"The chipgods smiled on you"
National election has cone and come. We are back in the top right-wing countries in Europe; hooooraaaayyyyy...... :-(
Loads of stuff you are going to need this week are only taught in other coming weeks. So we need to adjust a bit.
We are going to keep it short and nice.
motors The basis is a DC motor. It has a plus and a minus; how you connect this, depends on how the motor will turn. So they can turn both ways, but that is annoying as the Arduino only has one direction...
All the other motors we see are derevatis from the DC motor. They often use H-bridges. These are part of bridges.
We have a CNC-shield. This has an xyz-axis with all kinds of H-bridges.
With that you can drive steppermotors. Steppermotors take 200steps to make a 360degree turn. The steppermotor can even divide this in 32 micro-stepps: 6.400 positions in a 360 turn of the axis.
In the datasheets the power of a motor is often described in the grams it can move.
Almost everybody suffered this weeks; loads of new stuff to learn. We are nowhere done with this weeks topic and I think we need to revisit embedded programming quite a bit more often.
NOtes for the new week on Machines.
- New Arduino 20.0 is in beta and can now be tested.
Inspirations from around the world
We are going to use stuff we do not know yet. So we have to deal with making
Mechanical design Principles - stress-strain: how much force can be applied before deformation and break - hysterises: too much space between components. - forced loops: do the force go where they need to go, or are they bending the machine? - elastic averaging: a way to get two parts in an exact position by using different shapes (ball in triangle)
materials - Plastics - htpe (where cutting mats are made off) - Steel - you can mill alu on shopbot; just adjust feeds and speeds - Rubber - to damp vibrations. - Garolyte - It is a composite; is is a natural vibre composite - makes really nice stiff material parts - Wood - wood is for beginner machine building - it moves too much - Cement is interesting - this is stiff, very stiff - the non-moving parts need to be heavy and fixed - Ceramics, can be used, but are hard to deal with - Cardboard - cheap and cheerful machines
Fasteners - Locknuts: they don't walk when trembling is happening - bolts: think about shape: stick out or embedded - washers are important - they prevent deformation - lockwashers prevent creeping when vibration happens - Heatset
Framing - Extrusions are superstrong and buyable - there is a lot of stuff available to add to extrusions
Gears There are so many gears, they are a subject in itself - involute gear: when it is moving it has a continues contact. - cyclodial has the same qualities, but easier to fabricate. - Belts are flexibel in one axis, but not in the other, they are good for rotary to linear motion
I need hook and loop velcro! Much better then tie-wraps...
- Flexure; what is it? Sounds cool...
- whippletree: pull a force while alloweing for chaning positions
Previous years machine making