Another turning challenge...ridiculously small parts

[implmex]

Hi All:
So I've been screwing around for days now, finding a way to make these tiny little balls with stems and an M1 x 0.25 threaded bore.
The balls have been lapped using a technique I pinched from Rob Renzetti after seeing him demo the method on YouTube.
Here's a link for those who are interested:
MAKING PRECISION GAGE BALLS - YouTube

The balls need to be within a tenth for most of the circumference...no big deal, I turned them +0.002" and lapped them in using Rob's super technique.
The area around the stem is unimportant.

The other challenge was to find a way to hang onto them to poke in the M1.0 x 0.25 thread.
I finally found a workable way...I just leave them on a long bigger diameter stem so I can chuck them and drill right through the long stem with a clearance hole and then drop in my little drill and my M1 tap.

I tried a little fixture...no joy there...I can't grab them hard enough to keep them from spinning in the fixture when I try to tap them.
(This is 17-4 PH solution annealed...I'll harden them when I've made them all).

They get the flats cut and get chopped a bit long on the wire, then they go in that fixture that didn't work for the tapping, and get surface ground to length.

These have become outrageously expensive parts...I fucked around for days to get here.
I console myself with the knowledge that I took this on on a cost plus basis, and I don't think they'll find anyone else to try to make these; especially not since I have only four to make.

But the next ones are even shorter...this is gonna be fun!

Hope some of you find this interesting and useful.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[plastikdreams]

Interesting, bet that thread was fun.

 

[Milland]

Neat stuff, Marcus.

Any consideration of cutting in the hardened state? Even the tapping might not be too bad if final HT is H1050 or so.

 

[eKretz]

Looks like you got it done in the end, will be faster next time. What's the OD of the ball?

 

[gbent]

Dang, I think the giant fingers you bought are even bigger than Rivett608's.

I couldn't even see that, let alone make it. Thanks for sharing.

 

[boslab]

How about using a bolster material, a stub with hole, then get the part held in position and cast round with cerro matrix low temp metal, it’s often used to fix dies in place ( slip the die over the punch, lower into the bolster, cast in place, heat to remove, the stuff is good for a 10 ton power press or small toggle) just an idea,
Mark

 

[implmex]

Hi Milland:
I ran away from trying to drill and tap these at H900 which is where they need to end up.
I already have a small uncomfortable wet spot in my trousers even from tapping them in the soft state.

eKretz, the balls are 0.1059" to 0.1060" diameter.
I pinched Rob Renzetti's measuring protocol too. (That man is one smart dude!!)

I lap them before I thread them so if I goof one up, I haven't lost all that much.
So they're still easy to handle with the long stem on them.
We live in hope they don't move when I harden them, but the sample I tested stayed right on size.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[plastikdreams]

Hi Milland:
I ran away from trying to drill and tap these at H900 which is where they need to end up.
I already have a small uncomfortable wet spot in my trousers even from tapping them in the soft state.

eKretz, the balls are 0.1059" to 0.1060" diameter.
I pinched Rob Renzetti's measuring protocol too. (That man is one smart dude!!)

I lap them before I thread them so if I goof one up, I haven't lost all that much.
So they're still easy to handle with the long stem on them.
We live in hope they don't move when I harden them, but the sample I tested stayed right on size.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Fortunately 17-4 moves so little if any net shapes can be heat treated with good confidence...now when the oven that's always at 900°f is set to 1750°f and you don't realize it...it actually still doesn't move much, surprisingly.

 

[EPAIII]

Impressive job. I hope they harden OK.

 

[boslab]

Are they the posts for the dental “all on four” posts I was considering once?
Either way they are impressive
Mark

 

[wesg]

Just give them a 10 year lead time. You'll be able to 3d print them by then.

 

[TDegenhart]

For the tapping can you get a set of taps of increasing size so as to note thread all in one shot?

Now that the customer knows that you can do these, the next will be make them from carbide.

Tom

 

[TeachMePlease]

Would you just buy a damn Swiss machine already?


But seriously, nice work, Marcus!

 

[implmex]

Hi TeachMePlease:
You wrote:
"Would you just buy a damn Swiss machine already?"
You know I'm already lusting quietly after one...don't make me break my vows of celibacy in all things Swiss.

What I'd really like to play with is one of those Citizen L20's with the mini sized B axis Integrex style head.
Oh the things I could dream of with one of those!!

Sadly I doubt if there is enough medical type work in my area to justify...but a man can fantasize, can't he??

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[implmex]

Hi again All:
Here's the other part...this one was harder to make than the other one above.
I had to build a little fixture for it, in order grind it to length and put the wrench flats on with the surface grinder.
The wrench flats are 0.018" long...now I have to make a wrench!

Notice how rough it all looks under the scope.
Some of it is dirt and some of it is scratches and other defects.

Working at this scale is humbling...that ball looks perfect with the naked eye and feels sooo smooth when I run it against its socket, but it sure looks like shit when it's magnified and the light hits it a certain way.
I could go with a finer diamond grit when I polish them, but there's really no point in this application, and I've already spent a ton of time on them.



Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[Rocketdc]

Your work reminds me of a sculptor named Willard Wigan. He carves pieces so small you need a microscope to view them.

Gallery | Willard Wigan

 

[CITIZEN F16]

Nice work! If I was doing those I would have needed to start with trying to make 2 dozen, due to having sausage fingers on hands that have had a rough life. Who knows I may have lost them all and had to start over.

 

[mattthemuppet]

That's seriously impressive! I think machining gets exponentially harder the smaller your work. I made some ear studs out of stainless for a friend once and it took five or six tries to make two.

 

[boslab]

Do you lap in a copper split or hemispherical chamber lap or it the polish freehand?
Mark

 

[plastikdreams]

That's seriously impressive! I think machining gets exponentially harder the smaller your work. I made some ear studs out of stainless for a friend once and it took five or six tries to make two.

Smaller the parts, easier to lose them. Been there done that lol I learned to make an extra or 2.