UWE Bristol Engineering showcase 2015

Sean Thomas
Mechanical Engineering
Project Supervisor
Jason Matthews
RepRap Assembly Automation
The design that will be analysed is the Ormerod 2. It was released on 11th September 2014.
This particular RepRap has been selected because it was the newest design and there was
access to one which made understanding how it worked much easier.
Each sub-assembly will be analysed using a formalised ‘scoring’ system. The
goal of this system is to give an indication of how easy it is to automate the
assembly with the parts in their current forms. The parts which will be
redesigned will be within the assemblies which are already most suited to
automation, this structure for selecting sub-assemblies will result in
assemblies with less parts and fewer fixings meaning that each one will take
less time so more can be redesigned.
Original Z-Lower-Mount analysis
This assembly has 7 parts of which 6 are
fixings. This gives a score of 13.
There is 1 printed part with all the fixings
being attached from the same direction,
meaning this is a bottom-up assembly.
The printed part has no symmetry but its
shape would make it easy to create a rig
where the part will only fit in the correct
orientation.
Original Z-Lower-Mount
The way this system works will be to add together the total number of parts
and the number of fixings. For example if a sub assembly has 15 parts, of
which 5 are fixings, the ‘score’ will be 20. The aim at this stage is to identify
assemblies which have 3D printed parts that can be redesigned, therefore an
assembly will not be selected if it does not contain at least 1 printed part.
Redesigned Z-Lower-Mount Analysis
The original assembly had 7 parts where 6
are fixings this gives a score of 13. With the
redesigned part there are no fixings so there
is just a single part giving a score of 1. The
percentage reduction for this assembly is
92%. This part will change the overall
assembly process more than any other part
because it cannot be added at the same
point in the process that it currently is.
Redesigned Z-Lower-Mount
Project Summary
Can the assembly of a RepRap be automated?
Project Objectives:
• Research and understand automation techniques,
design for assembly and their limitations.
• Select a RepRap.
• Evaluate assembly processes to determine which
parts are best to redesign.
• Optimise design for automated assembly and
create CAD models.
• Analyse new parts to show how changes made
have improved parts for automatic assembly.
Project Conclusion:
Overall this thesis has shown that applying a few
simple techniques can make the assembly process
much simpler with small changes to overall design. It
has reinforced the idea that a small amount of effort
in the design stage can have a large positive impact
on later stages. However redesigning an already
existing product does have a lot of limitations, the
overall look of the product and its functionality have
to remain relatively untouched meaning that only
small scale changes can be made.
RepRap technology is changing rapidly and designs
become obsolete quickly.
Original Z-axis Lead Screw Analysis
This assembly consists of 5 parts where 3
are fixings. This results in a score of 8.
This could be completed as a bottom-up
assembly as there is 1 printed part and 3
nuts which are attached to a rod, if they
are all added from the same end then it
can be assembled bottom-up.
Original Z-Gear-Driven
Redesigned Z-Axis Lead Screw Analysis
This assembly still has 5 parts with 3 fixings
so the score remains 8. However the new
design makes the part much easier to feed
in an automatic assembly system.
Redesigned Z-Gear-Driven
This is why I have come to the conclusion that the
best way to further the progress of RepRap assembly
would be to design a new RepRap with the emphasis
on making assembly as simple and fast as possible for
a human. It is worth noting that this is view of the
technology’s inventor however this thesis has shown
that there is a lot of improvement still to be made.