Davidbot

5 axis

Linear Configuration

• Traveling column - http://www.youtube.com/watch?v=TqokK03BJsM
• Thermwood - http://www.thermwood.com/header/cnc_router_five_axis_main.htm
• Mobile gantry
• Moving bed, static head

Rotary Configuration

• Trunnion/rotary bed
• Head trunnion, rotary bed
• Head trunnion/rotary

Specs

• 48x48x24" working area
• +-.005" with 50N cutter load

Error

• Beam torsional deflection
• Beam linear deflection
• Spindle/mill deflection
• Spur/rack gear backlash
• Pulley clearance
• Belt stretch
• Motor torque angle

Bridge

• http://www.onlinemetalstore.com/items/6063_Aluminum_Square_Tube.cfm?item_id=148&size_no=18
• http://www.uscomposites.com/cloth.html#eglass

McMaster

• 1/2" racks
• 5/8" ballscrews and nuts

Epoxies

• http://www.shopmaninc.com/epoxy.html#kleerkote
• http://www.precisionepoxy.com/Epoxies.htm

• http://www.moglice.com
• See also Philadephia Resins
• http://www.cnczone.com/forums/showpost.php?p=396493&postcount=2683
• Devon Plastic Steel, WR-2 Epoxy
• JB Weld / Industroweld
• Masterbond EP30

• Friction reduction - 17% moly, 9% graphite
• Wear reduction - 6% aluminum, 8% copper, 9% aluminosilicate

Gears

• SB uses a 25T pinion on 20PA? racks
• Gear racks are taped on with 3M VHB tape

Belts

• Gates GT2 3mm
• 32:120 SDP-SI polycarbonate

ServoBelt

• T series profiles and Gates rounded profile will self mesh
• Use polyurethane steel reinforced T5 from Brecoflex
• 15T pinion, 75mm per turn, 32mm wide belt
• Pulleys are plated for low tooth clearance
• Turn down pulley dia to force teeth deeper into grooves and reduce lash (is this right?)
• Moglice/fill pulley clearance for less lash
• Backside idler min 30mm diameter
• 3M UHB (VHB?) tape for static belt
• Multiple side rollers are used to keep more dynamic and static belt teeth engaged
• possible to use small tractor wheel belt configuration
• license design for DIY sales
• Pulleys - Polytech Design, Econobelt, Brecoflex

Spindle

• Milwaukee 5625
• Triton 2.25 hp
• KINKDA
• Keri group

Motors

• Keling KL23H284-35-4B

Linear

• SBR rails
• Rollerblade wheels in molded/replicated V grooves
  • 608 bearing ~300lb radial, 150lb axial
• Steel V rollers

Rotary

• Rollerblade wheels in circular groove
  • Like thrust bearing
  • Straight like ball bearing
  • Angled like tapered roller bearing
• Cast moglice bearing on steel shafts
• Preloaded deep groove or angular contact bearings
• Close fitting (Freelon?) plain bearings
• Tapered roller bearings
• Trailer/car hub/spindle assembly
• Stuart platform

Rotary drive

• Belt drive
• Servo-belt drive
• Harmonic drive - China?
• Capstan drive
• Friction drive
• Ring gear drive
• Planetary gearbox (Anaheim automation)
• Worm drive
• Screw drive
• Howimat
• Electronic preload
• Preloaded spur gears
• Preloaded worm gear

Concrete

• Compression 5000-1200psi
• Tension ~350psi
• HPFRCC Tension 660psi

Concrete Types

• Pre-tensioned concrete
• Post-tensioned concrete
• SIFCON
• SIMCON
• HPFRCC
• HPFRC
• UHPFRC
• ECC (self compacting, others)
• Glass fiber reinforced
  • 14um/12mm monofilament fibers added at 1lb/yd (600g/m3) decreased cracking by ~75% and negligibly impacted SCC flow
• Steel fiber reinforced
• Natural fiber reinforced
  • Jute
  • Bamboo
  • Coir
• Self compacting
• Self compacting fiber reinforced
  • Lower large? aggregate content tends to reduce modulus
• Lightweight concrete
• Silica fumed low creep
  • If water/cement is .55 or higher 1kg silica fume can replace 3-4kg portland cement
  • 7% silica fumes halved creep
  • 5-8% by mass cement replacement (1:1) can increase ~20% compressive, flexural, tensile strength
• Expansive cement
• Type III cement increases early strength
• CEM III/A 42.5N LA may significantly reduce shrinkage (ground blast furnace)
• Water repellent admixtures
• Separation can be prevented with VMA, Limestone filler, Silica fume
  • LF has good fresh properties, comparable hard properties to VMA
  • Silica fume may? result in better hard properties (need data)

Suppliers

• Direct colors
• Buddy Rhodes
• Fritz-pak
• Grace construction
• Boston Sand Gravel
• Norchem - silica fume (densified and undensified)

Interesting Mix Designs

• French SCC design paper mixes
• Alabama SCC ingredient survey mixes

Concrete loading

• Tensile cracks propagation begins at about 30% of ultimate tensile strength

Concrete Ideas

• Self tensioning concrete