Help a newb do lumber math


chrisphr

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Decided to make Gregory Paolini's arts and crafts inspired coffee table as my first hardwood furniture project. There is a nice video series that goes with the plans, so feel pretty good about my chances of success.

First opportunity for experience will be buying rough sawn lumber, in this case QS white oak, $5 a bf at the local sawmill I plan to go to. Website lists quality as select/fas.

The plans say 16bf, but that sounds really light to me, maybe that is the bf for the milled finished cut list.

My calculations I think over estimate, perhaps more than necessary, I wanted to get your thoughts. The list below is the cultist followed by my bf calc:

Top: 1@3/4x23x46-3/4, 8bf 4/4

Breadboard end: 2@7/8x3x23-1/4, 4bf 5/4

Shelf: 1@3/4x14-3/4x46, 6bf 4/4

Leg: 4@2x2x18, 5bf 4/4 (these would be laminated, the veneered to make the legs appear QS from all 4 sides)

Lower rail: 2@3/4x4x18-1/2, 1.5bf 4/4

Upper rail: 2@3/4x3x18-1/2, 1.5bf 4/4

Upper rail long: 2@3/4x3x43-1/4, 4bf 4/4

Slat: 6@1/2x3-1/2x9, 2bf 3/4

Totals: 26bf 4/4, 4bf 5/4, 2bf 3/4, 32bf in total. Let me know how far off you think I am.

I was picturing 8ft boards 6" wide as I was putting this together. Here are the parts that are confusing to me:

Is it a reasonable expectation that the mill will have 3/4 and 5/4 lumber? If not, I suppose I could mill down 4/4 to 1/2". Do you think I can get 7/8" out of 4/4 lumber?

Thank you in advance for your wisdom!

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Mills will should have material in 3/4, 4/4, 5/4, 6/4, 8/4 on hand.

 

Getting 7/8 out of 4/4 lumber is possible if you're diligent in your milling

 

Looks to me like your plans are finished size, not rough cut.

 

Top: 1@3/4x23x46-3/4 - 7.47 BF

Breadboard end: 2@7/8x3x23 - .96 BF

Shelf: 1@3/4x14-3/4x46  - 4.71 BF

Leg: 4@2x2x18,  - 2 BF

Lower rail: 2@3/4x4x18-1/2 - 1.03 BF

Upper rail: 2@3/4x3x18-1/2 - .77 BF

Upper rail long: 2@3/4x3x43-1/4 - 1.8 BF

Slat: 6@1/2x3-1/2x9 - 1.31 BF

 

Total: 20.05 BF

 

I used this site to calculate - http://www.woodbin.com/calcs/footulator.htm

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Tables like this are easy for example your table is 2x4 your top (made up dimensions) is 2*4=8*.20=1.6 so round up to 10. Do the same for the sides @ 2x2 rounded up is 5 each. The shelf and apron will be the same as the top. That's 30 square feet and I'd buy all 5/4.

I would shy away veneering the leg if that is what the plan calls for and use a quadralinear or thin stave core. Gustav style legs failed often. I've done hundreds of those post on kitchen islands and learned the hard way.

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Tables like this are easy for example your table is 2x4 your top (made up dimensions) is 2*4=8*.20=1.6 so round up to 10. Do the same for the sides @ 2x2 rounded up is 5 each. The shelf and apron will be the same as the top. That's 30 square feet and I'd buy all 5/4.

I would shy away veneering the leg if that is what the plan calls for and use a quadralinear or thin stave core. Gustav style legs failed often. I've done hundreds of those post on kitchen islands and learned the hard way.

Thanks for the shortcut way to do the calculations, that is helpful.

Are you recommending 5/4 to ensure I can with confidence get to 3/4" finished with all boards I buy, or are you suggesting I target a thicker finished thickness?

Thanks for the heads up on the legs, furniture is not treated gently in my house, so durability counts! I didn't know the terms you used as alternative methods so googled them. What the plan calls for the legs is cutting a slice about a quarter inch thick to cover the lamination joints and make it appear it is quarter sawn on all four sides - I was (perhaps incorrectly) calling this a veneer. Looking up thin stave core, it looks similar. Is this a case of me using incorrect terms, or is thin stave core something different?

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Thanks for the shortcut way to do the calculations, that is helpful.

Are you recommending 5/4 to ensure I can with confidence get to 3/4" finished with all boards I buy, or are you suggesting I target a thicker finished thickness?

Thanks for the heads up on the legs, furniture is not treated gently in my house, so durability counts! I didn't know the terms you used as alternative methods so googled them. What the plan calls for the legs is cutting a slice about a quarter inch thick to cover the lamination joints and make it appear it is quarter sawn on all four sides - I was (perhaps incorrectly) calling this a veneer. Looking up thin stave core, it looks similar. Is this a case of me using incorrect terms, or is thin stave core something different?

Instead of gluing up 3 3/4 pieces and veneering the edge cut your pieces 1/4 preferably less and laminate them back together. This will make the leg more stable and keep the veneered edge from failing in the future. Quadalinear is best but thin stave works. 5/4 is easier to work with and makes it a bunch easier. In the long run the waste from 4/4 will be more than using 5/4.

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Are you picking through the rack to find these boards yourself?  Or do you have to run the numbers and tell your dealer that you want them to pull x feet of lumber?  I've always purchased lumber for one-off projects by the former method, so it's typically a matter of bringing a parts list into the racks and picking things board by board based on what they have.

 

As for thicknesses, there's a lot of variables here but, for certain I wouldn't go ordering 5/4 stock only to turn half of it into hamster bedding.  Workflow plays a role:  Rough cuts first before jointing and planing and you'll save a ton of thickness.  I've routinely been able to get 4/4 stock (especially for smaller pieces such as breadboards) to finish out at a strong 7/8".  How OCD are you when it comes to milling, anyway?  Does the inside face of the aprons or the underside of the top have to be planed all the way down smooth or can you let it pass with a few remaining marks from the sawmill?  Only pets and pests will ever notice and it'll save both wear on your knives as well as a gain you a few more fractions of an inch on the finished thickness.

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.

 

I hate to spend other people's money as much as the next guy on the forum ;-) but - As a novice (me too) I would err on the side of buying extra lumber. QS white oak can be used for so many other projects at $5/bd ft your doing pretty good on price, why not have extra on hand?

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Plan for extra width in the pieces used for the top to allow for "grain straightening".  QSWO has a very linier grain structure under the ray flecks, and quite often in rough stock that grain does not run parallel to the board edge.  If this is the case, it is best to cut a new edge on the band saw or with a jig saw that follows the grain not the original board edge.  On longer pieces for, say, a table top, this can mean that a 7" wide board might only yield a 5" wide finished piece. see the attached sketch.  This is another reason it is best to hand pick your stock if you can and always over buy.

 

Scan001 (3).pdf

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Thanks for all the great tips everyone! I did get some disappointing news, mill is all out of QSWO unless I want to wait for it to be sawn and dried. There should be an asterix next to the price on the website! :-).

I think I am going to go with walnut instead. I will definitely buy extra, I will need it for my inevitable mistakes. Since it is hard for me to find the time to drive to the mill, cost is definitely not the top priority.

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Chris, you are going to love working with walnut! My first real hardwood project was built using walnut and it was quite the experience. The smell of the wood while sanding, the luxurious feel of the wood after sanding. Truly art that has to be touched!!! Don't be surprised by the amount of sap wood you may find. Buy it anyway, the sapwood can be stained to come in line with the heartwood. At least you will know that the wood wasn't steamed ;-) If you own a bandsaw or will in the future, get yourself a few small pieces of 8/4 or 12/4 - happy hunting and post some pics of what you score!

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  • 4 weeks later...

Instead of gluing up 3 3/4 pieces and veneering the edge cut your pieces 1/4 preferably less and laminate them back together. This will make the leg more stable and keep the veneered edge from failing in the future. Quadalinear is best but thin stave works. 5/4 is easier to work with and makes it a bunch easier. In the long run the waste from 4/4 will be more than using 5/4.

PB, just now starting on the legs. I was planning on using your idea of slicing the pieces in 1/4 pieces then gluing them back together. Re-reading this post, my original plan was to use QSWO and attempt to construct in a way that the legs would appear QS on all sides. Now that I am using walnut and am not attempting to simulate any particular grain pattern on all four sides should I instead minimize the number of pieces I am gluing together (if I am careful with my milling, I might be able to get to the leg width in one lamination)? Wasn't sure if the thin laminations were intended to facilitate the veneer in the original plan, or is just best practice for table legs.

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PB, just now starting on the legs. I was planning on using your idea of slicing the pieces in 1/4 pieces then gluing them back together. Re-reading this post, my original plan was to use QSWO and attempt to construct in a way that the legs would appear QS on all sides. Now that I am using walnut and am not attempting to simulate any particular grain pattern on all four sides should I instead minimize the number of pieces I am gluing together (if I am careful with my milling, I might be able to get to the leg width in one lamination)? Wasn't sure if the thin laminations were intended to facilitate the veneer in the original plan, or is just best practice for table legs.

Yes the less glue lines the better since you are not veneering.

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