2/23/2014
Today, we went ahead and started making
clamps for the winch axle so we can prevent the strap from ripping out.
General idea is to secure the strap by wrapping it around the axle, then
adding clamps with bolts that both hold the clamp and the strap, and have the
clamps squeeze the strap and into the axle. Hopefully, we will be able to
add these to the axle Wednesday and start to test the winch again. Other
than this, not much else happened in terms other design things. For now,
the winch is now the only mechanism that has not reached or exceeded the
standards and requirements set for it thus far, so it is not as far along in
the detailed design process as the other mechanisms.
Approximate times of working: 12:00 PM -
6:00 PM
2/26/2014
Today was a heavy programming and making
the other things for the bot day (finishing bumpers, making extra parts,
finishing making conveniences for the regionals like battery cart, etecetera).
While we did get to attach the stuff for the winch, we did not get to
really test it extensively. We did try to winch back a couple times, but,
when it wouldn't work, we saw that we were missing a screw that tightens a lock
collar, which caused the bearing to pop out, so the shaft wouldn't really turn.
By the time we found that, we didn't have time to change it out, so we
couldn't really test the part we wanted to.
Approximate times of working: 3:30 PM -
7:30 PM
2/28/2014
Today was another day without changing too
much, although the winch was further tested. Unfortunately, the clamps
were not going to be the solution, because what they add to the radius of the
axle is far too much, and it stalls out the two mini CIMs. Because of
this, we went ahead and figured that possibly still using the backpack strap
could work, as long as there is a heavy duty safety strap/hard stop of some
sort, to prevent the backpack strap from breaking due to overextension.
Also, we cut down the clamp a bit, and realized we didn't have to have it
encircle the entire axle, but just part of the axle, which definitely helps
with the radius of the axle. Other than working on the winch strap,
lights were worked on, but that both doesn't change the overall design and is
only to help the drivers.
Approximate times of working: 3:30 PM -
7:30 PM
3/1/2014
Today was Maketopolis, a public mini Maker
Faire, hosted by Xerocraft (where we're building). We got to demo the
robot in public, but also got to heavily test the winch and the robot as a
whole. Overall, it worked extremely well, and the shooter was extremely
consistent, as well as intake and so on. Everything worked well, until
the strap broke again, but, rather than while firing and unwinding, while
winching back. This showed us we absolutely need to use the yellow strap.
After the strap broke, we went ahead and
decided to look at the stall torque of the mini CIMs, and found that it was at
about 200 inch pounds, which, by far, is not high enough for what we need, and
that is why it stalls with the yellow strap. Stall torque is the amount
of torque needed to stall a motor, and inch pounds is one of the units, which
means how many pounds of force the motor can take from one inch away from the
axle (foot pounds is more commonly used, but, since we are dealing with smaller
distances and motors, it's a lot easier to use inch pounds). From this,
we knew we couldn't stay with mini CIMs there unless we really changed the
gearing, which would be complicated and a bit of a process.
Because of this, we figured we could
switch the mini CIMs with the CIM motors on the drive train. When we
looked at the stall torque for the two CIMs, we saw it was 360 inch pounds,
which, as can be seen, is much better than the mini CIMs. Also, this
would only make us lose about 12% power in the drive train, so, overall, it
seemed like it was gaining a lot for not giving too much. By the end of
the day, we were able to change the motors out and reconnect everything, but
not test it, as it took the last hour or two of the day. Hopefully, this
ends up working, and all that is needed is testing it tomorrow.
Approximate times of working: 8:00 AM -
4:00 PM
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