I have always been worried that someday I would forget to remove the spindle wrench from my PM932 with disastrous results when I switched the machine on. I figured there had to be a reasonably simple way to lock the spindle rotation when changing arbors or chucks. On releasing the lock it would automatically retract. With a little head scratching and the repurposing of my spindle wrench… check out the pictures you will see what I came up with.
A couple of points. The position of the lock arms to the spindle is critical for full engagement. Though I was careful marking and drilling I wasn’t happy after the assembly with the tooth engagement. I didn’t want to wallow the base holes out so made some eccentric’s for the mounting holes so I could move the base plate around a bit.
The base is a piece of 6061 4” x 5.5” x .375” from the scrap pile, the base to head mounting bolts are ¼” x 28, the pivot shoulder bolts are ¼” x 20. I split the spindle wrench down the middle and then tigged some steel from the scrap bin on. It ended up at about .200” thick.
There is some flexibility in this design, you could flip the arms over, or put the pivot point on the back side of the spindle, modify to suit.
Another thing to mention is you will need to be able to turn the spindle slightly to engage the teeth while holding the lever over. Most easily done at the chuck end of the spindle. If you are using the ER or set screw type collet setups you have a place to hold but with the flush R8 types grabbing the end mill might not be attractive.
A couple of points. The position of the lock arms to the spindle is critical for full engagement. Though I was careful marking and drilling I wasn’t happy after the assembly with the tooth engagement. I didn’t want to wallow the base holes out so made some eccentric’s for the mounting holes so I could move the base plate around a bit.
The base is a piece of 6061 4” x 5.5” x .375” from the scrap pile, the base to head mounting bolts are ¼” x 28, the pivot shoulder bolts are ¼” x 20. I split the spindle wrench down the middle and then tigged some steel from the scrap bin on. It ended up at about .200” thick.
There is some flexibility in this design, you could flip the arms over, or put the pivot point on the back side of the spindle, modify to suit.
Another thing to mention is you will need to be able to turn the spindle slightly to engage the teeth while holding the lever over. Most easily done at the chuck end of the spindle. If you are using the ER or set screw type collet setups you have a place to hold but with the flush R8 types grabbing the end mill might not be attractive.
