Thursday, Oct 20 2016
I’m waiting for a replacement backing plate for my 3-jaw chuck. There is not enough meat left on the first one to fix my screw-ups. Short story: I machined the backing plate without it being fully seated on the spindle. I though it was. I was wrong. Once it fully seated it was no longer anywhere close to true. Live and learn.
In the mean while I can use my 4-jaw chuck. It’s a time-consuming pain to get the stock centered. Time is one thing I have.
Today I made a replacement index pin. The one that came with the lathe had a broken tip. The pin is kept under tension with a ball and spring so it doesn’t accidentally engage when the lathe is in operation. I didn’t have the needed size ball – 3/16". I did have some scrap brass that came out of an old door hinge. I made a 3/16" brass plug to replace the ball. In checking the depth of the hole to look for a spring in my junk pile I found the stock spring stuck in place by dirt and old oil. It didn’t take much work to free it up. Sometimes you get lucky.
Index pin engaged
Index pin disengaged
This is my replacement index pin made out of O1 tool steel. It does the job. The spring and plug mentioned above were dropped in the hole in the top of the headstock and depressed with a small screwdriver.
That provideed enough clearance to insert the index pin through the side of the headstock. Once the index pin was in place I inserted a groove pin into a 1/8" hole at the end of the index pin. The grove pin keeps the index pin from being accidentally pulled out of the headstock. I salvaged the groove pin from the original index pin.
Sunday, Oct 23 2016
A few odds and ends. The replacement backing plate for my three jaw chuck arrived. This time I made sure it was 100% on the spindle before machining. The backing plate and the chuck when mounted have less than .002" runout. But… measuring some drill rod in the chuck was much worse – almost .030" at one point.
There are no markings I can detect regarding jaw location. At least the jaws are numbered. I tried the jaws in all three possible locations and found the best had a run-out of less than .007". Good enough for most things. If I need better than that I’ll use the 4-jaw chuck and indicate until perfect. I marked the chuck so from now on I’ll know which jaw goes where.
I managed to modify a spring from my junk pile to fits the bull gear. This is needed to enable easier switching between direct drive and back gear drive for lower speeds. The spring keeps pressure on a 1/8" ball that holds the pin linking the bull gear to the drive pulleys in its engaged and disengaged positions. When I got the lathe the spring and ball were missing and the set screw that keeps the parts in place was jammed all the way against the pin. Much better now.
Indicator holder
I made this holder to mount my test indicator on the 1/4" rod of a magnetic base. The holder is aluminum. One end has a 5/32" hole for the indicator dovetail attachment. A set screw holds the attachment in place. The other end has the 1/4” hole for the rod. I made the thumb screw out of an 8-32 screw plus a piece of scrap brass. Loctite will keep the pieces together. I faced off the portion of the screw that was sitting proud of the brass. Works well.