Thin cutoff tool

[gbritnell]

Gentlemen,
 I have been having conversations with a fellow brass model builder on another forum. He builds some spectacular automotive models. The conversation revolved around adding rivets to a model, not so much for assembly purposes but more to replicate the actual full sized piece. The problem is in miniature sizes there is no good way to head the shank of the rivet once it's put through the hole. Now we're talking rivets in the 1-2 mm size.
 In my particular case it's how to accomplish this on my model Galion road grader. For rivets I have been using brass escutcheion pins. One of the ideas I had was to use the pin and nip it off allowing a small amount of the shank to protrude through the hole. A rivet head could be drilled and formed on the lathe, fluxed, slid over the shaft and touched with a tinned soldering iron. Time consuming but about the only way to make the model realistic.
 This morning my curiosity got the better of me and I decided to try what I had in mind so I turned and drilled a piece of brass. ( Escutcheon pin: .058 dia. shank, .118 dia. x .045 head) I then used a radius forming tool that I had made for another job. I then cut the head off using a home-made cutoff tool.
 I have a lot of hand ground cutoff and necking tools of different widths and lengths but I wanted one that was almost impossible to grind by hand. I had an old dull jewelers circular saw blade that is .01 thick. I made a small bar (.25 square) and put 2 tapped holes in it. One for a screw through the center of the saw blade and the other to pinch the blade so it wouldn't rotate. I then ground a flat on the blade and set it to center. The nice thing is when it's dull you just kiss the flat and rotate it to center again.
I'm going to show all the pictures that I took while making the rivet head but in particular the cutoff tool.
When using it there is hardly any force applied to cutting off small delicate parts and if cutting through threaded holes it leaves very little stock to clean up. (part of thread curl)

[crueby]

Have you tried a rivet forming tool like the aircraft style, which has a hollow on each jaw to form the head on both ends of the rivets? I've had good luck with that, at least on larger rivets (down to around 1.5mm shank size). There was a thread (or part of one? ) a while back on making one.

[gbritnell]

Hi Chris,
Many years ago when I built my 1" Case traction engine it uses 1/16 rivets for the boiler. Cole's sold a tool that would reach way inside the boiler. It had a die on both arms that matched the radius of the rivet head. It had a hammer pad on the one arm. You would reach in with the tool and line it up with the rivet head on the outside then hammer on the arm which would mushroom the other end of the rivet.
On the grader I'm using Escutcheon pins which are brass (harder) and in most cases there is no room to use a tool for trying to form the head.
gbritnell

[sco]

I've made thin parting blades from Scalpel blades before - worked pretty well.

Simon.

[mikemill]

George

  Very impressed by your grader, re thin parting of blades I have used old hand saw blades for years, they are approx. 0.050in also used for fine grooving

Mike

[petertha]

That's a great idea. I always assumed that the teeth were slightly raised relative to the main disc body thickness for some slight clearance, so part of the tooth had to be part of the cutting edge. But I've never actually checked. Obviously you have just ground the disc body. o you happen to know if maybe there is slight relief in the disc itself? (exaggerated pic).

I also don't quite understand the differences in this regard between jeweler saws, slitting saws & slotting saws. There certainly are a good selection of thin saw thicknesses to choose from & they are relatively inexpensive in HSS.

[gbritnell]

There is no clearance on this blade mainly because it's so thin. Most cutoff blades only have vertical clearance, T shaped or tapered. I don't cut very deep with this but it works fine.
As far as the difference between jeweler's saws and slitting saws I don't really know. Quite possibly just the size of the arbor that they mount to. There is an overlap of diameters and tooth count.
I do have a holder that uses custom made HSS cutoff and threading inserts made by the Warner Co.
gbritnell