I have a 303 stainless steel gear with a hole in the center which I want to enlarge from 10 mm to 40 mm.
The gear diameter is 60 mm and its thickness is 5 mm.
I have not taken the third HAAS class yet, so I’m considering that, or could it be made with the big lathe?
I have attached a before and after picture. Ignore the little holes in the after picture as I can easily make those manually.
I would think the lathe would be the tool of choice. Trick will be clamping it without damaging your gear teeth.
You have an already centered hole, which should make a good reference.
So maybe figure out how to put some aluminum shims between the gear and the jaws on the 4 jaw chuck and center it up that way. Then enlarging the hole should be relatively simple.
Some of the folks with more practice might know a better way.
The thread about the small T-slot table for the milling machine might also be of interest. That indexing fixture would be perfect for the 6 holes around the perimeter. Might be easier to do those first.
Thanks, I was not aware of this.
Bruce
Thanks for this advice, Todd.
No problem. Good luck with your project.
The center hole could also be machines out at the same time as the smaller holes.
It could be centered using the center of the rotatory table, with the new T-slot table made by @mikeglass
then using hold downs
along the edge you could do the rest of holes without having to clamp down into the gears.
I finally get it after taking your class, thank you David.
You’re welcome. Make it, and lets us know what worked and what didn’t. Then teach!
I’m having trouble envisioning cutting stock that thin without some way of reinforcing it. Enter “Superglue”. Glue to expendable material (wood, maybe?). Then cut in preferred way. Heat will allow quick separation from sacrifice and a smidge of acetone for cleanup…
Maybe I’m way off base, though, and .200" is plenty of beef to clamp across 5(just re-read original dimensions) 2.5" span.
This can also be done on the mill using the boring head. The coaxial center finder is the absolute best tool for centering to a hole.
Last night during the Sherline class showed how to use Rotary table in horizontal plane do do all holes, including using boring bar for center. When the rotary head is mounted at 90 degrees can cut teeth.
He is really exploring at this point how it can be done and possibly how their company can bring the work inside. The gear is SS and very relative to small diameter - making it very rigid.
If the blank has the teeth done, the center small hole can be used to locate it dead center on the rotary table. Then edge clamp, remove center pin and you can now enlarge the center hole with a boring bar, then do radial hole pattern and countersinks.
We discussed other ways it could be set up for a machining center. Like using matching teeth on the outside to hold in place to lock down, the fixture would have clearance under he part where holes go through so no sacrificial material needed. The blank being symmetrical doesn’t even have to be originated when loaded. Hold fixture holds while pattern being machined.
I told my coworker Eddie all about your Sherline Mill class and showed him video. We don’t have any mills where we work but we do have a lathe. Today he thought of a different way to cut the hole this using only the lathe and the hole saw shown in the attached photo.
The three gears show the three stages of “manufacture”, and the gear is designed to go around the 3D-printed part.
That works. If you have a cutter that size much faster.
Curious, do you have any idea how many holes that cutter can do before replacement?
Bruce, Use the rotary table for the mill to make the six holes. Then mount the gear to the plastic object. Mount the plastic object in the chuck, presenting the steel gear out in front of the chuck for boring bar enlargement. If the plastic object is too delicate to bear the torque involved, then make an aluminum round to which the gear can be bolted and chuck up the aluminum round, presenting the gear out in front of the chuck for boring out.
Excellent ideas, thanks! Eventually my brain will work this way…
Bob, that was a fantastic class today where you showed your ability to use the rotary table on the mill to make the six holes, and most of the class stuck around way after hours just to watch your magic.
Thank you for teaching these classes.
