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| kvom:
I turned the other side of the cam housings on the Hass lathe last night. It turns out one of my "good" ones was bad, so I have 2 good ones left. Hopefully I can drill all of the necessary hole (20 of them) without screwing up on at least one of the two. Since I have machine time this week, I'm going to CNC the driveshaft as well. I cut off 4 2.25" pieces of 3/4" 12L14 before leaving. I'll face off at home, and turn them on Thursday if all goes well. |
| kvom:
I turned the driveshaft on the Haas lathe at school last night. I started with 4 blanks and managed to get only one good part. Since I won't have access to the machine anytime in the near future, this is the last part for this engine I'll be able to make via CNC. However, at least I was able to run the two parts that have the critical dimensions. I still need to drill and tap 3 holes on the part. I bought a package of 2-56 taps on eBay yesterday, so hopefully I won't fubar this. |
| kvom:
I received the package of HSS 2-56 taps I bought on eBay a couple of days ago, so today I thought I'd test one before using it in anger. The test victim was a piece of 1/4" aluminum plate. I drilled a through hole with the requisite #50 drill. One impression is that the Bridgeport spindle is not very sensitive with drills this small. I pecked it mainly looking at the swarf coming out of the hole. Then off to the tapping stand. While the tap cut the threads very cleanly, again it was difficult to sense any feedback through the fingers. Nonetheless a SHCS screwed into the hole, so I can claim a success. This engine uses over 100 of these screws, so I'd better get used to drilling small holes and tapping them. |
| kvom:
Having made the soft jaws for the rotab, I wanted to use them for the cam housing. Here the portion that needs to be clamped is the 1" diameter nose. So I needed a pocket 1" in diameter wth a maximum depth of .400". First, I positioned the rotab as close as possible so that its center is lined up with the mill's spindle. The jaws are clamped onto a steel round to keep them fixed. With a 5/8" end mill, I drilled down into the jaws .400" and turned the rotab 360 degrees. Then with the mill turning I locked the y-axis and moved the x-axis .05", then again rotated the table one full turn. I repeated this until I moves the X-axis 3/16", resulting in a pocket 1" in diameter. With the pocket formed, I then used the endmill to level the top of the jaws so that the piece would sit level when clamped. Here's the result: Note that it is not sufficient to bore or drill the pocket using the mill, as the spindle may well be several thousandths off from the center of the rotab. Doing it this was ensures that the center of the pocket coincides with the center of rotation of the table. Next I chucked the piece in the soft jaw pocket, and using a DTI in the spindle indicated its inner diameter. Thisa allowed me to line up the center of the cam housing with the spindle, and thus also with the center of the rotab. Now with the rotab in the horizontal position I can drill the 10 mounting holes, with each pair 72 degrees from the next. Note that I don't have to worry about drilling through holes into the jaws. Once these holes are drilled, I will need to place the rotab in the vertical position without removing the cam housing, so that the pushrod holes can be drilled 72 degrees apart but 36 degrees from the mounting holes. Now with the holes drilled: I put the rotab into the vertical position, square it to the table, and then center the workpiece on the Y-axis using an edge finder. I quickly discover a small "problem": the jaws are too close to the work and too long to reach with a drill in the spindle. So my original plan won't work. I didn't want to cut the soft jaws down far enough to allow the drill to reach, as I want to re-use the jaws for other parts. The solution I came up with is to rotate the table so that the holes will be drilled between the jaws. I'll reclamp the work for each set of holes, and use the height gauge to ensure the proper alignment. I put pair of drill bits in the mounting holes, and then rotate the work so that the scribe of the gauge touches both; once in position I tighten the chuck. |
| NickG:
Good stuff, you're making good progress on this. :thumbup: Nick |
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