Final Project Rersources and Tips

Here is a grab bag of info to help with your final projects:

Lasercutter scheduling:

Refer to the lab calendar in another post and book times for your laser cutting - I suggest doing this asap - we will have a schedule up on the lasercutting room wall for tomorrow.

Materials you can cut:

I asked frank to prepare fr us a comprehensive materials list of what can and what cant be cut on the laser including maximum thicknesses. As far as thicknesses, it is a practical limitation not a technological one. In general we can’t cut anything over 1/2″. Wood is harder for the laser to cut than plastics. Very dense products like masonite are almost a no-go past 1/4″.

PROHIBITED:
Metal Sheets
Glass
LEXAN
CLOROPLAST
VINYL
PVC
TEFLON SHEETS

UNSURE:
FOAM CORE (lots of web sources say no–not sure why. I think it wont hurt to try it…)
POLYCARBONITE (conflicting reports–if someone really really wants to we can try it)

OK TO CUT:
Balsa Wood
ABS
Styrene
Delrin
hobby BassWood
Mylar
Cast/extruded acrylic
matte board
museum board
PAPER
CELL CAST ACRYLIC SHEETS
plywood: performance is practical limit. Ask David: he has experience and can explain what happens with thick plywood
particleboard/masonite: can cut but VERY unsatisfactory results IMO
LEATHER (can cut, but I have no experience)
FABRICS (have cut felt, works great)
MDF (OK if you really want to)

Buying other Plastics:

If you are after interesting plexi colors and or other lasering materials a great place to snoop around for cheap scraps is Gavreilli Plastics in North Hollywood. link to their site

Photocells (AKA Photoresistors, LDRs):

Using a bunch of photocells (up to six..) may be what you want for your project. The best resource I know of is ordering the $0.73 ones from Jameco Electronics. heres the link

I have about 20 photocells I can hand over while supplies last…

AllElecronics does not have photocells .. though I have seen them at radioshack..

Using 12V Electromechanics (motor/fan/solenoid) with a TIP120 transistor and a protection diode (like we did in class with the fan..):

here are three  photo/circuit/code reference links in case you never got this working or want to review/ look at it again (there is a nice photo in the arduino book as well):

http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads

http://ctheds.wordpress.com/2007/10/30/tip-120/

look under solenoids on this page (this will work for motors / fans - on/off):
http://www.arduino.cc/playground/Main/InterfacingWithHardware#Output

Solenoids:

I recommend using the 12V push solenoids you can get at All electronics:
http://www.allelectronics.com/make-a-store/item/SOL-108/SOLENOID-GUARDIAN-A420-067074/1.html

To figure out if your power supply (in this case a 12V wall wart) has enough current to power these and to see how many solenoids you could have going at the same time without burning out your power supply apply Ohm’s law (I = V/R) to make the calculation (http://en.wikipedia.org/wiki/Ohm%27s_law)

So to use the above solenoids as an example  we are looking to calculate I (current) using V (Volatge) and R(Rsistance):

To look up R we look at the resistance of the coil - in our case a 44 Ohm coil. so R = 44
Voltage is 12V as we will be using a 12V power supply for these so V = 12.

I = V/R
I = 12/44
I = 0.273 amps
I = 273 milliamps

So if you have a 1AMp (1000 milliamps) 12V power supply You could safely power 3 solenoids at the same time …

If you need more power or really want to use a pull solenoid - the most cost effective solution Ive found is these pull type 24V solenoids from all electronics:

http://www.allelectronics.com/make-a-store/item/SOL-111/SOLENOID-GUARDIAN-A420-066947-00/1.html

and one of these 24V power supply/ transformers depending on how many solenoids you want at the same time :
http://www.allelectronics.com/make-a-store/item/PS-6524/24VDC-6.5A-POWER-SUPPLY/1.html

http://www.allelectronics.com/make-a-store/item/ACTX-2415/24VAC-1.5A-WALL-TRANSFORMER/1.html

http://www.allelectronics.com/make-a-store/item/ACTX-2445/24-VAC-450-MA-WALL-TRANSFORMER/1.html

Motors:

I have a bunch of 9-12V motors that you can get from me if you need them for your project (thay are about $2.00 each) I bought them in bulk from Jameco  so let me know if  you need them

Fans:

most fans are 12V and come various sizes - a great place to get these is from All Electronics shop

TIP 120s / 1 amp rated - protection diodes:

If you need more Tip 120s I have a bunch for you or you can get them at al electronics

Dial Potentiometers / LEDS/ Resistors/ Light bulbs/ Buttons/ Battery cases / crimp connectors…etc:

All electronics is great for this stuff

Bring an idea to class and hopefully some parts

Giant Buttons:

Check out Happ Electronics for arcade style buttons and joysticks

http://www.happcontrols.com/

-E