Adapting a Molinari/Predator Extension
I want to make this perfectly clear: the Molinari and Predator extensions are identical.
A customer wanted to be able to use the Molinari extension from his Predator cue. The problem is that the Molinari bumper - which MUST be used with this extension - has metric threads. My lathe, which would supposedly cut metric threads, could only approximate the proper pitch. There was enough error that it just wouldn't work.
Yes, I could easily tap the hole & I did, in fact, purchase a tap set to suit but tests showed that the tapped threads were torn & ragged like you would expect. Most woods simply don't cut cleanly with a tap.
Yes, I'm spoiled. I prefer to live tool ALL threads. But since my lathe couldn't handle the correct pitch, I decided to make an adapter on my CNC machine. I programmed it to cut the internal metric threads and then cut external SAE threads, which I CAN cut on my lathe. It worked out very well.
You can see a video of the operation HERE.
I finally got to the point that I could install the adapter & decided to take a few pictures showing the process.
Here's the butt of the cue with the 7/8-14 threads already machined in it. Below are the Molinari bumper and the adapter shown in the video.
These pics show the adapter partially, then fully threaded into the butt. The last pic is just for show :-)
In this view, I've glued in the adapter, cut off the excess maple & exposed the threads. It's now ready to use.
And here's the finished product. I don't have an extension to show you how it fits but it simply inserts into the hole in the bumper & a half twist will lock it into place for the shot. Then, another half twist will remove it.
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I have since revised my method. I no longer thread the outside of the adapter - I simply turn a smooth diameter, then bore the buttsleeve to accommodate that diameter. Since the adapter is 13/16" in diameter and is installed 3/4" deep, this yields a glue surface of almost 2 square inches, which is certainly sufficient to retain the adapter. I will make another video showing this method the next time I get a request to modify someone's cue.
I may even begin selling the adapters since the new method can be practiced by anyone with a cue lathe.
Stay tuned!