Cutting Balsa
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Cutting Balsa
How do y'all go 'bout cutting balsa parts?
I'm a hobbiest of the low or no buddjet verity. I have a bit of balsa that where the elarons of a Zagi 400. I've almost used up all the balsa from one, and have hot been able to get a single good 2mm x 2mm x (4 to 10 cm) piece!
So ... how do you cut balsa?
I'm a hobbiest of the low or no buddjet verity. I have a bit of balsa that where the elarons of a Zagi 400. I've almost used up all the balsa from one, and have hot been able to get a single good 2mm x 2mm x (4 to 10 cm) piece!
So ... how do you cut balsa?
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Cutting Balsa
With a razor knife.
You need to get or make a balsa stripper to get long, even cuts. You can make one from a single edge razor/scraper blade and a couple of blocks of wood. Cut one block appx 1/2 inch tall, 4 inch long and the width of the desired strip stock. Cut another the same length, taller by the the height of the stock to be stripped and appx 1/4 nch thick. Glue and clamp together. Affix the razor blade to the stripping guide with a couple of screws, such that its cutting edge goes down at about a 45 deg angle, and it will just meet the tabletop when the guide isheld in cutting position. This stripper will last a LONG time if used properly.
Make your cuts in 1 pass for stock under 1/8 inch thick. For thicker stock, you need to make appx 1 pass per 1/8 inch thickness. If its over 1/4 inch thick... you just about need to get a miniature table saw to get good straight long pieces.
You need to get or make a balsa stripper to get long, even cuts. You can make one from a single edge razor/scraper blade and a couple of blocks of wood. Cut one block appx 1/2 inch tall, 4 inch long and the width of the desired strip stock. Cut another the same length, taller by the the height of the stock to be stripped and appx 1/4 nch thick. Glue and clamp together. Affix the razor blade to the stripping guide with a couple of screws, such that its cutting edge goes down at about a 45 deg angle, and it will just meet the tabletop when the guide isheld in cutting position. This stripper will last a LONG time if used properly.
Make your cuts in 1 pass for stock under 1/8 inch thick. For thicker stock, you need to make appx 1 pass per 1/8 inch thickness. If its over 1/4 inch thick... you just about need to get a miniature table saw to get good straight long pieces.
#3
Stripping Balsa
The stripper may be the most valuable single tool I own. Personally, I use a commercial one, but ya doesn't has to. A homemade one is well worth the effort and often more precise. (If you want a commercial one, though, I use the Master Airscrew tool which does an excellent job -- and I bought two of them at R/C flea markets for $2 or $3 each).
One thing I have found is that a hard piece of wood with a pronounced grain can drag the blade and make it very hard to get a straight cut. When that's happening, I have to recut the edge of the sheet stock with a metal yardstick and exacto knife, make sure the blade in the stripper is very sharp, and cut my strips in very shallow repeated cuts... sometimes taking only 1/16 or a little less on each pass so the blade can do the steering instead of having the grain drag it around.
Here's how I get shallower cuts with the Master Airscrew stripper without having to reset the blade... their stripper is designed such that the bottom is a grid of rectangular voids separated by vertical webs. I made a few "bolster blocks" for it in different thicknesses -- each bolster being a piece of scrap balsa the size of the bottom of the tool with a couple of little balsa strips glued on. The strips fit into one or two of the voids in the underside of the tool to keep the bolster from sliding out from under when the tool is used. The bolster just raises the tool off the surface, so the cut is shallower by whatever is the thickness of the bolster.
So, for instance, for stripping hard 1/4" sheet, I'll usually start with a 3/16" bolster so the first cut is only 1/16" deep. Then I can go to a 1/8" bolster for the next pass and I may not need one at all to cut the last 1/8". It's most important that the first pass(es) be straight and true, so they should be doing the easiest, shallowest cuts... after those, the partial cuts you've already made will help guide the blade, so you can take a bit more off on the later cutting passes.
Oh, the other thing on a stripper like mine is that the stripper guide face that rides along the edge of the wood is not quite verticle as manufactured... and that means that the tool will want to make slightly angled cuts, which you do not want. I trued mine by first truing up my sanding disk, then taking the blade and blade retainer off the stripper, backing up the blade carriage til it's flush with the face of the guide side of the tool body, scribbled on the carriage end and guide face, then sanded on the squared-up disk until the ink was almost completely gone. That made the guide face good and square and flat, and it made the blade carriage good and parallel to the guide. It was already a good tool, but it's way way better now.
One thing I have found is that a hard piece of wood with a pronounced grain can drag the blade and make it very hard to get a straight cut. When that's happening, I have to recut the edge of the sheet stock with a metal yardstick and exacto knife, make sure the blade in the stripper is very sharp, and cut my strips in very shallow repeated cuts... sometimes taking only 1/16 or a little less on each pass so the blade can do the steering instead of having the grain drag it around.
Here's how I get shallower cuts with the Master Airscrew stripper without having to reset the blade... their stripper is designed such that the bottom is a grid of rectangular voids separated by vertical webs. I made a few "bolster blocks" for it in different thicknesses -- each bolster being a piece of scrap balsa the size of the bottom of the tool with a couple of little balsa strips glued on. The strips fit into one or two of the voids in the underside of the tool to keep the bolster from sliding out from under when the tool is used. The bolster just raises the tool off the surface, so the cut is shallower by whatever is the thickness of the bolster.
So, for instance, for stripping hard 1/4" sheet, I'll usually start with a 3/16" bolster so the first cut is only 1/16" deep. Then I can go to a 1/8" bolster for the next pass and I may not need one at all to cut the last 1/8". It's most important that the first pass(es) be straight and true, so they should be doing the easiest, shallowest cuts... after those, the partial cuts you've already made will help guide the blade, so you can take a bit more off on the later cutting passes.
Oh, the other thing on a stripper like mine is that the stripper guide face that rides along the edge of the wood is not quite verticle as manufactured... and that means that the tool will want to make slightly angled cuts, which you do not want. I trued mine by first truing up my sanding disk, then taking the blade and blade retainer off the stripper, backing up the blade carriage til it's flush with the face of the guide side of the tool body, scribbled on the carriage end and guide face, then sanded on the squared-up disk until the ink was almost completely gone. That made the guide face good and square and flat, and it made the blade carriage good and parallel to the guide. It was already a good tool, but it's way way better now.
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Stripping Balsa
4 - 10 cm length pieces are realtively short. You can probably get away with a steel straight ege, and a hobby knife. 2mm is close to 1/16" - 5/64" so you can probably get away with 1/16 or 3/32" sheet. get a typical sheet (3" x 36" long), and chop one piece 4 - 10 cm long, then strip it to the desired width.. (color the top of the sheet before you cut, so you know which is the thick end!)