Lead In & Lead Out Moves.

[Dougal]

Hi guys.

Can anyone give a good rundown on the parameters for the different lead-in and leadout moves?

Imagine I'm trying to profile around a circle, what I'd like to avoid is the machine drilling straight down, then going around. I find this gives an unsightly cutter mark where the drill down lead in and the raise tool lead out happen.

So I'd like to get to grips with both the tangent and the spiral entry/exit. But I'm not having much luck.
Spiral seems to result in the cutter dancing between passes, the tangent results in cutviewer showing the cutter blasting straight through the piece I'm cutting.

So on a 25mm circular profile, what parameters do I use to get the cutter to spiral down in, taking maybe 1/3 of the circle to reach cutting depth of 1mm?
I thought this would be a spiral angle of 120, but that just drills down to full depth, then does the circle.

Can the tangent lead in/lead out be made to do a straight line instead of an arc? Can the length of the lead in/out be controlled?

[10bulls]

The spiral lead in will ramp down into the stock using the spiral angle specified.

The angle is the angle of attack relative to 0 degrees = horizontal. So 45 would spiral in on a 45 degree angle. 90 degrees is a vertical plunge. I would recommend using a gentle spiral angle 2-5 degrees.

When it has reached the depth increment depth it will cut a complete circuit then it needs to lift up to move across to the next spiral lead in start. This is what causes that dance and yes it can leave a bit of a tool mark.

In version 0.9.8, it is now possible to specify a 0 degree spiral ramp angle.
CamBam will then use the depth increment to calculate the angle so you get one continuous cut spiralling all the way to the target depth with an extra circuit at the target depth.
As this avoids the safe Z moves it will be faster and leave less tool marks.

At the end of the cut, rather than have the cutter lift straight up (which will leave another toolmark), you can add a lead out move.
This is where the tangent move is useful, so you just need a radius and leave the angle as 0.

I have attached a simple example of this. This will only work in the new 0.9.8 version.

[Dougal]

Excellent, that's exactly what I needed to know.