Completion of base
Here is the fully assembled base; at first galance a little like a storage box with some bits cut out of the sides but closer insection shows some mechanical and electrical components already in place:
- In the upper picture the small black squares on the left hand side are limit switches for the x-y- and z-carriages.
- The lower picture shows, on the reverse of the box, the timing belt pulley that will ensure even motion along both of the y-shafts.
As the previous post indicates, I found some ambiguities in the instructions that I would like to have ironed out before setting secondary school pupils lose to follow these instructions. A key part of this ambiguity for me is that the assembly instuctions use one ‘part number’ system to refer to the various parts but the parts themselves (supplied in a myriad of small plastic bags) are labelled with different ‘part numbers’ from the manufacturer; the bill of materials spreadsheet provides the vital link between these two numbering systems. The result of this is that I spent (wasted) a great deal of time cross-referencing between these; each threaded insert, nut, bolt etc. etc. needed to be carefuly checked, not least because each of these comes in a number of different sizes. It will be, however, a simple matter to edit the assembly instructions to include the manufacturers part numbers and I would strongly recommend this before pupils start work.
These points apart, there is nothing here that should prove difficult for secondary pupils and there is quite a lot of incidental learning to be gained about how to create a well-engineered structure based on thin sheet material. In particular the use of a soldering iron to melt the threaded inserts into the acrylic was very straightforward and effective and the use of inserts for nuts and bolts to secure the structure (bottom image) is exemplary.
Torben