tirsdag den 24. august 2010

Reprap fire auto kill switch

A quick and easy reprap kill switch.

Along with the Photoelectric Smoke Alarm (model HS-103) and Sartona Model 2606 remote 1000W power switch (http://www.harald-nyborg.dk/merinfo.asp?varenr=6137&n=10)
You need 2 transistors and 2 resistors and a small piece of strip board.

How it works;
The smoke detector sends a 9V high signal ( 1S period square wave) upon sensing smoke, this switches 2 transistors(your strip board), that ground 2 chip pins on the remote control circuit, thereby mimicking a switch off button press on remote control A for power switch A. ( Power switch at sending end ( remote) is Identified by Pins;A=pin6 B=pin7 C=pin8 D=pin10 in remote control circuit, and in power unit by dip switchs set as in table provided by manufacturer)(switch off send pin13 low in remote controls)(switch on send pin12 low in remote controls)
(Remote control data sheet http://rfelektronik.se/manuals/Datasheets/HX2262.pdf)

Connections between boards
Connect grounds between the 3 elements -ve terminals( remote , Transistor strip board, Smoke Alarm, )
Add 2 wires from the remote switch to the transistors on strip board, one wire from smoke alarm to transistors on strip board.

( It shows extra info of circuit in remote control, so you can change its use for example switch ON switch instead.)

tirsdag den 10. august 2010

Short cut to mendel gears

Alternative Mendel gears avoiding much gear filing and with the added benefit of improving precision, this gear started out as a steel pulley. Modified to a drive gear by the addition of M3 grub screw between the teeth and drilling out shaft hole to 5mm .

Grub screw detail. Drilled 2.5mm then tapped M3 thread with M3 tap set.

M3 grub screw created by; screwing two temporary M3 nuts on M3 bolt , cutting screw driver slot in threaded end of bolt, removing 1 nut to remove burs, cut other end of bolt off 4 mm away from screw driver slot end, then file end flat then remove other nut to remove burr.

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