Dream crank becomes SuperHawk crank

Dick Eastman · Post by **Dick Eastman** » Wed Jul 13, 2016 7:12 am

I had four cranks, disassembled three, one of which was from a Dream. It proved to have the best components, except one bearing and the stator end wheel. All three had swarf in the rod pins, after removing alum. plugs.
Prior to pressing all three apart, I turned the flywheels down, after indicating each one in. The Dream crank had a 123mm dia, the S Hawks, 121mm dia, so I made it the same. The heat treatment of these cranks required using TiNi coated inserts on my lathe, and still I could only take about .030" off at a time. Also, the Dream crank had smaller balancing holes [2 per wheel], .89 dia vs .94 dia, so I opened these up as well.
I built a fixture, similar to G Mans, but used a larger 1.25 dia ground rod for the guide pins, Blanchard ground the plates, and made a clamp to locate the cam sprocket into the wheel. I decided to press the center wheels together one at a time. A side note - one of the center wheels on the Dream crank took everything my 20 ton press had, and upon inspection, there was .003"press on that wheel, vs .0025" on all the other wheels; I took the center wheels to my local automotive machine shop, and honed the extra 1/2 thou out of the one wheel.
I clamped the center journal/sprocket pin into my clamping tool, and set it up in the mill, and indicated the sprocket in, so that the tooth was exactly perpendicular to the clamp, and dropped the wheel into the fixture [located by the crank pin and two dowels], and then slid the clamped pin over the guide pins. I then pressed these together, removed from the fixture [with the center journal clamp still attached], and clamped the ass'y in my mill and checked that the cam sprocket tooth remained centered to the crank pin. It indicated as before, within .001" TIR. I then removed the clamp, and put this ass'y back into the fixture, and pressed the second wheel on, and then checked it - everything lined up well.
I am well pleased with the accuracy of the mill, i just bought it, and installed the read-outs myself, got the glass scales indicated in, and checked the linear error of the scales against a known length. The DRO resolves to .0002" - the x-axis was dead on in 12.0000", and the y off .0004" - the fixture turned out quite well, due to this accuracy. The mill has hardened and ground ways, and I spent several weeks installing the phase inverter, DRO, and power feed

Dick Eastman · Post by **Dick Eastman** » Wed Jul 13, 2016 7:22 am

A couple more notes - I made some hard bronze [C954} bushings for the rods, 17mm od x 15mm id x 18mm long.. I finished the od, and left stock on the id; then pressed into the bored rod ends, and finish bored the id after ass'y.
Also a pic of the swarf in the crank pins - the drill flutes were full.

G-Man · Post by **G-Man** » Wed Jul 13, 2016 10:37 am

Dick

Beautiful work. I'm envious of your workshop and the space you have. Satisfying, isn't it?

G

Dick Eastman wrote:A couple more notes - I made some hard bronze [C954} bushings for the rods, 17mm od x 15mm id x 18mm long.. I finished the od, and left stock on the id; then pressed into the bored rod ends, and finish bored the id after ass'y.
Also a pic of the swarf in the crank pins - the drill flutes were full.

james robert · Post by **james robert** » Wed Jul 13, 2016 5:38 pm

Beautiful work Dick, Did you buy the guide pins already ground? I was thinking a shaper would be nice to finish the plates.

Dick Eastman · Post by **Dick Eastman** » Wed Jul 13, 2016 7:44 pm

G-Man wrote:Dick

Beautiful work. I'm envious of your workshop and the space you have. Satisfying, isn't it?

G

Dick Eastman wrote:A couple more notes - I made some hard bronze [C954} bushings for the rods, 17mm od x 15mm id x 18mm long.. I finished the od, and left stock on the id; then pressed into the bored rod ends, and finish bored the id after ass'y.
Also a pic of the swarf in the crank pins - the drill flutes were full.

Thanks, Graham. Seems like I'm spending more time tooling up than restoring pieces, but, as you well know, you gotta have the right tools. Yes, a certain amount of reward with good results. After 45 years in the trade, and taking for granted all the machine tools I had at my disposal, I had to have at least a mill and a lathe [need a surface grinder next].

james robert · Post by **james robert** » Wed Jul 13, 2016 7:58 pm

That lathe looks like the one i use at the museum. I still don't know what brand it is. Thanks for the pics.

Dick Eastman · Post by **Dick Eastman** » Wed Jul 13, 2016 8:03 pm

james robert wrote:Beautiful work Dick, Did you buy the guide pins already ground? I was thinking a shaper would be nice to finish the plates.

Thanks, James
The pins were bought from Enco, 1.25" dia X 36" long [when they had free shipping last month]. They mic close to nominal, and are o-1 [drill rod].
A shaper would be ok, but I bought hot roll at the local scrap metal dealer, and had a number of pcs Blanchard ground, including the plates for my press. And being hot roll [not cold roll], they stayed flat through out machining. I think that is most important for the top and bottom plates, as I bored both as one, put .0003" press into the bottom plate, +.0015" clearance in the top plate guide pin bores; it worked smoothly, and the pins are parallel. If you have a bow in the bottom plate, when press pressure is applied, the top plate will bind up on the pins. If your shaper can get the plates perfectly parallel, you'll be ok. Besides, Blanchard grinding is not expensive.
If you bore your own plates, be sure to tram the head in. My machine is new, but I still went through it and made some adjustments to the gibs, and then trammed the head - it checked out very well - am quite impressed with it