03-23-2014, 07:55 PM
Finished the bronze nut today, wish I hadn't had trouble with various issues. The nut fit onto the mating screw snug, and I screwed it in until there was about 3/4" of and inch showing through. I took the nut out of the chuck thinking it would run down the whole thread, not so. I had to put it back in and take another thousandth or two. That's a pain in the butt!
To line it up again I had a idea that worked perfect. I had left the tool setting at the last cut, though I had taken the part out and had shifted the spindle speed. To line it up again I put the part in the chuck, started the spindle and engaged the half nut. Using the spindle brake to stop just out in front of the part, I loosen the chuck and rotated the workpiece (nut) out onto the tool. Once the tool was fully engaged in the part, I snugged up the chuck.
It worked nearly perfect. Certainly got me closer that I could have gotten if I tried to line it up the conventional way with moves of the compound slide. The one pass I made took perhaps .002" off, and now the nut sails onto the screw all the way. It's just tiny bit more clearance than I'd hoped to get, but it'll be fine. Because the knee isn't counterbalanced all the force will always be on one side of the thread flank.
After finishing the internal 1-1/4"-5ACME thread, over to the Alliant-Prototrak milling machine for holes. First up, a three hole pattern. Drilling the pattern is super easy with the Prototrak control. Enter in the number of holes, the bolt circle radius, angles between the holes and off you go. A little harder is "circle milling" the counterbores. I don't have a 17/32" end mill not counter bore, so I simply recorded the coordinates used for drilling the holes and used that for center points for three circle milling cycles. I used a 3/8" end mill. My first pass came out at .526", though Darren had .530" on his print. Easy enough, I just edit the program to tell it the hole isn't a .265" radius, change it to .267" and it makes the hole bigger by .004", as seen in the 1:00 long video.
Here's a few finished photos.
![[Image: IMG_2219-r_zps0621dd89.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_2219-r_zps0621dd89.jpg)
![[Image: IMG_2221-r_zps2b6a9f0a.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_2221-r_zps2b6a9f0a.jpg)
![[Image: IMG_2223-r_zps907f5039.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_2223-r_zps907f5039.jpg)
Came out pretty good, not absolutely perfect. At least there's no chatter anywhere on the threads and it meets the print requirements. I'm happy with it, just wish I could have gotten to finishing the remaining features on the mating screw.
To line it up again I had a idea that worked perfect. I had left the tool setting at the last cut, though I had taken the part out and had shifted the spindle speed. To line it up again I put the part in the chuck, started the spindle and engaged the half nut. Using the spindle brake to stop just out in front of the part, I loosen the chuck and rotated the workpiece (nut) out onto the tool. Once the tool was fully engaged in the part, I snugged up the chuck.
It worked nearly perfect. Certainly got me closer that I could have gotten if I tried to line it up the conventional way with moves of the compound slide. The one pass I made took perhaps .002" off, and now the nut sails onto the screw all the way. It's just tiny bit more clearance than I'd hoped to get, but it'll be fine. Because the knee isn't counterbalanced all the force will always be on one side of the thread flank.
After finishing the internal 1-1/4"-5ACME thread, over to the Alliant-Prototrak milling machine for holes. First up, a three hole pattern. Drilling the pattern is super easy with the Prototrak control. Enter in the number of holes, the bolt circle radius, angles between the holes and off you go. A little harder is "circle milling" the counterbores. I don't have a 17/32" end mill not counter bore, so I simply recorded the coordinates used for drilling the holes and used that for center points for three circle milling cycles. I used a 3/8" end mill. My first pass came out at .526", though Darren had .530" on his print. Easy enough, I just edit the program to tell it the hole isn't a .265" radius, change it to .267" and it makes the hole bigger by .004", as seen in the 1:00 long video.
Here's a few finished photos.
Came out pretty good, not absolutely perfect. At least there's no chatter anywhere on the threads and it meets the print requirements. I'm happy with it, just wish I could have gotten to finishing the remaining features on the mating screw.