Preparing sawn timber - advice needed

[rkchapman]

I have layed out all the pieces of my bookcase to fit on the two sawn planks of 9x1 Sapele that I bought for the project, and realized that I've never actually converted sawn timber before, and I'm not sure the best way to proceed...

Here's the cutlist:

Is it best to
a) flatten the boards at full size, then cut them up
b) Cut into shorter lengths (where the cutting diagram permits), flatten those, then cut up
c) Cut into final size, then flatten

I don't have a planer though I do have a thicknesser and a drum sander. The thicknesser is prone to snip at the ends though. If the job is impossible without a planer, I could be persuaded to buy one. But even if I do it probably won't have 9 inch capacity...

 

[p111dom]

You don't need a planer but you'll need to make a sled to give the planer a flat side to reference against. The planks need to be less than 8 feet long if you're going to use MDF (as I would) for the sled. Im presuming you have a table saw??? You could buy half sheet of 18mm MDF from B&Q 2feet by 8 feet. To save hassle its better to get them to rip it again to two 1 by 8's. If your stock is pretty flat as in not wedge shaped then you can simply double sided tape it to the MDF board. Its advisable to screw a scrap piece of MDF to the rear of the jig (obviously much lower than the stock so it doesn't catch your planer knives) so if the tape fails the boards don't come apart while running throught the thicknesser. Simply run the combined jig and stock through the thicknesser until the top is flat then remove the stock from the jig, turn over and run through again.

If the stock is wedge shaped the in becomes a little more complicated. The best thing to do in this instance it to rip some one inch wide strips of MDF from the second board and stack them so they are higher than the stock. Glue them together so they run down the sides of the jig. This gives the thicknesser rollers something to grip onto so it can pull the jig through. These parts are sacrificial as they will get planed down with the stock.

Its a hassle but a half sheets of MDF will set you back about £10. Way less than buying a planer.

 

[Philly]

Richard
Yes, cut them into shorter sections. And if they are cupped in their width, rip them down into narrower sections before thicknessing them - you'll end up with thicker stock afterwards.
And by ripping them down you will be able to surface plane them on a 6 inch jointer.
Hope this helps
Philly

 

[OPJ]

If at all possible, skim about 0.5mm off each surface before setting out your components and cutting. With some boards, it's clear to see where the grain is and what it's doing. Otherwise, lightly cutting in to the surface will allow you to be more selective for grain and other characteristics. You could even use a hand plane or scraper.

Then, you should look to crosscut them in to more manageable lengths. If you've only got a small table saw then, a jigsaw may be the tool to use here, looking at your layout. After that, set the fence on your saw and start ripping!

For the sake of your own safety, try to keep lengths as long as possible (pairing components works well) when you come to planing them up.

 

[Ironballs]

Phil's advice is good, also worth bearing in mind that if you're prone to getting snipe when thicknessing that using shorter lengths reduces the risk - often it's the tipping of a poorly supported piece as it exits that will cause the other end to rise a little and get sniped.

Do also remember what the distance is between your in and outfeed rollers, you can't put anything through that is shorter than this distance or they'll get eaten!

 

[rkchapman]

Thanks for the tips everyone.

The boards don't seem to be cupped but there is quite a bit of twist in the shorter one (that seems to have developed since I bought it yesterday)

Am I better off using twisted sections for shorter pieces? Narrower pieces?

I was thinking that keeping boards long would minimize snip issues (at least, minimize the amount affected) but if shorter is better that makes life easier.

 

[BradNaylor]

I never actually work out a cutting diagram like that.

You will find that if you cut your planks to manageable and logical lengths and then cut the biggest pieces first from the smallest available length everything will sort itself out and you will be left with very little waste.

It doesn't sound very scientific, but it works!

Your diagram takes no account of defects in the wood or attractive figure which you may want to put at the front of your piece.

Experience will show you that a less regimented procedure tends to work better

Cheers
Brad

 

[rkchapman]

Your diagram takes no account of defects in the wood or attractive figure which you may want to put at the front of your piece.

This is true, and I don't intend to follow the cutting diagram religiously for that reason. I'm really using to work out at what lengths I can safely cut the timber when doing my initial "cut into manageble sizes" bit.

Another question - should I leave the wood in my shed to stabilize before I start, and if so for how long (and should I at least do the initial crosscuts first) ?

 

[Ironballs]

Leave the wood in your house to acclimatise, will be warmer and drier than your shed

 

[Night Train]

I normally take a scraping off the face of each board just to see the grain and any defects to avoid.
I would then try to arrange my cutting into sections of similar cross section so that a rip along the board wil give me a whole run of legs for instance. However, depending on the timber I might cross cut a leg lenght and then ripinto legs. It depends on the grain and defects.

I will rip to reduce cup and twist before planing and thicknessing though and I have been known to spend many hours with templates or measurements to make best use of the timber because of this.

Leaving it to acclimatise is good. Also leaving it acclimatise in between processing helps as well as processing in stages to allow for movement in between.

 

[rkchapman]

I tried the sled technique and it more or less worked - I had a 2 foot length that was fairly badly twisted and I've managed to trade 6mm of twist for half a mm or so of bow and some snipe.

I had used wedges at each end to support under the twisted wood to flatten one side but I suspect I should have supported the middle too (hence the bow).

 

[rkchapman]

As predicted by some above, the cutting diagram turned out to be mostly a waste of time... actually it turned out to be worse than that as I had some pieces on at the wrong size which means I now have my two sides dry assembed but about an inch narrower than they were in the plan.

I'm in two minds whether to recut the pieces to the original design or modify the design to accomodate the mistake.