This is the post where everything finally comes together.
I was up until now using pieces of a old kitchen cutting board for my test stand. While it was indeed made of hardwood I did not know what type, and I wanted my design to be reproduceable.
I spent two entire crafting sessions (about 3 hours each) thinking through my design for the enclosure and drawing it down on paper. I started with the patterns I had established for the bottom and front of the test stand. I then added panels for rear, top, and both sides.
I cut and drilled a set of panels in wood for the headstock: red oak for the top and bottom, and poplar for everything else. I found short panels of these at Home Depot as factory seconds which I got for a 10 percent discount.
In this next design iteration I fixed several errors:
1) I had noticed a corner of the test stand was cracked because of wood screw pressure since I had not thought to drill pilot holes for the screws to go in.
2) I had insufficient tolerance in the bottom panel and in the plywood motor support for the motor support screws. I increased my drill diameter to the next size up for the motor support screws in the new bottom panel. I also carefully redrilled the holes for the plywood motor support.
3) I knew all along that I had been using the wrong type of screws for the motor support. It is critical that the headstock bottom be able to slide on the lathe base without interference from nuts.
What I really wanted were countersunk 1/4 inch machine screws of about 2 inches length, so I got several in the same trip as I got the wood.
I then mounted the screws in reverse of my prior arrangement. The heads now fit into the countersunk holes, where before they had been holding the motor down.
4) The motor support screws needed to stay immobile while supporting the spring suspension. I used another set of nuts to fasten them just on the other side of the bottom panel.
5) Just like the nuts on the yoke screws, the nuts on the motor support screws tended to travel due to motor vibration. I found that after adjusting the tension of the spring suspension with a first set of nuts, that a second set of nuts could be used to keep the first set in place.
My new spring suspension system can be seen in this closeup picture:
Close up of improved suspension system for headstock motor
Again, I reiterate that the purpose of the suspension system is not just for fanciness: this system is crucial to allowing the headstock to rotate freely during operation, because it dampens runout caused by inherent inaccuracies introduced both by the motor, the chuck, the shaft coupling and by the use of hand tools during construction of the enclosure.
(Okay, so I cheated some and used a drill press rather than a drill, and a bandsaw rather than a miter box, but just to save time. When acting as an tools design engineer I reserve the right to take shortcuts even if the results are not neat, so long as they are functional. When I’m actually crafting the jewelry that’s when I will beg you to be critical of my efforts.)
The next picture shows my headstock during the start of its final construction. After I was satisfied with the spring tension on all four corners in the suspension system with just the bottom and front headstock piece present, I locked the tension into place with a second set of nuts. I then screwed on the back panel, resulting in the following picture.
Moved the motor and shaft from test stand to a headstock enclosure
At this point very slight tension spring adjustment might still be necessary after the back and top panels are screwed in place, since the pressure from the wood screws in mounting these panels could throw off the alignment somewhat. In my case I did not find such adjustments to be necessary.
Assembling the Mark One headstock
The coast was pretty much clear after the four main panels have been attached to each other in a square. After satisfying myself that no nuts were going anywhere while the motor ran, I attached the left and right side panels.
(Just prior to mounting the side panels, I detached my power cord from the motor, threaded the cord through a hold I made in the back, and reattached my connections with fresh electrical tape. NOTE: I didn’t mention anything about the fan motor speed control, because it didn’t seem relevant toward this design. The speed control was a plastic SP4T (single pole, 4 throw) rotary switch where each selection connected to a different tap on the stator winding. Very very clever, those Chinese, to fold a autotransformer into the motor design in order to simplify speed adjustment! I tip my proverbial hat off to them! In any case, I discarded the switch and permanently selected the tap wire leading to the highest speed setting. The others I taped aside along the main cord just to keep them safe.)
Behold my effort of 4 weeks of shop sessions!
The RezLathe Headstock, Mark One
Yes, the enclosure is quite ugly. The bandsaw is nice for fast work but I need to invest in either a table sander or that miter box I saw at last week’s flea market if I want my edges cut absolutely square. Or I could use the CNC mill to fly cut all of my wood blocks, but that would be 21rst century overkill upon a circa 1960 blast from the past.
Also I realized I missed something extremely important. The original fan motor took a 2 conductor electrical cord. I replaced it with a 3 conductor cord, but I still need to connect the neutral of that electrical cord to the motor chassis. I hereby resolve to ground my motor before my next post!
(NOTE: And an inline fuse would be extremely nice too. I’ll put that and an on/off toggle switch into the Mark Two. Along with the fly-cut wood panels.)
Applause? Just for getting this far?
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