Source for 4-40 acorn nuts (flexible staybolt caps)?

[JBodenmann]

Hello My Friends
I have been following this thread and must say Mike's solution is really cool. His stay bolt caps are the cat's meow. If I were to do this again that just might be my route. In the past I have just used the acorn nuts that are available. Get er' done! I don't think anyone has ever noticed. When building a model the most important thing is proportion. Not necessarily perfect scale. And clean neat workmanship. Also with locomotives, there was a traditional practice. Years ago nobody used firebox wrappers on their models. Now a model locomotive is naked without them. And these flexible stay bolt caps are a part of that.
Jack

[makinsmoke]

You said the tap hole was deeper. Can you slip it into a shallow socket and tap it deeper with a bottom tap?

Then if the depth of the socket is shallow enough, maybe a few whisks with a file will remove enough hex for looks?

[amadlinger]

Hi all,

The saga continues. I was able to pick up some 4-40 stainless steel cap nuts (cheaper than the brass, go figure). They are 0.260" tall out of the box, but there is about 0.070" of meat on the crown end (in comparison to 0.020" on the brass ones). I turned them down to 0.200" and cut a new radius, check it out in the photo below. Left-to-right is an original brass, original SS, and the modified SS.

What do you think?

Sincerely,
Adam

[Berkman]

I think just use the off the shelf brass, literally no one but you will notice the difference. Even veteran live steamers who closely look at your detailing will only notice how great the wrapper looks, not that .07 difference in height vs prototype.

[Greg_Lewis]

I vote with Adam. The tall ones just don't look right. Let's hope a form tool will work. Or finally a use for a ball turning attachment.

[Dick_Morris]

The modified nuts look great!

[NP317]

Ten Points Adam!
RussN

[diddler]

I love it, if you cant find it, make it. Well done Adam!

[ccvstmr]

Good show Adam! It's amazing what you can accomplish when you can grab a part in a machine...and modify that to suit your needs. Suspect when you're done, you won't want to see another acorn nut for years! Carl B.

[Steamer Al]

Looks great and worth the time! I like to dress up compression fitting nuts in the lathe and it sure makes a difference.

[amadlinger]

Hi all,

Thank you for the feedback! I have to say I was hoping you would all talk me out of the insanity of machining the crowns down on all these nuts, but the lower crown really does look a heck of a lot better - and more prototypical.

The first few nuts were turned down on my Monarch 10EE. However, that was too time consuming. I had a better(?) idea in the middle of the night and decided I had to try it. So I clamped a lathe tool in the vise of my 2.5-axis CNC Bridgeport, held the nut in the R8 collet, and made up a little program to do the work for me. Here's a video of the operation.

https://youtu.be/ISzdNv-AWfY

What do you think?

Sincerely,
Adam

[NP317]

Perfectly creative!
RussN