Punches for punching holes and forming rivet heads from drill bits? How?

[Sergei Slovenija]

How to form a hemispherical depression at the end of a punch blank? I probably can’t cope with hardening a raw workpiece; I have neither experience nor a muffle furnace with temperature control. I'm considering using inexpensive hammer drill chisels. As far as I found out, the chisels are made of steel type D2 and similar, but they are already heat-treated.

1) turning on a lathe using cubic boron nitride plates? But I don’t know the turning technique, where you need to move the cutter with both hands synchronously, transversely and longitudinally.

2) copper tool with abrasive? for expansion of a roughly machined hole? I believe that electrical erosion or hardening of a raw billet from a contractor, for such a small order, will not be very cheap.

Rivet hemisphere diameter ~14 mm

 

[hotponyshoes]

Something that size you should be able to harden and temper easily enough.
For a rivet tool I'd just heat the end up and form the depression by beating it onto a ball bearing

 

[Erie Fred]

Is there a reason why you don't just pay someone else to do this ?
Or simply buy the proper rivet set ?

Lathe turning, you'll find the center is revolving at zero, and with inserts you can't be sharp
with a no/very small radius edge.

 

[hotponyshoes]

Another option is get some 14mm shank mounted stones and grind it in

 

[Sergei Slovenija]

Is there a reason why you don't just pay someone else to do this ?
Or simply buy the proper rivet set ?

Lathe turning, you'll find the center is revolving at zero, and with inserts you can't be sharp
with a no/very small radius edge.

The set of punches in the hydraulic device for punching holes is very scarce and does not have the diameters I need. I want to adapt the same device for cold deformation of rivets, with a leg diameter of 8 mm and the formation of a hemispherical head. And these punches will have to be made from scratch. The steel must be hardened and have a certain toughness, resisting 31 tons of applied force. Having a gas melting furnace without a thermocouple, I imagine it would be difficult to create the correct punch. Unfortunately, I don’t know a single private turner (my grandfather is retired) who has the necessary set of equipment in his barn. Metalworking companies are overloaded with work and their prices, for my private wallet, are not very suitable for me.

I plan to simply cut off the unnecessary part from the tool with a chisel or punch tip, leaving the cylinder. I can center it.

 

[Milkybars]

bullnose milling cutters, will be your friend

 

[Sergei Slovenija]

Another option is get some 14mm shank mounted stones and grind it in

View attachment 424144

Do you think that the stones will not break down sooner and will not lose their shape when grinding hardened steel? The ball should be larger, because the rivet has a head shape that is part of a truncated ball.

 

[Sergei Slovenija]

bullnose milling cutters, will be your friend

+ + electric screwdriver

 

[Morrisman]

I made some rivet sets by grinding the end of a twist drill into a radius, and putting some round bar in the lathe I used a centre drill to get a centre hole to the right depth then worked the rounded off drill bit in until it was the right depth to give a decent head on the rivet. Worked quite well.

It was for copper and aluminium rivets so didn't need heat treating. It wouldn't have been to hard to get it red hot and quench it though.

 

[Erie Fred]

The set of punches in the hydraulic device for punching holes is very scarce and does not have the diameters I need. I want to adapt the same device for cold deformation of rivets, with a leg diameter of 8 mm and the formation of a hemispherical head. And these punches will have to be made from scratch. The steel must be hardened and have a certain toughness, resisting 31 tons of applied force. Having a gas melting furnace without a thermocouple, I imagine it would be difficult to create the correct punch. Unfortunately, I don’t know a single private turner (my grandfather is retired) who has the necessary set of equipment in his barn. Metalworking companies are overloaded with work and their prices, for my private wallet, are not very suitable for me.

I plan to simply cut off the unnecessary part from the tool with a chisel or punch tip, leaving the cylinder. I can center it.

If you could find the proper rivet set tools, and then modify them to fit your machine, it might prove easier.
Hard turning is not a problem, when doing the outside diameter of a simple straight shank.
Hard turning that profile is.

 

[Sergei Slovenija]

If you could find the proper rivet set tools, and then modify them to fit your machine, it might prove easier.
Hard turning is not a problem, when doing the outside diameter of a simple straight shank.
Hard turning that profile is.

I searched long and tediously. One punch from Makita costs about 100 euros, and it is just a hole punch, not a head former. I believe that this price order should be taken into account if you are looking for a ready-made solution with modifications. There was nothing suitable on AliExpress.

 

[hotponyshoes]

Do you think that the stones will not break down sooner and will not lose their shape when grinding hardened steel? The ball should be larger, because the rivet has a head shape that is part of a truncated ball.

Yes, the stones will wear quickly on hardened steel but they are cheap.

If you get bigger stones you can dress them to any shape you need.

 

[Sergei Slovenija]

I made some rivet sets by grinding the end of a twist drill into a radius, and putting some round bar in the lathe I used a centre drill to get a centre hole to the right depth then worked the rounded off drill bit in until it was the right depth to give a decent head on the rivet. Worked quite well.

It was for copper and aluminium rivets so didn't need heat treating. It wouldn't have been to hard to get it red hot and quench it though.

Quenching and tempering steel, focusing on the color of the hot metal, is not my strong point, I have no experience. “Hardening nails” for arrowheads in the flames of a fire, this was in my distant childhood. I wouldn't want to end up with a tool that falls apart or gets flattened after 10 rivets.

 

[Morrisman]

Quenching and tempering steel, focusing on the color of the hot metal, is not my strong point, I have no experience. “Hardening nails” for arrowheads in the flames of a fire, this was in my distant childhood. I wouldn't want to end up with a tool that falls apart or gets flattened after 10 rivets.

I did tempering in college, heating the metal and watching the colour bands move along until the straw colour was at the end of the chisel or punch, then quenching again.

I've never done it since then though, and that was 40+ years ago.

 

[Sergei Slovenija]

Yes, the stones will wear quickly on hardened steel but they are cheap.

If you get bigger stones you can dress them to any shape you need.

Will coolant supply be appropriate?

 

[hotponyshoes]

Quenching and tempering steel, focusing on the color of the hot metal, is not my strong point, I have no experience. “Hardening nails” for arrowheads in the flames of a fire, this was in my distant childhood. I wouldn't want to end up with a tool that falls apart or gets flattened after 10 rivets.

Use air hardening steel and temp paint. Nothing tricky about it.

 

[hotponyshoes]

Will coolant supply be appropriate?

Not needed if you go slow enough that you don't overheat the stock

 

[hotponyshoes]

I'd just put my pillar drill on the slowest speed, set the depth stop to 7mm, hang my coat on the handle and carry on with something else..

 

[Seadog]

bullnose milling cutters, will be your friend

Bullnose slot drill, as @Milkybars says

PS - I'm glad to see that you use the correct terminology too, Phillip.

 

[8ob]

How about getting the end of the tool cherry red and pressing it on to a ball bearing of the correct diameter. Sort the outer shape of the tool afterwards.

Bob