When making prints at home, one of the big time wasters is the via holes that connect the top and bottom layers. The best result is obtained by using rivets.
I've used studded rods in the past. You inserted the outermost rivet into the hole (press fit), bent the rod so that the rivet broke off, and continued to the next hole. Finally, soldering on both sides.
Pretty quick method. Unfortunately, I have not been able to find these bars anymore. They did not give as nice a result as hole rivets, and were significantly higher on the print, but probably the fastest method I have tried.
I now use rivets with an outer diameter of 0.8 mm and an inner diameter of 0.6 mm.
My old Method
I previously riveted each individual rivet with a homemade mandrel and a large hammer:
Made by drilling a 0.6 mm hole in a piece of steel, epoxying the shank of the drill into the hole, and cutting it to the appropriate length.
It is undoubtedly the slowest method, and quite tedious. It is also not easy to have everything aligned: the mandrel in a vise with an attached rivet, put the print over the rivet and push it through, and then a whack with a hammer via another mandrel. It took several minutes per rivet.
My new Method
My latest method makes use of a modified automatic punch, described below.
You insert a number of rivets into the upper side of the print, secure them with a piece of plastic, turn the print over and place it on a hard surface, e.g. a piece of marble, and gives each rivet a punch with the tool.
Watch a video of the process here:
Here is another print after some practice in using the tool:
This print can be seen in action here:
Modification of Automatic Punch
Purchased from Harald Nyborg (Danish shop), it is far too powerful, so I have modified it as follows:
1) The tip of the punch re-shaped
2) 0.8 mm spring replaced with 0.6 mm "home-rolled" version
3) 1 mm spring shortened 3 turns
This results in a tool that is really quick to use and gives a nice result.
Purchased automatic punch:
Remember that the softer spring has 2 purposes: 1) Holding the "trigger" part out to the side at the start. 2) Pull the trigger back when finished. The spring must therefore be crooked just like the original. (The trigger part is the one with the soft spring).
Leave the shortened part of the strong spring at the top of the puncher so that the sharp shortened edge does not slide up and down inside the puncher.
The re-shaping of the tip is done roughly with this setup:
Start by making a punch mark in a piece of iron, which can act as a centering point during the grinding (if you have a lathe, this operation is of course easier).
Insert the tip from the automatic puncher into a hand drill and place the tip in the centering point. Grind a new point by cutting off the existing one except for 0.6 mm. Then grind off the old tip.
Grind the tip conically so that the diameter is 1.5 mm where the transition to the pin begins.
It is important to get as small a radius as possible, and a perpendicular surface.
The result with too large a radius/non-perpendicular surface, the rivets crack:
The result with a suitably small radius and almost perpendicular surface:
To achieve the small radius, I shaped the cutting disc by sanding quite hard on a piece of 400 grit sandpaper. Sparks must be generated.
The rivets will be quite flat using this tool: