Setting a start point.

[JAZZCNC]

Work offsets(WO) are very usefull if you have large bed. You can basicly devide the bed up into individual sections that can quickly and easily be located using WO.
If used in combination with fixture jigs and location dowels it makes for very easy multipart cutting using different materials of different thickness's which can be left unattended. Just combine the code in one long G-code file by copy and paste and when the control comes across the new WO G-code it will move to that point and start a fresh adjusting for the offsets.!

Great for doing things like 2 sided cutting on multiple parts using fixture jigs. Cut the first side in G54 and while this is cutting set another to be cut in G55. While G55 is cutting remove G54 jig from machine reset part for other side and replace back in G54 position for the other side. The code will be set in such a way that after the first twin same cut it flips back and forth between front and back sides. . . . . Obviously this is job dependent but you get the idea.!!

[Ricardoco]

No doubt this is a really simple question, but how do people usually set a start point?

I apologise is the term "Start Point" is incorrect, and if so, please correct me.

On my machine, my start point is set manually at "X" and "Y" being zero (I.e. in the corner of the workpiece and "Z" being offset so it's at the top of the workpiece. It's a tedious job and leads to an inaccurate starting position at times.

I suspect that a start point which is set regardless of the workpiece would be better and I change the starting position and offset in Cut2d which I use to generate the GCode.

Thanks for your time.

James

Ok let me get this right, what you are asking is how you can put a piece of stock onto your work surface and have the corner assuming its a right angle be at x=0.0 & y=0.0 every time yes?

[jrob3rts]

Rocardoco - Thanks for that. It makes sense and I was considering a similar thing but making use of the T Slots for one axis and maybe bolt a piece of acrylic cut like a set square for the other.

Jay - Good point about the wear in a specific area, I had not considered that. Suspect it will be fine for now as it's for hobby use but as and when I have more time to spend on the machine I will take this into consideration.

James

[Ricardoco]

Rocardoco - Thanks for that. It makes sense and I was considering a similar thing but making use of the T Slots for one axis and maybe bolt a piece of acrylic cut like a set square for the other.

your very welcome and i also did it the way you have suggested in the begining but i kept moving it so decided on the pins..

[Robin Hewitt]

I know exactly what you mean, I used to find this a right PITA because when you produce a G Code you lose the original drawing, in my case a DXF file.

To fix it I rewrote my cutting software to read in the DXF and every circle shows on screen with a little red rectangle in the middle.

Right button the rectangle and it sets machine co-ordinates to the circle centre, left button it and it moves the tool to the circle centre.

I can also click left or right anywhere on the drawing, which is handy to make sure the cut doesn't overhang the billet.

What I do is drill some holes for locating bolts then clear the mill bed of everything.

I have a bunch of 3/4" thick mounts which have a T slot fixing and an offset stud with a female thread. I made 4 of each in M3 M4 M5 M6 and M8.

I locate the mounts by left buttoning rectangles, lock them in place, replace the billet and bolt it down.

If I have clear space and remembered to add a spare circle to the drawing, I pop in a centre hole so I can relocate if I lose position.

Lots of typing but I would not be without it.

When I am not machining the outside of the billet and need to align metal to the bed, I use the 10mm square tool steel bar I inset a few mm deep at the back of the bed. I cut the pocket for it with the mill so I know it is dead square. It has a splash guard holder on the top.

If trying to align to a centre scratch I start light with a centre drill and go progressively deeper with each attempt to erase the old mark. Really need a sensitive drill handle and a pendant for that.