Machining Realistic Scaled Nuts

[edan]

Hello,

I have wanted to help with tips/machining methods in this forum but so far I have not been able too. This idea is something I have used in the past and just wanted to pass it along.
This is geared more for the person who is just starting out in model making. I hope this is not too “basic” or has been posted before.

WARRNING
I am not suggesting that anyone machine a nut to this thickness. This specific example is for light usage and I am very careful when I torque a small nut like this. What I hope to help with is if anyone needs a little extra thickness in designing a small nut while trying to keep it looking realistic and not too thick.

When I design an engine and want to keep the parts realistic, I generally struggle with the fasteners. One area is in machining small nuts to a realistic thickness. The pdf shows what I now do when I am faced with this problem.

This is a 0-80 nut shown in the pdf. The .040 thickness is just what I think looks realistic for this scaled down nut. If I machine the nut to this thickness I would have approx 3.2 threads. (I know this would actually be less threads due to the chamfers, but for this example I will just use the mathematical answer.)
I now just machine a “flange” nut which adds the extra thickness I require. I then grind a HSS toolbit to a sharp point at approx slightly less then 20 degrees for the “false chamfer”. I angle the toolbit slightly so I can face the false “washer” while I cut onto the nut.

On the thicker nut I now have 4.08 threads which is not a lot but I have a personal rule of an absolute minimum of 4 full threads for a small nut like these. I do not know what is the actual requirement for number of threads. I have heard everything from “one full thread” is all that is required to theoretically hold, to produce enough threads that will match the screw diameter.

I hope this helps someone who is designing an engine and trying to get a little more threads into the design.

I do not have any pictures of what I have done in the past so I produced a fast render to show what I mean.






View attachment THIN NUTS.pdf

 

[cfellows]

Thanks, Edan, that's a nice idea and one I hadn't thought of.

Chuck

 

[Antman]

Thanks Edan, how do you machine the hex of the nut?
Ant

 

[Jasonb]

Interesting method, not sure what type of engines you are using these on but I find most old steam engines used single chamfer nuts so they would look wrong to me as the nut sits down on the washer They were also taller than what you show so that gets over the lack of threads.

The alternative would be washer head nuts where there is a small section of round under the hex of the nut the size of the AF or a fraction smaller which allows making from hex stock,. often found on hit & miss engines.

 

[Omnimill]

Interesting method, not sure what type of engines you are using these on but I find most old steam engines used single chamfer nuts so they would look wrong to me as the nut sits down on the washer They were also taller than what you show so that gets over the lack of threads.

I agree. It's an interesting idea and may look good on scale modern engines but to be honest I much prefer the look of older/thicker nuts.

It would be quite interesting to know what formula was used years ago to determine how thick nuts were to be manufactured.

Vic.

 

[Jasonb]

Before mr Whitworth came along you didn't have standard threads let alone nut sizes ;D

 

[Chitownmachine]

Thanks Edan, how do you machine the hex of the nut?
Ant

Use a hex collet block in the mill vice. Set yer depth for one side of the nut. Cut, turn block, repeat. If you dont have a hex block, you can use a rotary table and mill a flat ever 60 degrees. Hope this helps

 

[IanR]

It would be quite interesting to know what formula was used years ago to determine how thick nuts were to be manufactured.

Vic.
[/quote]

Pre WWII Whitworth and pre 1955 US Standard, nut height = stud diameter. BSF and later standards, nut height = 7/8 stud diameter.

 

[Omnimill]

Pre WWII Whitworth and pre 1955 US Standard, nut height = stud diameter. BSF and later standards, nut height = 7/8 stud diameter.

Thanks for that!

Vic.

 

[jtrout13]

A little late, but usually engineers design for a minimum of 3 full threads engaged.