Tool tip radii

Anyone have a method for a grinding jig to make a specific tool tip radius on for instance thread profile tool. Since different radii are required for stepped thread dia`s. It would be good to do this scientifically as oppposed to handraulic. Please share if you have a method or a tool/jig design.

I have never actually done this but... when I made my grinder I made it so the tool holder could hold a too tip right over or near its pivot point, so rotating teh holder will generate any radius from 0 to a couple of inches (if I had the patience)

Neil

Expert horologist Jim Arnfield showed us some tiny cutters that he had made

... profile cutters, to make the blanks for watch wheel cutters.

The material was 3mm wide "tool steel" and just machinable. So he made a little angled vice for the rotary table, and milled them. [Beautiful job.]

Worth a try if you happen to have access to a top quality jig borer !

... but, the idea could probably be developed to suit a small grinder.

MichaelG.

Hello Rod, I use the spark eroder to make a form tool for the radius.

Take a piece of HSS say 3/32"x 1/2" and 2" long. Grind a chamfer across on end at about 8 or 10 degrees, full depth.

Clamp the HSS in a small tool makers vice, face up, at about 5degrees with the chamfer at the high end. Clamp to the table of the spark eroder.

Turn down the end of a piece of copper rod to 0.002"diameter less than twice the radius you want to form, by about 1/4" long. Fasten in the chuck of the spark eroder.

Bring the quill down until the copper overlaps the end of the HSS. Move the HSS horizontally until it touches the copper. Raise the electrode clear and advance the HHS the depth of the rounding. Erode the end of the HSS.

You can space a number of different radii across the end of the HSS

For your single point screwing tool use a tubular electrode the inside diameter 0.002" larger in diameter than twice the tip radius and the elecrode machined away until only the depth of rounding plus the wall thickness remains.

Edited By John Ockleshaw 1 on 23/09/2012 03:47:38

Gray,

Looking forward to seeing that honing jig !!

All the best

MichaelG.

My initial enquiry was based on my thoughts for the redesign a redundant spindle type ball turning attachment. The initial setup of the blank, to centre it easily, was myMuch main problem. First thoughts involved a series of radius setup pins used "dry" against the grinding wheel. But wishing also to incorporate the cutter form angles (i.e. as in thread tips) it would require a protractor mechanism and/or a dividing head type pin wheel.

Getting quite involved hence my application to the forum.

Much looking forward to seeing Grahams honing jig design.

If a specific kit is available? I would appreciate the source.