Quote:
Originally Posted by Sh1ine
Our team is thinking about using some constant-force springs for our shooter. We are curious if you can double the springs up on the same axle.
To clarify, we are wondering if it is possible to open two springs, place them on top of one another and then let them roll into one package. Has anyone ever done this? How does it work if you have? Can you double the force in almost the same space as one spring?
Thanks in advance. |
1519's planning on using constant-force springs for our launcher... We used some (fiercely under-powered ones) on one of our intitial prototypes and just assembled the core of what we hope will be our competition launcher (also using constant force springs).
We're using 4 ~16lbf constant-force springs, with the potential to add smaller springs to tweak it (we already added two springs that we think are 7lbf). This gives us a total of 78lbf theoretically, which when we used our robot-weighing scale looked more like 65-72lbf. We have 8-10" of travel on this mechanism. Using human pull-back this seems to give a throw we're happy with (7+ vertical foot rise when fired straight up).
First, I'd be wary of springs that are on the order of 40lbf. We didn't inter-coil our 16lbf springs, but just pulling them back by hand to put them on a spool and bolt them to the launching mechanism was non-trivial enough that I frankly can't imagine doing it with much stronger springs (let alone 2.5x the strength!). I'm also unsure how inter-coiling springs or using larger springs affects the retracting speed... all I know is the little springs are quick enough for us.
Second, Vulcan Springs is providing a PDV for up to 6 springs. I didn't order them personally, but it sounded like it was easy to work with Vulcan Springs to get them. They were shipped promptly (next day?) and only took a few days to get to NH (I don't recall how many days). So, unless you really need the McMaster speed, I'd definitely recommend saving the $20+ per spring and use the PDV.
So far we like the constant force these springs provide!