Plazma 1 or 2 Y axes screws?

[Vern2]

Could use some table design help. I was thinking I needed to remove everything from the center of a plazma cnc table. This is because of the torch cutting arc. But a cnc table is much easier to build with a screw in the center of a table. A single motor in the middle is easier to control. I've not started the build yet and not buying plans either. I'm looking at making cowboy, and desert art in 1/8". 24" to 36" wide and 4' long. Hope I gave enough info.

Vern

[jacampb2]

Most comercial tables use a rack and pinion drive on one side of the table, w/ linear rails you should not have any racking if you design the gantry right.

[kf2qd]

Most commercial plasma and oxy/fuel machine use a gear and rack as it is much cheaper and lower maintenance than a screw type drive. Either have the teeth of the rack pointing down, or to one side with a spacer so the dirt and dust can fall off. You can keeop the pinions engaged by mounting your drive on a pivot and tensioning it with a spring. Another possibility would be to use a long timing belt, but I suspect it would require more maintanance that rack & pinion.

[JMS6449]

Most comercial tables use a rack and pinion drive on one side of the table, w/ linear rails you should not have any racking if you design the gantry right.

There are almost always a rack and pinion on both side on router, plasma cutter, waterjets or any other machine designed with a gantry.

The only way to use a single screw is a flying bridge design like Flow makes waterjets or Northwood makes sawjets for stone. Biesse also uses the same design for the wood routers that rapid a over 3000ipm.

[JMS6449]

Most comercial tables use a rack and pinion drive on one side of the table, w/ linear rails you should not have any racking if you design the gantry right.

There are almost always a rack and pinion on both side on router, plasma cutter, waterjets or any other machine designed with a gantry. The rack and pinion on the better equipment is of a helical design to eliminate most backlash.

The only way to use a single screw is a flying bridge design like Flow makes waterjets or Northwood makes sawjets for stone. Biesse also uses the same design for the wood routers that rapid a over 3000ipm.

[jacampb2]

I don't think so, at least not plasma and router tables that I have seen, both home brew and commercial. Maybe Industrial setups like a waterjet or the other machines you mentioned, but I have no experience there, and the OP didn't ask about them anyhow. Plasmacam, torchmate, plasmaroute, all fairly big players in the commercial plasma table game have the drive on one side of the table only, some of them can be ordered w/ dual drives, but IMO it is not normally necessary.

From what I understand, the biggest issue with screw drive on something the size of a CNC plasma table is screw whip. It takes a pretty large diameter screw to span the table length unsupported and not destroy itself or its ball nut due to sag and whip.

Later,
Jason