I just finished my spherical cutter and I have some pics of the build here for anyone who is interested. The requirements for the cutter where that it fitted into my QCTP, it could take a tangential tool, and that it could be accurately adjusted (I need to be able to make very accurate hemispheres for a particular job). I can also smell a very nice flyball governor around the corner! So here is the build:
This is the block with the dovetail cut to size to fit on the QCTP.
Height adjuster has been added.
Bearings in place.
Shaft with a 3 degree taper on the receiving end and a thread (you can't see) to ram the cutter onto the taper.
The female taper.
Dovetail has been cut and cap fabricated to cover bolt to provide a flat surface for the locking screw.
To accept the lever.
The long, long lever.
Lever bent and installed.
Parts for the lead screw bush.
Silver soldered together.
Tool holder blank with Gib Strip.
Tool holder has been roughly shaped with a hacksaw to be milled.
The setup used to mill the slot for receiving the tangential holder. A bit precarious I know, but it worked.
Here is the slot. As you can see, I was overly keen with the milling and took a little too much material off in one place there (I'll be covering that with a thick coat of paint!)
Reference ruler has been added.
Gib screws in place. This was a saga as I broke a tap in one of the three original holes, so I drilled four new ones and will be bringing the filler and paint out this time!
The Lead Screw.
The first sphere cut by the cutter and also the ball for the en of the lever.
My indexing setup for the micrometer dial. The Lead Screw thread is M5 x 0.8mm and there will be 80 increments on the wheel, giving a 0.01mm (4/10000") movement per increment. This will be a pain when I need to move from convex to concave but I really need the accuracy for that job! That job, by the way is making ball nose mills for cutting dies for bending trumpet tubing of unusual, but critical diameters. The idea is to form a die (split down the middle) with the external shape of the curved tube. Then clamp the die around the roughly bent tube and push spheres (of equal diameter to the bore of the pipe) through the pipe, thereby forcing the wall of the tube to form to the shape of the die.
The dial is indexed and in place! Now time for that paint.
There it is. You can just see the hidden circles where a broken tap resides! You can also see the locking screw hole.
This is what the whole thing looks like.
The Dial. Under the dial you can see where the set screw for locking the tool in place goes.
It still requires that I make some kind of reference for centering the tip of the tool in the x and z axis on my lathe. It may also require that I make a reference for lining up the tool tip on the axis of rotation of the assembly, so that I get accurate adjustments wen using the dial. When I've figured these out, I'll put a mark on the base of the tool holder so that I can use the reference ruler as a guide for the cuts prior to measuring the ball and then honing in on a final radius. Any ideas for the reference device would be appreciated.
Thanks for looking,
Hope you enjoyed it.