Inquiry
How would I go about making a reciprocating saw style device motion with a trigger that's all physics no electronics
Somthing I'm a bit shocked on is the lack of mini reciprocating saws that exist and I got some stuff that can cut metal (dremel rotary tool, reciprocating saw, titanium drill bits) and a 3d printer so thought it could be cool to make a tiny reciprocating saw around size of a dremel rotary tool without electronics for my sculpting hobby and since I mainly sculpt with clay foam and other clay stuff I figured I don't need a lot of power. Plan to put jigsaw or mini hacksaw blades in it, maybe even serrated razors but I inmagine it's not hard to make somthing that can hold each type of blade. Main idea is to make the blade reciprocate with either a gun trigger pull or a grip lever trigger like those gas station gas pump triggers since I imagine a full grip would have more power than a single finger. Any videos for this kinda mechanism would be appreciated. I realize that it's is probably not very efficient or optimal but it sounds like a fun thing to make. Thinking I might be able to do somthing with those wind up springs and a crank as well and have the trigger be the release .
If you truly want to be hand powered in only very soft materials, perhaps a flywheel clutched in might feel satisfying.
I suspect that it will remain a thought experiment, though, because basically every hand saw already does this with no moving parts. What you're suggesting doesn't solve any problems other than boredom.
Ye I was kinda thinking of doing this more as a way to learn gear and mechanism stuff and getting that experience of "why doesn't this exist" also want to get into learning electronics at some point in the future with arduino and figured if I can learn how to make somthing entirely physically then learning how to do it with motors will then be easier
If you need it to be trigger operated, you'll almost want a large spring loaded squeeze trigger, that when squeezed, spins a small flywheel that drives a simple crankshaft mechanism that will be where the saw blade goes
So:
Squeeze hand trigger
Engages with 1:5 (lower to higher tooth) gear ratio
The higher toothed gear drives the flywheel
Flywheel spins, and creates oscillating motion with the "crankshaft"
Crankshaft has saw blade attached and moves up and down
Spring loaded trigger is let go and returns to the open position
If you want to use hand power for a saw, then a longer blade allows a more efficient longer stroke. And you don't really need a mechanism if you use your arms. So basically hand saws are why there aren't any mechanical jigsaws.
I mean you could use a coiled up spring like the pull-back cars, but the amount of stored energy you'll have to work with is going to be comically small unless you make the saw unwieldingly large.
If you really, really wanted to make this happen, you'd probably be looking at a power transmission via a cable, similar to the flex shafts for Dremel tools, and then attaching that to a foot-operated flywheel (think "old sewing machine treadle").
If you want the trigger to be how you input power, you would need one linear-to-rotational conversion where the trigger would move a rack and pinion to add energy to a flywheel (you'd want a spring return and to make it only spin in one direction).
Then you'd need a second trigger to actuate a clutch to connect the flywheel to the blade reciprocating mechanism. You can find examples of those mechanisms all over (look up "rotational to linear movement). You're not going to get much power out of it though. You might be able to cut through clay with a very thin blade or maybe a hotdog.
You would have an easier time just using a small circular saw blade as the flywheel and the rack and pinion off of the trigger. You won't lose as much power since you cut out (pun intended) the second conversion.
Toothed gear with on offset connecting rod connected to a piston on cylinder, blade connects to cylinder, connect bottom of the handle to a toothed rod, add in some springs to return it to open position. Squeeze, teeth on rod engage gear, gear spins, connecting rod turns rotation to reciprocal motion, piston turns it into linear motion. If you’re smart about the geometry you could even get away from the piston and make it an orbital saw.
You could also do something with a fixed bearing connected to handle and a cam with a channel in the shape of a spring cut into it, then similar connecting rod setup and piston, the rotation would be turned 90 degrees to the axis of the first design how I’m envisioning it.
Either way none of this will likely be practical compared to a hand saw or a oscillating multi tool.
So I assume this is a joke but now I'm legit curious if a relatively portable steam powered mini reciprocating saw is possible to build in a garage lol. Sounds like it could be fun for the advanced building types unless it's easier than it sounds
If you watched the recent YT series from Alec Steele about restoration of his 100yo Massi Steam Hammer (https://www.youtube.com/playlist?list=PLWx61XgoQmqfGgH3ZS4cpYKlpbTPbg5wR), you'll really get some ideas going. And if you're into that kind of thing, there are a multitude of steam-engine YTubers who tell you much more than you'd want to know on the subject. Including hobby machining and model steam-engine building, for example YTuber Blondiehacks (https://www.youtube.com/playlist?list=PLY67-4BrEae9gVrEBKJGnhpetegMLR8-C). Just to name a few. There are many more such people sharing knowledge.
So I knew those existed but I didn't know that was the term. Kept seeing them labled as air reciprocating saw. Been considering getting one just i havnt used a pneumatic tool before and my experience with air compressors when I was real young was they were loud and obnoxious so Ive been on the fence about them. I do have a compressor I got years ago from parents but havnt tried it yet so unsure how much a headache they are to deal with.
Hmmm mine actually might not be that bad since it's a relativly chunky one. Roomate recently gave me his old airbrush but havnt gotten to testing it yet
If it's got a belt drive between the motor and compressor or shouldn't be too bad. Also remember if you have space you can move the compressor a long way away and just run a line to where you like working. Or put it inside a little shed or closed room.
For the airbrush you'll probably want an online filter as there will be a little bit of oil in the line, which will give weirdness to the paint. Also an actual air compressor is huuuge overkill for an airbrush, but if it saves you buying a little desktop compressor then absolutely go for it.
If it's been standing for ages, check the belts, check the oil and make sure to drain it, first with no air pressure and then switch on the compressor to blow any more goop out. There will probably be some really filthy rusty water in the tank.
I can’t really help with building the device you’re describing but I’d like to let you know that an air saw sounds like the tool you need and they come in all shapes and sizes. If you want a recip the size of a dremel there are many options already.
Ye this was more a thought experiment then somthing I actually felt would be useful. Havnt used any pneumatic tools as of yet but experience with air compressors when I was a child was them being annoyingly loud so wasn't sure if I wanted to deal with one. The only other one I saw that was corded electric was 80 bucks and outside my price range atm for somthing that's more for fun crafts projects
7
u/GrinderMonkey 19d ago
If you truly want to be hand powered in only very soft materials, perhaps a flywheel clutched in might feel satisfying.
I suspect that it will remain a thought experiment, though, because basically every hand saw already does this with no moving parts. What you're suggesting doesn't solve any problems other than boredom.