How to Make a Backing Plate

I received a buck 6 jaw chuck with my Logan Lathe, but it had no backing plate. Well, finding an two articles in the Village presses publications I decided it was time to do something about the situation. First article was how to restore a buck 6 jaw chuck ( I still have to do that some day...). The other was on casting and making a face plate. Face plate, backing plate, not much difference in my book so off we go.....

I have to date only used aluminum and Zinc alloys in my castings. Not exactly ideal materials for a backing plate but I figured I had nothing to loose by trying the backing plate in aluminum. Heck I could use the experience anyhow!

Home
Copyright 2003 by Mark Harrand.
Castings1
InternalThredingTool
1. Fist things first, we start with a pattern and the raw casting. The casting we are using is the one on the far left. The other two castings were to resurrect my drill press. The large hub was used for the set-true feature of the Buck 6 jaw chuck. There is also a hub on the other side which was machined to match the spindle on my lathe, in this case 1½" 8 tpi.

 2. Here is my boring bar/internal threading tool. Installed is the 60° threading bit. This is what I used to thread the spindle threads into the backing plate.
AdapterPlateThreading
AdapterPlateTest1
.3. Here I have faced off the back of the chuck and the hub for a mating surface on the spindle of the lathe. I then bored the center and have started threading. Notice that the threads start about ½" into the plate so they won't interfere with the mating of the hub when screwed onto the spindle.

 4. Before starting the backing plate, I created this "replica" of my spindle threads. It was on a 1" cast iron pipe coupling. The small hole at the base of the threads is a screw used to prevent the coupling from spinning on the pipe. Once I got a reliable fit here, I next tested the unit on the spindle of the lathe.
AdapterPlateTest2
AdapterPlateThreadedOnLathe
5. Well the first try did the trick. Threaded on nicely and seated with a satisfactory clunk! Notice I left it mounted in my four jaw chuck, just in case. This way alignment was maintained should I have needed to return to threading again.

 6. After releasing the four jaw chuck I put the backing plate back on the lathe for facing and truing it up the hub.
AdapterPlateFinishing
AdpaterPlateDrilling
7. Here it is faced trued and the location of the mounting holes transferred using locating punches.

 8. I then moved to the drill press and drilled and taped the holes for cap head bolts.
AdapterPlateCompleted
9. And there you have it. I have used it a couple dozen times so far and the aluminum seems to be holding up just fine. The true-set feature is fantastic. Now to restore that chuck..... Let's see that's number 23456 on the list of projects to go.
Home