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| kvom:
Still tooling up. Today I ordered two lathe chucks. One, from a guy on PM, is a 8" 3-jaw chuck with D1-3 mount and 2-piece jaws. This will go on the lathe when I need soft jaws. The other is a 6" plain back 3-jaw with 2-piece jaws that will go on the rotab using that Al disc as a backplate. Found it on eBay. Assuming TIR isn't too bad I should be able to center work on the rotab. Otherwise I can make some softjaws and center them that way. Otherwise no shop time today as I was helping a friend swap a transmission into his Jeep all afternoon. |
| kvom:
I ran the first half of the cam housing programs on Monday night. Since we have to share the lathe setups, I was limited to using the existing chuck jaws and could add only the boring bar to the tool holder. The existing 3-jaw chuck was set for 2.5" stock, so I needed to adjust the program to turn down from there as opposed to the 2" I had previewed. Since I couldn't drill the stock on the CNC lathe, I needed to cut off 1.5" thick discs of aluminum bar and then drill them 11/32 on the manual lathe. Using the Haas CNC lathe there is a longish setup process where you touch off the X and Z coordinates for each of the tools your program will use. In this case I was using a turning/facing tool, the boring bar, and the parting tool. Eventually I was ready to cut, but the first pass is always done by single stepping the program to make sure there are no gross errors that would break a tool or the machine. This took about 15 minutes to make the first piece. Next I measured the critical dimensions. The boring depth was .008" too shallow as measured by a depth mic; since this is the critical dimension of the part, I needed to adjust an offset for the boring bar to correct for it. The second part was run a bit faster, and then remeasured to confirm the dimension is fixed. The last two copies were run at full speed, taking 7 minutes machine time for each. One of the pieces received a slight ding, likely by hitting a chuck jaw when parted, so I have two "scrappies" and two good parts. The second program to form the nose will likely need to wait until next week, as a new set of jaws needs to be bored to chuck the 1.675" diameter. The jawqs on these lathes are hydraulic and have a fairly short range of motion, so they need to be bored to fit a given depth and diameter, similar to soft jaws. So producing the two good parts has taken approximately 6 hours, including programming, setup, and run time. It's interesting to work on, but obviously inefficient for small quantities. |
| kvom:
My cheap Chinese 6" plain back chuck arrived today, so I spent the afternoon working to get it mounted on the rotary table. The first order of business was to verify the bolt circle of the 3 mounting holes in the back. I used the DRO to verify that the diameter is 142mm. The holes are threaded M8-1.25, so it was off to the hardweare store to purchase bolts of the correct length. After drilling the holes, I countersunk them with a .5" endmill, but the hole was still a few thou too small. A few minutes with the grinder reduced the heads so that I could attach the chuck to the plate. With the chuck mounted, there is a 3/4" flange remaining for mounting slots. I milled these with the side flutes of a 1/2" endmill. Here's the result mounted on the rotab: I removed one of the top jaws for measurement, as I intend to make a set of soft jaws. The next step will be to center the chuck body on the table, and then meaure the runout with the supplied jaws. |
| kvom:
I got the rotab chuck dialed in today, although it took longer than it should have. I was holding the DTI in the spindle, but a better idea would have been to use the mag holder on the table. Indicating on the body of the chuck, I got it to within .001". Next I need to clamp a round bar and indicate to see how concentric the jaws might be. |
| kvom:
I chucked one of the "bad" cam housings in the rotab chuck and measured the runout. It was .0015, so I "think" I will be within tolerances for building the parts that need the rotab. Now for another issue, I needed to move the rotab closer to the center of the table. Now to re-center under the spindle, I no longer have access to the precise center hole of the rotab table. I think I will probably just use an edge finder againt the chuck body, or else on whatever workpiece is chucked. I could also try using a DTI against the table's outer diameter, although that's a bit more time consuming. Since the chuck runout is small, I don't think I gain anything that way. In the meantime, I ordered and received a parts list from Liney that has all the screws, bearings, balls, washers, etc. that is needed to complete the engine. |
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