-6mm wide!!!

Thats the trouble with wood I'm affraid - it's full of dust :wink: :lol:

Richard

 

[devonwoody]

Thank you Richard, never looked at it that way, my blood pressure has reduced after reading that.

 

[FatFreddysCat]

40% would be an awfully high wastage factor, but are you aware of how much wood is wasted in shavings, sawdust and offcuts? On stuff like English walnut I'd expect wastage to be 25%-ish whilst for rough sawn softwoods 12 to 20% is a truer estimate. Either way that's what we budget. And if you want something that's really bad for wastage try English burr walnut veneer. last lot we did the wastage factor was nearer 200%

 

[devonwoody]

Yes FFC, I think overall I am running at around 40% wastage on pure hobbywork. Plus what has already been wasted before arrival at my home.

 

[yetloh]

If that amount of dust is collecting in the machine I would be concerned about the amount in the workshop atmosphere. A recent Fine Woodworking had a good article on dramatically improving the extraction performance of table saws. If I had one I would certainly do the mods.

Jim

 

[devonwoody]

Regarding the tablesaw, I am using a 60T blade most of the time even for light ripping jobs. (Tony says he does the same ) Perhaps that is why the extraction system cannot cope with all the extra sawdust generated.

 

[Mikey R]

...On stuff like English walnut I'd expect wastage to be 25%-ish whilst for rough sawn softwoods 12 to 20% is a truer estimate. Either way that's what we budget. And if you want something that's really bad for wastage try English burr walnut veneer. last lot we did the wastage factor was nearer 200%

Hi, newbie question here -
To calculate your wastage percentage, I guess you are taking the volume you will require, and adding on the percentage that will be waste, to get the amount of timber needed to make the project?

So, 25% wastage will mean, if your project will need 4 cuft, then you will need to start with 5 cuft? And if your wastage is 200%, then to end with 4 cuft you'll need to start with 12 cuft?

Im asking as Im trying to figure out how much extra beech I'll need for my bench.

Cheers!

 

[yetloh]

I'm surprised you find such a low wastage rate. For waney edged oak I buy 50% more than my cutting list and spreadsheet calculator of cubic feet tells me I will need. If it is brown oak I buy twice the calculated amount. OK, it allows me to make say an extra leg blank in case of mistakes and I will have a little left over, but their is nothing worse than struggling to get the components out of the available wood and having to compromise or grain orientation and figure.

Jim