Lecture Notes¶
Wednesday - Neil time!¶
Press F in KiCad during tracing to automaticly
finish the trace
Open loop cnc machine
Closed loop cnc machine
Materials¶
Tri fold cardboard - Doesn't machine well Ridgit foam insulations MDF - machines smoothly - can be very toxic MDO - better MDF OSB "constructieplaat - recycled wood - eco friendly
Flute¶
2 than one flute mills The more flutes to smaller the bites the drill takes so the smoother the result is.
fewer flutes when removing a lot of material.
Flutes can have different coatings. Coatings can significantly extend the lifetime of the end mill
Different bits for center cutting and not center cutting
center cutting lets you directly go into the material Non center cutting is to clean the cuts.
Need to watch which way you're drilling it will have impact on the holes and cuts
Cutting materials¶
Down cut leaves loose material around the hole up cut destroys the bottom if you're going through the entire material at once
doing a combination can give you the benefit of both and leave a clean hole.
Machineries handbook
Chip load - how fast you let the tool spin/cut while moving. Too fast is bad too slow is bad. There is a sweetspot
For heavy metal machinery you need lubricants. For other stuff not really
locking the material in place¶
machining vise - good bar clamps - need a lot and to distribute the holding force vacuum bed - The vacuum hold the material down - need periodic maintenance because the holes can get clogged
Sacrificial layer¶
Set to Z=0
Bolts can get loose on the shopbot.
Dust¶
You need a dust collector because the cnc machine will create a lot of dust. If there's dust around the lab something is wrong.
Modification¶
flexible designs - Flexure Steam bending - Big box of steam to soften wood and shape it.
Japanese wood joints https://www.thingiverse.com/thing:169723
Tool paths¶
Kerf - Offset by tool diameter
Runout - The tool may not be attached straight to the machine so it will create sloped cuts
climb - cleaner cut but harder on machine - for finishing Conventional - To start out with is easier on the machine. Is more rough
2d top down 3d 4d Can curve the tool during cutting 5d all degrees of freedom
prototype by 3d printing or laser cut before you do the cnc job
Shopbot - Vcarve
Safety¶
Sharp material can fly out Material can get very hot - Fires Splinters
Always wear safety glasses Shoes no crocks or sandals Hair in a knot Ear protection
Never reach into a running machine Never do large format machining alone You want a second pair of eyes and ears always check each other Need to be well prepared
Know how to turn the machine off before turning it on
Before you start milling all the documentation has been done.
Extra notes¶
If you set the RPM too low it can't calculate the toolpath. For some reason when you change the rpm the the starting point changes when cutting a line.
Pocket allowance = offset
When doing the corners of a cut with filet. You need to double click the corner.
Check the grain of the wood. One side works better than the other. TODO: add this to main docs