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Hi Everyone & thanks for the comments Zee I appreciate it,I got a harebrained idea to make the crankshaft out of 1144 Stress-Proof thinking that it may stay a little straighter as the excess material was cut away. The smallest piece I could get that would work was 2 ?? dia. So a bunch of material needed to be removed.After facing the stock to length in my lathe at home I took the blank to work so I could cut it down in my mill there. Flood coolant, a face mill and a 10 hp. Spindle motor made quick work of it.Also while in the mill at work I drilled the centers and removed the excess material for the throw.Cutting to lengthThe Stress-Proof sure turns niceIn my mill at work getting ready to make the round bar into a rectanglePretty much to size; I left .050? on the thickness so I could finish it on my friends shaper later on.Set up to drill the centersAction shot!And the finished centersAfter the excess material was removed for the throw; I did have to straighten it a little. It had about .02? bow over the length; a little tweaking in the arbor press got it acceptable.Here is the blank set up in the lathe to turn the throw. The wire near the end is hold the blank against a threaded stud which I?m using to drive the blank. The stud is screwed into a hole in the flange of the collet adaptor.Action shot!Here it is with the throw pretty much finished. Besides the turning tool shown I also use small left and right hand insert tools to finish the inside faces of the cheeksUsing the band saw to blank out the extra material; the Roll-In saw makes this part of the job a breeze.Both sides have been cut and now it?s ready to go back in the lathe; it?s starting to look like a crankshaft now.Set up between centers and turning the long end.I ended up turning the shafts to fractional dimensions larger than the finished size so I could rough it out and use collets for holding the already turned ends. My original plan was to do the whole job between centers; but I was fighting chatter real bad and the collet solved this aggravating problem. Here it is flipped around and working on the short endHere is the set up in the mill to cut the key ways.And a closer shot.After the crank was finished I took it over to my friends shop and used his shaper to finish the cheeks to .750? thick. Remember that I had left them over size in anticipation of this. The shaper creates a finish that looks like it could have been ground. The shaper is also going to get a workout cutting the bearing pads on the body casting.As I told my buddy; the bench centers allow you analyze or agonize over really small TIR numbers. Over all I?m very happy with the way the crank turned out.Next up; starting work on the body casting.Thanks for checking in.Dave
Hi Dave, I'm really enjoying this build, the staggered depth bearing caps, in fact all to do with the bearings are a joy to behold.My one question is, will you be using oil or grease in the greasers, and does it matter which? (sorry, two questions!).Hugh.
I appreciate your taking the time to answer what is a novice question. I wonder whether cranks bow after time as the stresses are released. Could you season them after the first big cuts, and come back later to finish with light cuts. My crank is bowed after a few years of sitting. Strange. I'll follow your lead and straighten.
Looking great Dave, even down to the studs and nuts - single point threading is something I'm going to have to practise. The crank looks amazing, this is proper engineering - made me realise I'm just pittling about!
My buddy had already made the broach bushing for the tapered key; so I borrowed it and here is the broaching operation.