Master Airscrew Balsa Stripper

16 December 2015

I could not cut balsa strips accurately.
I used the stripper in 3 manners.
The first manner was to hold the balsa sheet and feed the stripper through the sheet. I could get  the sheet edge to run along the stripper but not to get the sheet to consistently lie flat on the perpendicular arm of the stripper. It seems that doing it in the air is not good enough.
My second method was to extend the blade until it nearly touches the base of the stripper and then with the balsa sheet flat on a working surface, to run the stripper along the edge of the balsa sheet. With this manner, I noticed the blade wandered due to its flex.
My third method was to reduce the blade to slightly less than the thickness of the sheet. Then I raised the balsa sheet and ran the stripper through. This seems to work better but it was a chore and I have to break loose the strip.
In my opinion, these are all failed attempts.

After thinking it through, I think it should be used like this for better strips.

Procedure:

1. Set the blade normally, where the grooves are. The tip of the blade do not extend longer than the depth of the stripper.
2. Raise the sheet on the work surface. The top of the sheet should be less than the depth of the stripper. The packing surface should be set behind the edge by more than the intended width of strip.
3. Run the stripper against the edge of the sheet and with the stripper flat on the work surface. Ignore the perpendicular arm of the stripper. The blade should run clear of the packing edge and off the work surface. 

This way, I will be using the cutting edge of the blade and not the cutting tip of the blade, and this is thicker, less flex. While it doesn't gaurantee that the strips will be straight, at least the cross section would be consistent.

Other considerations:

1. Use hard balsa sheet for stripping; soft light balsa sheet are of no use for strips, if it gives slightly when pressed with finger pressure alone, it is definitely non-loadbearing. Don't waste time stripping soft light strips, I can afford the 'additional' weight.
2. Use 2 wood blocks (now where can I get them?) to hold the balsa sheet in position: one as the packing piece to lay the balsa sheet, the other over the balsa sheet. They should be longer than the length of balsa sheet in used. While the length of balsa sheet is 36" or 1000mm, I think I will use shorter lengths simply because they are cumbersome otherwise. So, just cut the sheet to shorter length because I don't need strips that long.
3. While the grain of balsa sheet comes running along the edges and won't pose a problem, it has to be checked. If it is off, a straight edge and NT cutter should be used to set the edge along the grain before stripping it down to strips.
4. The first strip can be thrown away if the sheet's edge has any nicks or is rounded. Just use the second strip from the stripper.
5. A bit of curvature in the strip should be ok because balsa is pliable anyway, so just use it where there's some bend in the frame. If it is too much, again use a straight edge and NT cutter to set the edge of the sheet.
6. Unless the framework is symmetrical and all strips are of the same hardness, the frame will pull out of true because of the build up of stress when bending strips.
7. It looks nicer when longerons are the same width and the curved portion bent from balsa strips, but it is ok to use wider straight longerons or sheet keel pieces.
8. Steam the framework while it is still pinned to the building board to relieve stress, I think this is often overlooked and it should be done to relieve stress as much as possible before it is removed from the building board.