Forming round heads on small steel rivets.

Thanks John, for those drawings this has helped me a lot. Thanks Ken for asking the question

I found a large-ish nail punch at the local hardware shop which had a hollow point that was just the right size for rounding the heads of 5/16" steel rivets. Used a piece of 6mm plate on the anvil with some depressions made with a ball-shaped cutter in the mini-tool to support the work and the 'back-side' of the rivet while shaping the top. Made a number of depressions at various spacings so that adjacent rivets already set did not stop the next one from bedding down nicely. Found it a bit hard to support both the work and the rivet punch in one hand while wielding the hammer in the other, so the flat plate came in quite useful.

Once you have seated the rivet, if you make the free length of shank protruding beyond the material (the part you will punch to make the head) between 1.25 and 1.5 times the diameter of the shank. That will allow you enough material to form the head. Less than 1.25 x dia is too little to form a complete hemisphere, and more than 1.5 x dia is too much, which results in the bit nearest the plate/sheet being squashed out, like a fungus at the bottom of a mushroom.

The previous advice to use the pre-formed heads on the outside is good, but not always possible.

Pliers-style manual snap tools used to be available from a chap called Dave Noble, but seem not to have been obtainable for some years. There was a good design in MEW or ME some time ago, and I think Model Engineers Laser does the laser cut parts.. The trouble is the operating head is quite large and needs to be able to fit behind the rivet. There is also an air powered tool commonly called a crocodile (or alligator?) which squeezes rivets closed, forming a flat head or a mushroom head, depending on the anvils fitted to the tool. I have one of those tools, but, again, it is usually too large or has too short a throat to fit where I want to rivet.

Marcus

I restore vintage Austin's there are many parts that are riveted together, Austin used 3/16 steel rivets using a rivet snap was hard work. What I did was make a snap that would fit my air hammer this worked out very well, when using an air hammer wear ear protection as a must.

John

Thanks for the tip,John. I have some steamer trunks to replace the handles on and that is a good idea. No one else here to help.

Have you tried spinning them with a bit in a pillar drill.

One of the ME suppliers in Australia offers slot-less screws in various BA sizes. Perhaps they could be useful for those locations where the back-side of the rivet is not easily accessible for a rivet snap or a dolly? They need to be a light press fit in the hole so you can do up the nut without the shank turning. A touch of thread-lock (or solder if using brass or copper rivets) should stop them coming loose.

I should have said they were round-head screws not pan-head or countersunk.

Air hammer/ rivet gun, I spent many hours with a pneumatic rivet gun on aircraft rebuilds and repairs, for aircraft rivets the tails are backed up with a flat dolly, so the tail ends up a flat topped cylinder shape, regardless of the shape of the head, round or counter sunk.

Ian S C