Hola,
Nando, a friend of mine, sent to me this link. Good pics inside.
http://www.balsaboardseurope.com/
I hope you “woodaholics” will enjoy it!!!
Hola,
Nando, a friend of mine, sent to me this link. Good pics inside.
http://www.balsaboardseurope.com/
I hope you “woodaholics” will enjoy it!!!
Thanks for that,
I’ve never seen the insides of a hollow balsa blank before, very interesting the way they’re made…
Hola,
PICS on the web are a lot bigger if you “save them as…” to your PC.
I have a frind here who bought 2 balsa boards at Ecuador 3 years ago: one solid and one “lighter”.
He told me “lighter boards” are made like solid boards: clamp, shape BUT then, they hand-saw lengthwise the board, get 2 separate simmetric pieces and drill holes perpendicular to the stringer for lightenning each piece, being careful not to drill trough the deck, bottom and rails. Then they glue the 2 pieces together with a thin stringer betweem them and continue glassing.
I don’t know if this is true or partially true. PICS at balsaboardseurope show another different technique for hollow boards.
Very close to Paul Jensens hollowboards, just made entierly from (thick) balsa. Interesting. From what I’ve read here on swaylocks the way it was done in Ecuador by shaping it then pulling it apart and hollow it out is the norm.
Regardless, they are a little out of my budget…
regards,
…
Håvard
Hey Hicksy, check this out:
http://www.wetsand.com/travel/resource-travel.asp?ResourceID=2152
Another way to make hollow balsa boards.
I think the boards in balsaboardeurope.com are more similar to the original Tom Blake boards, just smaller and balsa made.
Jack
Here’s for you, Hicksy: this is a shot of a chambered red cedar board that I am currently building, lying on the racks. The chambering is done with a mortice-maker.
They’re using precisely skip kozminski’s (patented) technic for building hollow blanks.
More info here :
The chambering is done with a mortice-maker.
Very nice, and as the happy owner of a mortising machine ( as we spell it here ) ;
“Duuh - why didn’t I think of that?” Damn, that’s slick!
Just thinking about it, the square mortised cutouts might tend to shear/crack at the corners under stress ( along the grain) , though if you’re using solid sections between the mortised sections I think you’ll have no problems. Unlike a foam blank with a stringer, you have the whole board made of something with the same bending and compression characteristics.
Besides…if your mortising machine uses a round shank square mortising chisel, you could set it at 45° for those corner cuts, giving you a kind of ‘fillet’ or gusset at the corners.
Do you bandsaw the sections, mortise, glue-up and then shape rails and deck-camber? ?
Thanks
doc…
I’m very interested too. please post more pics and a brief explanation of what you are doing. Mortising Machine? Isn’t it a router? (I would use a router to do that kind of chambering)
Jack
Thanks Balsa and Jack
NOW I know what I’ll be making this summer!!!
Hi Doc, Jstephen and Hicksy. Thanks for showing interest. Here’s what I do:
First, select good, dry, red cedar lumber. The lighter the better, of course. This one was 8’ x 6" 4". (Red cedar is hard to find in widths over 6", but this is the minimum if you want to come out with some kind of rocker…)
You will need 6 pieces of 4" to make a reasonably wide board. Keep in mind you will have to joint-plane them (is that the right term, Doc?) to make them perfectly straight, which in turn will make glueing them quite easy. But you will lose some width doing this.
Arrange your lumbers side by side for colour, grain, etc… Write a number or any distinctive mark on each so that you can re-assemble them quickly in the same way.
Draw a rough outline. This will allow you to cut excess wood on the side lumbers.
Make a rocker template out of some cheap plywood or anything else and draw it on the 6" wide sides. The 3 center pieces will use the full template but you will have to position it correctly for the 3 others since they are shorter, OK?
Here’s the hard part: band-saw the rocker in each lumber. The more precise it is, the less work with the planer afterwards. But it’s still better to cut 1/8" outside than 1/8" INSIDE of the line drawn… Cutting long pieces with a band-saw requires some skill. I think Doc will agree…
Now you have your 6 pieces with the proper rocker in. (Well, nearly…) What I do here is a “blank” assembly. This means I don’t glue the pieces together but rather make them stay together using wood pegs between them. That’s a bit hard to explain, I’ll have some photos later in the day. Just wait…
Once this is done, you can draw the outline with your template and cut it out. Circular saw works best, of course your blade should be deep enough for the maximum thickness of the blank.
From then on, it’s just shaping as usual. You may go as far as rough finish. If we were using balsa, I wouldn’t shape the rails (clamps or straps may dent it when glueing) but red cedar is much stronger and won’t dent as easily. Still it’s better to leave an “error margin”…
Your board being basically shaped, separate the pieces. I find the “pegs” solution to be more practical than glueing and then banging the board on the floor to unglue it as I have seen it suggested here in other threads…
Make a chambering template, pretty much like you did with the rocker template, except with chambers in it. Draw it on each piece of wood, once again paying attention to the right position.
Then it’s up to the “mortising machine”… Photos will be posted…
Glue up the parts together, sand-finish, glass, enjoy or hang to the wall, that’s up to you…
(Sorry to have been so long. Photos will be easier to follow, I guess. Going to the shop to shoot some…)
All right, here we go again. So we have cut the rocker with a band-saw and drilled a few holes for fluted wooden pegs. Those will be forced into the holes, making for a steady blank assembly but still fairly easy to disassemble:
This is what your blank looks like once it has been outlined, roughly shaped and disassembled:
Use the chambering template for your first piece. Then use this first piece to draw the exact position of chambers on the next, and so on. Then you’re up for the mortising machine. Here it is:
The machine can be set with traveling stoppers at the beginning and end of the mortise, which makes it easy and quick to start and stop precisely at the right places each time.
The chisel is a square one with a drill inside of it. The drill makes a hole and the chisel cuts through the wood at the same time, “finishing” the four corners into a perfect square:
Here is half a chamber already done. The whole process takes about 3 to 5 minutes for each chamber once you get used to it and the machine has been correctly set, etc…
Now it’s done! (Except you have to do it again and again and again and…)
…and while you were working, good ol’ Wingosaurus Rex has been watching you all the time…
'Better make no mistakes!!!
They’re using precisely skip kozminski’s (patented) technic for building hollow blanks.
More info here :
Skips patented technique?? That’s just so much bullshit. I was using that method first in 1964, and I think Diff and Channin were using it by '69 or '70, and I’m sure it was used in the 30’s or 40’s by others. And has been the STANDEARD TECHNIQUE in the industry since the early '70’s. How the hell do you patent NORMAL AND ORDINARY WOODWORKING PROCESSES?
Skip’s technic is NOT the ordinary way to do a balsa board. To my understanding, it’s a very different approach from both the Blake/Jensen method and the traditionnal chambering technics. And he did patent the technic as this is how I learnt about it (by reading the patent).
Here’s what he says on his website :
… Now, they are basically two sheets of balsa separated every 6 or 8 inches by balsa separators which dictate the thickness and foil of the blank. These sheets and separators are then flexed and clamped over a jig or strongback that induces the rocker. Other guys cut their rocker out of straight pieces creating lots of expensive waste and they can never get 9 inches of nose rocker and 3 inches of tail rocker that I put on my 12 foot gun blank.
These compartmentalized cores are then cut into 3 or 4 pieces and glued up again on the rocker jig with 2-3 cedar or mahogany stringers. These multi-stringered cores are then finished off with strips of balsa that approximately focus on the plan shape of the finished stick. This is the only way I have found (after building about 1200 boards) to make a 20-25 pound, 9’6” which will be stronger than any foam 9’6”, even if it weighs 100 lb.
Patent number is : US 4302859
Patent can be downloaded here : http://www.patentmatic.com/
They’re using precisely skip kozminski’s (patented) technic for building hollow blanks.
More info here :
PierreB,
The above is your post following the excellent photos of a hollowing/chambering technique. The comments from Skips’ website that you posted in your response to my post, seem to describe something very different than in the photos, but none the less an ORDINARY woodworking process. In fact not too unlike the process of building wing ribs developed by the Wright Bros., and probably Bleriot (sp?). Point is it’s NOT new, with the possible exception of adding a cosmetic Balsa skin. Consequently I stand by my original post.
Nicely described - a couple of comments, if I may;
Keep in mind you will have to joint-plane them (is that the right term, Doc?) to make them perfectly straight, which in turn will make glueing them quite easy. But you will lose some width doing this.
That’s the correct term, though I just say ‘run them through the jointer’ - for those unfamiliar with what that is -
A Delta-Rockwell 4" jointer planer - think of it as a power plane upside down with a 90° fence on it. Instead of moving it across what you’re cutting, you feed the material through it.
( courtesy of the vacationing Keith Melville - mine is an open-stand version of the same tool. )
I generally cut things to allow for 2 passes through the jointer, each side, and set mine at around 3/32 of an inch- call it .75mm, 1.5mm total.
- Here’s the hard part: band-saw the rocker in each lumber. The more precise it is, the less work with the planer afterwards. But it’s still better to cut 1/8" outside than 1/8" INSIDE of the line drawn… Cutting long pieces with a band-saw requires some skill. I think Doc will agree…
That it is - a very sharp bandsaw blade is a big help, plus a strong light on your saw so that you can see the lines on the wood.
Another cute trick, by the way - if you have access to a shaper ( the woodworking machine, not the guy covered in foam dust ) you can fasten your template to the wood, use a top-mounted sleeve or bearing and a straight cutter to cut the outline shape. Slow, careful feed, of course. Especially nice if you’re making several, as the template can be reused time and again. Fasten it to the jointed pice of wood with screws, which can be placed where your mortises will go.
While I haven’t used this method ( naturally ) I have seen it used for making side planks for production small boats.
Lets see- do you use what we call a dowelling jig to drill the holes for your wood pegs ( or locating pins, as it were?
I like the vise/clamp arrangement on your mortiser - mine doesn’t have one, yet, though I think I can rig something with an old woodworking vise.
I note that you have your mortising chisels set in the machine so they send the chips into the mortise as you work from one end to the other. Mine is set up a little different, I have mine rotated 90° so that they come out on top of the piece I’m working on rather than in the mortise itself… But I cut a lot of quite narrow (1/4" ~6mm ) mortises in oak, so the chips tend to clog the mortise.
Nicely described…
Merci
doc…
Very well explained Balsa, Doc, Bill.
Tell me do these chambered boards need to be vented in any way?
Balsa, keep this thread going until it’s finished, I know lots of people will be interested in this process.