Acoustic Plates - Waste Factor

[erikbojerik]

A few days ago I took a billet of nice dry walnut and cut myself some back plates for acoustics, keeping track of the starting thickness and the final yield. If any of you guys have done this before, I'd like to compare my numbers and see how I'm doing, and if there's anything in my setup that I could tweek to improve the yield.

Starting billet: 1.45" thick, 8-1/2" wide, 22" long

bandsaw blade width: 0.035" (1" wide 2 TPI hook-tooth)

blade tooth width: 0.050"

kerf width: 0.060:

My sequence was this, starting with a planed billet:

1) Cut the plate off with a 0.125" gap between fence and blade edge (too optimistic, I know...now...)

2) Remove the saw marks on the plate (thickness sander)

3) Remove saw marks on the billet (thickness planer)

-repeat

I managed to get 3 sets of backs (0.103", 0.091" and 0.085") and one thin plate (0.070") for headstock laminates, so 6 cuts on the bandsaw. They are on the thin side, but OK maybe I'll make a classical or two.

So my yield breaks down like this:

Finished pieces: 0.628" (43%)

Kerf waste: 0.360" (25%)

Finishing waste: 0.462" (32%)

For each cut, waste from saw kerf (0.060") plus finishing (0.077") is 0.137" per cut.

How does this spec out compared to your numbers?

[fryovanni]

Hmmm...

It is kinda hard to check percentages against mine. If I am cutting back sets to sell I would have to cut thicker than that. Generally .14" is universally accepted, .125" is fine for most guys, .1" or less is too thin for most folks (makes it tricky to control while joining). I can say my Timberwolf will remove about .05" and requires another .02"-.03" or so to clean the saw marks. My woodslicer blades take .03" and require about .01"-.015" to clean (extreamly smooth cuts). As far as surfacing. I square my billets then cut. I don't re-surface between cuts unless the blade is cutting wrong (I check the surfaces with a staight edge between cuts). When I am all done cutting I set my thickness sander and just start running (all at the same time, less trouble that way). However that all pans out.... Real world 3/4" (two sets), 1" (2 sets and a veneer). 8/4 (1-7/8-2") will yeild a solid 4 sets plus veneers. I cut up a slab of Walnut for Chris a while ago we pulled 4 sets sides plus a neck blank 1" out of 2-1/2" slab (if memory serves 9 cuts yeilded about 1/2-5/8" waste *surfaced). The rest of the slab was mixed up backs and drop/carve tops (I don't have a clue what numbers held on those parts). I ripped another slab of Claro into two side and two back billets it yeilded 10 sets plus veneers (it was about 2-1/8" slabs).

It seems like you may be losing a little extra material on the clean up. Honestly a woodslicer could bring your losses down by 50% , and you know how expensive th wood is so the blade will pay for itself in a heartbeat. The thinner cut will cut harder wood with less effort because you are taking a lot less material, and the cut is smooooootttthhhhh.

All that is pretty much small numbers though. Sounds like your cuts are damn good mister.

Peace,Rich

[erikbojerik]

Thanks Rich....clearly I should be able to do better, even with my (cheap) blade taking a 0.060" bite.

I guess you get your Woodslicers from Highland, eh? Their resawing tutorial was pretty informative, I can see how freehanding it against a post fence (as I was doing) leads to more waste.

I think I can do better next time around.

[fryovanni]

Thanks Rich....clearly I should be able to do better, even with my (cheap) blade taking a 0.060" bite.

I guess you get your Woodslicers from Highland, eh? Their resawing tutorial was pretty informative, I can see how freehanding it against a post fence (as I was doing) leads to more waste.

I think I can do better next time around.

Your blade taking .060" bite is pretty normal (very close to what I get from Timberwolf). I tell you though Woodslicers will blow your mind with fine kerf, smooth cuts, and they run nice and cool (I do get them from Highland, I think they are the only place you can get them).

As far as the fence. I just use a billet (what ever wood I have handy). I found it is good to not have a lot of guide after the wood has cleared the blade, but it seems like a couple of inches keeps the wood against the guide better. One of these days I will upgrade to a larger saw and pick up a feed. Then I won't have to screw around with the "me" variable. Kinda like my sander (let the machine and conveyor do the job right, so I don't mess things up ).

Peace,Rich