From Prototyping (10-26-06)
skills – we get ideas of how to make a workable design. It is good that we
have solid models, but spending time machining helps us to see how
practical designs are. We learned the importance of tolerances even on
simple prototypes. For example, it turns out that the drill press and band
saw are not sufficient for constructing the jaws of the Pacman.
- It is
easier to improve on a design than it is to come up with a design from
scratch, from my experience. Having a prototype revealed the strengths and
weaknesses of the Pacman. For example, once we built the Pacman, it was
very clear that it would need to be hardened. Applying a small force to the
wire resulted in a marking on the blade.
Semester End Reflection
believe that we have enough good concepts that we can create a fully
team works well together with a variety of skills that compliment each
will be able to start prototyping right off the bat next semester
finally got the fuel jackets!
seemed to like many of our concepts
will have to all do some design work over break to really hit the ground
running next semester
didn’t produce nearly as many prototypes of the individual concepts as we
would have liked
- As a
team we all need to religiously devote time every day to work on
- As a
project management goal we need to break down specific tasks and post them
along with the job responsibility so that we are all held
accountable. Hopefully it will
Lessons Learned – 3-20-07
Lessons Learned – Tapping
size larger than what is on chart for drilled hole
– use finer thread, Aluminum/Brass – use coarser thread
Tap – for blind holes
possible – drill farther than 0.2” past the end of the threads. This gives
room for the chips to pile up, plus you don’t hit the end of the hole with
Taps with mill @ about 140 – ensures straight upness
Lessons Learned – Vice Stop
use mallet to position part with the vice stop. This resulted in a piece
being about 0.020” off.
Lessons Learned – Shear – 3-22-07
Situation - “Get the set up right,
and everthing be nice ‘n’ Smooth” – At first, Phil (our mentor) had to do a
lot of “clamp chasing”. Clamps had to be repositioned multiple times on each
part. The first part took about 2 hours to finish. To fix this problem
we tapped the tooling plate and made holes in the stock material so that the
stock material could be clamped to the tooling plate via two bolts. This new
setup/part design reduced the manufacturing time/part to about 40 minutes.
Lessons Learned – Always consider
placing holes in parts for clamping (via bolts), especially in smaller parts.
Lesson Learned – One good piece of
advice that we were given (by Steve Byerlein our instructor) was to assemble
everything and make sure it works before sending out the shears to be hardened.
This will prevent us from wasting time and money hardening shears that aren’t
going to work.
Lessons Learned – Top Bar – 3-28-07
Situation - While manufacturing the Top Bar, we ran into
some trouble. While cutting out the excess material (to form the “C” shape),
the excess material began to bow away from the Top Bar.
Lesson Learned - Cold rolled steel develops residual stresses
when it is processed. When we began to cut the long (36”) piece of cold rolled
steel, we were relieving the residual stresses. The result was, when we placed
the part on a flat table, the middle of the Top Bar was about 0.25” off of the
We decided to scrap the part and start over with a new
design. The new design does not use one solid piece. It uses 3 pieces of 1” bar
stock bolted together. The design will actually be easier to manufacture and
will eliminate any chance of deformation during the manufacturing process.
Situation – The stock material for Top Bar is
36” long and the part itself is 31” long. The travel on the mill will not allow
us to make all of the holes in the piece without moving it. Moving the piece
would add possibility of error to the manufacturing process.
Lesson Learned - The head on the mill
(containing the spindle) can swivel. So we can find the zeros (datums) on one
end and then drill a reference hole in the part that is relative to the datums
that we set. Next, we can swivel the mill head until we have enough travel to
finish the piece. At this point, we use the dial indicator to set a new zero.
We can move the piece until the dial indicator shows that the hole is centered
under the spindle. Then we can set the coordinates of the hole on the mill so
that we are still working from the same datums.