Scaling Up Thread Sizes

[Nik GParticipant @nikg]

Hi. Shortly looking to start building a Minnie Traction engine and have the 1" plans. Purchasing 2" Castings and Boiler kit so will need to scale up the plans accordingly.

When it comes to the quoted BA thread sizes on the plans is it simply a matter of looking to use something approx. twice the size, i.e 8BA becomes 3 or 2BA. Or is there a more scientific method.

Apologies if a stupid question.

[Nik GParticipant @nikg]

[JasonBModerator @jasonb]

Thats basically it, look up the major diameter of the thread, double it and then take the nearest available. The 1" mionnie tends to use 7BA more than 8BA as 7BA cuts quite easily onto 3/32" rod so go upto 2BA and then you can use 3/16" rod off the shelf rather than having to turn material down to 3BA size.

The 2" minnie can come up a bit chunky if you just doubel all the sizes so there are quite a few items that can be put on a diet.

[Nik GParticipant @nikg]

Thanks Jason, so likewise for 10BA go to 5BA and use 1/8" Rod off the shelf?

Had read that at 2" some parts can look chunky, presume there is no list as such, it's a matter of adjusting as build goes on so that it looks right?

[JasonBModerator @jasonb]

Thats it, you can always ask here if you are not sure what can be reduced and what can't.

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