Fixturing conundrum with Hemingway die filer kit

[timdotdParticipant @timdotd]

I’m part-way through the build of a Hemingway die filer kit, and I’m wondering about how to interpret the drawings and fixture the castings in order to machine some radial slots.

If I’m reading these right, the radii are measured from the “extended” dimension that I’ve ringed in red?

Then I’m wondering about the best way to fixture this for milling, because the larger of the two castings is too big to swing on my SC4.

I’ve got a rotary table, but it’s too small to easily clamp the castings down – so I was thinking of mounting the part to my lathe faceplate and bolting the faceplate to the rotary table.

The casting would have to be offset so that the “virtual” centre dimension is aligned with the rotary table centre, then the entire stack would need to be clamped to the mill table and offset so that the cutter would sweep the arc as the rotary table was turned.

Does this sound feasible (or advisable), or is there a more straightforward option I’ve overlooked?

[bernard towersParticipant @bernardtowers37738]

I used the hole that says 1/4 bsf to clock from. You need a centre pin of known dia and a 3/16 pin in what will be 1/4 bsf later and then a little bit of simple maths. if you fit it to a face plate you could mill it in the lathe (tool post miller)

[JasonBModerator @jasonb]

For jobs likethat it is sometimes easier to hot glue a bit of metal onto the casting so that you can mark out where the ctr should be. Then with the rotary table centred below the spindle position the work so your mark is also lined up and clamp in place.

Another option would be to put a bit of 3/8″ silver steel or the shank of a cutter in your collet and when that touches the side of the casting you will have that 3/16″ offset.

[bernard towersParticipant @bernardtowers37738]

[vintagengineerParticipant @vintagengineer]

If it works go with it!

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