Incredibly tiny valve handle for N Scale

[mmagliaro]

During my 0-6-0 project, you may all remember that narrowminded offered to try to machine an incredibly tiny valve handle to go into the side of a dome on the engine.  I was (and still am) rather keen to keep as much it made by myself as possible.  But nonetheless, he was intrigued by being able to actually machine something this small on a lathe.  The handle would have to be only about .028" in diameter and would have to have holes in its face and a stem on it, just like any larger-scale valve handle detail part you might buy for larger scale models.

I have been remiss in not examining the test piece he sent me more than a month ago.  But I finally got around to it.

I'd say, narrowminded, you succeeded stupendously!   I really had a hard time even photographing this thing.  It is so small that I could not get as close as I really wanted to, to capture how amazing this part is.  But I think the photo below will do.   The handle is the one in the middle, obviously.  The stem is out the back, so you can't see it, but trust me, it's there.

Just think about the act of machining a disk that small, and boring 5 holes through the face of it, evenly spaced around the perimeter.

BRAVO, narrowminded... BRAVO!

[MK]

Damn!!!!!   

[dnhouston]

@narrowminded FTW!  Incredible work!

[mark dance]

wow? perhaps it was EDM'd?   

md

[OldEastRR]

Reminds me of the story about a French machine company that produced a very very tiny bolt and sent it to a German manufacturer to show they could produce precision parts just like the Germans. The German company sent it back -- with a drilled and tapped hole in the body. 

[up1950s]

Scale wheels for car jacks and shopping carts !

[atsf3751]

That is awesome!!

[thomasjmdavis]

@narrowminded FTW!  Incredible work!

We need some way to give him 100 respect points or some other honorific.  Narrowminded, if you are out there in the ether, do you have a photo of that handle chucked in a lathe?  And what lathe do you have that can do work like that?  Incredible.

During my 0-6-0 project, you may all remember that narrowminded offered to try to machine an incredibly tiny valve handle to go into the side of a dome on the engine.  I was (and still am) rather keen to keep as much it made by myself as possible.  But nonetheless, he was intrigued by being able to actually machine something this small on a lathe.  The handle would have to be only about .028" in diameter and would have to have holes in its face and a stem on it, just like any larger-scale valve handle detail part you might buy for larger scale models.

I have been remiss in not examining the test piece he sent me more than a month ago.  But I finally got around to it.

I'd say, narrowminded, you succeeded stupendously!   I really had a hard time even photographing this thing.  It is so small that I could not get as close as I really wanted to, to capture how amazing this part is.  But I think the photo below will do.   The handle is the one in the middle, obviously.  The stem is out the back, so you can't see it, but trust me, it's there.

Just think about the act of machining a disk that small, and boring 5 holes through the face of it, evenly spaced around the perimeter.

BRAVO, narrowminded... BRAVO!

Max, could you position a Preiser figure into that photo?  I am envisioning the hand that would turn that handle. 

[mmagliaro]

Reminds me of the story about a French machine company that produced a very very tiny bolt and sent it to a German manufacturer to show they could produce precision parts just like the Germans. The German company sent it back -- with a drilled and tapped hole in the body.

Just for the record, while that story is good for teaching us all a lesson about boasting on ourselves, it is a long-told unsubstantiated "legend" story that been told as being between two American companies, the Americans and the Germans, The Russians and the Americans - you name it.  It appears in many other contexts where one country or company was trying to show up the other.  I can remember my father telling me this story as a kid and I can't remember if the two parties were the French and the Germans or who they were.

[peteski]

Just for the record, while that story is good for teaching us all a lesson about boasting on ourselves, it is a long-told unsubstantiated "legend" story that been told as being between two American companies, the Americans and the Germans, The Russians and the Americans - you name it.  It appears in many other contexts where one country or company was trying to show up the other.  I can remember my father telling me this story as a kid and I can't remember if the two parties were the French and the Germans or who they were.

Poland was not involved in this?  Odd . . . 

[MK]

LOL!!!!!!! 

[nkalanaga]

No, the Poles are the ones who made the Allen set screw to fit the new hole.

[narrowminded]

Nice picture taking, Max.  That's the best view I've had of that piece.   Over the next month I'm getting my cataracts fixed so maybe I can see these things better next time.  Really!

That was made in the typical home hobby machines that are all over the net, the Harbor Freight lathe and a Proxxon mill, but both have been reworked where required.  That included most assembly and fit details on the lathe and a rework of the spindle on the mill for true running.  I also added digital scales to the Z axis on the lathe and all three axis on the mill to make the positioning more convenient.  That is not necessary for the accuracy but is a very nice convenience.  Machining with cutters under .010" is another whole level of machining but still operates on the same basic principles that all machining does. The difference is that it requires a machine trueness that typical machining just doesn't require and then, especially in the case of the mill, a spindle capable of high enough RPM to keep the cutter SFPM at least somewhat close to conventional machining standards.  It's the same old stuff, just new pressure due to the proportions.

The least obvious but most important rework (as well as most challenging) was to the mill where I reworked the spindle to run within .00015"/ .0002" (1 1/2 to 2 tenths) out at the cutter edge.  That rework was done in the Chinese lathe, truing the angle and the concentricity of the collet bore, the shaft fit to the spindle bearings, then truing the collet nut thread to run true with the new re-worked spindle dimensions.  Judicious use of a .0005" indicator (five tenths indicator, $24.95 on special), then splitting those .0005" lines by eye, afforded sufficient measurements, then very carefully sharpened and hand stoned high speed tool steel cutters to make the cuts.  To mill parts that accurate with cutters that small a true spindle is absolutely imperative as well as high speed (15 to 20k+ RPM).  When contemplating the whole spindle re-work it was checking and measuring, measuring and checking, then deliberating how to set it up, what cutters to use/ make, and finally executing the arrived at plan. With fingers crossed it was about three full days effort using no more than the most basic machinist tools.  It worked.

With the mill spindle trued the hardest part of making that handwheel was actually machining the stem to .008" or so and the next hardest part was finding the damn part in the chip tray when it parted off.    What isn't necessarily evident is the diminutive size of all of those elements.  The through holes are .006" diameter and the spoke between the holes is just over .002" (about 2/3 of a hair).  And the best part is, with the re-worked tools, I'm pretty sure I could get one through at about 1/2 that size but I question whether it could be noticed with the naked eye. 

Bottom line, that was a fun challenge that forced an exercise well worth the effort.  I was getting good parts from those machines, reliably holding .0005" tolerance as needed, but now have the capability for accuracy beyond that and beyond what's normally available to the spare bedroom shop guys, or most any shop not doing micro-machining, for that matter.  And it makes every part that much better at no extra effort.

Thanks for posting that, Max. It's the first good view I've had of it.

[narrowminded]

A little irony on the jokes about drilling the small parts, that was a German machine spindle that I reworked so it could drill smaller than it ever would as it was made.

[peteski]

I was waiting with my praises until narrwminded (hopefully) posted some info about how he made that part.  And I was not disappointed.

But now I don't know what is the largest accomplishment:  making the tiny part itself, or fine-tuning those hobby-grade machines to be able to produce that small part?
Heck, both are incredible accomplishments.
A big thumbs-up from Peteski!