Archive for category Machine Shop
I just caught George Bulliss in a weak moment. [grin]
You can say you knew me before …
A needle case emerged from the bottom of a drawer in need of repair:
The original joint used solvent glue and I suppose I could refresh it with acetone, but two blobs of hot melt glue seemed easier and, IMO, more durable.
In any event, it’s once more ready for use:
Hooray for another zero-dollar repair, although you can see why nobody else does them these days.
An upcoming show-n-tell prompted me to make sure the HP 7475A plotter still worked and verify the pen stash. One of the ceramic pens expired during the first test plot and a refill didn’t improve its disposition, so I pulled a new-old-stock pen from its wrapper.
As expected, the defunct pen’s ink supply core had worn down to the surrounding ceramic nib:
The new pen looks like it has a brush sticking out:
The new pen’s core looks slightly larger and, in fact, it’s labeled as 0.4 mm rather than 0.3 mm. The new-old-stock pen stash includes a few 0.2 mm ceramic pens; I should think of something requiring hairline detail.
It passed the manual scribble test and promptly ran out of ink during its first plot. I injected some blue ink and it’s now plotting happily for the first time in its life.
Although the original Tektronix Circuit Computer had relentlessly monochrome scales, a dash of color added a festive holiday look:
Well, OK, that’s excessive.
The intent was to see how the pens behaved, with an eye toward accenting general-purpose circular slide rule scales with a few colored characters.
The green pen shows how I built the arrows by drawing a line through vertical arrow characters:
I like blue ink entirely too much, having used a blue pen as my daily writer for most of my adult life:
Red ink for “backwards” scales and suchlike would work well, even if it’s too vivid for the tick marks:
Those are all on unlaminated plain paper, with plenty of room for improvement.
Seeing as how I’d be doing all the “tool changes” manually, optimizing the plotting sequence would be mandatory: one pen change per color per deck!
Cheap 1 mm pens produce scratchy lines:
More expensive 0.5 mm Pilot Precise V5RT pens produce well-filled lines:
For reference, the cheap pens use a collet holder:
The Pilot V5RT pens use a custom holder:
A 3D printer really simplifies making things!
Although a sex bolt works as a central pivot, even the shortest one available in a cheap assortment is too long for three paper decks and an acrylic cursor:
An eyelet / grommet intended for leather crafting works better:
That’s the front side, with the stylin’ rounded head, in “gunmetal” gray. The shank is 5 mm ID (the advertised size), 5.5 mm (-ish) OD, 4 mm long beyond the 10 mm OD head. All dimensions vary unpredictably between sellers, so expect nothing in particular and you won’t be disappointed.
The back side gets the washer:
The entire stack is 1.7 mm tall: three 0.4 mm laminated decks and the 0.5 mm polypropylene cursor. The 4 mm shank length seems excessive, but works out well in practice, even if I need more practice at smoothly swaging shank over washer. It’s sufficiently good looking in person.
Note: the washer goes on convex side outward!
The set includes a hole punch suitable for leather work and slightly too small for paper, plus the swaging punch and die required for the washer.
The matte mailing labels on the Kenmore 158’s hand hole cover plate did such a good job reducing the glare from the additional LEDs as to make the shiny hardware around the needle seem overly bright. I suggested gentle sandblasting might improve the situation without changing any surfaces in contact with the fabric.
I was given a spare presser foot to demonstrate my case:
The overhead light in the shop produces glare from the nice, shiny steel surfaces similar to what Mary sees from the sewing machine.
A few minutes applying 220 grit blast media with Tiny Sandblaster™ definitely changed its appearance:
In person, the finish is neutral gray overall, with those odd brown areas appearing only in photographs, perhaps due to the various lights in the shop. The slight texture variations seem to correspond to minor differences in the plating (?) over the steel surface. It definitely cuts down the glare:
The needle clamp and screw across the top of that picture travel up and down, so we decided to deglare them along with the “good” foot:
Another Tiny Sandblaster™ session knocked back their shine:
Those parts came out slightly less matte, perhaps due to reduced pressure in the propellant can. Seeing as how I’ve had the sandblaster for a couple of decades, I figured it’s time to use the propellant but, as expected, the in-can valve doesn’t re-seal properly, so I’ll be using compressed air the next time around.
After rinsing and blowing and rinsing and blowing the grit out of the threads, everything went back together as expected:
I’m not doing either of the plates until we have more experience with the matte hardware, but it looks pretty good to me.