Plasma Table

[ex apprentice]

Hi all
I know this is exactly a Mach question but I am sure there are quite a few people in the group who could comment and advise

I am in the process of building my plasma table (4m x 2m) the gantry will be driven both sides (slaved drive) via toothed belts
My question is this :

I am considering articulating the cross beam to each carriage, will it work?

The theory behind my thinking is as follows :
I have read and think I understand the independant homing of both the drives and this should take out any skew in squareness at that point.
making the assumption that the cross beam is perpendicular and that the machine doesn't loose steps or any other factor effects one side and not the other the cross beam should remain perpendicular?
If I articulate the cross beam to each carriage then this allows a level of tolerance in building the machine so instead of having a fixed assembly (welded or bolted) the assembly can skew
But each time it homes this should bring the cross beam back to square
making another assumption that the homing switches are spot on and true to each other
if the cross beam and carriages are fixed and not 100% square then the homing would be trying to bend the fixed assembly square ?

Looking forward to comments and advice
Regards
Ex apprentice

[rrc1962]

I don't see the need or benefit in making the gantry articulating.  There would be no need to skew the gantry during a part run.  The only advantage I see is that is the gantry goes out of square, it wouldn't bind, but if it's going out of square that often and binding, there is a problem that needs to be addressed.  Barring a visit from Murphy, the gantry should stay square.   

[ex apprentice]

Thanks for your thoughts rrc1962 maybe I am just thinking to much and making things more complicated than they need to be??

[kf2qd]

I used to build Plasma/Oxy-fuel gantries and a rigid gantry to end truck will probably stay much more square as compared to an articulated one. The other factor to consider is that the more rigid your machine is, the better results you will have. Start out by making sure the machine is as square as possible when you assemble it and then the squaring routine will have as little work to do as possible. You don't want teh squaring routine to be trying to compensate for poor construction/assembly.