In case anyone else wants to create an interlock....
I have a pre-color change Rikon 18" bandsaw (model 10-345, 2.5Hp, 11 FLA), and it has the handy blade tension release lever. It uses a typical dbl-pole/sngl-throw (DPST) mechanical switch rated at 20A - but this has burned out on me once already (and factored into decision). I discovered that if you forget to move the lever and start the saw with no tension on the blade it makes a mess:
Bandsaw 001.jpg
This is a close-up of the top edge of the lower door where the blade has taken a bite. Hard on blades; hard on the door; hard on egos.
As you can see in the photo, I have committed this cerebral flatulence once and my father has done the same. That was enough for me, so I decided to build an interlock to the start circuit, and considered 2 alternatives:
- Interrupt the power to the existing Start/Stop switch across a new DPST limit switch (L/S) rated for full amps/volts of the motor. Position of the blade tension carrier triggers the L/S. This has the advantage of simplicity and minimal new parts; downside is that the cheapest L/S I could find rated for >11A was $350.
- Replace the OEM Start/Stop with a magnetic starter - with 240VAC coil - and a SPST L/S. The L/S now only needs to carry the amp draw of the starter coil, and has the added plus of not allowing the saw to re-start after a power failure (i.e. grid fail or CB trip).
In both cases, I considered trying to locate the L/S so that a blade 'break' would also cause the starter to drop out, but finally tossed it as too complicated and probably prone to damage from either blade teeth strikes or similar disasters. I just don't need the added maintenance hassle.
I sourced all the parts for option 2 online for ~$125 and I liked the anti-restart benefit, so option 2 it is - -
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