Shape Library

I'm still not clear on what you want to do. Do you just want to cut holes and not sever the part? I think you could take the A axis position (in degrees 0,90, 180,270), divide it by 90 and multiply the result by the width (80mm).
This would result in an offset for each face of 0,80,160,240mm. Then you could let External offsets do its thing. But I think you would have to make sure you were back on face 0 before turning offsets off to allow them to unwind. (actually the offsets might need to be negative)

tommylight wrote:

I really hope no one sees this......
Phill, what are the chances of adding a square tube thingy to this ? Some details :
4 Axis machine with say X is the long one, Y is the short one, Z is the usual automatic THC thingy and A is the rotating one,
Since we use THCAD and that thing is fast and smooth, i would skip all the complicated math required and just have A axis move in 90 degree increments as that would simplify everything immensely, the only thing remaining to tackle would be at every A axis move of 90 Degree there would have to be added an Y axis move of the width of the square tube, say 80mm, and the THC would do it's job of following the up and down during that period. There is also the caveat that the feed rates of the A and Y axis would have to be tuned to move in sync so the torch does not loose position, but that is another topic altogether.
New thread, or delete and disappear ?

I am not 100% sure what you mean. Would this just be a feature that you would append after a shape and it would rotate A 90^o then move X to zero which would be the edge of the tube and Y to somewhere.
So you would cut a shape, do this move then cut another shape...

Still trying to get my head around it, is this the machine layout?


Do you need to account for wall thickness when you rotate to the next face?

Maybe if you had a bit of gcode I could look at.

I'm not sure Tommy's idea makes sense.

A square tube has a radius on the corners. An 80mm square tube typically will have a 5mm radius. so a side will include an arc of 45 degrees at each side (eg from the centre of the arc on one side to the centre of the arc on the other)
The length of each corner arc is = 2 π r (θ/360)
So an 80mm tube won't be 80mm. If you don't account for the arc on the corners, the cuts won't join up. So to do it properly , the torch wold need to rotate around these arcs so the cut remains perpendicular.

I know using leaving it to the THC will end up cutting at a 45 degree angle if it was a wrapped rotary but I don't think the maths can be simply ignored.

All you need is one of these:

Meh! I've got 200 pieces welded up that were cut on this machine sitting in the back of my ute to go to powdercoating in the morning..

tommylight wrote:

phillc54 wrote:

All you need is one of these:

No i do not, i am building one of those !

Wouldn't building it imply that you need it???

Now if you'd already built it...