Rivetting over fasteners

[JonL]

I'm just making the smokebox of the Burrell and will shortly need to fit the 1/8 rivets. I'm going to have to buy some rivet squeezers in order to get a nice finish but am wondering about the logic of using round headed unslotted screws with a nut inside. Will this be inferior to the rivetted joint? Will the ability to remove the bolts if needs be offset the lower strength of the joint?

I need to get a rivet squeezer at some point (just bought a copy of model engineer showing how to make one) but am open minded to either technique if one shows significant advantages.

Thanks, Jon

[don9f]

If you have to have the “squeezed” rivet heads on show, they need to be accurately formed to give a consistent appearance, otherwise it can look awful. In that case I personally would use steel roundhead, slotless screws which are available in a suitable size, similar to a 1/8th rivet from here for example. You haven’t mentioned exactly what the fasteners are doing, but I can’t imagine the “lower strength of the joint” would be a problem. You could fit brass nuts if you thought corrosion might be a problem.

When we restored 9F 92214, it’s smokebox was built up and fastened to the boiler in this way.....much easier than riveting! It hasn’t fallen off yet!

Cheers   Don

[JonL]

It's the ring of rivets in a ring at the front and back of the smokebox. As you say, it might be easier to get this consistently right if I don't try!

I suspect I'll still need to get a squeezer or reaction blocks and snaps for the wheel strakes.

Thanks for the tips, I see both brass and steel are available, I might go brass to avoid the corrosion issue, or steel with brass nuts.

[92220]

Hi Jon.

You could do what I did for the rivets on the smokebox of my loco. I made a simple squeezer with a spherical socket anvil, machined with a suitable round ended slot drill, to support a standard snaphead rivet head. The other anvil was a plain turned piece of silver steel rod that formed the end flat, and fitted into a drilled hole in the squeezer. This anvil was made long enough that it would fit through the smokebox door ring, and flatten the rivets inside the smokebox. It worked a dream and every rivet looks perfect, regardless of how tidy it is inside the smokebox. Actually they worked out fine inside as well. If you wanted to form a rounded head inside then it would just be a case of producing an identical anvil to the outside one, and making sure all the rivets were exactly the right length.

Having flat heads inside the smokebox, makes an accurate length unimportant. I made my squeezer out of a piece of 1/2" x 2", or metric equivalent, mild steel flat machined down to 7/16" thick. Just make sure the minimum material width, inside the throat of the squeezer, is at least 1/2" wide and the squeezer will be plenty strong enough to form 1/8" iron rivets. I didn't bother making a handle for it either....just the squeezer head it's surprising how little effort is required to form the heads of iron/steel rivets. The moveable anvil, for the outside of the squeezer, was fitted into a drilled hole in the end of a 5/6" BSF cap screw. Metric equivalents if those are the taps you have.

Bob.

Bob.

[thumpersdad]

I have thought about something similar in the past, but could not work out how to adequately tighten the screws. Do you have any ideas about that?

Also, in your case, is there any problem seating the nuts on the concave inside surface of your smokebox?

Eric

[JonL]

I'll probably just take the flats off on the side that goes against the smokebox and use a washer

[ettingtonliam]

If you are using brass nuts (a good idea, imho) then no problem, they will just bed themselves down.

[don9f]

Dec 9, 2021 7:41:25 GMT thumpersdad said:

I have thought about something similar in the past, but could not work out how to adequately tighten the screws. Do you have any ideas about that?

A good point....it would rely on enough friction between the screw and the hole it fitted in, plus the nut not being a tight fit!

On the real thing I talked about, the shank of each screw was coated in red lead (I seem to remember) and tightened up with an impact wrench. I do recall that a few of the domed heads (out of over 180) had to be gingerly held with mole grips until getting “a bite”, but obviously not so easy on a model.

Cheers   Don

[bostin]

Round head machine screws with no slot is the way to go. EKP do them. Also by bolting the smokebox on when the time comes for either boiler or smokebox replacement it makes life so much easier. Have done boiler swaps on both a 4 !/2" Burrell and 4" Foster and it works treat. Also used them on a full size chimney for our aveling roller without issue.