village idiot builds a plasma table.........

[Robin Hewitt]

I tried and failed, my gantry was 2.75m of 4" square aluminium box section and it did the long axis. I started out by taking a 4m length of the stuff, supporting it at the ends and dumping weights in the middle to see how far it bent. Hardly at all. You don't need to swing huge amounts of iron just to move a torch. It had a 15mm profile rail along one side, screwed from behind so the black dust could not sneak in past the wipers.
I threw the towel in when I discovered the T5 belting and pulleys I had bought were unbelievably slack.
If you have pinions at either side of the gantry connect them with a low inertia shaft. Thin walled aluminium tube perhaps.
I could ramble on all day, it was fun.

[warwick]

not a huge amount done today, anchored the table to the floor and adjusted it for leval and true,,,iv gone with 80x80x5mm box for the x axis....the brackets are just 2" of 50x6 angle welded to the legs still need to round the brackets off and repaint....

[Robin Hewitt]

Slats, you will support the work piece on slats. Think how you will support your slats. If they have to flex a bit to fit they are more likely to behave themselves.

If it is a small piece of metal you will need the slats close together with more support from below. If it is a large sheet the slats can be further apart. Why not put slats close together in one corner and further apart over the rest of the table?
The other slat function is the tilt. You cut a complete part and instead of resting flat on two slats or falling through it tilts and jambs itself at an angle. The tool slams in to it on a rapid transit and does hideous damage to itself. You would need vast numbers of slats to avoid this but it is quite predictable. You can put a bumper ring around the tool tip to spot them and apply the brakes.

[warwick]

i quite like the mixed slat idea!...im going to use 100x50x6 angle to support the slats which will be spaced 20mm away from the main frame so i can eventualy turn it into a water table with down draft air extraction...im planning to use magnets to hold the torch to the z axis so if it hits anything it will break away.............

[warwick]

had an evening of drilling tonight..managed to secure the first linear rail..then started fabricating the gantry

[warwick]

managed to get the gantry mocked up today