Spindle Door Latch Fix

Before I got the PDB I had purchased the 31217 Spindle Door Latch Upgrade which for me has always been sketchy. https://www.tormach.com/store/index....kaAgIoEALw_wcB Today the latch opened during a long machining operation, opening the spindle interlock switch stopping the spindle and ruining an endmill. Yeah the spindle stops but the program keeps running. My fix was to drill and tap a 1/4-28 hole thru the latch handle and install a 1/4-28 SHCS with Shear-loc thumb knob. Because of the PDB the Spindle door rarely needs to be opened nowadays and the thmbscrew will make sure it doesn't come open when a program is running.

Don

Attachment 418744

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Today the latch opened during a long machining operation

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Happened to me, too! That was on a manual change mill, so this upgrade wouldn't have worked.

Btw, I think the main problem is flex in the sheet metal of the door, making the latch not quite "catch" properly, and the door finally slipping open when the latch disengages by vibration. Slapping the door closed seems to cause that. Meanwhile, carefully closing the door, making sure to feel for positive engagement of the latch, has made it never happen for me.

Which leads me to believe that a different latch design with better guides for the retaining mechanism would be appropriate. A door lock style bolt? A T/dogbone plunger? Anything better than that shallow tongue-in-groove outside-only retainer...