The
interrupter disc is made of 0.04" aluminum and has a 27mm spindle mouting
hole. Please note that the two small round holes serve no purpose -- they were
used to secure the part during manufacture.Index Pulse Interrupter Disc for The 7x10, 7x12 and 7x14 Sieg C2 Mini Lathes
This one-slot interrupter disc fits the popular 7x10, 7x12 and 7x14 mini lathes made in China by Sieg and marketed by Grizzly, Harbor Freight, Enco and many more US suppliers. It has a center hole that is 27mm in diameter, the same size as the threaded rear end of the spindle. It is meant to be used with a slotted optical interrupter such as the Fairchild H21A1 (available from Digi-Key) to provide a one pulse per revolution input signal to the computer's parallel port and set up in Mach3 Turn as the spindle index pulse input. The disc can be mounted between the two jam nuts on the back of the spindle. The H21A1 (or similar) opto-interrupter will require two resistors and a simple mounting bracket and a cable to run to your breakout board.
The
interrupter disc is made of 0.04" aluminum and has a 27mm spindle mouting
hole. Please note that the two small round holes serve no purpose -- they were
used to secure the part during manufacture.
The price is $5.00 plus $2.00 shipping and handling charge for a total of $7.00. I only accept PayPal payments for this item. I do not ship this item overseas.
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The disc is shown mounted on the spindle of my Grizzly 7x12. You can see the
opto-interrupter mounted on a small aluminum bracket that is held to the lathe
by the hex cap screw in the upper left of the picture. I used two #6-32 cap
screws to hold the opto-interrupter to the bracket. The screws almost self-tapped
into the plastic sensor housing, but I ran a tap through just to make sure it
wouldn't split. The blue stuff is heat shrink tubing that is covering the two
resistors and the cable connections to the opto-interrupter. Under that blue
heat shrink are smaller pieces of heat shrink covering the individual connections
and resistors, so nothing shorts together. The gap on the opto-interrupter straddles
the interrupter disc and creates a pulse every time the slot in the disc runs
through the gap, when properly wired. There is an infrared emitting LED on one
side of the gap and an infrared detecting phototransistor on the other side.
The cable requires just three conductors; one for +5V, one for ground and one
for the sensor output signal. The cable I used has a shield conductor which
I used for the signal ground. This should help shield the signal from external
electrical noise. Be very careful that this signal ground is isolated from the
lathe frame which is connected to the AC mains ground.
See the schematic for the sensor wiring below.
You may contact me by email: probe (at) tetralite (dot) com
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