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| Oh dear, he's off polishing his crank again. |
I observe that there a lot of dings and dents in the (mill knee lift) crank handle that I want to polish.
It's in front, the machine is from 197, the handle is mild steel, it's constantly right under the mill vise, so that's to be expected.
I have decided to diminish some of the worst dings by peening. For those just joining the class, dings and dents raise the material around them, cuz for there to be a hole, the material has to go somewhere, after all. If we carefully smack the material around and over the raised bits, starting at a short distance from the hole and moving inward, we can damn near erase the hole's existence (almost, not quite) faster than a denounced general could be removed from a Russian propaganda photograph.
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| (before peen) |
Really, it goes rather quickly, only light taps are required (just a lot of them), but in this one case, this bloody handle is covered in dents, and I am not going to do them all because arthritis, patience, and madness. 😱
Nevertheless, doing the most egregious divots will markedly improve its final appearance, once I get around to the cleaning and polishing stage. "Cleaning" in this case means using a very coarse grade of polishing compound first, which actually cuts, and will further smooth the edges of the divots. Then I go straight to the finest grade I have, skipping the ones in between, for final polishing.
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| (after peen) |
This is the last handle and dial on the mill. The dial graduations and surfaces need to be righteous on this one, because it is the only (thousandths) dial I actually use and my failing, cataract-laden eyes need to be able to read it. The other axes are covered by the DRO which of course can be read from across the room.
Hey I wonder if older machinist/hobbyists could get a DRO covered as supportive medical equipment? 😂
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| (see? perfectly normal) |
What I didn't expect were the table handles. The table handles mount over the shaft with a thin bronze bearing between, a floating pin transfers torque from the handle to the shaft via a hub. This adds more slop than was already there, but the dial remains locked to the screw which is what matters. Then the handle is retained with a spring, which is fully compressed (?!?) and retained in turn by a beveled washer and a nut. Odd.
All I can think is that the pin is very soft and sacrificial, because this thing came with a factory table power feed, and if the handle hits something while turning, you'd prefer not to tear up the gears inside the power feed. Trust me, you don't want to open an old Bridgeport table feed unless you absolutely have to.†
My guess is that those are meant to be shear pins. Except they are a quarter-inch thick and a file test suggests it's mild steel not leadalloy or pure aluminum or brass or anything else soft, so I don't figure they're gonna shear no matter what happens. Maybe someone got tired of the right thing shearing off all the time because the operator kept leaving their stool near one end of the table...
You know, I should probably replace them before I forget.
If I ever restore my table feed, I think I'll use soft (pure) aluminum or maybe as soft a brass as I can find. Actually brass, because I'd have to buy a length of aluminum and I only need two little pieces 3/4 in long. Art stores sell pure-aluminum wire for armatures / maquettes, but I don't think they sell it that thick.
And if anyone reading this knows what's up with those fully-compressed springs, please comment or email me.
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† I absolutely have to, to resurrect mine from the dead,
but that is going to be another big project requiring a
long series of long posts. Which I'm starting to get
obsessed with, which means I'll probably start it soon.
At least I have have the replacement (Minarik) DC
motor drive on hand, but the restoration is nevertheless
heinous. The original Bridgeport power feed is a bad
/ strange / baffling design.
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