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a nine cylinder radial engine, plans by "ageless engines"
madjackghengis:
Sometimes a person does something that seems reasonable, but makes you want to cry afterwards. Having been aligning multi-piece crank assemblies for some thirty odd years, I had to check the crank I just assembled, and come to find out the shafts are not aligned, but have as much as seven and eight thousandths eccentricity. Now is the time I regret using the mill for the crank cheeks, and will go back, make a new set, assuming I don't ruin the shafts, dissassembling the whole thing, and hopefully this time get all faces in the same plane, so there is a reasonable accuracy in the shaft rotation. For those who have used the method of running shafts through holes in both crank sides, and then cut out the middle section, this is where you win.
with the main bearings on V blocks, and the dial indicator on the ends of the shafts, they are obviously not straight.
Since the shafts were straight when machined, and each "second end" clocked in before turning, it is the crank cheeks causing the eccentricity and must be replaced. And I thought foolishly, I was ready to move forward, Ha :bang: teach me to measure something I don't want the answer to :bang: I have to think about this, I will not use the same method to make the crank cheeks, this is definitely about the two faces, inner and outer, being other than parallel. With Harley engines, I just start hitting the flywheels with a lead hammer, and continue until the shafts are within a thousandth of an inch. These have already, not succumed to that treatment. I think I will use the shaper exclusively for the faces, and the mill only for boring the necessary accurate holes. When using a multi-element face cutter on hardened steel, it tends to deflect as the individual inserts enter and leave the metal, often leaving a wavy pattern on the surface which is always visible, but not always easily measurable for accuracy. Perhaps if I machine the cheeks parallel and a quarter inch thick, ensuring to my best ability the parallel factor, and then add metal to the counter weight end with rivets, after the crank is proven out straight and round turning. Time for some thought and some research, it will not do as it is. Mad Jack :bang: :bang: :bang:
madjackghengis:
And to Zeroaxe, that wheel is attached to one of those artsy fartsy motorcycles made out of coat hanger wire, string, beads, and any other old thing, and is art far beyond any artistry I can accomplish, because it has no measuring, no fixed dimensions, and looks good without having to work. My mom keeps saying I should make such things as they sell well, but I can't see them in the pile of metal I have, all I see is things that require machining and fitting, and can't be just hung together, although other people just don't understand why I can't, after all, I can weld like the artist, and I can bend the wires like he can, and I know what all kinds of cool things look like, I just can't twist them out of coat hangers and odd bits and pieces, but have to make the individual parts, and they have to turn and fit, and the like.
They look good, and sit nice on shelves, but they don't run and make noise, almost like having models!!Mad Jack :headbang:
Bernd:
MAd Jack,
Just a thought here on seperating the shafts from the cheeks. How about grinding or cutting with a slitting saw, a slot on the cheeks by the shafts in line with them. In other words relieve the tension on the hole that holds the shafts in. Kind of like splitting an old bearing to get it out of the hole. I think thar would make it easier to take apart.
Bernd
madjackghengis:
Thanks for the suggestion on the disassembly of the crank, as it turned out, it disassembled rather easily, the crank pin punching out with a brass drift, as it was not meant to be permanent, and with the front and rear shafts pressing out with an arbor press with only a little more effort. Measuring the inner cheek faces showed the three insert face mill left the cheek faces quite other than flat, with as much as two and a half thousandths difference just on opposite sides of the crank pin holes on both cheeks which is exactly what I expected given the way the shafts were out of alignment.
crank disassembled, ready for measuring and checking the shafts
Starting the new blank for the crank cheeks
the delicious aroma of suferated lard cutting oil, as the shaper cuts the steel
a look at the cut from the back side
the blank cut to size, a thousandth taper from one edge to the other, which will be filed to a micrometer measured flat when the cheek is cut to shape, after the holes are properly bored.
The old cheeks sitting on top of the blank, showing plenty of room.
Bernd:
Nice save Mad Jack. :thumbup:
Looks like a surface grinder would come in mighty handy to get them parallel.
Bernd
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