Bend over (and over and over…)

Some of the parts for the voind robot project are built from bent sheet metal. This is the case for the two stainless steel chassis side plates on which the main ballscrew is mounted:


Fortunately, having sourced the chassis construction to a very competent expert on metal fabrication, I never had to account for the material along the bending lines and only specified the final dimensions of the finished parts:


However as I soon discovered while fabricating the X Assembly cable guides supports from aluminum sheet, correct calculation of both bend allowance and bend deduction are paramount for obtaining a precisely dimensioned part from metal bending.

The failure to understand how to correctly incorporate the bending into the flat part design was partially responsible for multiple attempts at this part fabrication:


We finally got it right after using a mockup of the part which included the main bends but using only a narrow cross section of the finished part (the part on the upper right image above). Taking precise notes of the bending lines and adjusting them accordingly on the production part landed us with a precisely dimensioned part (almost) ready for integration!


More bending action lies ahead as we prepare to fabricate the more complex Y Assembly Cable Guide supports.


Screws and more

For the voind robot project we are using nearly two dozen screw references, mixing types (DIN 7984, 912) and sizes (M2 to M5, 6 to 35 millimeters lengths).


The screw types and positions were established during the design phase taking into consideration the dimensions of the parts, the forces involved, the clearances for the screw heads (and nuts) and also how to reach the screws during assembly and maintenance.


Most of times the screws had mating threads cut into one of the parts using a manual tap.


Some tap operations proved to be very challenging, specially when cutting M3 threads into stainless steel beams and in particular the one where we could not use a tap handle due to the part geometry:


In the end we assembled quite an impressive array of screws, nuts and washers references!