FabLab Academy 2012

Manchester Lab

David Forgham-Bailey

Week  6: Computer-controlled machining

Course Notes:

more than just cutting - upto 7 axis and more - robotic arm etc -
Roland Modela
Type of material influences type of tool -
Rigid foam insulation - polyeurothane foam - veneer plywood - mdf - moulds/final parts - MDO - OSB-aluminium - Lexon-polycarbonate glass
Find local suppliers for materials....
Tooling: moves swarf away form cut - ONSRUD- SDS TOOLS - find uk equiv... - Coatings: - make tool harder - A1TIN - cast iron - hard - T1C - vioet brown - alloys - Titanium Nitrate - Gold - Gen purpose - T1DR - specialist

centre cutting/slot cutting - up/down cut - good for finish on both sides of ply - takes waste away from cut and face of material
mechanical feed - cutting depth - flat/bull end - flat cuts rectangular slots - rough path leaves steps - bull finishing tool - use smaller step order -
Diameter of tool / tool holding diam - steps shorter than flute depth - length of tool - ensure long enough for work - Speed: - rpm of cutter - feed - speed in lateral plane - Wood - highest rpm is 18000 see tooling catalogue for speed/feed chart - 1/4 in tool (0.015mm) 18000rpm - chipload calculator for Shopbot - if tool is hot after cut then feed rate too slow

Lubricants: dishwasher fluid?
Fixturing: vises/clamps/screws - design positions when designing tool path - draw hole where not cutting path - double sided carpet tape - adhesive - encapsulation -
Kerf - diam of tool - offset - thickness of tool - cut on inside/outside/on line - (changes with tool width)

Rhinocam-file formats -


    Software: - Inkscape/Rhino/
    Hardware: ShopBot - sanding equipment -

Weekly Assignment: Make Something Big


I began this task with the firm idea of making a magic box - I have had woodworking plans for manufacturing a magic box for a number of years. But on reflection, the clash between Open Source and The Magician's Code persuaded me to find something different.

I found an old plan of a 4x8ft sheet of ply which made a workstation and matching stool and left no waste material - I spent a weekend rejigging the plan to incorporate snapfit joints and made up a 3D model to ensure the joints were correctly aligned. - I had reservations about being able to secure the plywood to the Shopbot bed - but hoped it might be possible to use carpet tape. I decided to have a reserve plan if this was not possible.
My research for ideas brought me to a set of play planks which I had as a child in the 1950's - (see images) - these are now called linkerlogs and an opensource project.  

From Mechanics Illustrated  Dec 1953:

playlogs 1


I used

    Materials: 1/2inch plywood sheet - 4ft x 8ft
    Machine Settings:1/4inch tool(up/down cut) - 18000rpm


shopbot 2

Shopbot bed - in action:

shopbot 4

Kit Assembled:

Kit assembledKit assembledKit assembledKit assembled


External Links: