Strip straightening

Balsa is a natural material that has once had a life of it's own... It has internal stresses that are released when you cut it. If I can't get a straight strip (I cut all my stripwood) from one plank, I'll try another... It's just the nature of the material.

BTW, the first strip from the edge of a plank is often bent, but the next may be straight... try it

-- Philip Rawson

A live balsa tree has a tremendous amount of internal stress. Each time it is cut, some of the stress is relieved. This makes the wood warp easily. There's not much you can do about it. Most of the strips that you cut will straighten easily when you glue them in place. Trash the ones that don't, or utilize the bends to your advantage such as curved stringers.

Dr.1 Driver "There's a Hun in the sun!"

Both Philip and DR1 are correct. Many balsa suppliers cut strips with multiple saw blades on a single shaft similar to a ganged dado saw setup. This relieves the stresses on both sides of the multiple strips at the same time while allowing many to be cut simultaneously and close to straight. I do it with the Micro-Mart table saw with spacers I machine myself however I can't do multiple strips. I don't know if a multiple blade stripper could be invented? Probably not.

have you tried cutting a bunch oversize then clamping together and hand planing them to final size??

Are you pushing down too hard on the top of the stripper? Once I didn't have the blade extended far enough and in order to make a clean cut, I push down a bit and this causes the strip to curl up as I passed. Other than that I have no trouble with balsa warping coming out of the stripper. Gord Schindler MAAC6694

have you tried cutting a bunch oversize then clamping together and hand planing with a long bodied plane to final size?

Anyne who is relying on a piece of balsa to stay straight without bracing anyway, deserves all the disasters they get IMHO.

Select god medium quarter gran stock for stripping, and discard pieces that have considerable hardness variation across the width.

Wood should not, if from a vertical trunk, have many internal stesses if its dried properly.

Branches ALWAYS have it, as to trees that grew lopsided.

I use a straight edge to make the first cut with a blade. Now there i

a true edge to start useing my balsa stripper. Very few, if any problems with warpage when making strips sown to 1/16. Perhaps I hav been lucky. I do keep a sharp blade in the stripper. And I keep m balsa flat and dry

-- mode

----------------------------------------------------------------------- mode1's Profile:

TNP, Balsa grows so fast that it has tremendous internal stresses in the wood. Add to that the fact that it is almost impossible to get good size pieces of nearly equal density and you have the recipe for curled wood. Even medium soft woods such as fir and pine can have a lot of stress in it. I used to cut furniture frames (just out of high school) and many times you could tell just by looking at the wood. Had some that when you went to rip it it would slit on its own as soon as the blade hit it.

Yup. but if its decentr wood, it won;t have too man streses in it.

Balsa is in sheet form. If thesheet is squarte and flat and of even density, and not too thick, its equalised its stressees more or less.

I suspect the OP 's curling is due to actual physical deformation in cutting..

Good medium quarter grain stock, now my right eye has healed up..

DO NOT take doggie for a walk down the garden on a moonless night without a torch.

Those maple trees jump out and get you!

Here is what I do: Pick the balsa sheets with the straightest grain. I like "A" grain for stripping purposes. "C" grain tend to have pre-loaded stresses when stripped, since the edge is now in the "A" direction. Some of the sheets of balsa you get grain that does not run along the edge of the sheet. Now, take a straight-edge and cut the first cut so that the grain does align with the edge. Now, use your balsa stripper, and run lightly across the sheet, not trying to cut the strip in one shot. Once there is a groove in the wood, the stripper tends to track very smoothly. Trying to force the entire kerf of the blade through the balsa in one shot would stress-load the strip with curve bowing away from the sheet.

-Fritz

-----------== Posted via Newsfeed.Com - Uncensored Usenet News ==----------

-----= Over 100,000 Newsgroups - Unlimited Fast Downloads - 19 Servers =-----

This will probably seem like an ignorant question but how does one go about ordering balsa? I have picked up pieces here and there at the LHS's but have never purchased kit quantities. At the LHS its just balsa, no grades or hardness choices that I have ever seen. I have a couple of plans I am thinking of building in the future plus my winter project is going to be a Super Sportster 40 RCM twin engine kit conversion. I am pretty sure I will need specific grades of balsa for those. I am sure this is a no brainer for the plan and scratch builders but, up till now, I have only used what was in the kits or bought balsa for small repairs. Advice appreciated!

The grade of the balsa is easily determined by looking for the grain at the end of the sheet. but companies like Midwest paints the ends to make it difficult. Once you have a piece of balsa, you can make a cut across the sheet to see what grain it actually is.

Now that you've done this, look at the sheet and see the pattern on the face. It takes only a couple of sheets before you can recognize the pattern of "A" grain sheets (long dark lines running close together on the white sheet) vs. "C" grain (mottled dark areas looking like briar) vs. "B" grain (something in between, and most common). Save the "C" grain for ribs, make stringers from the "A" and use "B" for everything else.

My LHS used to tell me when a new shipment of balsa comes in and I go there with a balance and stress-meter. These days I buy a stack of balsa from Lone Star and spend a night grading and sorting.

Good luck, and when not sure, don't be afraid to just try it .

-Fritz

-----------== Posted via Newsfeed.Com - Uncensored Usenet News ==----------

-----= Over 100,000 Newsgroups - Unlimited Fast Downloads - 19 Servers =-----

"stress meter"??????

It's popularly called "The Bend Test". Dr.1 Driver "There's a Hun in the sun!"