Mechanical and Machine Design

So the assignment this week is a group assignment where we all help out and document our individual efforts. The group documentation can be found here.
We decided to build a 4-axis CNC hot wire cutter!
Assignment:

Make a machine, including the end effector
build the passive parts and operate it manually.

Automate your machine
Document the group project and your individual contribution.


 

Building the stages

After a quick chat with the group, we all agreed on what to help out with. I decided to help build the stages with shirley. This began with preparing some cutsheets based on what was given to us already. After sourcing them, it was certain that the job will need to be don in two parts. First we decided to just slice the cut sheet into two and the rotate the cardboard half way:



We also did some test cuts so that the score lines and cut lines were just right:



The ideal values were as follows:
Cutting: speed 2.7 power 100
Scoring: speed 10.0 power 100

The first cut sheet turned out very inaccurate so we added a jigsaw style joint to the deisgn and made two cutsheets and tested it:



After making this stage, we noticed a seried of design flaws that needed altering. There were no holes for one stage to sit in another stage. We also added holes for end switches to sit in should we get the chance to add them. We also altered the space where the servo motor moves the end effector so that it will actually hit the endstop without falling out of place. Other issues included parts overlapping eachother.



Here all the circled ares are where we made alterations:



Here are the final stages:





To glue them together we used 3M Photo Mount. A spray glue which was quick to work with.


Machine housing

In an attempt to prevent our machine from ending up in the machine graveyard at the lab, we needed to work on a good housing from it. We started to work on a design, tasking inspiration from the ultimaker 3D printer:



Deciding on the dimensions of the cutting area was based on the distance that the stages could move (28 cm). We figured that the dimensions should be 28cm in the y and z axis, then 56 cm in the x axis (ie the width). If the machine would be wider, the maximum angle the machine would be able to cut would be decreased. But any less and the size of foam that would be cut would be very small.

Sadly this is how far we were able to get with it before going on to help set up the machine for testing. Koen then took on the task of designing the housing. I helped prepare the cut sheets and addemble the housing that he designed.





Sadly, this is where my part in the assignment finished. But it was great fun!