brown_hawk
05-04-2008, 07:14 PM
It’s already been admitted that I am lazy and anal, and this little device proves both. It is set up to indicate when a router bit or saw blade is at a given height - without the bending over, aligning the eye with the blade, and trying to find the exact moment when the blade reaches the given height.
Parts: A bulb holder or buzzer, a battery compartment, some wire, and two wires with an alligator clip on each end. Also a bulb and the batteries, and a piece of scrap wood.
All of my parts were laying around the house, but you could find them at Radio Shack. It starts out with the battery holder of any broken electronic gadget. Mine was a broken electronic temperature sensor. I took the front off, isolated the battery compartment, and took a band saw to remove plastic that I didn’t want. To the battery compartment, there are two wires that run off to power the device. Keep those attached to the battery compartment. Mine was for two AAA batteries. I drilled holes in the remaining plastic so that I could screw it to a piece of scrap board.
Next is a flashlight bulb holder. Mine is for a screw in bulb, and came from Radio Shack many, many moons ago. These have two tabs or wires. One goes to the center of the bulb base, and the other will contact the side of the bulb to complete the circuit. You could also use a buzzer. Since I’m cheap and had the light holder, I used it. Keep in mind that if you use a light, it needs to match the battery power you are using. A nine volt battery will quickly burn out a bulb meant for 2 AAA’s. The holder had two screw tabs for screwing to the board.
I soldered one wire from the battery compartment to the tab going to the center of the bulb holder. You might want to replace these wires if they look too small. The other wire from the battery compartment I made sure was long enough and twisted the end into a ball and put some solder on it. This was so that the alligator clips would be able to have a firm grip. You could also just solder the wires to these points instead of using the clips.
The next step is simply screw the battery and bulb holder to the board, insert the bulb and the batteries.
Attach one of the alligator wires to the second tab of the bulb holder, (or solder it if you want to do that.) Attach the other alligator wire to the wire from the battery compartment.
The next step is to attach the wire from the bulb to the router bit (or saw blade). Attach the other wire to a metal height scale. For my router, I used a combination square laid across the router plate opening. I had a piece of paper between the metal plate and the square. The paper may or may not be necessary to insulate from metal to metal contact. Just run a test. WIth the one clip attached to the router bit, and the other attached to the combination square, I simply raised the router bit until the circuit was completed and the light turned on.
A couple of things to watch out for is that the bit or blade is clean, no dirt, paint, tar, or anything which might prevent good contact. At the other end, make sure that the metal you are using is also clean and has no finish that interferes with conductivity. I have a really nifty aluminum router bit height gauge that is worthless for this procedure as the really nifty finish allows absolutely no conductivity.
On the other hand, when I wrapped a strip of aluminum foil around it, and put the clip on the foil, the gauge worked perfectly for this setup, so a plastic gauge with foil should also work.
Hopefully, this will ease a few aching backs and some eyestrain. It certainly has for me. Enjoy!
Hawk
Parts: A bulb holder or buzzer, a battery compartment, some wire, and two wires with an alligator clip on each end. Also a bulb and the batteries, and a piece of scrap wood.
All of my parts were laying around the house, but you could find them at Radio Shack. It starts out with the battery holder of any broken electronic gadget. Mine was a broken electronic temperature sensor. I took the front off, isolated the battery compartment, and took a band saw to remove plastic that I didn’t want. To the battery compartment, there are two wires that run off to power the device. Keep those attached to the battery compartment. Mine was for two AAA batteries. I drilled holes in the remaining plastic so that I could screw it to a piece of scrap board.
Next is a flashlight bulb holder. Mine is for a screw in bulb, and came from Radio Shack many, many moons ago. These have two tabs or wires. One goes to the center of the bulb base, and the other will contact the side of the bulb to complete the circuit. You could also use a buzzer. Since I’m cheap and had the light holder, I used it. Keep in mind that if you use a light, it needs to match the battery power you are using. A nine volt battery will quickly burn out a bulb meant for 2 AAA’s. The holder had two screw tabs for screwing to the board.
I soldered one wire from the battery compartment to the tab going to the center of the bulb holder. You might want to replace these wires if they look too small. The other wire from the battery compartment I made sure was long enough and twisted the end into a ball and put some solder on it. This was so that the alligator clips would be able to have a firm grip. You could also just solder the wires to these points instead of using the clips.
The next step is simply screw the battery and bulb holder to the board, insert the bulb and the batteries.
Attach one of the alligator wires to the second tab of the bulb holder, (or solder it if you want to do that.) Attach the other alligator wire to the wire from the battery compartment.
The next step is to attach the wire from the bulb to the router bit (or saw blade). Attach the other wire to a metal height scale. For my router, I used a combination square laid across the router plate opening. I had a piece of paper between the metal plate and the square. The paper may or may not be necessary to insulate from metal to metal contact. Just run a test. WIth the one clip attached to the router bit, and the other attached to the combination square, I simply raised the router bit until the circuit was completed and the light turned on.
A couple of things to watch out for is that the bit or blade is clean, no dirt, paint, tar, or anything which might prevent good contact. At the other end, make sure that the metal you are using is also clean and has no finish that interferes with conductivity. I have a really nifty aluminum router bit height gauge that is worthless for this procedure as the really nifty finish allows absolutely no conductivity.
On the other hand, when I wrapped a strip of aluminum foil around it, and put the clip on the foil, the gauge worked perfectly for this setup, so a plastic gauge with foil should also work.
Hopefully, this will ease a few aching backs and some eyestrain. It certainly has for me. Enjoy!
Hawk