Lathe alarm

[mklotz]

I added a swarf-catcher tray to my lathe's carriage. It can be seen here...

http://www.homemadetools.net/forum/l...7406#post37017

Although the tray clears the bottom of the chucks, when working near to the chuck face the tray can hit the face of the headstock behind the chuck. If I'm threading this means that the leadscrew can try to drive the tray through the headstock if I'm not watching closely. (Don't ask me how I discovered this.)

This and other situations convinced me that the lathe needed an alarm to warn me of impending disasters. The device I made...

is fairly simple. A nine volt buzzer alarm and its battery are housed in a plastic container. If the two copper wires emerging from the top of the container are shorted the buzzer sounds loudly enough to get my attention. A microswitch with a long actuator is wired via bell wire across these contacts; pressing the actuator sounds the alarm.

In front is a piece of brass with a neodymium magnet cemented to it. The microswitch will be attached to the brass flag. Then it's just a matter of sticking the switch under the swarf tray so the actuator contacts the headstock early enough to trigger the buzzer hung somewhere near my ear via one of the hooked copper wires.

The switch can also be stuck to the lathe ways to announce other potentially dangerous positionings of the carriage.

[olderdan]

Ingenious as ever Marv,
I always use stiff cardboard trays which are easily replaceable and will squash if things over travel, also easy to pick up and dump the swarf. I find the best source of said cardboard is beer boxes which also makes good templates if needed.
I never throw anything away until I can think of no further use for it.

[tonyfoale]

I use the aluminium cooking trays that some food comes packaged in. They collapse easily. I also use them under bench grinder wheels to catch the stuff not caught by the covers.

[DIYer]

Thanks mklotz! We've added your Lathe Alarm to our Lathe Accessories category,
as well as to your builder page: mklotz's Homemade Tools. Your receipt:

Lathe Alarm by mklotz

tags: lathe, safety

[benkeller3]

I have been thinking about making something just like this for my shaper. Long runs can lead your attention to move to other jobs... your design is perfect simple and movable to multiple machines. Thanks

[Toolmaker51]

Ingenious as ever Marv,
I always use stiff cardboard trays which are easily replaceable and will squash if things over travel, also easy to pick up and dump the swarf. I find the best source of said cardboard is beer boxes which also makes good templates if needed.
I never throw anything away until I can think of no further use for it.

Well, immature and humdrum as it sounds, I get more cereal box cardboard than beer cartons. It is great tray stock, oh yes. Good pattern material and the thinnest variety is duck eggs for checking grinding wheel profiles, sharp corners in particular. Hold the bare [unprinted] face forward to direction of wheel. Inked side reduces the fuzzy resulting edge. If you clamp in a small vise to 'burn' the shape [kept steady], it's not bad at all against squares and radius gauges.
And avoid spendy buys like optical comparators.
BTW, the bags are great moving small parts around, not tearing as easily like sandwich bags. Sharp stuff will penetrate yet doesn't usually instigate rips. I keep one in the car for rain; good security for the cell phone. Another is combo raincoat-envelope for my ever present clipboard.

[Saltfever]

I love the simplicity of the "place anywhere" magnet & micro-switch. I am seeing this for the first time! Wish I had seen this many years ago. Great idea and Thanks Marv.

[mklotz]

For other tool applications it may make sense to turn the tool off rather than buzz an alarm. If that's the case, build something like my remote controlled relay and power the tool through the relay.

Remotely controlled relay

Then wire the microswitch to the relay with light bell wire (there's only a tiny current through the microswitch) and let it turn the tool off when the event of interest occurs.