How to fabricate plywood fins without power tools?

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OldManRocket

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Do any of you make your own plywood fins without the use of power tools? If so, how do you go about it? If that is not feasible, can it be done easily with "hand" power tools? I'm thinking cut out with a jigsaw and then use a sanding block for final shaping. It seems like a jigsaw might be hard to handle on 1/8" plywood. Would a scrollsaw be a better choice? Is there a "best" practice? I'm not ready to invest in a full set of power tools yet but would like to be able to design and build some custom MPR/HPR rockets.
 
I use a jigsaw for cut, then a belt sander for next stage shaping, then hand finish with a sanding block.

1/8" hasn't been an issue for me I just keep the cut close to the supporting 2x6 the 1/8" ply is sitting on while I cut.

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A hobby razor saw might work. The backing support might make it tough. I seem to remember using a hacksaw blade, but this was many years ago. Power tools spoiled me.
 
A scrollsaw works fine on thinner plywoods, and sanding blocks will help with the match sanding.
 
I had forgotten about coping saws. That might well be the answer. I would really like to accomplish a scratch build using just hand tools before moving on to power. Silly maybe, especially this late in life, but I'm not in a hurry.
 
Hand sanding plywood is difficult / take a long time!

Jig saw will do the job, but the edges will be somewhat wavy. (tape where you want to cut, and get the widest blade you can, and the one that says "clean cut". Go slow)

A bandsaw is your best bet..

alternatively, you can design your fins, then get them laser cut. it'll take a week or two to get them, but they are cut to exactly what you drew / want, without investing in power tools. (Of course, after about 3 or four sets of fins, you'll have paid off the band saw, another 4 for a bench top belt sander)

Keep your eye open for Kijiji or Varagesales listings.. also, some bigger cities have "DIY" maker spaces. Sign up, as they have all the tools you want (and people to help you!)

Lastly, call the local cabinet maker. I'm sure once you talk to him, he'll be able to help out! (for a fee of course!)
 
Where are you located? Is there a club nearby? I'm sure a member with power tools would be happy to help you. But if you're determined to use hand tools, I'd use a hacksaw. It will give you smoother cuts, and straighter than a coping saw. 1/8" plywood should be relatively easy to cut. Hacksaw blades come in different TPI (teeth per inch), and I would recommend 24 or 32.

https://www.acehardware.com/family/...WARE&fbc=1&lmdn=Brand&fbn=Brands|ACE+HARDWARE
 
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Do any of you make your own plywood fins without the use of power tools? If so, how do you go about it? If that is not feasible, can it be done easily with "hand" power tools? I'm thinking cut out with a jigsaw and then use a sanding block for final shaping. It seems like a jigsaw might be hard to handle on 1/8" plywood. Would a scrollsaw be a better choice? Is there a "best" practice? I'm not ready to invest in a full set of power tools yet but would like to be able to design and build some custom MPR/HPR rockets.

I have used a razor saw to make straight cuts in thin plywood. I’ve used a coping saw for curved cuts. The quality of the tool and blades makes a huge difference.
I used to hate using my old Black and Decker jigsaw. One day I decided to try a new Makita that was about four times the price. Using the blades that came with the Makita, the difference was absolutely amazing. Using the right blade and a high quality saw made a ton of difference.
I’m convinced a high quality scroll saw would also impress me; my Dremel one doesn’t.
As far as sanding. It’s entirely possible to sand very well manually. Again, use good quality sandpaper and don’t be afraid to start with a bit coarser grit. When you get it roughly the shape you want, move the twice the grit. Sand until you’re halfway through the sanding marks from the previous grit. Keep doing that and you’ll get done much more quickly than going right to a fine sandpaper. Most people try to do too much with a finer grit and become frustrated by how long it takes.


Steve Shannon
 
As someone who is power too challenged (I really wish I had bit the bullet and bought more table tools 18 years ago when I got into HPR), I have cut fins with a razor utility knife and a razor saw. I have also used a jigsaw and a RotoZip. By hand it is really tough and none of these give a manufacturer quality cut (DUH). I agree with Steve that really coarse grit is your friend. To that end, I use a palm sander and home-spun blocks. Spend more and get a cloth backed paper. I think mine was from a belt sander but a big chunk has lasted me a long time. Also, if you are going to bevel the edges anyway (which is also slow by hand!), you might as well to the final edge clean up once they thinner.
 
I send parts that I can’t cut easily to upscaleCNC. His prices are reasonable and turn around has been very good.
 
As someone who is power too challenged (I really wish I had bit the bullet and bought more table tools 18 years ago when I got into HPR), I have cut fins with a razor utility knife and a razor saw. I have also used a jigsaw and a RotoZip. By hand it is really tough and none of these give a manufacturer quality cut (DUH). I agree with Steve that really coarse grit is your friend. To that end, I use a palm sander and home-spun blocks. Spend more and get a cloth backed paper. I think mine was from a belt sander but a big chunk has lasted me a long time. Also, if you are going to bevel the edges anyway (which is also slow by hand!), you might as well to the final edge clean up once they thinner.

And a set of good quality rasps is great to have for edge work.


Steve Shannon
 
Lots of good ideas here! I had never heard of "makerspaces" before but it turns out there are a couple of them nearby. I will have to check those out. I still want to try making a set of fins using hand tools, just for the experience, but it looks like there are lots of other opportunities for trying out power tools as well.
 
when cutting plywood fins, i use a scrollsaw. typically, ill lay out the fin on one piece, then stack 3 or 4, tape together, then cut all out at once.
 
Late to the party-

I've cut plywood fins -- and lots of other pieces from plywood -- using a dozuki panel saw. i got mine at a consignment shop, Rockler sells one just like it.

[video=youtube;0RT5AmhJduI]https://www.youtube.com/watch?v=0RT5AmhJduI[/video]

For beveled edges on plywood, I've used a razor plane. I've never tried to airfoil or round the edge of a piece of plywood with unpowered hand tools, but I am sure you could use a moulding plane or a radius sanding block. Its actually pretty easy to make a radius block. For cutting tight curves, I'd choose a jeweler's saw over a carpenter's coping saw; cuts on the pull stroke, and you can get round blades, with spiral teeth, so that the blade will cut in every direction.
 
A miter box with a crosscut saw works great if you are patient. I have a table saw and a sliding compound miter saw, but I still use one occasionally if it is bad weather and I don't want to create a bunch of dust inside the barn.


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How big a fin, you didn't state, but if you can find a hacksaw blade that has 18tpi you're in business. Put it in a handle, and be careful. Lacking a handle, make one of duct tape. Sand it to size with all of them clamped together. 24tpi will work, 32 is a bit fine.

Cheers,
Lucifer
 
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When you get it roughly the shape you want, move the twice the grit. Sand until you’re halfway through the sanding marks from the previous grit. Keep doing that and you’ll get done much more quickly than going right to a fine sandpaper. Most people try to do too much with a finer grit and become frustrated by how long it takes.

Steve Shannon

One trick I learned when I was a carpenter when I needed to sand something with precision was to mark the edge/surface I was sanding with either pencil or permanent marker. That way you can tell when you have sanded things evenly. It is very easy to think you are sanding an entire surface and complete miss areas. Marking them helps this a lot.

When I used to be a timber framer/log builder we went through tons of rust orange spray paint. You would cut your notches and then put the pieces together while the paint was still wet. They would imprint on each piece and you could easily tell where you needed to rasp/sand/remove material rather than guessing.

Edward
 
Telescope mirror makers use a similar test, they call the Sharpie test. When polishing a mirror, they can tell if it's polished when all of the marker is gone from the surface with one polishing session.
 
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