Boiler studs through or blind

[Martin Rock-EvansParticipant @martinrock-evans77799]

I'm building a 3" Burrell Traction Engine and have a commercial copper boiler. It has come time to fit the cylinder to the boiler. The drawings call for 24 2BA copper studs, but I can't workout if the tapped holes in the boiler for the studs should be through holes, or blind.

The boiler is 1/8", with a second 1/8" pad silver soldered onto the inside where the cylinder sits (so there's 1/4" of copper to bolt to). The studs are radial (so need to be inserted after placing the cylinder and can't be soldered in place). A through hole would give 7-8 threads. However, if I go for a blind hole, I'm not sure I'd get more than 3 threads (and I'd be worried about ensuring the holes are exactly the right depth). What would be the normal practice?

Many thanks in advance,

Martin

[Martin Rock-EvansParticipant @martinrock-evans77799]

[Clive Brown 1Participant @clivebrown1]

Definitely a through hole for a good tapped thread. FWIIW, my 1 1/2" Allchin has phosphor bronze studs with brass nuts silver soldered on to make what are effectively bolts that look like nutted studs, as recommended. Copper might be OK for your studs, but I'd think that PB takes a better thread.

[JasonBModerator @jasonb]

Both my engines have through holes and that seems to be usual practice.

You can also make up bolts with a pimple on the head to look like the end of an exposed stud then there is no need to solder. Either way make them as bolts or proper studs with a plain section that goes through the saddle so there is a bit less gap for steam to find its way out of.

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