By Fred Kachelhofer
A member of the Barnesville Woodturners
Background
For an easy reference to the original article on making the MDF faceplates please visit
my article in
Wood News 35
and reference Step 4. In making the first of the MDF faceplates, it was not a problem to keep the tap lined up in the center of the steel faceplate when running the tap through the MDF. In trying to make additional faceplates, a different grade of MDF was used and there were problems in keeping the tap lined up with the axis of the metal threads. In the long run this is not really a huge problem since the tapped piece is placed on the lathe and the piece rounded up for the new axis. This is also true for facing off the front of tapped piece prior to gluing on the cap of the faceplate.
Solution
As stated above, the problem was the tap not running true through the bore of the metal threads on steel faceplate. The obvious solution was to create a guide for the tap to hold it in the center of the bore. The shaft of the tap is 5/8" and the inside diameter of the threads does not really matter since all the guide needs to do is slide inside the threads of the faceplate. A piece of hardwood was placed in a four jaw chuck and turned until the steel faceplate threads could slide over the wooden piece. Try not to get this fit too tight. Make the piece about the length of the threads in the steel faceplate. The picture above shows the piece slipped over the tap with the 15 mm socket in place.
The threads are tapped just as they were before, except you now have a guide to keep you lined up as you make the tapped hole in the MDF. I place the steel faceplate in the jaws of a vise to hold the piece steady. As before, I run the tap down all the way through the MDF rather than trying to go part way and then backing the tap out. Either way would be OK. The steel faceplate is just easier to hold in the vise and turn the tap in one direction.
Now in case you do make the fit too tight and have problems getting the guide bushing through the MDF threads, set up the tap as shown in the picture. Place the chuck in the headstock. Use a 3/8" socket adapter (available at tool and hardware stores) to hold the 15 mm socket. Place the live center on the tail stock in the indentation on the tap. Then sand lightly to get the clearance that you need. Of course you can tell that my first guide was too tight or it would no have been necessary to figure out how to make it fit.
After the tap is run through the MDF, put the CA glue and activator on the threads to stabilize them. Run the tap through the threads to chase and clean them up for an easier fit on the lathe. The faceplate hub is now complete and ready for truing up and gluing the cap to the outer end of the hub.
The results were quite remarkable. After removing the hub from the steel faceplate and screwing it on the lathe, there was very little wobble or run-out from the threads not being of the axis of rotation. It is well worth the time to make the little wooden guide bushing to assure the tap will go through straight.
You can email Fred Kachelhofer at Kplus10@bellsouth.net
