One of the things I needed to add to the workspace, in order to do the Japanese metalwork and engraving, is an adjustable height work platform and Ideally with a turntable. The reason for this is that it makes it so much easier to work with a microscope.
Yesterday the UPS guy dropped off the welding pipe stand I ordered as a base for this. Ray Cover uses these in his engraving class and they are a very decent solution. The only thing is you have to add a flat platform and a turntable to them. While the current stainless knives were in the kiln tempering today I decided to see if I could knock out the turntable assembly.
So the first thing to do is collect the materials needed:
That would be some 1.75 inch 1018 round bar a 0.5 x 3.5 inch grade 8 bolt with nut, washer and machine thrust bushing an brass countersunk screw 1/4-20 and a 12x12x0.25 inch plate of hot rolled. (I wound up not using the set screws)
Net up log 3.5 inches of bar stock.
Then load up the GCode for an 8.5″ circle into the CNC table software.
Let the machine plasma cut the circle for the turntable platform.
Here it is without the scrap. (I will admit now that the table is slightly out of calibration and I wound up with a mild ovoid. Such is life)
To warm up on the lathe work, I took the grade 8 bolt chucked it up and faced it off. Then I center drilled it, followed by a #3 drill IIRC (0.213 inches) and tapped it to 1/4-20. No, tapping grade 8 bolts is not fun.
The bolt is the axle and the screw will hold the table to it.
The next part was the majority of work. I had to take the round bar, turn most of it down to the inside diameter of the upright tube on the stand while leaving enough lip to support the piece. It also needed a 9/16 inch hole drilled through it and a pocket on each end for the 1.125 inch outer diameter of the bearing. The pockets needed to be .375 deep with a relief cut in the center to clear the inner bearing race. Here is what it looks like finished.
here it is fit to the tube on the stand. What you can barely see there on the left is a 0.25″ hole that was already in the tube. I used that and marked the bearing holder for a 1/4-20 hole. A thumbscrew will pass though the tube and thread into the bearing holder, thus locking the bearing holder in the tube and providing a spindle lock for the turntable.
Then, find the center of the table. This is where I confirmed the slight ovoid nature of my circular cut. Drill a .25″ hole and countersink it. Wipe down all the parts and prep for final assembly, with loctite.
Here is the axle in the bearings installed with the thumbscrew, before putting the table on.
Holds the engraving ball just fine.
Works well with the pitch bowl.
The only thing left to do is get the new chair into the shop and pay with the height and see if I need to shorten the base at all. I can take almost 7 inches off the bottom of the legs, and about an inch off the bottom of the adjusting tube if I need to. That however will wait for another day. The blades are finished tempering so tomorrow I grind.