After seeing what Gain in NM and Maryak have done I thought it would be a greak first project for me to tackle. The series in Home Shop Machinist and is fairly well documented.
I started with the tools I would need for the machining of the parts:
Then I started on the crankcase (or the trial run as I call it):
The crankcase is titanium 6/4 grade and was a bear to machine. Until I used carbide! I tried HSS and ground my tools but they wore out and work hardened the surface quickly. I switched to c6 carbide as that was all I had and it worked! It looks worse in the photo than in real life.
The Ti needed no clean up, only filing of burrs on edges. The bore came out very smooth as did the rear crank cavity. The only rough patch is boring the rear there are lines where I missed the depth slightly. Since the crank bushing goes past this as the thrust face I am not to worried.
The problem I had was I made the snout and drilled the hole to .500. Then I bored it out to .600. When I turned the crankcase around to bore the rear cavity I was unable to get it concentric! I had a dial indicator on it in the 4 jaw and got it between the lines (each one .001) but when I tried a cut longitudinally I found it cutting les that the entire piece. I bored the rear and then sent the boring bar down the crank snout so that both bores were concentric but the outside of the snout is not by a small margin (I notice it!).
Also, when machining the sides in the mill I missed the mark for the mounting tabs so I omitted them. I also had the jaws of the milling vise mark up the rear top so I beveled the top, removing clearance for the cylinder studs! Oh well...
I disconnect the gear train when using the dial indicator so I can turn the chuck over (4 jaw) and it seems that the backlash of the gears makes perfect alignment difficult. Anyone have a better idea?
I have 3 more billets to use so I learned what I needed on this one and should start the next 3 soon. I still need some cast iron for the piston and some tooling (reamers and such) but I am very excited with the start.
I know the project is ambitious and the material difficult but that is why it is my hobby and not my job.
Thanks for looking,
Sean
I started with the tools I would need for the machining of the parts:
Then I started on the crankcase (or the trial run as I call it):
The crankcase is titanium 6/4 grade and was a bear to machine. Until I used carbide! I tried HSS and ground my tools but they wore out and work hardened the surface quickly. I switched to c6 carbide as that was all I had and it worked! It looks worse in the photo than in real life.
The Ti needed no clean up, only filing of burrs on edges. The bore came out very smooth as did the rear crank cavity. The only rough patch is boring the rear there are lines where I missed the depth slightly. Since the crank bushing goes past this as the thrust face I am not to worried.
The problem I had was I made the snout and drilled the hole to .500. Then I bored it out to .600. When I turned the crankcase around to bore the rear cavity I was unable to get it concentric! I had a dial indicator on it in the 4 jaw and got it between the lines (each one .001) but when I tried a cut longitudinally I found it cutting les that the entire piece. I bored the rear and then sent the boring bar down the crank snout so that both bores were concentric but the outside of the snout is not by a small margin (I notice it!).
Also, when machining the sides in the mill I missed the mark for the mounting tabs so I omitted them. I also had the jaws of the milling vise mark up the rear top so I beveled the top, removing clearance for the cylinder studs! Oh well...
I disconnect the gear train when using the dial indicator so I can turn the chuck over (4 jaw) and it seems that the backlash of the gears makes perfect alignment difficult. Anyone have a better idea?
I have 3 more billets to use so I learned what I needed on this one and should start the next 3 soon. I still need some cast iron for the piston and some tooling (reamers and such) but I am very excited with the start.
I know the project is ambitious and the material difficult but that is why it is my hobby and not my job.
Thanks for looking,
Sean