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Blunt Start Thread (Higbee) Questions


Cast Iron
Jun 24, 2010
Plantersville, TX
Apart from change the spindle in spindle revs, which would index the Z Start, I can't see where alphonso has done what you're suggesting he has, perhaps you can point that out where he has.

As I've stated in earlier Posts, the safest and fairly universally accepted methods of setting a Threading Tool in Z is to use the leading edge of the Insert as the reference. Given that the centre line of the Thread Form of the Threading insert is an amount back from the Leading Edge and it would be dumb not to set Leading Edge of a grooving tool to be used to cut the Higbee, there is more than a fair chance that Start in Z for the Grooving Tool will correct, relative to the actual position of the Thread Form of the Threading tool.

Further, I don't think there has been any mention, apart from your own, of using Tool Offsets to adjust the Z Start position of the Grooving Tool.

If a change in Spindle Speed were to be used to index the start position of the Grooving Tool, that is editing the program and not the Tool Offset. If G32, G92, or FS15 Standard (single line Multi-repetitive Cycles) G76 cycles used, then the Start for the Higbee could be made with a Q address, which is easily calculated and made in the program.
I didnt suggest he did anything he didnt state. I said some do what he said he did and then offset to get it right ( of course, only if an offset is needed ). I dont see where I implied anyone mentioned offsets other than I.

It seems as if you have taken offense to something I stated. That was not my intention, and I dont disagree with anything you have written. I have merely stated what is typically done in this part of the world. There was no argument or offense intended.

I would like to add that changing the spindle speed is not always an option, some customers are quite strict about form and higher or lower spindle speeds affect length of higbee. As others have mentioned, some we have to do on the mill to achieve the radius required.

On edit: We rarely edit spindle speed to achieve timing. We edit the start point to get the timing, and the end point to get ensure it is higbeed to full thread form. It has been some years since I worked there, but even as an employee at Baker Hughes ( Baker Oil Tools ) we had to do this.
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